webidl binder

2 files changed, 5032 insertions, 0 deletions

diff --git a/third_party/WebIDL.py b/third_party/WebIDL.py
new file mode 100644
index 00000000..867a7cbc
--- /dev/null
+++ b/third_party/WebIDL.py
@@ -0,0 +1,5030 @@
+# from http://mxr.mozilla.org/mozilla-central/source/dom/bindings/parser/WebIDL.py
+# rev 501baeb3a034
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+""" A WebIDL parser. """
+
+from ply import lex, yacc
+import re
+import os
+import traceback
+import math
+
+# Machinery
+
+def parseInt(literal):
+    string = literal
+    sign = 0
+    base = 0
+
+    if string[0] == '-':
+        sign = -1
+        string = string[1:]
+    else:
+        sign = 1
+
+    if string[0] == '0' and len(string) > 1:
+        if string[1] == 'x' or string[1] == 'X':
+            base = 16
+            string = string[2:]
+        else:
+            base = 8
+            string = string[1:]
+    else:
+        base = 10
+
+    value = int(string, base)
+    return value * sign
+
+# Magic for creating enums
+def M_add_class_attribs(attribs, start):
+    def foo(name, bases, dict_):
+        for v, k in enumerate(attribs):
+            dict_[k] = start + v
+        assert 'length' not in dict_
+        dict_['length'] = start + len(attribs)
+        return type(name, bases, dict_)
+    return foo
+
+def enum(*names, **kw):
+    if len(kw) == 1:
+        base = kw['base'].__class__
+        start = base.length
+    else:
+        assert len(kw) == 0
+        base = object
+        start = 0
+    class Foo(base):
+        __metaclass__ = M_add_class_attribs(names, start)
+        def __setattr__(self, name, value):  # this makes it read-only
+            raise NotImplementedError
+    return Foo()
+
+class WebIDLError(Exception):
+    def __init__(self, message, locations, warning=False):
+        self.message = message
+        self.locations = [str(loc) for loc in locations]
+        self.warning = warning
+
+    def __str__(self):
+        return "%s: %s%s%s" % (self.warning and 'warning' or 'error',
+                                 self.message,
+                                 ", " if len(self.locations) != 0 else "",
+                                 "\n".join(self.locations))
+
+class Location(object):
+    def __init__(self, lexer, lineno, lexpos, filename):
+        self._line = None
+        self._lineno = lineno
+        self._lexpos = lexpos
+        self._lexdata = lexer.lexdata
+        self._file = filename if filename else "<unknown>"
+
+    def __eq__(self, other):
+        return self._lexpos == other._lexpos and \
+               self._file == other._file
+
+    def filename(self):
+        return self._file
+
+    def resolve(self):
+        if self._line:
+            return
+
+        startofline = self._lexdata.rfind('\n', 0, self._lexpos) + 1
+        endofline = self._lexdata.find('\n', self._lexpos, self._lexpos + 80)
+        if endofline != -1:
+            self._line = self._lexdata[startofline:endofline]
+        else:
+            self._line = self._lexdata[startofline:]
+        self._colno = self._lexpos - startofline
+
+        # Our line number seems to point to the start of self._lexdata
+        self._lineno += self._lexdata.count('\n', 0, startofline)
+
+    def get(self):
+        self.resolve()
+        return "%s line %s:%s" % (self._file, self._lineno, self._colno)
+
+    def _pointerline(self):
+        return " " * self._colno + "^"
+
+    def __str__(self):
+        self.resolve()
+        return "%s line %s:%s\n%s\n%s" % (self._file, self._lineno, self._colno,
+                                          self._line, self._pointerline())
+
+class BuiltinLocation(object):
+    def __init__(self, text):
+        self.msg = text + "\n"
+
+    def __eq__(self, other):
+        return isinstance(other, BuiltinLocation) and \
+               self.msg == other.msg
+
+    def filename(self):
+        return '<builtin>'
+
+    def resolve(self):
+        pass
+
+    def get(self):
+        return self.msg
+
+    def __str__(self):
+        return self.get()
+
+
+# Data Model
+
+class IDLObject(object):
+    def __init__(self, location):
+        self.location = location
+        self.userData = dict()
+
+    def filename(self):
+        return self.location.filename()
+
+    def isInterface(self):
+        return False
+
+    def isEnum(self):
+        return False
+
+    def isCallback(self):
+        return False
+
+    def isType(self):
+        return False
+
+    def isDictionary(self):
+        return False;
+
+    def isUnion(self):
+        return False
+
+    def getUserData(self, key, default):
+        return self.userData.get(key, default)
+
+    def setUserData(self, key, value):
+        self.userData[key] = value
+
+    def addExtendedAttributes(self, attrs):
+        assert False # Override me!
+
+    def handleExtendedAttribute(self, attr):
+        assert False # Override me!
+
+    def _getDependentObjects(self):
+        assert False # Override me!
+
+    def getDeps(self, visited=None):
+        """ Return a set of files that this object depends on.  If any of
+            these files are changed the parser needs to be rerun to regenerate
+            a new IDLObject.
+
+            The visited argument is a set of all the objects already visited.
+            We must test to see if we are in it, and if so, do nothing.  This
+            prevents infinite recursion."""
+
+        # NB: We can't use visited=set() above because the default value is
+        # evaluated when the def statement is evaluated, not when the function
+        # is executed, so there would be one set for all invocations.
+        if visited == None:
+            visited = set()
+
+        if self in visited:
+            return set()
+
+        visited.add(self)
+
+        deps = set()
+        if self.filename() != "<builtin>":
+            deps.add(self.filename())
+
+        for d in self._getDependentObjects():
+            deps = deps.union(d.getDeps(visited))
+
+        return deps
+
+class IDLScope(IDLObject):
+    def __init__(self, location, parentScope, identifier):
+        IDLObject.__init__(self, location)
+
+        self.parentScope = parentScope
+        if identifier:
+            assert isinstance(identifier, IDLIdentifier)
+            self._name = identifier
+        else:
+            self._name = None
+
+        self._dict = {}
+
+    def __str__(self):
+        return self.QName()
+
+    def QName(self):
+        if self._name:
+            return self._name.QName() + "::"
+        return "::"
+
+    def ensureUnique(self, identifier, object):
+        """
+            Ensure that there is at most one 'identifier' in scope ('self').
+            Note that object can be None.  This occurs if we end up here for an
+            interface type we haven't seen yet.
+        """
+        assert isinstance(identifier, IDLUnresolvedIdentifier)
+        assert not object or isinstance(object, IDLObjectWithIdentifier)
+        assert not object or object.identifier == identifier
+
+        if identifier.name in self._dict:
+            if not object:
+                return
+
+            # ensureUnique twice with the same object is not allowed
+            assert id(object) != id(self._dict[identifier.name])
+
+            replacement = self.resolveIdentifierConflict(self, identifier,
+                                                         self._dict[identifier.name],
+                                                         object)
+            self._dict[identifier.name] = replacement
+            return
+
+        assert object
+
+        self._dict[identifier.name] = object
+
+    def resolveIdentifierConflict(self, scope, identifier, originalObject, newObject):
+        if isinstance(originalObject, IDLExternalInterface) and \
+           isinstance(newObject, IDLExternalInterface) and \
+           originalObject.identifier.name == newObject.identifier.name:
+            return originalObject
+
+        if (isinstance(originalObject, IDLExternalInterface) or
+            isinstance(newObject, IDLExternalInterface)):
+            raise WebIDLError(
+                "Name collision between "
+                "interface declarations for identifier '%s' at '%s' and '%s'"
+                % (identifier.name,
+                    originalObject.location, newObject.location), [])
+
+        # We do the merging of overloads here as opposed to in IDLInterface
+        # because we need to merge overloads of NamedConstructors and we need to
+        # detect conflicts in those across interfaces. See also the comment in
+        # IDLInterface.addExtendedAttributes for "NamedConstructor".
+        if originalObject.tag == IDLInterfaceMember.Tags.Method and \
+           newObject.tag == IDLInterfaceMember.Tags.Method:
+            return originalObject.addOverload(newObject)
+
+        # Default to throwing, derived classes can override.
+        conflictdesc = "\n\t%s at %s\n\t%s at %s" % \
+          (originalObject, originalObject.location, newObject, newObject.location)
+
+        raise WebIDLError(
+            "Multiple unresolvable definitions of identifier '%s' in scope '%s%s"
+            % (identifier.name, str(self), conflictdesc), [])
+
+    def _lookupIdentifier(self, identifier):
+        return self._dict[identifier.name]
+
+    def lookupIdentifier(self, identifier):
+        assert isinstance(identifier, IDLIdentifier)
+        assert identifier.scope == self
+        return self._lookupIdentifier(identifier)
+
+class IDLIdentifier(IDLObject):
+    def __init__(self, location, scope, name):
+        IDLObject.__init__(self, location)
+
+        self.name = name
+        assert isinstance(scope, IDLScope)
+        self.scope = scope
+
+    def __str__(self):
+        return self.QName()
+
+    def QName(self):
+        return self.scope.QName() + self.name
+
+    def __hash__(self):
+        return self.QName().__hash__()
+
+    def __eq__(self, other):
+        return self.QName() == other.QName()
+
+    def object(self):
+        return self.scope.lookupIdentifier(self)
+
+class IDLUnresolvedIdentifier(IDLObject):
+    def __init__(self, location, name, allowDoubleUnderscore = False,
+                 allowForbidden = False):
+        IDLObject.__init__(self, location)
+
+        assert len(name) > 0
+
+        if name[:2] == "__" and name != "__content" and name != "___noSuchMethod__"  and not allowDoubleUnderscore:
+            raise WebIDLError("Identifiers beginning with __ are reserved",
+                              [location])
+        if name[0] == '_' and not allowDoubleUnderscore:
+            name = name[1:]
+        # TODO: Bug 872377, Restore "toJSON" to below list.
+        # We sometimes need custom serialization, so allow toJSON for now.
+        if (name in ["constructor", "toString"] and
+            not allowForbidden):
+            raise WebIDLError("Cannot use reserved identifier '%s'" % (name),
+                              [location])
+
+        self.name = name
+
+    def __str__(self):
+        return self.QName()
+
+    def QName(self):
+        return "<unresolved scope>::" + self.name
+
+    def resolve(self, scope, object):
+        assert isinstance(scope, IDLScope)
+        assert not object or isinstance(object, IDLObjectWithIdentifier)
+        assert not object or object.identifier == self
+
+        scope.ensureUnique(self, object)
+
+        identifier = IDLIdentifier(self.location, scope, self.name)
+        if object:
+            object.identifier = identifier
+        return identifier
+
+    def finish(self):
+        assert False # Should replace with a resolved identifier first.
+
+class IDLObjectWithIdentifier(IDLObject):
+    def __init__(self, location, parentScope, identifier):
+        IDLObject.__init__(self, location)
+
+        assert isinstance(identifier, IDLUnresolvedIdentifier)
+
+        self.identifier = identifier
+
+        if parentScope:
+            self.resolve(parentScope)
+
+        self.treatNullAs = "Default"
+
+    def resolve(self, parentScope):
+        assert isinstance(parentScope, IDLScope)
+        assert isinstance(self.identifier, IDLUnresolvedIdentifier)
+        self.identifier.resolve(parentScope, self)
+
+    def checkForStringHandlingExtendedAttributes(self, attrs,
+                                                 isDictionaryMember=False,
+                                                 isOptional=False):
+        """
+        A helper function to deal with TreatNullAs.  Returns the list
+        of attrs it didn't handle itself.
+        """
+        assert isinstance(self, IDLArgument) or isinstance(self, IDLAttribute)
+        unhandledAttrs = list()
+        for attr in attrs:
+            if not attr.hasValue():
+                unhandledAttrs.append(attr)
+                continue
+
+            identifier = attr.identifier()
+            value = attr.value()
+            if identifier == "TreatNullAs":
+                if not self.type.isDOMString() or self.type.nullable():
+                    raise WebIDLError("[TreatNullAs] is only allowed on "
+                                      "arguments or attributes whose type is "
+                                      "DOMString",
+                                      [self.location])
+                if isDictionaryMember:
+                    raise WebIDLError("[TreatNullAs] is not allowed for "
+                                      "dictionary members", [self.location])
+                if value != 'EmptyString':
+                    raise WebIDLError("[TreatNullAs] must take the identifier "
+                                      "'EmptyString', not '%s'" % value,
+                                      [self.location])
+                self.treatNullAs = value
+            else:
+                unhandledAttrs.append(attr)
+
+        return unhandledAttrs
+
+class IDLObjectWithScope(IDLObjectWithIdentifier, IDLScope):
+    def __init__(self, location, parentScope, identifier):
+        assert isinstance(identifier, IDLUnresolvedIdentifier)
+
+        IDLObjectWithIdentifier.__init__(self, location, parentScope, identifier)
+        IDLScope.__init__(self, location, parentScope, self.identifier)
+
+class IDLIdentifierPlaceholder(IDLObjectWithIdentifier):
+    def __init__(self, location, identifier):
+        assert isinstance(identifier, IDLUnresolvedIdentifier)
+        IDLObjectWithIdentifier.__init__(self, location, None, identifier)
+
+    def finish(self, scope):
+        try:
+            scope._lookupIdentifier(self.identifier)
+        except:
+            raise WebIDLError("Unresolved type '%s'." % self.identifier,
+                              [self.location])
+
+        obj = self.identifier.resolve(scope, None)
+        return scope.lookupIdentifier(obj)
+
+class IDLExternalInterface(IDLObjectWithIdentifier):
+    def __init__(self, location, parentScope, identifier):
+        assert isinstance(identifier, IDLUnresolvedIdentifier)
+        assert isinstance(parentScope, IDLScope)
+        self.parent = None
+        IDLObjectWithIdentifier.__init__(self, location, parentScope, identifier)
+        IDLObjectWithIdentifier.resolve(self, parentScope)
+
+    def finish(self, scope):
+        pass
+
+    def validate(self):
+        pass
+
+    def isExternal(self):
+        return True
+
+    def isInterface(self):
+        return True
+
+    def isConsequential(self):
+        return False
+
+    def addExtendedAttributes(self, attrs):
+        assert len(attrs) == 0
+
+    def resolve(self, parentScope):
+        pass
+
+    def getJSImplementation(self):
+        return None
+
+    def isJSImplemented(self):
+        return False
+
+    def getNavigatorProperty(self):
+        return None
+
+    def _getDependentObjects(self):
+        return set()
+
+class IDLInterface(IDLObjectWithScope):
+    def __init__(self, location, parentScope, name, parent, members,
+                 isPartial):
+        assert isinstance(parentScope, IDLScope)
+        assert isinstance(name, IDLUnresolvedIdentifier)
+        assert not isPartial or not parent
+
+        self.parent = None
+        self._callback = False
+        self._finished = False
+        self.members = []
+        # namedConstructors needs deterministic ordering because bindings code
+        # outputs the constructs in the order that namedConstructors enumerates
+        # them.
+        self.namedConstructors = list()
+        self.implementedInterfaces = set()
+        self._consequential = False
+        self._isPartial = True
+        # self.interfacesBasedOnSelf is the set of interfaces that inherit from
+        # self or have self as a consequential interface, including self itself.
+        # Used for distinguishability checking.
+        self.interfacesBasedOnSelf = set([self])
+        # self.interfacesImplementingSelf is the set of interfaces that directly
+        # have self as a consequential interface
+        self.interfacesImplementingSelf = set()
+        self._hasChildInterfaces = False
+        self._isOnGlobalProtoChain = False
+        # Tracking of the number of reserved slots we need for our
+        # members and those of ancestor interfaces.
+        self.totalMembersInSlots = 0
+        # Tracking of the number of own own members we have in slots
+        self._ownMembersInSlots = 0
+
+        IDLObjectWithScope.__init__(self, location, parentScope, name)
+
+        if not isPartial:
+            self.setNonPartial(location, parent, members)
+        else:
+            # Just remember our members for now
+            self.members = members
+
+    def __str__(self):
+        return "Interface '%s'" % self.identifier.name
+
+    def ctor(self):
+        identifier = IDLUnresolvedIdentifier(self.location, "constructor",
+                                             allowForbidden=True)
+        try:
+            return self._lookupIdentifier(identifier)
+        except:
+            return None
+
+    def resolveIdentifierConflict(self, scope, identifier, originalObject, newObject):
+        assert isinstance(scope, IDLScope)
+        assert isinstance(originalObject, IDLInterfaceMember)
+        assert isinstance(newObject, IDLInterfaceMember)
+
+        retval = IDLScope.resolveIdentifierConflict(self, scope, identifier,
+                                                    originalObject, newObject)
+
+        # Might be a ctor, which isn't in self.members
+        if newObject in self.members:
+            self.members.remove(newObject)
+        return retval
+
+    def finish(self, scope):
+        if self._finished:
+            return
+
+        self._finished = True
+
+        if self._isPartial:
+            raise WebIDLError("Interface %s does not have a non-partial "
+                              "declaration" % self.identifier.name,
+                              [self.location])
+
+        assert not self.parent or isinstance(self.parent, IDLIdentifierPlaceholder)
+        parent = self.parent.finish(scope) if self.parent else None
+        if parent and isinstance(parent, IDLExternalInterface):
+            raise WebIDLError("%s inherits from %s which does not have "
+                              "a definition" %
+                              (self.identifier.name,
+                               self.parent.identifier.name),
+                              [self.location])
+        assert not parent or isinstance(parent, IDLInterface)
+
+        self.parent = parent
+
+        assert iter(self.members)
+
+        if self.parent:
+            self.parent.finish(scope)
+
+            self.parent._hasChildInterfaces = True
+
+            self.totalMembersInSlots = self.parent.totalMembersInSlots
+
+            # Interfaces with [Global] must not have anything inherit from them
+            if self.parent.getExtendedAttribute("Global"):
+                # Note: This is not a self.parent.isOnGlobalProtoChain() check
+                # because ancestors of a [Global] interface can have other
+                # descendants.
+                raise WebIDLError("[Global] interface has another interface "
+                                  "inheriting from it",
+                                  [self.location, self.parent.location])
+
+            # Callbacks must not inherit from non-callbacks or inherit from
+            # anything that has consequential interfaces.
+            # XXXbz Can non-callbacks inherit from callbacks?  Spec issue pending.
+            # XXXbz Can callbacks have consequential interfaces?  Spec issue pending
+            if self.isCallback():
+                if not self.parent.isCallback():
+                    raise WebIDLError("Callback interface %s inheriting from "
+                                      "non-callback interface %s" %
+                                      (self.identifier.name,
+                                       self.parent.identifier.name),
+                                      [self.location, self.parent.location])
+            elif self.parent.isCallback():
+                raise WebIDLError("Non-callback interface %s inheriting from "
+                                  "callback interface %s" %
+                                  (self.identifier.name,
+                                   self.parent.identifier.name),
+                                  [self.location, self.parent.location])
+
+        for iface in self.implementedInterfaces:
+            iface.finish(scope)
+
+        cycleInGraph = self.findInterfaceLoopPoint(self)
+        if cycleInGraph:
+            raise WebIDLError("Interface %s has itself as ancestor or "
+                              "implemented interface" % self.identifier.name,
+                              [self.location, cycleInGraph.location])
+
+        if self.isCallback():
+            # "implements" should have made sure we have no
+            # consequential interfaces.
+            assert len(self.getConsequentialInterfaces()) == 0
+            # And that we're not consequential.
+            assert not self.isConsequential()
+
+        # Now resolve() and finish() our members before importing the
+        # ones from our implemented interfaces.
+
+        # resolve() will modify self.members, so we need to iterate
+        # over a copy of the member list here.
+        for member in list(self.members):
+            member.resolve(self)
+
+        for member in self.members:
+            member.finish(scope)
+
+        ctor = self.ctor()
+        if ctor is not None:
+            ctor.finish(scope)
+
+        for ctor in self.namedConstructors:
+            ctor.finish(scope)
+
+        # Make a copy of our member list, so things that implement us
+        # can get those without all the stuff we implement ourselves
+        # admixed.
+        self.originalMembers = list(self.members)
+
+        # Import everything from our consequential interfaces into
+        # self.members.  Sort our consequential interfaces by name
+        # just so we have a consistent order.
+        for iface in sorted(self.getConsequentialInterfaces(),
+                            cmp=cmp,
+                            key=lambda x: x.identifier.name):
+            # Flag the interface as being someone's consequential interface
+            iface.setIsConsequentialInterfaceOf(self)
+            additionalMembers = iface.originalMembers;
+            for additionalMember in additionalMembers:
+                for member in self.members:
+                    if additionalMember.identifier.name == member.identifier.name:
+                        raise WebIDLError(
+                            "Multiple definitions of %s on %s coming from 'implements' statements" %
+                            (member.identifier.name, self),
+                            [additionalMember.location, member.location])
+            self.members.extend(additionalMembers)
+            iface.interfacesImplementingSelf.add(self)
+
+        for ancestor in self.getInheritedInterfaces():
+            ancestor.interfacesBasedOnSelf.add(self)
+            for ancestorConsequential in ancestor.getConsequentialInterfaces():
+                ancestorConsequential.interfacesBasedOnSelf.add(self)
+
+        for member in self.members:
+            if (member.isAttr() and member.isUnforgeable() and
+                not hasattr(member, "originatingInterface")):
+                member.originatingInterface = self
+
+        # Compute slot indices for our members before we pull in
+        # unforgeable members from our parent.
+        for member in self.members:
+            if (member.isAttr() and
+                (member.getExtendedAttribute("StoreInSlot") or
+                 member.getExtendedAttribute("Cached"))):
+                member.slotIndex = self.totalMembersInSlots
+                self.totalMembersInSlots += 1
+                if member.getExtendedAttribute("StoreInSlot"):
+                    self._ownMembersInSlots += 1
+
+        if self.parent:
+            # Make sure we don't shadow any of the [Unforgeable] attributes on
+            # our ancestor interfaces.  We don't have to worry about
+            # consequential interfaces here, because those have already been
+            # imported into the relevant .members lists.  And we don't have to
+            # worry about anything other than our parent, because it has already
+            # imported its ancestors unforgeable attributes into its member
+            # list.
+            for unforgeableAttr in (attr for attr in self.parent.members if
+                                    attr.isAttr() and not attr.isStatic() and
+                                    attr.isUnforgeable()):
+                shadows = [ m for m in self.members if
+                            (m.isAttr() or m.isMethod()) and
+                            not m.isStatic() and
+                            m.identifier.name == unforgeableAttr.identifier.name ]
+                if len(shadows) != 0:
+                    locs = [unforgeableAttr.location] + [ s.location for s
+                                                          in shadows ]
+                    raise WebIDLError("Interface %s shadows [Unforgeable] "
+                                      "members of %s" %
+                                      (self.identifier.name,
+                                       ancestor.identifier.name),
+                                      locs)
+                # And now just stick it in our members, since we won't be
+                # inheriting this down the proto chain.  If we really cared we
+                # could try to do something where we set up the unforgeable
+                # attributes of ancestor interfaces, with their corresponding
+                # getters, on our interface, but that gets pretty complicated
+                # and seems unnecessary.
+                self.members.append(unforgeableAttr)
+
+        # Ensure that there's at most one of each {named,indexed}
+        # {getter,setter,creator,deleter}, at most one stringifier,
+        # and at most one legacycaller.  Note that this last is not
+        # quite per spec, but in practice no one overloads
+        # legacycallers.
+        specialMembersSeen = {}
+        for member in self.members:
+            if not member.isMethod():
+                continue
+
+            if member.isGetter():
+                memberType = "getters"
+            elif member.isSetter():
+                memberType = "setters"
+            elif member.isCreator():
+                memberType = "creators"
+            elif member.isDeleter():
+                memberType = "deleters"
+            elif member.isStringifier():
+                memberType = "stringifiers"
+            elif member.isJsonifier():
+                memberType = "jsonifiers"
+            elif member.isLegacycaller():
+                memberType = "legacycallers"
+            else:
+                continue
+
+            if (memberType != "stringifiers" and memberType != "legacycallers" and
+                memberType != "jsonifiers"):
+                if member.isNamed():
+                    memberType = "named " + memberType
+                else:
+                    assert member.isIndexed()
+                    memberType = "indexed " + memberType
+
+            if memberType in specialMembersSeen:
+                raise WebIDLError("Multiple " + memberType + " on %s" % (self),
+                                   [self.location,
+                                    specialMembersSeen[memberType].location,
+                                    member.location])
+
+            specialMembersSeen[memberType] = member
+
+        if self._isOnGlobalProtoChain:
+            # Make sure we have no named setters, creators, or deleters
+            for memberType in ["setter", "creator", "deleter"]:
+                memberId = "named " + memberType + "s"
+                if memberId in specialMembersSeen:
+                    raise WebIDLError("Interface with [Global] has a named %s" %
+                                      memberType,
+                                      [self.location,
+                                       specialMembersSeen[memberId].location])
+            # Make sure we're not [OverrideBuiltins]
+            if self.getExtendedAttribute("OverrideBuiltins"):
+                raise WebIDLError("Interface with [Global] also has "
+                                  "[OverrideBuiltins]",
+                                  [self.location])
+            # Mark all of our ancestors as being on the global's proto chain too
+            parent = self.parent
+            while parent:
+                # Must not inherit from an interface with [OverrideBuiltins]
+                if parent.getExtendedAttribute("OverrideBuiltins"):
+                    raise WebIDLError("Interface with [Global] inherits from "
+                                      "interface with [OverrideBuiltins]",
+                                      [self.location, parent.location])
+                parent._isOnGlobalProtoChain = True
+                parent = parent.parent
+
+    def validate(self):
+        for member in self.members:
+            member.validate()
+
+            # Check that PutForwards refers to another attribute and that no
+            # cycles exist in forwarded assignments.
+            if member.isAttr():
+                iface = self
+                attr = member
+                putForwards = attr.getExtendedAttribute("PutForwards")
+                if putForwards and self.isCallback():
+                    raise WebIDLError("[PutForwards] used on an attribute "
+                                      "on interface %s which is a callback "
+                                      "interface" % self.identifier.name,
+                                      [self.location, member.location])
+
+                while putForwards is not None:
+                    forwardIface = attr.type.unroll().inner
+                    fowardAttr = None
+
+                    for forwardedMember in forwardIface.members:
+                        if (not forwardedMember.isAttr() or
+                            forwardedMember.identifier.name != putForwards[0]):
+                            continue
+                        if forwardedMember == member:
+                            raise WebIDLError("Cycle detected in forwarded "
+                                              "assignments for attribute %s on "
+                                              "%s" %
+                                              (member.identifier.name, self),
+                                              [member.location])
+                        fowardAttr = forwardedMember
+                        break
+
+                    if fowardAttr is None:
+                        raise WebIDLError("Attribute %s on %s forwards to "
+                                          "missing attribute %s" %
+                              (attr.identifier.name, iface, putForwards),
+                              [attr.location])
+
+                    iface = forwardIface
+                    attr = fowardAttr
+                    putForwards = attr.getExtendedAttribute("PutForwards")
+
+
+    def isInterface(self):
+        return True
+
+    def isExternal(self):
+        return False
+
+    def setIsConsequentialInterfaceOf(self, other):
+        self._consequential = True
+        self.interfacesBasedOnSelf.add(other)
+
+    def isConsequential(self):
+        return self._consequential
+
+    def setCallback(self, value):
+        self._callback = value
+
+    def isCallback(self):
+        return self._callback
+
+    def isSingleOperationInterface(self):
+        assert self.isCallback() or self.isJSImplemented()
+        return (
+            # JS-implemented things should never need the
+            # this-handling weirdness of single-operation interfaces.
+            not self.isJSImplemented() and
+            # Not inheriting from another interface
+            not self.parent and
+            # No consequential interfaces
+            len(self.getConsequentialInterfaces()) == 0 and
+            # No attributes of any kinds
+            not any(m.isAttr() for m in self.members) and
+            # There is at least one regular operation, and all regular
+            # operations have the same identifier
+            len(set(m.identifier.name for m in self.members if
+                    m.isMethod() and not m.isStatic())) == 1)
+
+    def inheritanceDepth(self):
+        depth = 0
+        parent = self.parent
+        while parent:
+            depth = depth + 1
+            parent = parent.parent
+        return depth
+
+    def hasConstants(self):
+        return any(m.isConst() for m in self.members)
+
+    def hasInterfaceObject(self):
+        if self.isCallback():
+            return self.hasConstants()
+        return not hasattr(self, "_noInterfaceObject")
+
+    def hasInterfacePrototypeObject(self):
+        return not self.isCallback() and self.getUserData('hasConcreteDescendant', False)
+
+    def addExtendedAttributes(self, attrs):
+        self._extendedAttrDict = {}
+        for attr in attrs:
+            identifier = attr.identifier()
+
+            # Special cased attrs
+            if identifier == "TreatNonCallableAsNull":
+                raise WebIDLError("TreatNonCallableAsNull cannot be specified on interfaces",
+                                  [attr.location, self.location])
+            if identifier == "TreatNonObjectAsNull":
+                raise WebIDLError("TreatNonObjectAsNull cannot be specified on interfaces",
+                                  [attr.location, self.location])
+            elif identifier == "NoInterfaceObject":
+                if not attr.noArguments():
+                    raise WebIDLError("[NoInterfaceObject] must take no arguments",
+                                      [attr.location])
+
+                if self.ctor():
+                    raise WebIDLError("Constructor and NoInterfaceObject are incompatible",
+                                      [self.location])
+
+                self._noInterfaceObject = True
+            elif identifier == "Constructor" or identifier == "NamedConstructor" or identifier == "ChromeConstructor":
+                if identifier == "Constructor" and not self.hasInterfaceObject():
+                    raise WebIDLError(str(identifier) + " and NoInterfaceObject are incompatible",
+                                      [self.location])
+
+                if identifier == "NamedConstructor" and not attr.hasValue():
+                    raise WebIDLError("NamedConstructor must either take an identifier or take a named argument list",
+                                      [attr.location])
+
+                if identifier == "ChromeConstructor" and not self.hasInterfaceObject():
+                    raise WebIDLError(str(identifier) + " and NoInterfaceObject are incompatible",
+                                      [self.location])
+
+                args = attr.args() if attr.hasArgs() else []
+
+                retType = IDLWrapperType(self.location, self)
+                
+                if identifier == "Constructor" or identifier == "ChromeConstructor":
+                    name = "constructor"
+                    allowForbidden = True
+                else:
+                    name = attr.value()
+                    allowForbidden = False
+
+                methodIdentifier = IDLUnresolvedIdentifier(self.location, name,
+                                                           allowForbidden=allowForbidden)
+
+                method = IDLMethod(self.location, methodIdentifier, retType,
+                                   args, static=True)
+                # Constructors are always NewObject and are always
+                # assumed to be able to throw (since there's no way to
+                # indicate otherwise) and never have any other
+                # extended attributes.
+                method.addExtendedAttributes(
+                    [IDLExtendedAttribute(self.location, ("NewObject",)),
+                     IDLExtendedAttribute(self.location, ("Throws",))])
+                if identifier == "ChromeConstructor":
+                    method.addExtendedAttributes(
+                        [IDLExtendedAttribute(self.location, ("ChromeOnly",))])
+
+                if identifier == "Constructor" or identifier == "ChromeConstructor":
+                    method.resolve(self)
+                else:
+                    # We need to detect conflicts for NamedConstructors across
+                    # interfaces. We first call resolve on the parentScope,
+                    # which will merge all NamedConstructors with the same
+                    # identifier accross interfaces as overloads.
+                    method.resolve(self.parentScope)
+
+                    # Then we look up the identifier on the parentScope. If the
+                    # result is the same as the method we're adding then it
+                    # hasn't been added as an overload and it's the first time
+                    # we've encountered a NamedConstructor with that identifier.
+                    # If the result is not the same as the method we're adding
+                    # then it has been added as an overload and we need to check
+                    # whether the result is actually one of our existing
+                    # NamedConstructors.
+                    newMethod = self.parentScope.lookupIdentifier(method.identifier)
+                    if newMethod == method:
+                        self.namedConstructors.append(method)
+                    elif not newMethod in self.namedConstructors:
+                        raise WebIDLError("NamedConstructor conflicts with a NamedConstructor of a different interface",
+                                          [method.location, newMethod.location])
+            elif (identifier == "ArrayClass"):
+                if not attr.noArguments():
+                    raise WebIDLError("[ArrayClass] must take no arguments",
+                                      [attr.location])
+                if self.parent:
+                    raise WebIDLError("[ArrayClass] must not be specified on "
+                                      "an interface with inherited interfaces",
+                                      [attr.location, self.location])
+            elif identifier == "Global":
+                if not attr.noArguments():
+                    raise WebIDLError("[Global] must take no arguments",
+                                      [attr.location])
+                self._isOnGlobalProtoChain = True
+            elif (identifier == "NeedNewResolve" or
+                  identifier == "OverrideBuiltins" or
+                  identifier == "NoDelete" or
+                  identifier == "ChromeOnly"):
+                # Known extended attributes that do not take values
+                if not attr.noArguments():
+                    raise WebIDLError("[%s] must take no arguments" % identifier,
+                                      [attr.location])
+            elif (identifier == "Pref" or
+                  identifier == "JSImplementation" or
+                  identifier == "HeaderFile" or
+                  identifier == "NavigatorProperty" or
+                  identifier == "AvailableIn" or
+                  identifier == "Prefix" or
+                  identifier == "Func"):
+                # Known extended attributes that take a string value
+                if not attr.hasValue():
+                    raise WebIDLError("[%s] must have a value" % identifier,
+                                      [attr.location])
+            else:
+                raise WebIDLError("Unknown extended attribute %s on interface" % identifier,
+                                  [attr.location])
+
+            attrlist = attr.listValue()
+            self._extendedAttrDict[identifier] = attrlist if len(attrlist) else True
+
+    def addImplementedInterface(self, implementedInterface):
+        assert(isinstance(implementedInterface, IDLInterface))
+        self.implementedInterfaces.add(implementedInterface)
+
+    def getInheritedInterfaces(self):
+        """
+        Returns a list of the interfaces this interface inherits from
+        (not including this interface itself).  The list is in order
+        from most derived to least derived.
+        """
+        assert(self._finished)
+        if not self.parent:
+            return []
+        parentInterfaces = self.parent.getInheritedInterfaces()
+        parentInterfaces.insert(0, self.parent)
+        return parentInterfaces
+
+    def getConsequentialInterfaces(self):
+        assert(self._finished)
+        # The interfaces we implement directly
+        consequentialInterfaces = set(self.implementedInterfaces)
+
+        # And their inherited interfaces
+        for iface in self.implementedInterfaces:
+            consequentialInterfaces |= set(iface.getInheritedInterfaces())
+
+        # And now collect up the consequential interfaces of all of those
+        temp = set()
+        for iface in consequentialInterfaces:
+            temp |= iface.getConsequentialInterfaces()
+
+        return consequentialInterfaces | temp
+
+    def findInterfaceLoopPoint(self, otherInterface):
+        """
+        Finds an interface, amongst our ancestors and consequential interfaces,
+        that inherits from otherInterface or implements otherInterface
+        directly.  If there is no such interface, returns None.
+        """
+        if self.parent:
+            if self.parent == otherInterface:
+                return self
+            loopPoint = self.parent.findInterfaceLoopPoint(otherInterface)
+            if loopPoint:
+                return loopPoint
+        if otherInterface in self.implementedInterfaces:
+            return self
+        for iface in self.implementedInterfaces:
+            loopPoint = iface.findInterfaceLoopPoint(otherInterface)
+            if loopPoint:
+                return loopPoint
+        return None
+
+    def getExtendedAttribute(self, name):
+        return self._extendedAttrDict.get(name, None)
+
+    def setNonPartial(self, location, parent, members):
+        assert not parent or isinstance(parent, IDLIdentifierPlaceholder)
+        if not self._isPartial:
+            raise WebIDLError("Two non-partial definitions for the "
+                              "same interface",
+                              [location, self.location])
+        self._isPartial = False
+        # Now make it look like we were parsed at this new location, since
+        # that's the place where the interface is "really" defined
+        self.location = location
+        assert not self.parent
+        self.parent = parent
+        # Put the new members at the beginning
+        self.members = members + self.members
+
+    def getJSImplementation(self):
+        classId = self.getExtendedAttribute("JSImplementation")
+        if not classId:
+            return classId
+        assert isinstance(classId, list)
+        assert len(classId) == 1
+        return classId[0]
+
+    def isJSImplemented(self):
+        return bool(self.getJSImplementation())
+
+    def getNavigatorProperty(self):
+        naviProp = self.getExtendedAttribute("NavigatorProperty")
+        if not naviProp:
+            return None
+        assert len(naviProp) == 1
+        assert isinstance(naviProp, list)
+        assert len(naviProp[0]) != 0
+        return naviProp[0]
+
+    def hasChildInterfaces(self):
+        return self._hasChildInterfaces
+
+    def isOnGlobalProtoChain(self):
+        return self._isOnGlobalProtoChain
+
+    def _getDependentObjects(self):
+        deps = set(self.members)
+        deps.union(self.implementedInterfaces)
+        if self.parent:
+            deps.add(self.parent)
+        return deps
+
+    def hasMembersInSlots(self):
+        return self._ownMembersInSlots != 0
+
+class IDLDictionary(IDLObjectWithScope):
+    def __init__(self, location, parentScope, name, parent, members):
+        assert isinstance(parentScope, IDLScope)
+        assert isinstance(name, IDLUnresolvedIdentifier)
+        assert not parent or isinstance(parent, IDLIdentifierPlaceholder)
+
+        self.parent = parent
+        self._finished = False
+        self.members = list(members)
+
+        IDLObjectWithScope.__init__(self, location, parentScope, name)
+
+    def __str__(self):
+        return "Dictionary '%s'" % self.identifier.name
+
+    def isDictionary(self):
+        return True;
+
+    def finish(self, scope):
+        if self._finished:
+            return
+
+        self._finished = True
+
+        if self.parent:
+            assert isinstance(self.parent, IDLIdentifierPlaceholder)
+            oldParent = self.parent
+            self.parent = self.parent.finish(scope)
+            if not isinstance(self.parent, IDLDictionary):
+                raise WebIDLError("Dictionary %s has parent that is not a dictionary" %
+                                  self.identifier.name,
+                                  [oldParent.location, self.parent.location])
+
+            # Make sure the parent resolves all its members before we start
+            # looking at them.
+            self.parent.finish(scope)
+
+        for member in self.members:
+            member.resolve(self)
+            if not member.isComplete():
+                member.complete(scope)
+                assert member.type.isComplete()
+
+        # Members of a dictionary are sorted in lexicographic order
+        self.members.sort(cmp=cmp, key=lambda x: x.identifier.name)
+
+        inheritedMembers = []
+        ancestor = self.parent
+        while ancestor:
+            if ancestor == self:
+                raise WebIDLError("Dictionary %s has itself as an ancestor" %
+                                  self.identifier.name,
+                                  [self.identifier.location])
+            inheritedMembers.extend(ancestor.members)
+            ancestor = ancestor.parent
+
+        # Catch name duplication
+        for inheritedMember in inheritedMembers:
+            for member in self.members:
+                if member.identifier.name == inheritedMember.identifier.name:
+                    raise WebIDLError("Dictionary %s has two members with name %s" %
+                                      (self.identifier.name, member.identifier.name),
+                                      [member.location, inheritedMember.location])
+
+    def validate(self):
+        def typeContainsDictionary(memberType, dictionary):
+            """
+            Returns a tuple whose:
+
+                - First element is a Boolean value indicating whether
+                  memberType contains dictionary.
+
+                - Second element is:
+                    A list of locations that leads from the type that was passed in
+                    the memberType argument, to the dictionary being validated,
+                    if the boolean value in the first element is True.
+
+                    None, if the boolean value in the first element is False.
+            """
+
+            if memberType.nullable() or \
+               memberType.isArray() or \
+               memberType.isSequence():
+                return typeContainsDictionary(memberType.inner, dictionary)
+
+            if memberType.isDictionary():
+                if memberType.inner == dictionary:
+                    return (True, [memberType.location])
+
+                (contains, locations) = dictionaryContainsDictionary(memberType.inner, \
+                                                                     dictionary)
+                if contains:
+                    return (True, [memberType.location] + locations)
+
+            if memberType.isUnion():
+                for member in memberType.flatMemberTypes:
+                    (contains, locations) = typeContainsDictionary(member, dictionary)
+                    if contains:
+                        return (True, locations)
+
+            return (False, None)
+
+        def dictionaryContainsDictionary(dictMember, dictionary):
+            for member in dictMember.members:
+                (contains, locations) = typeContainsDictionary(member.type, dictionary)
+                if contains:
+                    return (True, [member.location] + locations)
+
+            if dictMember.parent:
+                if dictMember.parent == dictionary:
+                    return (True, [dictMember.location])
+                else:
+                    (contains, locations) = dictionaryContainsDictionary(dictMember.parent, dictionary)
+                    if contains:
+                        return (True, [dictMember.location] + locations)
+
+            return (False, None)
+
+        for member in self.members:
+            if member.type.isDictionary() and member.type.nullable():
+                raise WebIDLError("Dictionary %s has member with nullable "
+                                  "dictionary type" % self.identifier.name,
+                                  [member.location])
+            (contains, locations) = typeContainsDictionary(member.type, self)
+            if contains:
+                raise WebIDLError("Dictionary %s has member with itself as type." %
+                                  self.identifier.name,
+                                  [member.location] + locations)
+
+    def addExtendedAttributes(self, attrs):
+        assert len(attrs) == 0
+
+    def _getDependentObjects(self):
+        deps = set(self.members)
+        if (self.parent):
+            deps.add(self.parent)
+        return deps
+
+class IDLEnum(IDLObjectWithIdentifier):
+    def __init__(self, location, parentScope, name, values):
+        assert isinstance(parentScope, IDLScope)
+        assert isinstance(name, IDLUnresolvedIdentifier)
+
+        if len(values) != len(set(values)):
+            raise WebIDLError("Enum %s has multiple identical strings" % name.name,
+                              [location])
+
+        IDLObjectWithIdentifier.__init__(self, location, parentScope, name)
+        self._values = values
+
+    def values(self):
+        return self._values
+
+    def finish(self, scope):
+        pass
+
+    def validate(self):
+        pass
+
+    def isEnum(self):
+        return True
+
+    def addExtendedAttributes(self, attrs):
+        assert len(attrs) == 0
+
+    def _getDependentObjects(self):
+        return set()
+
+class IDLType(IDLObject):
+    Tags = enum(
+        # The integer types
+        'int8',
+        'uint8',
+        'int16',
+        'uint16',
+        'int32',
+        'uint32',
+        'int64',
+        'uint64',
+        # Additional primitive types
+        'bool',
+        'unrestricted_float',
+        'float',
+        'unrestricted_double',
+        # "double" last primitive type to match IDLBuiltinType
+        'double',
+        # Other types
+        'any',
+        'domstring',
+        'bytestring',
+        'object',
+        'date',
+        'void',
+        # Funny stuff
+        'interface',
+        'dictionary',
+        'enum',
+        'callback',
+        'union',
+        'sequence',
+        'array'
+        )
+
+    def __init__(self, location, name):
+        IDLObject.__init__(self, location)
+        self.name = name
+        self.builtin = False
+
+    def __eq__(self, other):
+        return other and self.builtin == other.builtin and self.name == other.name
+
+    def __ne__(self, other):
+        return not self == other
+
+    def __str__(self):
+        return str(self.name)
+
+    def isType(self):
+        return True
+
+    def nullable(self):
+        return False
+
+    def isPrimitive(self):
+        return False
+
+    def isBoolean(self):
+        return False
+
+    def isNumeric(self):
+        return False
+
+    def isString(self):
+        return False
+
+    def isByteString(self):
+        return False
+
+    def isDOMString(self):
+        return False
+
+    def isVoid(self):
+        return self.name == "Void"
+
+    def isSequence(self):
+        return False
+
+    def isArray(self):
+        return False
+
+    def isArrayBuffer(self):
+        return False
+
+    def isArrayBufferView(self):
+        return False
+
+    def isTypedArray(self):
+        return False
+
+    def isCallbackInterface(self):
+        return False
+
+    def isNonCallbackInterface(self):
+        return False
+
+    def isGeckoInterface(self):
+        """ Returns a boolean indicating whether this type is an 'interface'
+            type that is implemented in Gecko. At the moment, this returns
+            true for all interface types that are not types from the TypedArray
+            spec."""
+        return self.isInterface() and not self.isSpiderMonkeyInterface()
+
+    def isSpiderMonkeyInterface(self):
+        """ Returns a boolean indicating whether this type is an 'interface'
+            type that is implemented in Spidermonkey.  At the moment, this
+            only returns true for the types from the TypedArray spec. """
+        return self.isInterface() and (self.isArrayBuffer() or \
+                                       self.isArrayBufferView() or \
+                                       self.isTypedArray())
+
+    def isDictionary(self):
+        return False
+
+    def isInterface(self):
+        return False
+
+    def isAny(self):
+        return self.tag() == IDLType.Tags.any
+
+    def isDate(self):
+        return self.tag() == IDLType.Tags.date
+
+    def isObject(self):
+        return self.tag() == IDLType.Tags.object
+
+    def isPromise(self):
+        return False
+
+    def isComplete(self):
+        return True
+
+    def includesRestrictedFloat(self):
+        return False
+
+    def isFloat(self):
+        return False
+
+    def isUnrestricted(self):
+        # Should only call this on float types
+        assert self.isFloat()
+
+    def isSerializable(self):
+        return False
+
+    def tag(self):
+        assert False # Override me!
+
+    def treatNonCallableAsNull(self):
+        assert self.tag() == IDLType.Tags.callback
+        return self.nullable() and self.inner._treatNonCallableAsNull
+
+    def treatNonObjectAsNull(self):
+        assert self.tag() == IDLType.Tags.callback
+        return self.nullable() and self.inner._treatNonObjectAsNull
+
+    def addExtendedAttributes(self, attrs):
+        assert len(attrs) == 0
+
+    def resolveType(self, parentScope):
+        pass
+
+    def unroll(self):
+        return self
+
+    def isDistinguishableFrom(self, other):
+        raise TypeError("Can't tell whether a generic type is or is not "
+                        "distinguishable from other things")
+
+class IDLUnresolvedType(IDLType):
+    """
+        Unresolved types are interface types 
+    """
+
+    def __init__(self, location, name):
+        IDLType.__init__(self, location, name)
+
+    def isComplete(self):
+        return False
+
+    def complete(self, scope):
+        obj = None
+        try:
+            obj = scope._lookupIdentifier(self.name)
+        except:
+            raise WebIDLError("Unresolved type '%s'." % self.name,
+                              [self.location])
+
+        assert obj
+        if obj.isType():
+            # obj itself might not be complete; deal with that.
+            assert obj != self
+            if not obj.isComplete():
+                obj = obj.complete(scope)
+            return obj
+
+        name = self.name.resolve(scope, None)
+        return IDLWrapperType(self.location, obj)
+
+    def isDistinguishableFrom(self, other):
+        raise TypeError("Can't tell whether an unresolved type is or is not "
+                        "distinguishable from other things")
+
+class IDLNullableType(IDLType):
+    def __init__(self, location, innerType):
+        assert not innerType.isVoid()
+        assert not innerType == BuiltinTypes[IDLBuiltinType.Types.any]
+
+        IDLType.__init__(self, location, innerType.name)
+        self.inner = innerType
+        self.builtin = False
+
+    def __eq__(self, other):
+        return isinstance(other, IDLNullableType) and self.inner == other.inner
+
+    def __str__(self):
+        return self.inner.__str__() + "OrNull"
+
+    def nullable(self):
+        return True
+
+    def isCallback(self):
+        return self.inner.isCallback()
+
+    def isPrimitive(self):
+        return self.inner.isPrimitive()
+
+    def isBoolean(self):
+        return self.inner.isBoolean()
+
+    def isNumeric(self):
+        return self.inner.isNumeric()
+
+    def isString(self):
+        return self.inner.isString()
+
+    def isByteString(self):
+        return self.inner.isByteString()
+
+    def isDOMString(self):
+        return self.inner.isDOMString()
+
+    def isFloat(self):
+        return self.inner.isFloat()
+
+    def isUnrestricted(self):
+        return self.inner.isUnrestricted()
+
+    def includesRestrictedFloat(self):
+        return self.inner.includesRestrictedFloat()
+
+    def isInteger(self):
+        return self.inner.isInteger()
+
+    def isVoid(self):
+        return False
+
+    def isSequence(self):
+        return self.inner.isSequence()
+
+    def isArray(self):
+        return self.inner.isArray()
+
+    def isArrayBuffer(self):
+        return self.inner.isArrayBuffer()
+
+    def isArrayBufferView(self):
+        return self.inner.isArrayBufferView()
+
+    def isTypedArray(self):
+        return self.inner.isTypedArray()
+
+    def isDictionary(self):
+        return self.inner.isDictionary()
+
+    def isInterface(self):
+        return self.inner.isInterface()
+
+    def isCallbackInterface(self):
+        return self.inner.isCallbackInterface()
+
+    def isNonCallbackInterface(self):
+        return self.inner.isNonCallbackInterface()
+
+    def isEnum(self):
+        return self.inner.isEnum()
+
+    def isUnion(self):
+        return self.inner.isUnion()
+
+    def isSerializable(self):
+        return self.inner.isSerializable()
+
+    def tag(self):
+        return self.inner.tag()
+
+    def resolveType(self, parentScope):
+        assert isinstance(parentScope, IDLScope)
+        self.inner.resolveType(parentScope)
+
+    def isComplete(self):
+        return self.inner.isComplete()
+
+    def complete(self, scope):
+        self.inner = self.inner.complete(scope)
+        if self.inner.nullable():
+            raise WebIDLError("The inner type of a nullable type must not be "
+                              "a nullable type",
+                              [self.location, self.inner.location])
+        if self.inner.isUnion():
+            if self.inner.hasNullableType:
+                raise WebIDLError("The inner type of a nullable type must not "
+                                  "be a union type that itself has a nullable "
+                                  "type as a member type", [self.location])
+
+        self.name = self.inner.name
+        return self
+
+    def unroll(self):
+        return self.inner.unroll()
+
+    def isDistinguishableFrom(self, other):
+        if (other.nullable() or (other.isUnion() and other.hasNullableType) or
+            other.isDictionary()):
+            # Can't tell which type null should become
+            return False
+        return self.inner.isDistinguishableFrom(other)
+
+    def _getDependentObjects(self):
+        return self.inner._getDependentObjects()
+
+class IDLSequenceType(IDLType):
+    def __init__(self, location, parameterType):
+        assert not parameterType.isVoid()
+
+        IDLType.__init__(self, location, parameterType.name)
+        self.inner = parameterType
+        self.builtin = False
+
+    def __eq__(self, other):
+        return isinstance(other, IDLSequenceType) and self.inner == other.inner
+
+    def __str__(self):
+        return self.inner.__str__() + "Sequence"
+
+    def nullable(self):
+        return False
+
+    def isPrimitive(self):
+        return False;
+
+    def isString(self):
+        return False;
+
+    def isByteString(self):
+        return False
+
+    def isDOMString(self):
+        return False
+
+    def isVoid(self):
+        return False
+
+    def isSequence(self):
+        return True
+
+    def isArray(self):
+        return False
+
+    def isDictionary(self):
+        return False
+
+    def isInterface(self):
+        return False
+
+    def isEnum(self):
+        return False
+
+    def isSerializable(self):
+        return self.inner.isSerializable()
+
+    def includesRestrictedFloat(self):
+        return self.inner.includesRestrictedFloat()
+
+    def tag(self):
+        return IDLType.Tags.sequence
+
+    def resolveType(self, parentScope):
+        assert isinstance(parentScope, IDLScope)
+        self.inner.resolveType(parentScope)
+
+    def isComplete(self):
+        return self.inner.isComplete()
+
+    def complete(self, scope):
+        self.inner = self.inner.complete(scope)
+        self.name = self.inner.name
+        return self
+
+    def unroll(self):
+        return self.inner.unroll()
+
+    def isDistinguishableFrom(self, other):
+        if other.isUnion():
+            # Just forward to the union; it'll deal
+            return other.isDistinguishableFrom(self)
+        return (other.isPrimitive() or other.isString() or other.isEnum() or
+                other.isDate() or other.isNonCallbackInterface())
+
+    def _getDependentObjects(self):
+        return self.inner._getDependentObjects()
+
+class IDLUnionType(IDLType):
+    def __init__(self, location, memberTypes):
+        IDLType.__init__(self, location, "")
+        self.memberTypes = memberTypes
+        self.hasNullableType = False
+        self.hasDictionaryType = False
+        self.flatMemberTypes = None
+        self.builtin = False
+
+    def __eq__(self, other):
+        return isinstance(other, IDLUnionType) and self.memberTypes == other.memberTypes
+
+    def isVoid(self):
+        return False
+
+    def isUnion(self):
+        return True
+
+    def isSerializable(self):
+        return all(m.isSerializable() for m in self.memberTypes)
+
+    def includesRestrictedFloat(self):
+        return any(t.includesRestrictedFloat() for t in self.memberTypes)
+
+    def tag(self):
+        return IDLType.Tags.union
+
+    def resolveType(self, parentScope):
+        assert isinstance(parentScope, IDLScope)
+        for t in self.memberTypes:
+            t.resolveType(parentScope)
+
+    def isComplete(self):
+        return self.flatMemberTypes is not None
+
+    def complete(self, scope):
+        def typeName(type):
+            if isinstance(type, IDLNullableType):
+                return typeName(type.inner) + "OrNull"
+            if isinstance(type, IDLWrapperType):
+                return typeName(type._identifier.object())
+            if isinstance(type, IDLObjectWithIdentifier):
+                return typeName(type.identifier)
+            if isinstance(type, IDLType) and (type.isArray() or type.isSequence()):
+                return str(type)
+            return type.name
+
+        for (i, type) in enumerate(self.memberTypes):
+            if not type.isComplete():
+                self.memberTypes[i] = type.complete(scope)
+
+        self.name = "Or".join(typeName(type) for type in self.memberTypes)
+        self.flatMemberTypes = list(self.memberTypes)
+        i = 0
+        while i < len(self.flatMemberTypes):
+            if self.flatMemberTypes[i].nullable():
+                if self.hasNullableType:
+                    raise WebIDLError("Can't have more than one nullable types in a union",
+                                      [nullableType.location, self.flatMemberTypes[i].location])
+                if self.hasDictionaryType:
+                    raise WebIDLError("Can't have a nullable type and a "
+                                      "dictionary type in a union",
+                                      [dictionaryType.location,
+                                       self.flatMemberTypes[i].location])
+                self.hasNullableType = True
+                nullableType = self.flatMemberTypes[i]
+                self.flatMemberTypes[i] = self.flatMemberTypes[i].inner
+                continue
+            if self.flatMemberTypes[i].isDictionary():
+                if self.hasNullableType:
+                    raise WebIDLError("Can't have a nullable type and a "
+                                      "dictionary type in a union",
+                                      [nullableType.location,
+                                       self.flatMemberTypes[i].location])
+                self.hasDictionaryType = True
+                dictionaryType = self.flatMemberTypes[i]
+            elif self.flatMemberTypes[i].isUnion():
+                self.flatMemberTypes[i:i + 1] = self.flatMemberTypes[i].memberTypes
+                continue
+            i += 1
+
+        for (i, t) in enumerate(self.flatMemberTypes[:-1]):
+            for u in self.flatMemberTypes[i + 1:]:
+                if not t.isDistinguishableFrom(u):
+                    raise WebIDLError("Flat member types of a union should be "
+                                      "distinguishable, " + str(t) + " is not "
+                                      "distinguishable from " + str(u),
+                                      [self.location, t.location, u.location])
+
+        return self
+
+    def isDistinguishableFrom(self, other):
+        if self.hasNullableType and other.nullable():
+            # Can't tell which type null should become
+            return False
+        if other.isUnion():
+            otherTypes = other.unroll().memberTypes
+        else:
+            otherTypes = [other]
+        # For every type in otherTypes, check that it's distinguishable from
+        # every type in our types
+        for u in otherTypes:
+            if any(not t.isDistinguishableFrom(u) for t in self.memberTypes):
+                return False
+        return True
+
+    def _getDependentObjects(self):
+        return set(self.memberTypes)
+
+class IDLArrayType(IDLType):
+    def __init__(self, location, parameterType):
+        assert not parameterType.isVoid()
+        if parameterType.isSequence():
+            raise WebIDLError("Array type cannot parameterize over a sequence type",
+                              [location])
+        if parameterType.isDictionary():
+            raise WebIDLError("Array type cannot parameterize over a dictionary type",
+                              [location])
+
+        IDLType.__init__(self, location, parameterType.name)
+        self.inner = parameterType
+        self.builtin = False
+
+    def __eq__(self, other):
+        return isinstance(other, IDLArrayType) and self.inner == other.inner
+
+    def __str__(self):
+        return self.inner.__str__() + "Array"
+
+    def nullable(self):
+        return False
+
+    def isPrimitive(self):
+        return False
+
+    def isString(self):
+        return False
+
+    def isByteString(self):
+        return False
+
+    def isDOMString(self):
+        return False
+
+    def isVoid(self):
+        return False
+
+    def isSequence(self):
+        assert not self.inner.isSequence()
+        return False
+
+    def isArray(self):
+        return True
+
+    def isDictionary(self):
+        assert not self.inner.isDictionary()
+        return False
+
+    def isInterface(self):
+        return False
+
+    def isEnum(self):
+        return False
+
+    def tag(self):
+        return IDLType.Tags.array
+
+    def resolveType(self, parentScope):
+        assert isinstance(parentScope, IDLScope)
+        self.inner.resolveType(parentScope)
+
+    def isComplete(self):
+        return self.inner.isComplete()
+
+    def complete(self, scope):
+        self.inner = self.inner.complete(scope)
+        self.name = self.inner.name
+
+        if self.inner.isDictionary():
+            raise WebIDLError("Array type must not contain "
+                              "dictionary as element type.",
+                              [self.inner.location])
+
+        assert not self.inner.isSequence()
+
+        return self
+
+    def unroll(self):
+        return self.inner.unroll()
+
+    def isDistinguishableFrom(self, other):
+        if other.isUnion():
+            # Just forward to the union; it'll deal
+            return other.isDistinguishableFrom(self)
+        return (other.isPrimitive() or other.isString() or other.isEnum() or
+                other.isDate() or other.isNonCallbackInterface())
+
+    def _getDependentObjects(self):
+        return self.inner._getDependentObjects()
+
+class IDLTypedefType(IDLType, IDLObjectWithIdentifier):
+    def __init__(self, location, innerType, name):
+        IDLType.__init__(self, location, innerType.name)
+
+        identifier = IDLUnresolvedIdentifier(location, name)
+
+        IDLObjectWithIdentifier.__init__(self, location, None, identifier)
+
+        self.inner = innerType
+        self.name = name
+        self.builtin = False
+
+    def __eq__(self, other):
+        return isinstance(other, IDLTypedefType) and self.inner == other.inner
+
+    def __str__(self):
+        return self.identifier.name
+
+    def nullable(self):
+        return self.inner.nullable()
+
+    def isPrimitive(self):
+        return self.inner.isPrimitive()
+
+    def isBoolean(self):
+        return self.inner.isBoolean()
+
+    def isNumeric(self):
+        return self.inner.isNumeric()
+
+    def isString(self):
+        return self.inner.isString()
+
+    def isByteString(self):
+        return self.inner.isByteString()
+
+    def isDOMString(self):
+        return self.inner.isDOMString()
+
+    def isVoid(self):
+        return self.inner.isVoid()
+
+    def isSequence(self):
+        return self.inner.isSequence()
+
+    def isArray(self):
+        return self.inner.isArray()
+
+    def isDictionary(self):
+        return self.inner.isDictionary()
+
+    def isArrayBuffer(self):
+        return self.inner.isArrayBuffer()
+
+    def isArrayBufferView(self):
+        return self.inner.isArrayBufferView()
+
+    def isTypedArray(self):
+        return self.inner.isTypedArray()
+
+    def isInterface(self):
+        return self.inner.isInterface()
+
+    def isCallbackInterface(self):
+        return self.inner.isCallbackInterface()
+
+    def isNonCallbackInterface(self):
+        return self.inner.isNonCallbackInterface()
+
+    def isComplete(self):
+        return False
+
+    def complete(self, parentScope):
+        if not self.inner.isComplete():
+            self.inner = self.inner.complete(parentScope)
+        assert self.inner.isComplete()
+        return self.inner
+
+    def finish(self, parentScope):
+        # Maybe the IDLObjectWithIdentifier for the typedef should be
+        # a separate thing from the type?  If that happens, we can
+        # remove some hackery around avoiding isInterface() in
+        # Configuration.py.
+        self.complete(parentScope)
+
+    def validate(self):
+        pass
+
+    # Do we need a resolveType impl?  I don't think it's particularly useful....
+
+    def tag(self):
+        return self.inner.tag()
+
+    def unroll(self):
+        return self.inner.unroll()
+
+    def isDistinguishableFrom(self, other):
+        return self.inner.isDistinguishableFrom(other)
+
+    def _getDependentObjects(self):
+        return self.inner._getDependentObjects()
+
+class IDLWrapperType(IDLType):
+    def __init__(self, location, inner):
+        IDLType.__init__(self, location, inner.identifier.name)
+        self.inner = inner
+        self._identifier = inner.identifier
+        self.builtin = False
+
+    def __eq__(self, other):
+        return isinstance(other, IDLWrapperType) and \
+               self._identifier == other._identifier and \
+               self.builtin == other.builtin
+
+    def __str__(self):
+        return str(self.name) + " (Wrapper)"
+
+    def nullable(self):
+        return False
+
+    def isPrimitive(self):
+        return False
+
+    def isString(self):
+        return False
+
+    def isByteString(self):
+        return False
+
+    def isDOMString(self):
+        return False
+
+    def isVoid(self):
+        return False
+
+    def isSequence(self):
+        return False
+
+    def isArray(self):
+        return False
+
+    def isDictionary(self):
+        return isinstance(self.inner, IDLDictionary)
+
+    def isInterface(self):
+        return isinstance(self.inner, IDLInterface) or \
+               isinstance(self.inner, IDLExternalInterface)
+
+    def isCallbackInterface(self):
+        return self.isInterface() and self.inner.isCallback()
+
+    def isNonCallbackInterface(self):
+        return self.isInterface() and not self.inner.isCallback()
+
+    def isEnum(self):
+        return isinstance(self.inner, IDLEnum)
+
+    def isPromise(self):
+        return isinstance(self.inner, IDLInterface) and \
+               self.inner.identifier.name == "Promise"
+
+    def isSerializable(self):
+        if self.isInterface():
+            if self.inner.isExternal():
+                return False
+            return any(m.isMethod() and m.isJsonifier() for m in self.inner.members)
+        elif self.isEnum():
+            return True
+        elif self.isDictionary():
+            return all(m.type.isSerializable() for m in self.inner.members)
+        else:
+            raise WebIDLError("IDLWrapperType wraps type %s that we don't know if "
+                              "is serializable" % type(self.inner), [self.location])
+
+    def resolveType(self, parentScope):
+        assert isinstance(parentScope, IDLScope)
+        self.inner.resolve(parentScope)
+
+    def isComplete(self):
+        return True
+
+    def tag(self):
+        if self.isInterface():
+            return IDLType.Tags.interface
+        elif self.isEnum():
+            return IDLType.Tags.enum
+        elif self.isDictionary():
+            return IDLType.Tags.dictionary
+        else:
+            assert False
+
+    def isDistinguishableFrom(self, other):
+        if other.isUnion():
+            # Just forward to the union; it'll deal
+            return other.isDistinguishableFrom(self)
+        assert self.isInterface() or self.isEnum() or self.isDictionary()
+        if self.isEnum():
+            return (other.isPrimitive() or other.isInterface() or other.isObject() or
+                    other.isCallback() or other.isDictionary() or
+                    other.isSequence() or other.isArray() or
+                    other.isDate())
+        if self.isDictionary() and other.nullable():
+            return False
+        if other.isPrimitive() or other.isString() or other.isEnum() or other.isDate():
+            return True
+        if self.isDictionary():
+            return other.isNonCallbackInterface()
+
+        assert self.isInterface()
+        if other.isInterface():
+            if other.isSpiderMonkeyInterface():
+                # Just let |other| handle things
+                return other.isDistinguishableFrom(self)
+            assert self.isGeckoInterface() and other.isGeckoInterface()
+            if self.inner.isExternal() or other.unroll().inner.isExternal():
+                return self != other
+            return (len(self.inner.interfacesBasedOnSelf &
+                        other.unroll().inner.interfacesBasedOnSelf) == 0 and
+                    (self.isNonCallbackInterface() or
+                     other.isNonCallbackInterface()))
+        if (other.isDictionary() or other.isCallback() or
+            other.isSequence() or other.isArray()):
+            return self.isNonCallbackInterface()
+
+        # Not much else |other| can be
+        assert other.isObject()
+        return False
+
+    def _getDependentObjects(self):
+        # NB: The codegen for an interface type depends on
+        #  a) That the identifier is in fact an interface (as opposed to
+        #     a dictionary or something else).
+        #  b) The native type of the interface.
+        #  If we depend on the interface object we will also depend on
+        #  anything the interface depends on which is undesirable.  We
+        #  considered implementing a dependency just on the interface type
+        #  file, but then every modification to an interface would cause this
+        #  to be regenerated which is still undesirable.  We decided not to
+        #  depend on anything, reasoning that:
+        #  1) Changing the concrete type of the interface requires modifying
+        #     Bindings.conf, which is still a global dependency.
+        #  2) Changing an interface to a dictionary (or vice versa) with the
+        #     same identifier should be incredibly rare.
+        return set()
+
+class IDLBuiltinType(IDLType):
+
+    Types = enum(
+        # The integer types
+        'byte',
+        'octet',
+        'short',
+        'unsigned_short',
+        'long',
+        'unsigned_long',
+        'long_long',
+        'unsigned_long_long',
+        # Additional primitive types
+        'boolean',
+        'unrestricted_float',
+        'float',
+        'unrestricted_double',
+        # IMPORTANT: "double" must be the last primitive type listed
+        'double',
+        # Other types
+        'any',
+        'domstring',
+        'bytestring',
+        'object',
+        'date',
+        'void',
+        # Funny stuff
+        'ArrayBuffer',
+        'ArrayBufferView',
+        'Int8Array',
+        'Uint8Array',
+        'Uint8ClampedArray',
+        'Int16Array',
+        'Uint16Array',
+        'Int32Array',
+        'Uint32Array',
+        'Float32Array',
+        'Float64Array'
+        )
+
+    TagLookup = {
+            Types.byte: IDLType.Tags.int8,
+            Types.octet: IDLType.Tags.uint8,
+            Types.short: IDLType.Tags.int16,
+            Types.unsigned_short: IDLType.Tags.uint16,
+            Types.long: IDLType.Tags.int32,
+            Types.unsigned_long: IDLType.Tags.uint32,
+            Types.long_long: IDLType.Tags.int64,
+            Types.unsigned_long_long: IDLType.Tags.uint64,
+            Types.boolean: IDLType.Tags.bool,
+            Types.unrestricted_float: IDLType.Tags.unrestricted_float,
+            Types.float: IDLType.Tags.float,
+            Types.unrestricted_double: IDLType.Tags.unrestricted_double,
+            Types.double: IDLType.Tags.double,
+            Types.any: IDLType.Tags.any,
+            Types.domstring: IDLType.Tags.domstring,
+            Types.bytestring: IDLType.Tags.bytestring,
+            Types.object: IDLType.Tags.object,
+            Types.date: IDLType.Tags.date,
+            Types.void: IDLType.Tags.void,
+            Types.ArrayBuffer: IDLType.Tags.interface,
+            Types.ArrayBufferView: IDLType.Tags.interface,
+            Types.Int8Array: IDLType.Tags.interface,
+            Types.Uint8Array: IDLType.Tags.interface,
+            Types.Uint8ClampedArray: IDLType.Tags.interface,
+            Types.Int16Array: IDLType.Tags.interface,
+            Types.Uint16Array: IDLType.Tags.interface,
+            Types.Int32Array: IDLType.Tags.interface,
+            Types.Uint32Array: IDLType.Tags.interface,
+            Types.Float32Array: IDLType.Tags.interface,
+            Types.Float64Array: IDLType.Tags.interface
+        }
+
+    def __init__(self, location, name, type):
+        IDLType.__init__(self, location, name)
+        self.builtin = True
+        self._typeTag = type
+
+    def isPrimitive(self):
+        return self._typeTag <= IDLBuiltinType.Types.double
+
+    def isBoolean(self):
+        return self._typeTag == IDLBuiltinType.Types.boolean
+
+    def isNumeric(self):
+        return self.isPrimitive() and not self.isBoolean()
+
+    def isString(self):
+        return self._typeTag == IDLBuiltinType.Types.domstring or \
+               self._typeTag == IDLBuiltinType.Types.bytestring
+
+    def isByteString(self):
+        return self._typeTag == IDLBuiltinType.Types.bytestring
+
+    def isDOMString(self):
+        return self._typeTag == IDLBuiltinType.Types.domstring
+
+    def isInteger(self):
+        return self._typeTag <= IDLBuiltinType.Types.unsigned_long_long
+
+    def isArrayBuffer(self):
+        return self._typeTag == IDLBuiltinType.Types.ArrayBuffer
+
+    def isArrayBufferView(self):
+        return self._typeTag == IDLBuiltinType.Types.ArrayBufferView
+
+    def isTypedArray(self):
+        return self._typeTag >= IDLBuiltinType.Types.Int8Array and \
+               self._typeTag <= IDLBuiltinType.Types.Float64Array
+
+    def isInterface(self):
+        # TypedArray things are interface types per the TypedArray spec,
+        # but we handle them as builtins because SpiderMonkey implements
+        # all of it internally.
+        return self.isArrayBuffer() or \
+               self.isArrayBufferView() or \
+               self.isTypedArray()
+
+    def isNonCallbackInterface(self):
+        # All the interfaces we can be are non-callback
+        return self.isInterface()
+
+    def isFloat(self):
+        return self._typeTag == IDLBuiltinType.Types.float or \
+               self._typeTag == IDLBuiltinType.Types.double or \
+               self._typeTag == IDLBuiltinType.Types.unrestricted_float or \
+               self._typeTag == IDLBuiltinType.Types.unrestricted_double
+
+    def isUnrestricted(self):
+        assert self.isFloat()
+        return self._typeTag == IDLBuiltinType.Types.unrestricted_float or \
+               self._typeTag == IDLBuiltinType.Types.unrestricted_double
+
+    def isSerializable(self):
+        return self.isPrimitive() or self.isDOMString() or self.isDate()
+
+    def includesRestrictedFloat(self):
+        return self.isFloat() and not self.isUnrestricted()
+
+    def tag(self):
+        return IDLBuiltinType.TagLookup[self._typeTag]
+
+    def isDistinguishableFrom(self, other):
+        if other.isUnion():
+            # Just forward to the union; it'll deal
+            return other.isDistinguishableFrom(self)
+        if self.isBoolean():
+            return (other.isNumeric() or other.isString() or other.isEnum() or
+                    other.isInterface() or other.isObject() or
+                    other.isCallback() or other.isDictionary() or
+                    other.isSequence() or other.isArray() or
+                    other.isDate())
+        if self.isNumeric():
+            return (other.isBoolean() or other.isString() or other.isEnum() or
+                    other.isInterface() or other.isObject() or
+                    other.isCallback() or other.isDictionary() or
+                    other.isSequence() or other.isArray() or
+                    other.isDate())
+        if self.isString():
+            return (other.isPrimitive() or other.isInterface() or
+                    other.isObject() or
+                    other.isCallback() or other.isDictionary() or
+                    other.isSequence() or other.isArray() or
+                    other.isDate())
+        if self.isAny():
+            # Can't tell "any" apart from anything
+            return False
+        if self.isObject():
+            return other.isPrimitive() or other.isString() or other.isEnum()
+        if self.isDate():
+            return (other.isPrimitive() or other.isString() or other.isEnum() or
+                    other.isInterface() or other.isCallback() or
+                    other.isDictionary() or other.isSequence() or
+                    other.isArray())
+        if self.isVoid():
+            return not other.isVoid()
+        # Not much else we could be!
+        assert self.isSpiderMonkeyInterface()
+        # Like interfaces, but we know we're not a callback
+        return (other.isPrimitive() or other.isString() or other.isEnum() or
+                other.isCallback() or other.isDictionary() or
+                other.isSequence() or other.isArray() or other.isDate() or
+                (other.isInterface() and (
+                 # ArrayBuffer is distinguishable from everything
+                 # that's not an ArrayBuffer or a callback interface
+                 (self.isArrayBuffer() and not other.isArrayBuffer()) or
+                 # ArrayBufferView is distinguishable from everything
+                 # that's not an ArrayBufferView or typed array.
+                 (self.isArrayBufferView() and not other.isArrayBufferView() and
+                  not other.isTypedArray()) or
+                 # Typed arrays are distinguishable from everything
+                 # except ArrayBufferView and the same type of typed
+                 # array
+                 (self.isTypedArray() and not other.isArrayBufferView() and not
+                  (other.isTypedArray() and other.name == self.name)))))
+
+    def _getDependentObjects(self):
+        return set()
+
+BuiltinTypes = {
+      IDLBuiltinType.Types.byte:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Byte",
+                         IDLBuiltinType.Types.byte),
+      IDLBuiltinType.Types.octet:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Octet",
+                         IDLBuiltinType.Types.octet),
+      IDLBuiltinType.Types.short:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Short",
+                         IDLBuiltinType.Types.short),
+      IDLBuiltinType.Types.unsigned_short:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "UnsignedShort",
+                         IDLBuiltinType.Types.unsigned_short),
+      IDLBuiltinType.Types.long:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Long",
+                         IDLBuiltinType.Types.long),
+      IDLBuiltinType.Types.unsigned_long:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "UnsignedLong",
+                         IDLBuiltinType.Types.unsigned_long),
+      IDLBuiltinType.Types.long_long:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "LongLong",
+                         IDLBuiltinType.Types.long_long),
+      IDLBuiltinType.Types.unsigned_long_long:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "UnsignedLongLong",
+                         IDLBuiltinType.Types.unsigned_long_long),
+      IDLBuiltinType.Types.boolean:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Boolean",
+                         IDLBuiltinType.Types.boolean),
+      IDLBuiltinType.Types.float:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Float",
+                         IDLBuiltinType.Types.float),
+      IDLBuiltinType.Types.unrestricted_float:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "UnrestrictedFloat",
+                         IDLBuiltinType.Types.unrestricted_float),
+      IDLBuiltinType.Types.double:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Double",
+                         IDLBuiltinType.Types.double),
+      IDLBuiltinType.Types.unrestricted_double:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "UnrestrictedDouble",
+                         IDLBuiltinType.Types.unrestricted_double),
+      IDLBuiltinType.Types.any:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Any",
+                         IDLBuiltinType.Types.any),
+      IDLBuiltinType.Types.domstring:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "String",
+                         IDLBuiltinType.Types.domstring),
+      IDLBuiltinType.Types.bytestring:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "ByteString",
+                         IDLBuiltinType.Types.bytestring),
+      IDLBuiltinType.Types.object:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Object",
+                         IDLBuiltinType.Types.object),
+      IDLBuiltinType.Types.date:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Date",
+                         IDLBuiltinType.Types.date),
+      IDLBuiltinType.Types.void:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Void",
+                         IDLBuiltinType.Types.void),
+      IDLBuiltinType.Types.ArrayBuffer:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "ArrayBuffer",
+                         IDLBuiltinType.Types.ArrayBuffer),
+      IDLBuiltinType.Types.ArrayBufferView:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "ArrayBufferView",
+                         IDLBuiltinType.Types.ArrayBufferView),
+      IDLBuiltinType.Types.Int8Array:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Int8Array",
+                         IDLBuiltinType.Types.Int8Array),
+      IDLBuiltinType.Types.Uint8Array:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Uint8Array",
+                         IDLBuiltinType.Types.Uint8Array),
+      IDLBuiltinType.Types.Uint8ClampedArray:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Uint8ClampedArray",
+                         IDLBuiltinType.Types.Uint8ClampedArray),
+      IDLBuiltinType.Types.Int16Array:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Int16Array",
+                         IDLBuiltinType.Types.Int16Array),
+      IDLBuiltinType.Types.Uint16Array:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Uint16Array",
+                         IDLBuiltinType.Types.Uint16Array),
+      IDLBuiltinType.Types.Int32Array:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Int32Array",
+                         IDLBuiltinType.Types.Int32Array),
+      IDLBuiltinType.Types.Uint32Array:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Uint32Array",
+                         IDLBuiltinType.Types.Uint32Array),
+      IDLBuiltinType.Types.Float32Array:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Float32Array",
+                         IDLBuiltinType.Types.Float32Array),
+      IDLBuiltinType.Types.Float64Array:
+          IDLBuiltinType(BuiltinLocation("<builtin type>"), "Float64Array",
+                         IDLBuiltinType.Types.Float64Array)
+    }
+
+
+integerTypeSizes = {
+        IDLBuiltinType.Types.byte: (-128, 127),
+        IDLBuiltinType.Types.octet:  (0, 255),
+        IDLBuiltinType.Types.short: (-32768, 32767),
+        IDLBuiltinType.Types.unsigned_short: (0, 65535),
+        IDLBuiltinType.Types.long: (-2147483648, 2147483647),
+        IDLBuiltinType.Types.unsigned_long: (0, 4294967295),
+        IDLBuiltinType.Types.long_long: (-9223372036854775808,
+                                         9223372036854775807),
+        IDLBuiltinType.Types.unsigned_long_long: (0, 18446744073709551615)
+    }
+
+def matchIntegerValueToType(value):
+    for type, extremes in integerTypeSizes.items():
+        (min, max) = extremes
+        if value <= max and value >= min:
+            return BuiltinTypes[type]
+
+    return None
+
+class IDLValue(IDLObject):
+    def __init__(self, location, type, value):
+        IDLObject.__init__(self, location)
+        self.type = type
+        assert isinstance(type, IDLType)
+
+        self.value = value
+
+    def coerceToType(self, type, location):
+        if type == self.type:
+            return self # Nothing to do
+
+        # We first check for unions to ensure that even if the union is nullable
+        # we end up with the right flat member type, not the union's type.
+        if type.isUnion():
+            # We use the flat member types here, because if we have a nullable
+            # member type, or a nested union, we want the type the value
+            # actually coerces to, not the nullable or nested union type.
+            for subtype in type.unroll().flatMemberTypes:
+                try:
+                    coercedValue = self.coerceToType(subtype, location)
+                    # Create a new IDLValue to make sure that we have the
+                    # correct float/double type.  This is necessary because we
+                    # use the value's type when it is a default value of a
+                    # union, and the union cares about the exact float type.
+                    return IDLValue(self.location, subtype, coercedValue.value)
+                except:
+                    pass
+        # If the type allows null, rerun this matching on the inner type, except
+        # nullable enums.  We handle those specially, because we want our
+        # default string values to stay strings even when assigned to a nullable
+        # enum.
+        elif type.nullable() and not type.isEnum():
+            innerValue = self.coerceToType(type.inner, location)
+            return IDLValue(self.location, type, innerValue.value)
+
+        elif self.type.isInteger() and type.isInteger():
+            # We're both integer types.  See if we fit.
+
+            (min, max) = integerTypeSizes[type._typeTag]
+            if self.value <= max and self.value >= min:
+                # Promote
+                return IDLValue(self.location, type, self.value)
+            else:
+                raise WebIDLError("Value %s is out of range for type %s." %
+                                  (self.value, type), [location])
+        elif self.type.isInteger() and type.isFloat():
+            # Convert an integer literal into float
+            if -2**24 <= self.value <= 2**24:
+                floatType = BuiltinTypes[IDLBuiltinType.Types.float]
+                return IDLValue(self.location, floatType, float(self.value))
+            else:
+                raise WebIDLError("Converting value %s to %s will lose precision." %
+                                  (self.value, type), [location])
+        elif self.type.isString() and type.isEnum():
+            # Just keep our string, but make sure it's a valid value for this enum
+            enum = type.unroll().inner
+            if self.value not in enum.values():
+                raise WebIDLError("'%s' is not a valid default value for enum %s"
+                                  % (self.value, enum.identifier.name),
+                                  [location, enum.location])
+            return self
+        elif self.type.isFloat() and type.isFloat():
+            if (not type.isUnrestricted() and
+                (self.value == float("inf") or self.value == float("-inf") or
+                 math.isnan(self.value))):
+                raise WebIDLError("Trying to convert unrestricted value %s to non-unrestricted"
+                                  % self.value, [location]);
+            return self
+        raise WebIDLError("Cannot coerce type %s to type %s." %
+                          (self.type, type), [location])
+
+    def _getDependentObjects(self):
+        return set()
+
+class IDLNullValue(IDLObject):
+    def __init__(self, location):
+        IDLObject.__init__(self, location)
+        self.type = None
+        self.value = None
+
+    def coerceToType(self, type, location):
+        if (not isinstance(type, IDLNullableType) and
+            not (type.isUnion() and type.hasNullableType) and
+            not (type.isUnion() and type.hasDictionaryType) and
+            not type.isDictionary() and
+            not type.isAny()):
+            raise WebIDLError("Cannot coerce null value to type %s." % type,
+                              [location])
+
+        nullValue = IDLNullValue(self.location)
+        if type.isUnion() and not type.nullable() and type.hasDictionaryType:
+            # We're actually a default value for the union's dictionary member.
+            # Use its type.
+            for t in type.flatMemberTypes:
+                if t.isDictionary():
+                    nullValue.type = t
+                    return nullValue
+        nullValue.type = type
+        return nullValue
+
+    def _getDependentObjects(self):
+        return set()
+
+class IDLUndefinedValue(IDLObject):
+    def __init__(self, location):
+        IDLObject.__init__(self, location)
+        self.type = None
+        self.value = None
+
+    def coerceToType(self, type, location):
+        if not type.isAny():
+            raise WebIDLError("Cannot coerce undefined value to type %s." % type,
+                              [location])
+
+        undefinedValue = IDLUndefinedValue(self.location)
+        undefinedValue.type = type
+        return undefinedValue
+
+    def _getDependentObjects(self):
+        return set()
+
+class IDLInterfaceMember(IDLObjectWithIdentifier):
+
+    Tags = enum(
+        'Const',
+        'Attr',
+        'Method'
+    )
+
+    Special = enum(
+        'Static',
+        'Stringifier'
+    )
+
+    def __init__(self, location, identifier, tag):
+        IDLObjectWithIdentifier.__init__(self, location, None, identifier)
+        self.tag = tag
+        self._extendedAttrDict = {}
+
+    def isMethod(self):
+        return self.tag == IDLInterfaceMember.Tags.Method
+
+    def isAttr(self):
+        return self.tag == IDLInterfaceMember.Tags.Attr
+
+    def isConst(self):
+        return self.tag == IDLInterfaceMember.Tags.Const
+
+    def addExtendedAttributes(self, attrs):
+        for attr in attrs:
+            self.handleExtendedAttribute(attr)
+            attrlist = attr.listValue()
+            self._extendedAttrDict[attr.identifier()] = attrlist if len(attrlist) else True
+
+    def handleExtendedAttribute(self, attr):
+        pass
+
+    def getExtendedAttribute(self, name):
+        return self._extendedAttrDict.get(name, None)
+
+class IDLConst(IDLInterfaceMember):
+    def __init__(self, location, identifier, type, value):
+        IDLInterfaceMember.__init__(self, location, identifier,
+                                    IDLInterfaceMember.Tags.Const)
+
+        assert isinstance(type, IDLType)
+        if type.isDictionary():
+            raise WebIDLError("A constant cannot be of a dictionary type",
+                              [self.location])
+        self.type = type
+        self.value = value
+
+        if identifier.name == "prototype":
+            raise WebIDLError("The identifier of a constant must not be 'prototype'",
+                              [location])
+
+    def __str__(self):
+        return "'%s' const '%s'" % (self.type, self.identifier)
+
+    def finish(self, scope):
+        if not self.type.isComplete():
+            type = self.type.complete(scope)
+            if not type.isPrimitive() and not type.isString():
+                locations = [self.type.location, type.location]
+                try:
+                    locations.append(type.inner.location)
+                except:
+                    pass
+                raise WebIDLError("Incorrect type for constant", locations)
+            self.type = type
+
+        # The value might not match the type
+        coercedValue = self.value.coerceToType(self.type, self.location)
+        assert coercedValue
+
+        self.value = coercedValue
+
+    def validate(self):
+        pass
+
+    def _getDependentObjects(self):
+        return set([self.type, self.value])
+
+class IDLAttribute(IDLInterfaceMember):
+    def __init__(self, location, identifier, type, readonly, inherit=False,
+                 static=False, stringifier=False):
+        IDLInterfaceMember.__init__(self, location, identifier,
+                                    IDLInterfaceMember.Tags.Attr)
+
+        assert isinstance(type, IDLType)
+        self.type = type
+        self.readonly = readonly
+        self.inherit = inherit
+        self.static = static
+        self.lenientThis = False
+        self._unforgeable = False
+        self.stringifier = stringifier
+        self.enforceRange = False
+        self.clamp = False
+        self.slotIndex = None
+
+        if static and identifier.name == "prototype":
+            raise WebIDLError("The identifier of a static attribute must not be 'prototype'",
+                              [location])
+
+        if readonly and inherit:
+            raise WebIDLError("An attribute cannot be both 'readonly' and 'inherit'",
+                              [self.location])
+
+    def isStatic(self):
+        return self.static
+
+    def __str__(self):
+        return "'%s' attribute '%s'" % (self.type, self.identifier)
+
+    def finish(self, scope):
+        if not self.type.isComplete():
+            t = self.type.complete(scope)
+
+            assert not isinstance(t, IDLUnresolvedType)
+            assert not isinstance(t, IDLTypedefType)
+            assert not isinstance(t.name, IDLUnresolvedIdentifier)
+            self.type = t
+
+        if self.type.isDictionary() and not self.getExtendedAttribute("Cached"):
+            raise WebIDLError("An attribute cannot be of a dictionary type",
+                              [self.location])
+        if self.type.isSequence() and not self.getExtendedAttribute("Cached"):
+            raise WebIDLError("A non-cached attribute cannot be of a sequence "
+                              "type", [self.location])
+        if self.type.isUnion():
+            for f in self.type.unroll().flatMemberTypes:
+                if f.isDictionary():
+                    raise WebIDLError("An attribute cannot be of a union "
+                                      "type if one of its member types (or "
+                                      "one of its member types's member "
+                                      "types, and so on) is a dictionary "
+                                      "type", [self.location, f.location])
+                if f.isSequence():
+                    raise WebIDLError("An attribute cannot be of a union "
+                                      "type if one of its member types (or "
+                                      "one of its member types's member "
+                                      "types, and so on) is a sequence "
+                                      "type", [self.location, f.location])
+        if not self.type.isInterface() and self.getExtendedAttribute("PutForwards"):
+            raise WebIDLError("An attribute with [PutForwards] must have an "
+                              "interface type as its type", [self.location])
+
+        if not self.type.isInterface() and self.getExtendedAttribute("SameObject"):
+            raise WebIDLError("An attribute with [SameObject] must have an "
+                              "interface type as its type", [self.location])
+
+    def validate(self):
+        if ((self.getExtendedAttribute("Cached") or
+             self.getExtendedAttribute("StoreInSlot")) and
+            not self.getExtendedAttribute("Constant") and
+            not self.getExtendedAttribute("Pure")):
+            raise WebIDLError("Cached attributes and attributes stored in "
+                              "slots must be constant or pure, since the "
+                              "getter won't always be called.",
+                              [self.location])
+        if self.getExtendedAttribute("Frozen"):
+            if not self.type.isSequence() and not self.type.isDictionary():
+                raise WebIDLError("[Frozen] is only allowed on sequence-valued "
+                                  "and dictionary-valued attributes",
+                                  [self.location])
+
+    def handleExtendedAttribute(self, attr):
+        identifier = attr.identifier()
+        if identifier == "SetterThrows" and self.readonly:
+            raise WebIDLError("Readonly attributes must not be flagged as "
+                              "[SetterThrows]",
+                              [self.location])
+        elif (((identifier == "Throws" or identifier == "GetterThrows") and
+               self.getExtendedAttribute("StoreInSlot")) or
+              (identifier == "StoreInSlot" and
+               (self.getExtendedAttribute("Throws") or
+                self.getExtendedAttribute("GetterThrows")))):
+            raise WebIDLError("Throwing things can't be [Pure] or [Constant] "
+                              "or [SameObject] or [StoreInSlot]",
+                              [attr.location])
+        elif identifier == "LenientThis":
+            if not attr.noArguments():
+                raise WebIDLError("[LenientThis] must take no arguments",
+                                  [attr.location])
+            if self.isStatic():
+                raise WebIDLError("[LenientThis] is only allowed on non-static "
+                                  "attributes", [attr.location, self.location])
+            if self.getExtendedAttribute("CrossOriginReadable"):
+                raise WebIDLError("[LenientThis] is not allowed in combination "
+                                  "with [CrossOriginReadable]",
+                                  [attr.location, self.location])
+            if self.getExtendedAttribute("CrossOriginWritable"):
+                raise WebIDLError("[LenientThis] is not allowed in combination "
+                                  "with [CrossOriginWritable]",
+                                  [attr.location, self.location])
+            self.lenientThis = True
+        elif identifier == "Unforgeable":
+            if not self.readonly:
+                raise WebIDLError("[Unforgeable] is only allowed on readonly "
+                                  "attributes", [attr.location, self.location])
+            if self.isStatic():
+                raise WebIDLError("[Unforgeable] is only allowed on non-static "
+                                  "attributes", [attr.location, self.location])
+            self._unforgeable = True
+        elif identifier == "SameObject" and not self.readonly:
+            raise WebIDLError("[SameObject] only allowed on readonly attributes",
+                              [attr.location, self.location])
+        elif identifier == "Constant" and not self.readonly:
+            raise WebIDLError("[Constant] only allowed on readonly attributes",
+                              [attr.location, self.location])
+        elif identifier == "PutForwards":
+            if not self.readonly:
+                raise WebIDLError("[PutForwards] is only allowed on readonly "
+                                  "attributes", [attr.location, self.location])
+            if self.isStatic():
+                raise WebIDLError("[PutForwards] is only allowed on non-static "
+                                  "attributes", [attr.location, self.location])
+            if self.getExtendedAttribute("Replaceable") is not None:
+                raise WebIDLError("[PutForwards] and [Replaceable] can't both "
+                                  "appear on the same attribute",
+                                  [attr.location, self.location])
+            if not attr.hasValue():
+                raise WebIDLError("[PutForwards] takes an identifier",
+                                  [attr.location, self.location])
+        elif identifier == "Replaceable":
+            if self.getExtendedAttribute("PutForwards") is not None:
+                raise WebIDLError("[PutForwards] and [Replaceable] can't both "
+                                  "appear on the same attribute",
+                                  [attr.location, self.location])
+        elif identifier == "LenientFloat":
+            if self.readonly:
+                raise WebIDLError("[LenientFloat] used on a readonly attribute",
+                                  [attr.location, self.location])
+            if not self.type.includesRestrictedFloat():
+                raise WebIDLError("[LenientFloat] used on an attribute with a "
+                                  "non-restricted-float type",
+                                  [attr.location, self.location])
+        elif identifier == "EnforceRange":
+            if self.readonly:
+                raise WebIDLError("[EnforceRange] used on a readonly attribute",
+                                  [attr.location, self.location])
+            self.enforceRange = True
+        elif identifier == "Clamp":
+            if self.readonly:
+                raise WebIDLError("[Clamp] used on a readonly attribute",
+                                  [attr.location, self.location])
+            self.clamp = True
+        elif identifier == "StoreInSlot":
+            if self.getExtendedAttribute("Cached"):
+                raise WebIDLError("[StoreInSlot] and [Cached] must not be "
+                                  "specified on the same attribute",
+                                  [attr.location, self.location])
+        elif identifier == "Cached":
+            if self.getExtendedAttribute("StoreInSlot"):
+                raise WebIDLError("[Cached] and [StoreInSlot] must not be "
+                                  "specified on the same attribute",
+                                  [attr.location, self.location])
+        elif (identifier == "CrossOriginReadable" or
+              identifier == "CrossOriginWritable"):
+            if not attr.noArguments():
+                raise WebIDLError("[%s] must take no arguments" % identifier,
+                                  [attr.location])
+            if self.isStatic():
+                raise WebIDLError("[%s] is only allowed on non-static "
+                                  "attributes" % identifier,
+                                  [attr.location, self.location])
+            if self.getExtendedAttribute("LenientThis"):
+                raise WebIDLError("[LenientThis] is not allowed in combination "
+                                  "with [%s]" % identifier,
+                                  [attr.location, self.location])
+        elif (identifier == "Pref" or
+              identifier == "SetterThrows" or
+              identifier == "Pure" or
+              identifier == "Throws" or
+              identifier == "GetterThrows" or
+              identifier == "ChromeOnly" or
+              identifier == "SameObject" or
+              identifier == "Constant" or
+              identifier == "Func" or
+              identifier == "Frozen" or
+              identifier == "AvailableIn" or
+              identifier == "Const" or
+              identifier == "Value" or
+              identifier == "NewObject"):
+            # Known attributes that we don't need to do anything with here
+            pass
+        else:
+            raise WebIDLError("Unknown extended attribute %s on attribute" % identifier,
+                              [attr.location])
+        IDLInterfaceMember.handleExtendedAttribute(self, attr)
+
+    def resolve(self, parentScope):
+        assert isinstance(parentScope, IDLScope)
+        self.type.resolveType(parentScope)
+        IDLObjectWithIdentifier.resolve(self, parentScope)
+
+    def addExtendedAttributes(self, attrs):
+        attrs = self.checkForStringHandlingExtendedAttributes(attrs)
+        IDLInterfaceMember.addExtendedAttributes(self, attrs)
+
+    def hasLenientThis(self):
+        return self.lenientThis
+
+    def isUnforgeable(self):
+        return self._unforgeable
+
+    def _getDependentObjects(self):
+        return set([self.type])
+
+class IDLArgument(IDLObjectWithIdentifier):
+    def __init__(self, location, identifier, type, optional=False, defaultValue=None, variadic=False, dictionaryMember=False):
+        IDLObjectWithIdentifier.__init__(self, location, None, identifier)
+
+        assert isinstance(type, IDLType)
+        self.type = type
+
+        self.optional = optional
+        self.defaultValue = defaultValue
+        self.variadic = variadic
+        self.dictionaryMember = dictionaryMember
+        self._isComplete = False
+        self.enforceRange = False
+        self.clamp = False
+        self._allowTreatNonCallableAsNull = False
+
+        self._extraAttributes = {}
+
+        assert not variadic or optional
+
+    def getExtendedAttribute(self, name):
+        return self._extraAttributes.get(name)
+
+    def addExtendedAttributes(self, attrs):
+        attrs = self.checkForStringHandlingExtendedAttributes(
+            attrs,
+            isDictionaryMember=self.dictionaryMember,
+            isOptional=self.optional)
+        for attribute in attrs:
+            identifier = attribute.identifier()
+            if identifier == "Clamp":
+                if not attribute.noArguments():
+                    raise WebIDLError("[Clamp] must take no arguments",
+                                      [attribute.location])
+                if self.enforceRange:
+                    raise WebIDLError("[EnforceRange] and [Clamp] are mutually exclusive",
+                                      [self.location]);
+                self.clamp = True
+            elif identifier == "EnforceRange":
+                if not attribute.noArguments():
+                    raise WebIDLError("[EnforceRange] must take no arguments",
+                                      [attribute.location])
+                if self.clamp:
+                    raise WebIDLError("[EnforceRange] and [Clamp] are mutually exclusive",
+                                      [self.location]);
+                self.enforceRange = True
+            elif identifier == "TreatNonCallableAsNull":
+                self._allowTreatNonCallableAsNull = True
+            elif identifier in ['Ref', 'Const']:
+                # ok in emscripten
+                self._extraAttributes[identifier] = True
+            else:
+                raise WebIDLError("Unhandled extended attribute on an argument",
+                                  [attribute.location])
+
+    def isComplete(self):
+        return self._isComplete
+
+    def complete(self, scope):
+        if self._isComplete:
+            return
+
+        self._isComplete = True
+
+        if not self.type.isComplete():
+            type = self.type.complete(scope)
+            assert not isinstance(type, IDLUnresolvedType)
+            assert not isinstance(type, IDLTypedefType)
+            assert not isinstance(type.name, IDLUnresolvedIdentifier)
+            self.type = type
+
+        if ((self.type.isDictionary() or
+             self.type.isUnion() and self.type.unroll().hasDictionaryType) and
+            self.optional and not self.defaultValue):
+            # Default optional dictionaries to null, for simplicity,
+            # so the codegen doesn't have to special-case this.
+            self.defaultValue = IDLNullValue(self.location)
+        elif self.type.isAny():
+            assert (self.defaultValue is None or
+                    isinstance(self.defaultValue, IDLNullValue))
+            # optional 'any' values always have a default value
+            if self.optional and not self.defaultValue and not self.variadic:
+                # Set the default value to undefined, for simplicity, so the
+                # codegen doesn't have to special-case this.
+                self.defaultValue = IDLUndefinedValue(self.location)
+
+        # Now do the coercing thing; this needs to happen after the
+        # above creation of a default value.
+        if self.defaultValue:
+            self.defaultValue = self.defaultValue.coerceToType(self.type,
+                                                               self.location)
+            assert self.defaultValue
+
+    def allowTreatNonCallableAsNull(self):
+        return self._allowTreatNonCallableAsNull
+
+    def _getDependentObjects(self):
+        deps = set([self.type])
+        if self.defaultValue:
+            deps.add(self.defaultValue)
+        return deps
+
+class IDLCallbackType(IDLType, IDLObjectWithScope):
+    def __init__(self, location, parentScope, identifier, returnType, arguments):
+        assert isinstance(returnType, IDLType)
+
+        IDLType.__init__(self, location, identifier.name)
+
+        self._returnType = returnType
+        # Clone the list
+        self._arguments = list(arguments)
+
+        IDLObjectWithScope.__init__(self, location, parentScope, identifier)
+
+        for (returnType, arguments) in self.signatures():
+            for argument in arguments:
+                argument.resolve(self)
+
+        self._treatNonCallableAsNull = False
+        self._treatNonObjectAsNull = False
+
+    def isCallback(self):
+        return True
+
+    def signatures(self):
+        return [(self._returnType, self._arguments)]
+
+    def tag(self):
+        return IDLType.Tags.callback
+
+    def finish(self, scope):
+        if not self._returnType.isComplete():
+            type = self._returnType.complete(scope)
+
+            assert not isinstance(type, IDLUnresolvedType)
+            assert not isinstance(type, IDLTypedefType)
+            assert not isinstance(type.name, IDLUnresolvedIdentifier)
+            self._returnType = type
+
+        for argument in self._arguments:
+            if argument.type.isComplete():
+                continue
+
+            type = argument.type.complete(scope)
+
+            assert not isinstance(type, IDLUnresolvedType)
+            assert not isinstance(type, IDLTypedefType)
+            assert not isinstance(type.name, IDLUnresolvedIdentifier)
+            argument.type = type
+
+    def validate(self):
+        pass
+
+    def isDistinguishableFrom(self, other):
+        if other.isUnion():
+            # Just forward to the union; it'll deal
+            return other.isDistinguishableFrom(self)
+        return (other.isPrimitive() or other.isString() or other.isEnum() or
+                other.isNonCallbackInterface() or other.isDate())
+
+    def addExtendedAttributes(self, attrs):
+        unhandledAttrs = []
+        for attr in attrs:
+            if attr.identifier() == "TreatNonCallableAsNull":
+                self._treatNonCallableAsNull = True
+            elif attr.identifier() == "TreatNonObjectAsNull":
+                self._treatNonObjectAsNull = True
+            else:
+                unhandledAttrs.append(attr)
+        if self._treatNonCallableAsNull and self._treatNonObjectAsNull:
+            raise WebIDLError("Cannot specify both [TreatNonCallableAsNull] "
+                              "and [TreatNonObjectAsNull]", [self.location])
+        if len(unhandledAttrs) != 0:
+            IDLType.addExtendedAttributes(self, unhandledAttrs)
+
+    def _getDependentObjects(self):
+        return set([self._returnType] + self._arguments)
+
+class IDLMethodOverload:
+    """
+    A class that represents a single overload of a WebIDL method.  This is not
+    quite the same as an element of the "effective overload set" in the spec,
+    because separate IDLMethodOverloads are not created based on arguments being
+    optional.  Rather, when multiple methods have the same name, there is an
+    IDLMethodOverload for each one, all hanging off an IDLMethod representing
+    the full set of overloads.
+    """
+    def __init__(self, returnType, arguments, location):
+        self.returnType = returnType
+        # Clone the list of arguments, just in case
+        self.arguments = list(arguments)
+        self.location = location
+
+    def _getDependentObjects(self):
+        deps = set(self.arguments)
+        deps.add(self.returnType)
+        return deps
+
+class IDLMethod(IDLInterfaceMember, IDLScope):
+
+    Special = enum(
+        'Getter',
+        'Setter',
+        'Creator',
+        'Deleter',
+        'LegacyCaller',
+        base=IDLInterfaceMember.Special
+    )
+
+    TypeSuffixModifier = enum(
+        'None',
+        'QMark',
+        'Brackets'
+    )
+
+    NamedOrIndexed = enum(
+        'Neither',
+        'Named',
+        'Indexed'
+    )
+
+    def __init__(self, location, identifier, returnType, arguments,
+                 static=False, getter=False, setter=False, creator=False,
+                 deleter=False, specialType=NamedOrIndexed.Neither,
+                 legacycaller=False, stringifier=False, jsonifier=False):
+        # REVIEW: specialType is NamedOrIndexed -- wow, this is messed up.
+        IDLInterfaceMember.__init__(self, location, identifier,
+                                    IDLInterfaceMember.Tags.Method)
+
+        self._hasOverloads = False
+
+        assert isinstance(returnType, IDLType)
+
+        # self._overloads is a list of IDLMethodOverloads
+        self._overloads = [IDLMethodOverload(returnType, arguments, location)]
+
+        assert isinstance(static, bool)
+        self._static = static
+        assert isinstance(getter, bool)
+        self._getter = getter
+        assert isinstance(setter, bool)
+        self._setter = setter
+        assert isinstance(creator, bool)
+        self._creator = creator
+        assert isinstance(deleter, bool)
+        self._deleter = deleter
+        assert isinstance(legacycaller, bool)
+        self._legacycaller = legacycaller
+        assert isinstance(stringifier, bool)
+        self._stringifier = stringifier
+        assert isinstance(jsonifier, bool)
+        self._jsonifier = jsonifier
+        self._specialType = specialType
+
+        if static and identifier.name == "prototype":
+            raise WebIDLError("The identifier of a static operation must not be 'prototype'",
+                              [location])
+
+        self.assertSignatureConstraints()
+
+    def __str__(self):
+        return "Method '%s'" % self.identifier
+
+    def assertSignatureConstraints(self):
+        if self._getter or self._deleter:
+            assert len(self._overloads) == 1
+            overload = self._overloads[0]
+            arguments =  overload.arguments
+            assert len(arguments) == 1
+            assert arguments[0].type == BuiltinTypes[IDLBuiltinType.Types.domstring] or \
+                   arguments[0].type == BuiltinTypes[IDLBuiltinType.Types.unsigned_long]
+            assert not arguments[0].optional and not arguments[0].variadic
+            assert not self._getter or not overload.returnType.isVoid()
+
+        if self._setter or self._creator:
+            assert len(self._overloads) == 1
+            arguments = self._overloads[0].arguments
+            assert len(arguments) == 2
+            assert arguments[0].type == BuiltinTypes[IDLBuiltinType.Types.domstring] or \
+                   arguments[0].type == BuiltinTypes[IDLBuiltinType.Types.unsigned_long]
+            assert not arguments[0].optional and not arguments[0].variadic
+            assert not arguments[1].optional and not arguments[1].variadic
+
+        if self._stringifier:
+            assert len(self._overloads) == 1
+            overload = self._overloads[0]
+            assert len(overload.arguments) == 0
+            assert overload.returnType == BuiltinTypes[IDLBuiltinType.Types.domstring]
+
+        if self._jsonifier:
+            assert len(self._overloads) == 1
+            overload = self._overloads[0]
+            assert len(overload.arguments) == 0
+            assert overload.returnType == BuiltinTypes[IDLBuiltinType.Types.object]
+
+    def isStatic(self):
+        return self._static
+
+    def isGetter(self):
+        return self._getter
+
+    def isSetter(self):
+        return self._setter
+
+    def isCreator(self):
+        return self._creator
+
+    def isDeleter(self):
+        return self._deleter
+
+    def isNamed(self):
+        assert self._specialType == IDLMethod.NamedOrIndexed.Named or \
+               self._specialType == IDLMethod.NamedOrIndexed.Indexed
+        return self._specialType == IDLMethod.NamedOrIndexed.Named
+
+    def isIndexed(self):
+        assert self._specialType == IDLMethod.NamedOrIndexed.Named or \
+               self._specialType == IDLMethod.NamedOrIndexed.Indexed
+        return self._specialType == IDLMethod.NamedOrIndexed.Indexed
+
+    def isLegacycaller(self):
+        return self._legacycaller
+
+    def isStringifier(self):
+        return self._stringifier
+
+    def isJsonifier(self):
+        return self._jsonifier
+
+    def hasOverloads(self):
+        return self._hasOverloads
+
+    def isIdentifierLess(self):
+        return self.identifier.name[:2] == "__" and self.identifier.name != "__noSuchMethod__"
+
+    def resolve(self, parentScope):
+        assert isinstance(parentScope, IDLScope)
+        IDLObjectWithIdentifier.resolve(self, parentScope)
+        IDLScope.__init__(self, self.location, parentScope, self.identifier)
+        for (returnType, arguments) in self.signatures():
+            for argument in arguments:
+                argument.resolve(self)
+
+    def addOverload(self, method):
+        assert len(method._overloads) == 1
+
+        if self._extendedAttrDict != method ._extendedAttrDict:
+            raise WebIDLError("Extended attributes differ on different "
+                              "overloads of %s" % method.identifier,
+                              [self.location, method.location])
+
+        self._overloads.extend(method._overloads)
+
+        self._hasOverloads = True
+
+        if self.isStatic() != method.isStatic():
+            raise WebIDLError("Overloaded identifier %s appears with different values of the 'static' attribute" % method.identifier,
+                              [method.location])
+
+        if self.isLegacycaller() != method.isLegacycaller():
+            raise WebIDLError("Overloaded identifier %s appears with different values of the 'legacycaller' attribute" % method.identifier,
+                              [method.location])
+
+        # Can't overload special things!
+        assert not self.isGetter()
+        assert not method.isGetter()
+        assert not self.isSetter()
+        assert not method.isSetter()
+        assert not self.isCreator()
+        assert not method.isCreator()
+        assert not self.isDeleter()
+        assert not method.isDeleter()
+        assert not self.isStringifier()
+        assert not method.isStringifier()
+        assert not self.isJsonifier()
+        assert not method.isJsonifier()
+
+        return self
+
+    def signatures(self):
+        return [(overload.returnType, overload.arguments) for overload in
+                self._overloads]
+
+    def finish(self, scope):
+        overloadWithPromiseReturnType = None
+        overloadWithoutPromiseReturnType = None
+        for overload in self._overloads:
+            variadicArgument = None
+
+            arguments = overload.arguments
+            for (idx, argument) in enumerate(arguments):
+                if not argument.isComplete():
+                    argument.complete(scope)
+                assert argument.type.isComplete()
+
+                if (argument.type.isDictionary() or
+                    (argument.type.isUnion() and
+                     argument.type.unroll().hasDictionaryType)):
+                    # Dictionaries and unions containing dictionaries at the
+                    # end of the list or followed by optional arguments must be
+                    # optional.
+                    if (not argument.optional and
+                        all(arg.optional for arg in arguments[idx+1:])):
+                        raise WebIDLError("Dictionary argument or union "
+                                          "argument containing a dictionary "
+                                          "not followed by a required argument "
+                                          "must be optional",
+                                          [argument.location])
+
+                    # An argument cannot be a Nullable Dictionary
+                    if argument.type.nullable():
+                        raise WebIDLError("An argument cannot be a nullable "
+                                          "dictionary or nullable union "
+                                          "containing a dictionary",
+                                          [argument.location])
+
+                # Only the last argument can be variadic
+                if variadicArgument:
+                    raise WebIDLError("Variadic argument is not last argument",
+                                      [variadicArgument.location])
+                if argument.variadic:
+                    variadicArgument = argument
+
+            returnType = overload.returnType
+            if not returnType.isComplete():
+                returnType = returnType.complete(scope)
+                assert not isinstance(returnType, IDLUnresolvedType)
+                assert not isinstance(returnType, IDLTypedefType)
+                assert not isinstance(returnType.name, IDLUnresolvedIdentifier)
+                overload.returnType = returnType
+
+            if returnType.isPromise():
+                overloadWithPromiseReturnType = overload
+            else:
+                overloadWithoutPromiseReturnType = overload
+
+        # Make sure either all our overloads return Promises or none do
+        if overloadWithPromiseReturnType and overloadWithoutPromiseReturnType:
+            raise WebIDLError("We have overloads with both Promise and "
+                              "non-Promise return types",
+                              [overloadWithPromiseReturnType.location,
+                               overloadWithoutPromiseReturnType.location])
+
+        if overloadWithPromiseReturnType and self._legacycaller:
+            raise WebIDLError("May not have a Promise return type for a "
+                              "legacycaller.",
+                              [overloadWithPromiseReturnType.location])
+
+        # Now compute various information that will be used by the
+        # WebIDL overload resolution algorithm.
+        self.maxArgCount = max(len(s[1]) for s in self.signatures())
+        self.allowedArgCounts = [ i for i in range(self.maxArgCount+1)
+                                  if len(self.signaturesForArgCount(i)) != 0 ]
+
+    def validate(self):
+        # Make sure our overloads are properly distinguishable and don't have
+        # different argument types before the distinguishing args.
+        for argCount in self.allowedArgCounts:
+            possibleOverloads = self.overloadsForArgCount(argCount)
+            if len(possibleOverloads) == 1:
+                continue
+            distinguishingIndex = self.distinguishingIndexForArgCount(argCount)
+            for idx in range(distinguishingIndex):
+                firstSigType = possibleOverloads[0].arguments[idx].type
+                for overload in possibleOverloads[1:]:
+                    if overload.arguments[idx].type != firstSigType:
+                        raise WebIDLError(
+                            "Signatures for method '%s' with %d arguments have "
+                            "different types of arguments at index %d, which "
+                            "is before distinguishing index %d" %
+                            (self.identifier.name, argCount, idx,
+                             distinguishingIndex),
+                            [self.location, overload.location])
+
+    def overloadsForArgCount(self, argc):
+        return [overload for overload in self._overloads if
+                len(overload.arguments) == argc or
+                (len(overload.arguments) > argc and
+                 all(arg.optional for arg in overload.arguments[argc:])) or
+                (len(overload.arguments) < argc and
+                 len(overload.arguments) > 0 and
+                 overload.arguments[-1].variadic)]
+
+    def signaturesForArgCount(self, argc):
+        return [(overload.returnType, overload.arguments) for overload
+                in self.overloadsForArgCount(argc)]
+
+    def locationsForArgCount(self, argc):
+        return [overload.location for overload in self.overloadsForArgCount(argc)]
+
+    def distinguishingIndexForArgCount(self, argc):
+        def isValidDistinguishingIndex(idx, signatures):
+            for (firstSigIndex, (firstRetval, firstArgs)) in enumerate(signatures[:-1]):
+                for (secondRetval, secondArgs) in signatures[firstSigIndex+1:]:
+                    if idx < len(firstArgs):
+                        firstType = firstArgs[idx].type
+                    else:
+                        assert(firstArgs[-1].variadic)
+                        firstType = firstArgs[-1].type
+                    if idx < len(secondArgs):
+                        secondType = secondArgs[idx].type
+                    else:
+                        assert(secondArgs[-1].variadic)
+                        secondType = secondArgs[-1].type
+                    if not firstType.isDistinguishableFrom(secondType):
+                        return False
+            return True
+        signatures = self.signaturesForArgCount(argc)
+        for idx in range(argc):
+            if isValidDistinguishingIndex(idx, signatures):
+                return idx
+        # No valid distinguishing index.  Time to throw
+        locations = self.locationsForArgCount(argc)
+        raise WebIDLError("Signatures with %d arguments for method '%s' are not "
+                          "distinguishable" % (argc, self.identifier.name),
+                          locations)
+
+    def handleExtendedAttribute(self, attr):
+        identifier = attr.identifier()
+        if identifier == "GetterThrows":
+            raise WebIDLError("Methods must not be flagged as "
+                              "[GetterThrows]",
+                              [attr.location, self.location])
+        elif identifier == "SetterThrows":
+            raise WebIDLError("Methods must not be flagged as "
+                              "[SetterThrows]",
+                              [attr.location, self.location])
+        elif identifier == "Unforgeable":
+            raise WebIDLError("Methods must not be flagged as "
+                              "[Unforgeable]",
+                              [attr.location, self.location])
+        elif identifier == "SameObject":
+            raise WebIDLError("Methods must not be flagged as [SameObject]",
+                              [attr.location, self.location]);
+        elif identifier == "Constant":
+            raise WebIDLError("Methods must not be flagged as [Constant]",
+                              [attr.location, self.location]);
+        elif identifier == "PutForwards":
+            raise WebIDLError("Only attributes support [PutForwards]",
+                              [attr.location, self.location])
+        elif identifier == "LenientFloat":
+            # This is called before we've done overload resolution
+            assert len(self.signatures()) == 1
+            sig = self.signatures()[0]
+            if not sig[0].isVoid():
+                raise WebIDLError("[LenientFloat] used on a non-void method",
+                                  [attr.location, self.location])
+            if not any(arg.type.includesRestrictedFloat() for arg in sig[1]):
+                raise WebIDLError("[LenientFloat] used on an operation with no "
+                                  "restricted float type arguments",
+                                  [attr.location, self.location])
+        elif (identifier == "Throws" or
+              identifier == "NewObject" or
+              identifier == "ChromeOnly" or
+              identifier == "Pref" or
+              identifier == "Func" or
+              identifier == "AvailableIn" or
+              identifier == "Pure" or
+              identifier == "CrossOriginCallable" or
+              identifier == "Ref" or
+              identifier == "Value" or
+              identifier == "Operator" or
+              identifier == "WebGLHandlesContextLoss"):
+            # Known attributes that we don't need to do anything with here
+            pass
+        else:
+            raise WebIDLError("Unknown extended attribute %s on method" % identifier,
+                              [attr.location])
+        IDLInterfaceMember.handleExtendedAttribute(self, attr)
+
+    def returnsPromise(self):
+        return self._overloads[0].returnType.isPromise()
+
+    def _getDependentObjects(self):
+        deps = set()
+        for overload in self._overloads:
+            deps.union(overload._getDependentObjects())
+        return deps
+
+class IDLImplementsStatement(IDLObject):
+    def __init__(self, location, implementor, implementee):
+        IDLObject.__init__(self, location)
+        self.implementor = implementor;
+        self.implementee = implementee
+
+    def finish(self, scope):
+        assert(isinstance(self.implementor, IDLIdentifierPlaceholder))
+        assert(isinstance(self.implementee, IDLIdentifierPlaceholder))
+        implementor = self.implementor.finish(scope)
+        implementee = self.implementee.finish(scope)
+        # NOTE: we depend on not setting self.implementor and
+        # self.implementee here to keep track of the original
+        # locations.
+        if not isinstance(implementor, IDLInterface):
+            raise WebIDLError("Left-hand side of 'implements' is not an "
+                              "interface",
+                              [self.implementor.location])
+        if implementor.isCallback():
+            raise WebIDLError("Left-hand side of 'implements' is a callback "
+                              "interface",
+                              [self.implementor.location])
+        if not isinstance(implementee, IDLInterface):
+            raise WebIDLError("Right-hand side of 'implements' is not an "
+                              "interface",
+                              [self.implementee.location])
+        if implementee.isCallback():
+            raise WebIDLError("Right-hand side of 'implements' is a callback "
+                              "interface",
+                              [self.implementee.location])
+        implementor.addImplementedInterface(implementee)
+
+    def validate(self):
+        pass
+
+    def addExtendedAttributes(self, attrs):
+        assert len(attrs) == 0
+
+class IDLExtendedAttribute(IDLObject):
+    """
+    A class to represent IDL extended attributes so we can give them locations
+    """
+    def __init__(self, location, tuple):
+        IDLObject.__init__(self, location)
+        self._tuple = tuple
+
+    def identifier(self):
+        return self._tuple[0]
+
+    def noArguments(self):
+        return len(self._tuple) == 1
+
+    def hasValue(self):
+        return len(self._tuple) >= 2 and isinstance(self._tuple[1], str)
+
+    def value(self):
+        assert(self.hasValue())
+        return self._tuple[1]
+
+    def hasArgs(self):
+        return (len(self._tuple) == 2 and isinstance(self._tuple[1], list) or
+                len(self._tuple) == 3)
+
+    def args(self):
+        assert(self.hasArgs())
+        # Our args are our last element
+        return self._tuple[-1]
+
+    def listValue(self):
+        """
+        Backdoor for storing random data in _extendedAttrDict
+        """
+        return list(self._tuple)[1:]
+
+# Parser
+
+class Tokenizer(object):
+    tokens = [
+        "INTEGER",
+        "FLOATLITERAL",
+        "IDENTIFIER",
+        "STRING",
+        "WHITESPACE",
+        "OTHER"
+        ]
+
+    def t_FLOATLITERAL(self, t):
+        r'(-?(([0-9]+\.[0-9]*|[0-9]*\.[0-9]+)([Ee][+-]?[0-9]+)?|[0-9]+[Ee][+-]?[0-9]+|Infinity))|NaN'
+        t.value = float(t.value)
+        return t
+
+    def t_INTEGER(self, t):
+        r'-?(0([0-7]+|[Xx][0-9A-Fa-f]+)?|[1-9][0-9]*)'
+        try:
+            # Can't use int(), because that doesn't handle octal properly.
+            t.value = parseInt(t.value)
+        except:
+            raise WebIDLError("Invalid integer literal",
+                              [Location(lexer=self.lexer,
+                                        lineno=self.lexer.lineno,
+                                        lexpos=self.lexer.lexpos,
+                                        filename=self._filename)])
+        return t
+
+    def t_IDENTIFIER(self, t):
+        r'[A-Z_a-z][0-9A-Z_a-z]*'
+        t.type = self.keywords.get(t.value, 'IDENTIFIER')
+        return t
+
+    def t_STRING(self, t):
+        r'"[^"]*"'
+        t.value = t.value[1:-1]
+        return t
+
+    def t_WHITESPACE(self, t):
+        r'[\t\n\r ]+|[\t\n\r ]*((//[^\n]*|/\*.*?\*/)[\t\n\r ]*)+'
+        pass
+
+    def t_ELLIPSIS(self, t):
+        r'\.\.\.'
+        t.type = self.keywords.get(t.value)
+        return t
+
+    def t_OTHER(self, t):
+        r'[^\t\n\r 0-9A-Z_a-z]'
+        t.type = self.keywords.get(t.value, 'OTHER')
+        return t
+
+    keywords = {
+        "module": "MODULE",
+        "interface": "INTERFACE",
+        "partial": "PARTIAL",
+        "dictionary": "DICTIONARY",
+        "exception": "EXCEPTION",
+        "enum": "ENUM",
+        "callback": "CALLBACK",
+        "typedef": "TYPEDEF",
+        "implements": "IMPLEMENTS",
+        "const": "CONST",
+        "null": "NULL",
+        "true": "TRUE",
+        "false": "FALSE",
+        "serializer": "SERIALIZER",
+        "stringifier": "STRINGIFIER",
+        "jsonifier": "JSONIFIER",
+        "unrestricted": "UNRESTRICTED",
+        "attribute": "ATTRIBUTE",
+        "readonly": "READONLY",
+        "inherit": "INHERIT",
+        "static": "STATIC",
+        "getter": "GETTER",
+        "setter": "SETTER",
+        "creator": "CREATOR",
+        "deleter": "DELETER",
+        "legacycaller": "LEGACYCALLER",
+        "optional": "OPTIONAL",
+        "...": "ELLIPSIS",
+        "::": "SCOPE",
+        "Date": "DATE",
+        "DOMString": "DOMSTRING",
+        "ByteString": "BYTESTRING",
+        "any": "ANY",
+        "boolean": "BOOLEAN",
+        "byte": "BYTE",
+        "double": "DOUBLE",
+        "float": "FLOAT",
+        "long": "LONG",
+        "object": "OBJECT",
+        "octet": "OCTET",
+        "optional": "OPTIONAL",
+        "sequence": "SEQUENCE",
+        "short": "SHORT",
+        "unsigned": "UNSIGNED",
+        "void": "VOID",
+        ":": "COLON",
+        ";": "SEMICOLON",
+        "{": "LBRACE",
+        "}": "RBRACE",
+        "(": "LPAREN",
+        ")": "RPAREN",
+        "[": "LBRACKET",
+        "]": "RBRACKET",
+        "?": "QUESTIONMARK",
+        ",": "COMMA",
+        "=": "EQUALS",
+        "<": "LT",
+        ">": "GT",
+        "ArrayBuffer": "ARRAYBUFFER",
+        "or": "OR"
+        }
+
+    tokens.extend(keywords.values())
+
+    def t_error(self, t):
+        raise WebIDLError("Unrecognized Input",
+               [Location(lexer=self.lexer,
+                         lineno=self.lexer.lineno,
+                         lexpos=self.lexer.lexpos,
+                         filename = self.filename)])
+
+    def __init__(self, outputdir, lexer=None):
+        if lexer:
+            self.lexer = lexer
+        else:
+            self.lexer = lex.lex(object=self,
+                                 outputdir=outputdir,
+                                 lextab='webidllex',
+                                 reflags=re.DOTALL)
+
+class Parser(Tokenizer):
+    def getLocation(self, p, i):
+        return Location(self.lexer, p.lineno(i), p.lexpos(i), self._filename)
+
+    def globalScope(self):
+        return self._globalScope
+
+    # The p_Foo functions here must match the WebIDL spec's grammar.
+    # It's acceptable to split things at '|' boundaries.
+    def p_Definitions(self, p):
+        """ 
+            Definitions : ExtendedAttributeList Definition Definitions
+        """
+        if p[2]:
+            p[0] = [p[2]]
+            p[2].addExtendedAttributes(p[1])
+        else:
+            assert not p[1]
+            p[0] = []
+
+        p[0].extend(p[3])
+
+    def p_DefinitionsEmpty(self, p):
+        """
+            Definitions :
+        """
+        p[0] = []
+
+    def p_Definition(self, p):
+        """
+            Definition : CallbackOrInterface
+                       | PartialInterface
+                       | Dictionary
+                       | Exception
+                       | Enum
+                       | Typedef
+                       | ImplementsStatement
+        """
+        p[0] = p[1]
+        assert p[1] # We might not have implemented something ...
+
+    def p_CallbackOrInterfaceCallback(self, p):
+        """
+            CallbackOrInterface : CALLBACK CallbackRestOrInterface
+        """
+        if p[2].isInterface():
+            assert isinstance(p[2], IDLInterface)
+            p[2].setCallback(True)
+
+        p[0] = p[2]
+
+    def p_CallbackOrInterfaceInterface(self, p):
+        """
+            CallbackOrInterface : Interface
+        """
+        p[0] = p[1]
+
+    def p_CallbackRestOrInterface(self, p):
+        """
+            CallbackRestOrInterface : CallbackRest
+                                    | Interface
+        """
+        assert p[1]
+        p[0] = p[1]
+
+    def p_Interface(self, p):
+        """
+            Interface : INTERFACE IDENTIFIER Inheritance LBRACE InterfaceMembers RBRACE SEMICOLON
+        """
+        location = self.getLocation(p, 1)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 2), p[2])
+        members = p[5]
+        parent = p[3]
+
+        try:
+            if self.globalScope()._lookupIdentifier(identifier):
+                p[0] = self.globalScope()._lookupIdentifier(identifier)
+                if not isinstance(p[0], IDLInterface):
+                    raise WebIDLError("Partial interface has the same name as "
+                                      "non-interface object",
+                                      [location, p[0].location])
+                p[0].setNonPartial(location, parent, members)
+                return
+        except Exception, ex:
+            if isinstance(ex, WebIDLError):
+                raise ex
+            pass
+
+        p[0] = IDLInterface(location, self.globalScope(), identifier, parent,
+                            members, isPartial=False)
+
+    def p_InterfaceForwardDecl(self, p):
+        """
+            Interface : INTERFACE IDENTIFIER SEMICOLON
+        """
+        location = self.getLocation(p, 1)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 2), p[2])
+
+        try:
+            if self.globalScope()._lookupIdentifier(identifier):
+                p[0] = self.globalScope()._lookupIdentifier(identifier)
+                if not isinstance(p[0], IDLExternalInterface):
+                    raise WebIDLError("Name collision between external "
+                                      "interface declaration for identifier "
+                                      "%s and %s" % (identifier.name, p[0]),
+                                      [location, p[0].location])
+                return
+        except Exception, ex:
+            if isinstance(ex, WebIDLError):
+                raise ex
+            pass
+
+        p[0] = IDLExternalInterface(location, self.globalScope(), identifier)
+
+    def p_PartialInterface(self, p):
+        """
+            PartialInterface : PARTIAL INTERFACE IDENTIFIER LBRACE InterfaceMembers RBRACE SEMICOLON
+        """
+        location = self.getLocation(p, 2)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 3), p[3])
+        members = p[5]
+
+        try:
+            if self.globalScope()._lookupIdentifier(identifier):
+                p[0] = self.globalScope()._lookupIdentifier(identifier)
+                if not isinstance(p[0], IDLInterface):
+                    raise WebIDLError("Partial interface has the same name as "
+                                      "non-interface object",
+                                      [location, p[0].location])
+                # Just throw our members into the existing IDLInterface.  If we
+                # have extended attributes, those will get added to it
+                # automatically.
+                p[0].members.extend(members)
+                return
+        except Exception, ex:
+            if isinstance(ex, WebIDLError):
+                raise ex
+            pass
+
+        p[0] = IDLInterface(location, self.globalScope(), identifier, None,
+                            members, isPartial=True)
+        pass
+
+    def p_Inheritance(self, p):
+        """
+            Inheritance : COLON ScopedName
+        """
+        p[0] = IDLIdentifierPlaceholder(self.getLocation(p, 2), p[2])
+
+    def p_InheritanceEmpty(self, p):
+        """
+            Inheritance :
+        """
+        pass
+
+    def p_InterfaceMembers(self, p):
+        """
+            InterfaceMembers : ExtendedAttributeList InterfaceMember InterfaceMembers
+        """
+        p[0] = [p[2]] if p[2] else []
+
+        assert not p[1] or p[2]
+        p[2].addExtendedAttributes(p[1])
+
+        p[0].extend(p[3])
+
+    def p_InterfaceMembersEmpty(self, p):
+        """
+            InterfaceMembers :
+        """
+        p[0] = []
+
+    def p_InterfaceMember(self, p):
+        """
+            InterfaceMember : Const
+                            | AttributeOrOperation
+        """
+        p[0] = p[1]
+
+    def p_Dictionary(self, p):
+        """
+            Dictionary : DICTIONARY IDENTIFIER Inheritance LBRACE DictionaryMembers RBRACE SEMICOLON
+        """
+        location = self.getLocation(p, 1)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 2), p[2])
+        members = p[5]
+        p[0] = IDLDictionary(location, self.globalScope(), identifier, p[3], members)
+
+    def p_DictionaryMembers(self, p):
+        """
+            DictionaryMembers : ExtendedAttributeList DictionaryMember DictionaryMembers
+                             |
+        """
+        if len(p) == 1:
+            # We're at the end of the list
+            p[0] = []
+            return
+        # Add our extended attributes
+        p[2].addExtendedAttributes(p[1])
+        p[0] = [p[2]]
+        p[0].extend(p[3])
+
+    def p_DictionaryMember(self, p):
+        """
+            DictionaryMember : Type IDENTIFIER DefaultValue SEMICOLON
+        """
+        # These quack a lot like optional arguments, so just treat them that way.
+        t = p[1]
+        assert isinstance(t, IDLType)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 2), p[2])
+        defaultValue = p[3]
+
+        p[0] = IDLArgument(self.getLocation(p, 2), identifier, t, optional=True,
+                           defaultValue=defaultValue, variadic=False,
+                           dictionaryMember=True)
+
+    def p_DefaultValue(self, p):
+        """
+            DefaultValue : EQUALS ConstValue
+                         |
+        """
+        if len(p) > 1:
+            p[0] = p[2]
+        else:
+            p[0] = None
+
+    def p_Exception(self, p):
+        """
+            Exception : EXCEPTION IDENTIFIER Inheritance LBRACE ExceptionMembers RBRACE SEMICOLON
+        """
+        pass
+
+    def p_Enum(self, p):
+        """
+            Enum : ENUM IDENTIFIER LBRACE EnumValueList RBRACE SEMICOLON
+        """
+        location = self.getLocation(p, 1)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 2), p[2])
+
+        values = p[4]
+        assert values
+        p[0] = IDLEnum(location, self.globalScope(), identifier, values)
+
+    def p_EnumValueList(self, p):
+        """
+            EnumValueList : STRING EnumValueListComma
+        """
+        p[0] = [p[1]]
+        p[0].extend(p[2])
+
+    def p_EnumValueListComma(self, p):
+        """
+            EnumValueListComma : COMMA EnumValueListString
+        """
+        p[0] = p[2]
+
+    def p_EnumValueListCommaEmpty(self, p):
+        """
+            EnumValueListComma :
+        """
+        p[0] = []
+
+    def p_EnumValueListString(self, p):
+        """
+            EnumValueListString : STRING EnumValueListComma
+        """
+        p[0] = [p[1]]
+        p[0].extend(p[2])
+
+    def p_EnumValueListStringEmpty(self, p):
+        """
+            EnumValueListString :
+        """
+        p[0] = []
+
+    def p_CallbackRest(self, p):
+        """
+            CallbackRest : IDENTIFIER EQUALS ReturnType LPAREN ArgumentList RPAREN SEMICOLON
+        """
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 1), p[1])
+        p[0] = IDLCallbackType(self.getLocation(p, 1), self.globalScope(),
+                               identifier, p[3], p[5])
+
+    def p_ExceptionMembers(self, p):
+        """
+            ExceptionMembers : ExtendedAttributeList ExceptionMember ExceptionMembers
+                             |
+        """
+        pass
+
+    def p_Typedef(self, p):
+        """
+            Typedef : TYPEDEF Type IDENTIFIER SEMICOLON
+        """
+        typedef = IDLTypedefType(self.getLocation(p, 1), p[2], p[3])
+        typedef.resolve(self.globalScope())
+        p[0] = typedef
+
+    def p_ImplementsStatement(self, p):
+        """
+            ImplementsStatement : ScopedName IMPLEMENTS ScopedName SEMICOLON
+        """
+        assert(p[2] == "implements")
+        implementor = IDLIdentifierPlaceholder(self.getLocation(p, 1), p[1])
+        implementee = IDLIdentifierPlaceholder(self.getLocation(p, 3), p[3])
+        p[0] = IDLImplementsStatement(self.getLocation(p, 1), implementor,
+                                      implementee)
+
+    def p_Const(self, p):
+        """
+            Const : CONST ConstType IDENTIFIER EQUALS ConstValue SEMICOLON
+        """
+        location = self.getLocation(p, 1)
+        type = p[2]
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 3), p[3])
+        value = p[5]
+        p[0] = IDLConst(location, identifier, type, value)
+
+    def p_ConstValueBoolean(self, p):
+        """
+            ConstValue : BooleanLiteral
+        """
+        location = self.getLocation(p, 1)
+        booleanType = BuiltinTypes[IDLBuiltinType.Types.boolean]
+        p[0] = IDLValue(location, booleanType, p[1])
+
+    def p_ConstValueInteger(self, p):
+        """
+            ConstValue : INTEGER
+        """
+        location = self.getLocation(p, 1)
+
+        # We don't know ahead of time what type the integer literal is.
+        # Determine the smallest type it could possibly fit in and use that.
+        integerType = matchIntegerValueToType(p[1])
+        if integerType == None:
+            raise WebIDLError("Integer literal out of range", [location])
+
+        p[0] = IDLValue(location, integerType, p[1])
+
+    def p_ConstValueFloat(self, p):
+        """
+            ConstValue : FLOATLITERAL
+        """
+        location = self.getLocation(p, 1)
+        p[0] = IDLValue(location, BuiltinTypes[IDLBuiltinType.Types.unrestricted_float], p[1])
+
+    def p_ConstValueString(self, p):
+        """
+            ConstValue : STRING
+        """
+        location = self.getLocation(p, 1)
+        stringType = BuiltinTypes[IDLBuiltinType.Types.domstring]
+        p[0] = IDLValue(location, stringType, p[1])
+
+    def p_ConstValueNull(self, p):
+        """
+            ConstValue : NULL
+        """
+        p[0] = IDLNullValue(self.getLocation(p, 1))
+
+    def p_BooleanLiteralTrue(self, p):
+        """
+            BooleanLiteral : TRUE
+        """
+        p[0] = True
+
+    def p_BooleanLiteralFalse(self, p):
+        """
+            BooleanLiteral : FALSE
+        """
+        p[0] = False
+
+    def p_AttributeOrOperation(self, p):
+        """
+            AttributeOrOperation : Attribute
+                                 | Operation
+        """
+        p[0] = p[1]
+
+    def p_AttributeWithQualifier(self, p):
+        """
+            Attribute : Qualifier AttributeRest
+        """
+        static = IDLInterfaceMember.Special.Static in p[1]
+        stringifier = IDLInterfaceMember.Special.Stringifier in p[1]
+        (location, identifier, type, readonly) = p[2]
+        p[0] = IDLAttribute(location, identifier, type, readonly, static=static,
+                            stringifier=stringifier)
+
+    def p_Attribute(self, p):
+        """
+            Attribute : Inherit AttributeRest
+        """
+        (location, identifier, type, readonly) = p[2]
+        p[0] = IDLAttribute(location, identifier, type, readonly, inherit=p[1])
+
+    def p_AttributeRest(self, p):
+        """
+            AttributeRest : ReadOnly ATTRIBUTE Type IDENTIFIER SEMICOLON
+        """
+        location = self.getLocation(p, 2)
+        readonly = p[1]
+        t = p[3]
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 4), p[4])
+        p[0] = (location, identifier, t, readonly)
+
+    def p_ReadOnly(self, p):
+        """
+            ReadOnly : READONLY
+        """
+        p[0] = True
+
+    def p_ReadOnlyEmpty(self, p):
+        """
+            ReadOnly :
+        """
+        p[0] = False
+
+    def p_Inherit(self, p):
+        """
+            Inherit : INHERIT
+        """
+        p[0] = True
+
+    def p_InheritEmpty(self, p):
+        """
+            Inherit :
+        """
+        p[0] = False
+
+    def p_Operation(self, p):
+        """
+            Operation : Qualifiers OperationRest
+        """
+        qualifiers = p[1]
+
+        # Disallow duplicates in the qualifier set
+        if not len(set(qualifiers)) == len(qualifiers):
+            raise WebIDLError("Duplicate qualifiers are not allowed",
+                              [self.getLocation(p, 1)])
+
+        static = IDLInterfaceMember.Special.Static in p[1]
+        # If static is there that's all that's allowed.  This is disallowed
+        # by the parser, so we can assert here.
+        assert not static or len(qualifiers) == 1
+
+        stringifier = IDLInterfaceMember.Special.Stringifier in p[1]
+        # If stringifier is there that's all that's allowed.  This is disallowed
+        # by the parser, so we can assert here.
+        assert not stringifier or len(qualifiers) == 1
+
+        getter = True if IDLMethod.Special.Getter in p[1] else False
+        setter = True if IDLMethod.Special.Setter in p[1] else False
+        creator = True if IDLMethod.Special.Creator in p[1] else False
+        deleter = True if IDLMethod.Special.Deleter in p[1] else False
+        legacycaller = True if IDLMethod.Special.LegacyCaller in p[1] else False
+
+        if getter or deleter:
+            if setter or creator:
+                raise WebIDLError("getter and deleter are incompatible with setter and creator",
+                                  [self.getLocation(p, 1)])
+
+        (returnType, identifier, arguments) = p[2]
+
+        assert isinstance(returnType, IDLType)
+
+        specialType = IDLMethod.NamedOrIndexed.Neither
+
+        if getter or deleter:
+            if len(arguments) != 1:
+                raise WebIDLError("%s has wrong number of arguments" %
+                                  ("getter" if getter else "deleter"),
+                                  [self.getLocation(p, 2)])
+            argType = arguments[0].type
+            if argType == BuiltinTypes[IDLBuiltinType.Types.domstring]:
+                specialType = IDLMethod.NamedOrIndexed.Named
+            elif argType == BuiltinTypes[IDLBuiltinType.Types.unsigned_long]:
+                specialType = IDLMethod.NamedOrIndexed.Indexed
+            else:
+                raise WebIDLError("%s has wrong argument type (must be DOMString or UnsignedLong)" %
+                                  ("getter" if getter else "deleter"),
+                                  [arguments[0].location])
+            if arguments[0].optional or arguments[0].variadic:
+                raise WebIDLError("%s cannot have %s argument" %
+                                  ("getter" if getter else "deleter",
+                                   "optional" if arguments[0].optional else "variadic"),
+                                   [arguments[0].location])
+        if getter:
+            if returnType.isVoid():
+                raise WebIDLError("getter cannot have void return type",
+                                  [self.getLocation(p, 2)])
+        if setter or creator:
+            if len(arguments) != 2:
+                raise WebIDLError("%s has wrong number of arguments" %
+                                  ("setter" if setter else "creator"),
+                                  [self.getLocation(p, 2)])
+            argType = arguments[0].type
+            if argType == BuiltinTypes[IDLBuiltinType.Types.domstring]:
+                specialType = IDLMethod.NamedOrIndexed.Named
+            elif argType == BuiltinTypes[IDLBuiltinType.Types.unsigned_long]:
+                specialType = IDLMethod.NamedOrIndexed.Indexed
+            else:
+                raise WebIDLError("%s has wrong argument type (must be DOMString or UnsignedLong)" %
+                                  ("setter" if setter else "creator"),
+                                  [arguments[0].location])
+            if arguments[0].optional or arguments[0].variadic:
+                raise WebIDLError("%s cannot have %s argument" %
+                                  ("setter" if setter else "creator",
+                                   "optional" if arguments[0].optional else "variadic"),
+                                  [arguments[0].location])
+            if arguments[1].optional or arguments[1].variadic:
+                raise WebIDLError("%s cannot have %s argument" %
+                                  ("setter" if setter else "creator",
+                                   "optional" if arguments[1].optional else "variadic"),
+                                  [arguments[1].location])
+
+        if stringifier:
+            if len(arguments) != 0:
+                raise WebIDLError("stringifier has wrong number of arguments",
+                                  [self.getLocation(p, 2)])
+            if not returnType.isDOMString():
+                raise WebIDLError("stringifier must have DOMString return type",
+                                  [self.getLocation(p, 2)])
+
+        # identifier might be None.  This is only permitted for special methods.
+        if not identifier:
+            if not getter and not setter and not creator and \
+               not deleter and not legacycaller and not stringifier:
+                raise WebIDLError("Identifier required for non-special methods",
+                                  [self.getLocation(p, 2)])
+
+            location = BuiltinLocation("<auto-generated-identifier>")
+            identifier = IDLUnresolvedIdentifier(location, "__%s%s%s%s%s%s%s" %
+                ("named" if specialType == IDLMethod.NamedOrIndexed.Named else \
+                 "indexed" if specialType == IDLMethod.NamedOrIndexed.Indexed else "",
+                 "getter" if getter else "",
+                 "setter" if setter else "",
+                 "deleter" if deleter else "",
+                 "creator" if creator else "",
+                 "legacycaller" if legacycaller else "",
+                 "stringifier" if stringifier else ""), allowDoubleUnderscore=True)
+
+        method = IDLMethod(self.getLocation(p, 2), identifier, returnType, arguments,
+                           static=static, getter=getter, setter=setter, creator=creator,
+                           deleter=deleter, specialType=specialType,
+                           legacycaller=legacycaller, stringifier=stringifier)
+        p[0] = method
+
+    def p_Stringifier(self, p):
+        """
+            Operation : STRINGIFIER SEMICOLON
+        """
+        identifier = IDLUnresolvedIdentifier(BuiltinLocation("<auto-generated-identifier>"),
+                                             "__stringifier",
+                                             allowDoubleUnderscore=True)
+        method = IDLMethod(self.getLocation(p, 1),
+                           identifier,
+                           returnType=BuiltinTypes[IDLBuiltinType.Types.domstring],
+                           arguments=[],
+                           stringifier=True)
+        p[0] = method
+
+    def p_Jsonifier(self, p):
+        """
+            Operation : JSONIFIER SEMICOLON
+        """
+        identifier = IDLUnresolvedIdentifier(BuiltinLocation("<auto-generated-identifier>"),
+                                             "__jsonifier", allowDoubleUnderscore=True)
+        method = IDLMethod(self.getLocation(p, 1),
+                           identifier,
+                           returnType=BuiltinTypes[IDLBuiltinType.Types.object],
+                           arguments=[],
+                           jsonifier=True)
+        p[0] = method
+
+    def p_QualifierStatic(self, p):
+        """
+            Qualifier : STATIC
+        """
+        p[0] = [IDLInterfaceMember.Special.Static]
+
+    def p_QualifierStringifier(self, p):
+        """
+            Qualifier : STRINGIFIER
+        """
+        p[0] = [IDLInterfaceMember.Special.Stringifier]
+
+    def p_Qualifiers(self, p):
+        """
+            Qualifiers : Qualifier
+                       | Specials
+        """
+        p[0] = p[1]
+
+    def p_Specials(self, p):
+        """
+            Specials : Special Specials
+        """
+        p[0] = [p[1]]
+        p[0].extend(p[2])
+
+    def p_SpecialsEmpty(self, p):
+        """
+            Specials :
+        """
+        p[0] = []
+
+    def p_SpecialGetter(self, p):
+        """
+            Special : GETTER
+        """
+        p[0] = IDLMethod.Special.Getter
+
+    def p_SpecialSetter(self, p):
+        """
+            Special : SETTER
+        """
+        p[0] = IDLMethod.Special.Setter
+
+    def p_SpecialCreator(self, p):
+        """
+            Special : CREATOR
+        """
+        p[0] = IDLMethod.Special.Creator
+
+    def p_SpecialDeleter(self, p):
+        """
+            Special : DELETER
+        """
+        p[0] = IDLMethod.Special.Deleter
+
+    def p_SpecialLegacyCaller(self, p):
+        """
+            Special : LEGACYCALLER
+        """
+        p[0] = IDLMethod.Special.LegacyCaller
+
+    def p_OperationRest(self, p):
+        """
+            OperationRest : ReturnType OptionalIdentifier LPAREN ArgumentList RPAREN SEMICOLON
+        """
+        p[0] = (p[1], p[2], p[4])
+
+    def p_OptionalIdentifier(self, p):
+        """
+            OptionalIdentifier : IDENTIFIER
+        """
+        p[0] = IDLUnresolvedIdentifier(self.getLocation(p, 1), p[1])
+
+    def p_OptionalIdentifierEmpty(self, p):
+        """
+            OptionalIdentifier :
+        """
+        pass
+
+    def p_ArgumentList(self, p):
+        """
+            ArgumentList : Argument Arguments
+        """
+        p[0] = [p[1]] if p[1] else []
+        p[0].extend(p[2])
+
+    def p_ArgumentListEmpty(self, p):
+        """
+            ArgumentList :
+        """
+        p[0] = []
+
+    def p_Arguments(self, p):
+        """
+            Arguments : COMMA Argument Arguments
+        """
+        p[0] = [p[2]] if p[2] else []
+        p[0].extend(p[3])
+
+    def p_ArgumentsEmpty(self, p):
+        """
+            Arguments :
+        """
+        p[0] = []
+
+    def p_Argument(self, p):
+        """
+            Argument : ExtendedAttributeList Optional Type Ellipsis ArgumentName DefaultValue
+        """
+        t = p[3]
+        assert isinstance(t, IDLType)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 5), p[5])
+
+        optional = p[2]
+        variadic = p[4]
+        defaultValue = p[6]
+
+        if not optional and defaultValue:
+            raise WebIDLError("Mandatory arguments can't have a default value.",
+                              [self.getLocation(p, 6)])
+
+        # We can't test t.isAny() here and give it a default value as needed,
+        # since at this point t is not a fully resolved type yet (e.g. it might
+        # be a typedef).  We'll handle the 'any' case in IDLArgument.complete.
+
+        if variadic:
+            if optional:
+                raise WebIDLError("Variadic arguments should not be marked optional.",
+                                  [self.getLocation(p, 2)])
+            optional = variadic
+
+        p[0] = IDLArgument(self.getLocation(p, 5), identifier, t, optional, defaultValue, variadic)
+        p[0].addExtendedAttributes(p[1])
+
+    def p_ArgumentName(self, p):
+        """
+            ArgumentName : IDENTIFIER
+                         | ATTRIBUTE
+                         | CALLBACK
+                         | CONST
+                         | CREATOR
+                         | DELETER
+                         | DICTIONARY
+                         | ENUM
+                         | EXCEPTION
+                         | GETTER
+                         | IMPLEMENTS
+                         | INHERIT
+                         | INTERFACE
+                         | LEGACYCALLER
+                         | PARTIAL
+                         | SERIALIZER
+                         | SETTER
+                         | STATIC
+                         | STRINGIFIER
+                         | JSONIFIER
+                         | TYPEDEF
+                         | UNRESTRICTED
+        """
+        p[0] = p[1]
+
+    def p_Optional(self, p):
+        """
+            Optional : OPTIONAL
+        """
+        p[0] = True
+
+    def p_OptionalEmpty(self, p):
+        """
+            Optional :
+        """
+        p[0] = False
+
+    def p_Ellipsis(self, p):
+        """
+            Ellipsis : ELLIPSIS
+        """
+        p[0] = True
+
+    def p_EllipsisEmpty(self, p):
+        """
+            Ellipsis :
+        """
+        p[0] = False
+
+    def p_ExceptionMember(self, p):
+        """
+            ExceptionMember : Const
+                            | ExceptionField
+        """
+        pass
+
+    def p_ExceptionField(self, p):
+        """
+            ExceptionField : Type IDENTIFIER SEMICOLON
+        """
+        pass
+
+    def p_ExtendedAttributeList(self, p):
+        """
+            ExtendedAttributeList : LBRACKET ExtendedAttribute ExtendedAttributes RBRACKET
+        """
+        p[0] = [p[2]]
+        if p[3]:
+            p[0].extend(p[3])
+
+    def p_ExtendedAttributeListEmpty(self, p):
+        """
+            ExtendedAttributeList :
+        """
+        p[0] = []
+
+    def p_ExtendedAttribute(self, p):
+        """
+            ExtendedAttribute : ExtendedAttributeNoArgs
+                              | ExtendedAttributeArgList
+                              | ExtendedAttributeIdent
+                              | ExtendedAttributeNamedArgList
+        """
+        p[0] = IDLExtendedAttribute(self.getLocation(p, 1), p[1])
+
+    def p_ExtendedAttributeEmpty(self, p):
+        """
+            ExtendedAttribute :
+        """
+        pass
+
+    def p_ExtendedAttributes(self, p):
+        """
+            ExtendedAttributes : COMMA ExtendedAttribute ExtendedAttributes
+        """
+        p[0] = [p[2]] if p[2] else []
+        p[0].extend(p[3])
+
+    def p_ExtendedAttributesEmpty(self, p):
+        """
+            ExtendedAttributes :
+        """
+        p[0] = []
+
+    def p_Other(self, p):
+        """
+            Other : INTEGER
+                  | FLOATLITERAL
+                  | IDENTIFIER
+                  | STRING
+                  | OTHER
+                  | ELLIPSIS
+                  | COLON
+                  | SCOPE
+                  | SEMICOLON
+                  | LT
+                  | EQUALS
+                  | GT
+                  | QUESTIONMARK
+                  | DATE
+                  | DOMSTRING
+                  | BYTESTRING
+                  | ANY
+                  | ATTRIBUTE
+                  | BOOLEAN
+                  | BYTE
+                  | LEGACYCALLER
+                  | CONST
+                  | CREATOR
+                  | DELETER
+                  | DOUBLE
+                  | EXCEPTION
+                  | FALSE
+                  | FLOAT
+                  | GETTER
+                  | IMPLEMENTS
+                  | INHERIT
+                  | INTERFACE
+                  | LONG
+                  | MODULE
+                  | NULL
+                  | OBJECT
+                  | OCTET
+                  | OPTIONAL
+                  | SEQUENCE
+                  | SETTER
+                  | SHORT
+                  | STATIC
+                  | STRINGIFIER
+                  | JSONIFIER
+                  | TRUE
+                  | TYPEDEF
+                  | UNSIGNED
+                  | VOID
+        """
+        pass
+
+    def p_OtherOrComma(self, p):
+        """
+            OtherOrComma : Other
+                         | COMMA
+        """
+        pass
+
+    def p_TypeSingleType(self, p):
+        """
+            Type : SingleType
+        """
+        p[0] = p[1]
+
+    def p_TypeUnionType(self, p):
+        """
+            Type : UnionType TypeSuffix
+        """
+        p[0] = self.handleModifiers(p[1], p[2])
+
+    def p_SingleTypeNonAnyType(self, p):
+        """
+            SingleType : NonAnyType
+        """
+        p[0] = p[1]
+
+    def p_SingleTypeAnyType(self, p):
+        """
+            SingleType : ANY TypeSuffixStartingWithArray
+        """
+        p[0] = self.handleModifiers(BuiltinTypes[IDLBuiltinType.Types.any], p[2])
+
+    def p_UnionType(self, p):
+        """
+            UnionType : LPAREN UnionMemberType OR UnionMemberType UnionMemberTypes RPAREN
+        """
+        types = [p[2], p[4]]
+        types.extend(p[5])
+        p[0] = IDLUnionType(self.getLocation(p, 1), types)
+
+    def p_UnionMemberTypeNonAnyType(self, p):
+        """
+            UnionMemberType : NonAnyType
+        """
+        p[0] = p[1]
+
+    def p_UnionMemberTypeArrayOfAny(self, p):
+        """
+            UnionMemberTypeArrayOfAny : ANY LBRACKET RBRACKET
+        """
+        p[0] = IDLArrayType(self.getLocation(p, 2),
+                            BuiltinTypes[IDLBuiltinType.Types.any])
+
+    def p_UnionMemberType(self, p):
+        """
+            UnionMemberType : UnionType TypeSuffix
+                            | UnionMemberTypeArrayOfAny TypeSuffix
+        """
+        p[0] = self.handleModifiers(p[1], p[2])
+
+    def p_UnionMemberTypes(self, p):
+        """
+            UnionMemberTypes : OR UnionMemberType UnionMemberTypes
+        """
+        p[0] = [p[2]]
+        p[0].extend(p[3])
+
+    def p_UnionMemberTypesEmpty(self, p):
+        """
+            UnionMemberTypes : 
+        """
+        p[0] = []
+
+    def p_NonAnyType(self, p):
+        """
+            NonAnyType : PrimitiveOrStringType TypeSuffix
+                       | ARRAYBUFFER TypeSuffix
+                       | OBJECT TypeSuffix
+        """
+        if p[1] == "object":
+            type = BuiltinTypes[IDLBuiltinType.Types.object]
+        elif p[1] == "ArrayBuffer":
+            type = BuiltinTypes[IDLBuiltinType.Types.ArrayBuffer]
+        else:
+            type = BuiltinTypes[p[1]]
+
+        p[0] = self.handleModifiers(type, p[2])
+
+    def p_NonAnyTypeSequenceType(self, p):
+        """
+            NonAnyType : SEQUENCE LT Type GT Null
+        """
+        innerType = p[3]
+        type = IDLSequenceType(self.getLocation(p, 1), innerType)
+        if p[5]:
+            type = IDLNullableType(self.getLocation(p, 5), type)
+        p[0] = type
+
+    def p_NonAnyTypeScopedName(self, p):
+        """
+            NonAnyType : ScopedName TypeSuffix
+        """
+        assert isinstance(p[1], IDLUnresolvedIdentifier)
+
+        type = None
+
+        try:
+            if self.globalScope()._lookupIdentifier(p[1]):
+                obj = self.globalScope()._lookupIdentifier(p[1])
+                if obj.isType():
+                    type = obj
+                else:
+                    type = IDLWrapperType(self.getLocation(p, 1), p[1])
+                p[0] = self.handleModifiers(type, p[2])
+                return
+        except:
+            pass
+
+        type = IDLUnresolvedType(self.getLocation(p, 1), p[1])
+        p[0] = self.handleModifiers(type, p[2])
+
+    def p_NonAnyTypeDate(self, p):
+        """
+            NonAnyType : DATE TypeSuffix
+        """
+        p[0] = self.handleModifiers(BuiltinTypes[IDLBuiltinType.Types.date],
+                                    p[2])
+
+    def p_ConstType(self, p):
+        """
+            ConstType : PrimitiveOrStringType Null
+        """
+        type = BuiltinTypes[p[1]]
+        if p[2]:
+            type = IDLNullableType(self.getLocation(p, 1), type)
+        p[0] = type
+
+    def p_ConstTypeIdentifier(self, p):
+        """
+            ConstType : IDENTIFIER Null
+        """
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 1), p[1])
+
+        type = IDLUnresolvedType(self.getLocation(p, 1), identifier)
+        if p[2]:
+            type = IDLNullableType(self.getLocation(p, 1), type)
+        p[0] = type
+
+    def p_PrimitiveOrStringTypeUint(self, p):
+        """
+            PrimitiveOrStringType : UnsignedIntegerType
+        """
+        p[0] = p[1]
+
+    def p_PrimitiveOrStringTypeBoolean(self, p):
+        """
+            PrimitiveOrStringType : BOOLEAN
+        """
+        p[0] = IDLBuiltinType.Types.boolean
+
+    def p_PrimitiveOrStringTypeByte(self, p):
+        """
+            PrimitiveOrStringType : BYTE
+        """
+        p[0] = IDLBuiltinType.Types.byte
+
+    def p_PrimitiveOrStringTypeOctet(self, p):
+        """
+            PrimitiveOrStringType : OCTET
+        """
+        p[0] = IDLBuiltinType.Types.octet
+
+    def p_PrimitiveOrStringTypeFloat(self, p):
+        """
+            PrimitiveOrStringType : FLOAT
+        """
+        p[0] = IDLBuiltinType.Types.float
+
+    def p_PrimitiveOrStringTypeUnrestictedFloat(self, p):
+        """
+            PrimitiveOrStringType : UNRESTRICTED FLOAT
+        """
+        p[0] = IDLBuiltinType.Types.unrestricted_float
+
+    def p_PrimitiveOrStringTypeDouble(self, p):
+        """
+            PrimitiveOrStringType : DOUBLE
+        """
+        p[0] = IDLBuiltinType.Types.double
+
+    def p_PrimitiveOrStringTypeUnrestictedDouble(self, p):
+        """
+            PrimitiveOrStringType : UNRESTRICTED DOUBLE
+        """
+        p[0] = IDLBuiltinType.Types.unrestricted_double
+
+    def p_PrimitiveOrStringTypeDOMString(self, p):
+        """
+            PrimitiveOrStringType : DOMSTRING
+        """
+        p[0] = IDLBuiltinType.Types.domstring
+
+    def p_PrimitiveOrStringTypeBytestring(self, p):
+        """
+            PrimitiveOrStringType : BYTESTRING
+        """
+        p[0] = IDLBuiltinType.Types.bytestring
+
+    def p_UnsignedIntegerTypeUnsigned(self, p):
+        """
+            UnsignedIntegerType : UNSIGNED IntegerType
+        """
+        p[0] = p[2] + 1 # Adding one to a given signed integer type
+                        # gets you the unsigned type.
+
+    def p_UnsignedIntegerType(self, p):
+        """
+            UnsignedIntegerType : IntegerType
+        """
+        p[0] = p[1]
+
+    def p_IntegerTypeShort(self, p):
+        """
+            IntegerType : SHORT
+        """
+        p[0] = IDLBuiltinType.Types.short
+
+    def p_IntegerTypeLong(self, p):
+        """
+            IntegerType : LONG OptionalLong
+        """
+        if p[2]:
+            p[0] = IDLBuiltinType.Types.long_long
+        else:
+            p[0] = IDLBuiltinType.Types.long
+
+    def p_OptionalLong(self, p):
+        """
+            OptionalLong : LONG
+        """
+        p[0] = True
+
+    def p_OptionalLongEmpty(self, p):
+        """
+            OptionalLong :
+        """
+        p[0] = False
+
+    def p_TypeSuffixBrackets(self, p):
+        """
+            TypeSuffix : LBRACKET RBRACKET TypeSuffix
+        """
+        p[0] = [(IDLMethod.TypeSuffixModifier.Brackets, self.getLocation(p, 1))]
+        p[0].extend(p[3])
+
+    def p_TypeSuffixQMark(self, p):
+        """
+            TypeSuffix : QUESTIONMARK TypeSuffixStartingWithArray
+        """
+        p[0] = [(IDLMethod.TypeSuffixModifier.QMark, self.getLocation(p, 1))]
+        p[0].extend(p[2])
+
+    def p_TypeSuffixEmpty(self, p):
+        """
+            TypeSuffix :
+        """
+        p[0] = []
+
+    def p_TypeSuffixStartingWithArray(self, p):
+        """
+            TypeSuffixStartingWithArray : LBRACKET RBRACKET TypeSuffix
+        """
+        p[0] = [(IDLMethod.TypeSuffixModifier.Brackets, self.getLocation(p, 1))]
+        p[0].extend(p[3])
+
+    def p_TypeSuffixStartingWithArrayEmpty(self, p):
+        """
+            TypeSuffixStartingWithArray :
+        """
+        p[0] = []
+
+    def p_Null(self, p):
+        """
+            Null : QUESTIONMARK
+                 |
+        """
+        if len(p) > 1:
+            p[0] = True
+        else:
+            p[0] = False
+
+    def p_ReturnTypeType(self, p):
+        """
+            ReturnType : Type
+        """
+        p[0] = p[1]
+
+    def p_ReturnTypeVoid(self, p):
+        """
+            ReturnType : VOID
+        """
+        p[0] = BuiltinTypes[IDLBuiltinType.Types.void]
+
+    def p_ScopedName(self, p):
+        """
+            ScopedName : AbsoluteScopedName
+                       | RelativeScopedName
+        """
+        p[0] = p[1]
+
+    def p_AbsoluteScopedName(self, p):
+        """
+            AbsoluteScopedName : SCOPE IDENTIFIER ScopedNameParts
+        """
+        assert False
+        pass
+
+    def p_RelativeScopedName(self, p):
+        """
+            RelativeScopedName : IDENTIFIER ScopedNameParts
+        """
+        assert not p[2] # Not implemented!
+
+        p[0] = IDLUnresolvedIdentifier(self.getLocation(p, 1), p[1])
+
+    def p_ScopedNameParts(self, p):
+        """
+            ScopedNameParts : SCOPE IDENTIFIER ScopedNameParts
+        """
+        assert False
+        pass
+
+    def p_ScopedNamePartsEmpty(self, p):
+        """
+            ScopedNameParts :
+        """
+        p[0] = None
+
+    def p_ExtendedAttributeNoArgs(self, p):
+        """
+            ExtendedAttributeNoArgs : IDENTIFIER
+        """
+        p[0] = (p[1],)
+
+    def p_ExtendedAttributeArgList(self, p):
+        """
+            ExtendedAttributeArgList : IDENTIFIER LPAREN ArgumentList RPAREN
+        """
+        p[0] = (p[1], p[3])
+
+    def p_ExtendedAttributeIdent(self, p):
+        """
+            ExtendedAttributeIdent : IDENTIFIER EQUALS STRING
+                                   | IDENTIFIER EQUALS IDENTIFIER
+        """
+        p[0] = (p[1], p[3])
+
+    def p_ExtendedAttributeNamedArgList(self, p):
+        """
+            ExtendedAttributeNamedArgList : IDENTIFIER EQUALS IDENTIFIER LPAREN ArgumentList RPAREN
+        """
+        p[0] = (p[1], p[3], p[5])
+
+    def p_error(self, p):
+        if not p:
+            raise WebIDLError("Syntax Error at end of file. Possibly due to missing semicolon(;), braces(}) or both",
+                              [self._filename])
+        else:
+            raise WebIDLError("invalid syntax", [Location(self.lexer, p.lineno, p.lexpos, self._filename)])
+
+    def __init__(self, outputdir='', lexer=None):
+        Tokenizer.__init__(self, outputdir, lexer)
+        self.parser = yacc.yacc(module=self,
+                                outputdir=outputdir,
+                                tabmodule='webidlyacc',
+                                errorlog=yacc.NullLogger(),
+                                picklefile='WebIDLGrammar.pkl')
+        self._globalScope = IDLScope(BuiltinLocation("<Global Scope>"), None, None)
+        self._installBuiltins(self._globalScope)
+        self._productions = []
+
+        self._filename = "<builtin>"
+        self.lexer.input(Parser._builtins)
+        self._filename = None
+
+        self.parser.parse(lexer=self.lexer,tracking=True)
+
+    def _installBuiltins(self, scope):
+        assert isinstance(scope, IDLScope)
+
+        # xrange omits the last value.
+        for x in xrange(IDLBuiltinType.Types.ArrayBuffer, IDLBuiltinType.Types.Float64Array + 1):
+            builtin = BuiltinTypes[x]
+            name = builtin.name
+
+            typedef = IDLTypedefType(BuiltinLocation("<builtin type>"), builtin, name)
+            typedef.resolve(scope)
+
+    @ staticmethod
+    def handleModifiers(type, modifiers):
+        for (modifier, modifierLocation) in modifiers:
+            assert modifier == IDLMethod.TypeSuffixModifier.QMark or \
+                   modifier == IDLMethod.TypeSuffixModifier.Brackets
+
+            if modifier == IDLMethod.TypeSuffixModifier.QMark:
+                type = IDLNullableType(modifierLocation, type)
+            elif modifier == IDLMethod.TypeSuffixModifier.Brackets:
+                type = IDLArrayType(modifierLocation, type)
+
+        return type
+
+    def parse(self, t, filename=None):
+        self.lexer.input(t)
+
+        #for tok in iter(self.lexer.token, None):
+        #    print tok
+
+        self._filename = filename
+        self._productions.extend(self.parser.parse(lexer=self.lexer,tracking=True))
+        self._filename = None
+
+    def finish(self):
+        # First, finish all the IDLImplementsStatements.  In particular, we
+        # have to make sure we do those before we do the IDLInterfaces.
+        # XXX khuey hates this bit and wants to nuke it from orbit.
+        implementsStatements = [ p for p in self._productions if
+                                 isinstance(p, IDLImplementsStatement)]
+        otherStatements = [ p for p in self._productions if
+                            not isinstance(p, IDLImplementsStatement)]
+        for production in implementsStatements:
+            production.finish(self.globalScope())
+        for production in otherStatements:
+            production.finish(self.globalScope())
+
+        # Do any post-finish validation we need to do
+        for production in self._productions:
+            production.validate()
+
+        # De-duplicate self._productions, without modifying its order.
+        seen = set()
+        result = []
+        for p in self._productions:
+            if p not in seen:
+                seen.add(p)
+                result.append(p)
+        return result
+
+    def reset(self):
+        return Parser(lexer=self.lexer)
+
+    # Builtin IDL defined by WebIDL
+    _builtins = """
+        typedef unsigned long long DOMTimeStamp;
+    """
+
+def main():
+    # Parse arguments.
+    from optparse import OptionParser
+    usageString = "usage: %prog [options] files"
+    o = OptionParser(usage=usageString)
+    o.add_option("--cachedir", dest='cachedir', default=None,
+                 help="Directory in which to cache lex/parse tables.")
+    o.add_option("--verbose-errors", action='store_true', default=False,
+                 help="When an error happens, display the Python traceback.")
+    (options, args) = o.parse_args()
+
+    if len(args) < 1:
+        o.error(usageString)
+
+    fileList = args
+    baseDir = os.getcwd()
+
+    # Parse the WebIDL.
+    parser = Parser(options.cachedir)
+    try:
+        for filename in fileList:
+            fullPath = os.path.normpath(os.path.join(baseDir, filename))
+            f = open(fullPath, 'rb')
+            lines = f.readlines()
+            f.close()
+            print fullPath
+            parser.parse(''.join(lines), fullPath)
+        parser.finish()
+    except WebIDLError, e:
+        if options.verbose_errors:
+            traceback.print_exc()
+        else:
+            print e
+
+if __name__ == '__main__':
+    main()
+
diff --git a/third_party/__init__.py b/third_party/__init__.py
new file mode 100644
index 00000000..8fa2136f
--- /dev/null
+++ b/third_party/__init__.py
@@ -0,0 +1,2 @@
+#
+