Put uglify back the way it was.

Makes for an easier-to-review pull request.

1 files changed, 1856 insertions, 780 deletions

diff --git a/tools/eliminator/node_modules/uglify-js/lib/process.js b/tools/eliminator/node_modules/uglify-js/lib/process.js
index 88ce490f..da38caa7 100644
--- a/tools/eliminator/node_modules/uglify-js/lib/process.js
+++ b/tools/eliminator/node_modules/uglify-js/lib/process.js
@@ -1,6 +1,6 @@
 /***********************************************************************
 
-  A JavaScript tokenizer / parser / beautifier.
+  A JavaScript tokenizer / parser / beautifier / compressor.
 
   This version is suitable for Node.js.  With minimal changes (the
   exports stuff) it should work on any JS platform.
@@ -10,6 +10,12 @@
 
   Exported functions:
 
+    - ast_mangle(ast, options) -- mangles the variable/function names
+      in the AST.  Returns an AST.
+
+    - ast_squeeze(ast) -- employs various optimizations to make the
+      final generated code even smaller.  Returns an AST.
+
     - gen_code(ast, options) -- generates JS code from the AST.  Pass
       true (or an object, see the code for some options) as second
       argument to get "pretty" (indented) code.
@@ -59,8 +65,8 @@ var jsp = require("./parse-js"),
     OPERATORS = jsp.OPERATORS;
 
 function NodeWithLine(str, line) {
-  this.str = str;
-  this.line = line;
+    this.str = str;
+    this.line = line;
 }
 
 NodeWithLine.prototype = new String();
@@ -74,809 +80,1871 @@ String.prototype.lineComment = function() { return ""; }
 /* -----[ helper for AST traversal ]----- */
 
 function ast_walker() {
-  function _vardefs(defs) {
-    return [ this[0], MAP(defs, function(def){
-      var a = [ def[0] ];
-      if (def.length > 1)
-        a[1] = walk(def[1]);
-      return a;
-    }) ];
-  };
-  function _block(statements) {
-    var out = [ this[0] ];
-    if (statements != null)
-      out.push(MAP(statements, walk));
-    return out;
-  };
-  var walkers = {
-    "string": function(str) {
-      return [ this[0], str ];
-    },
-    "num": function(num) {
-      return [ this[0], num ];
-    },
-    "name": function(name) {
-      return [ this[0], name ];
-    },
-    "toplevel": function(statements) {
-      return [ this[0], MAP(statements, walk) ];
-    },
-    "block": _block,
-    "splice": _block,
-    "var": _vardefs,
-    "const": _vardefs,
-    "try": function(t, c, f) {
-      return [
-        this[0],
-        MAP(t, walk),
-        c != null ? [ c[0], MAP(c[1], walk) ] : null,
-        f != null ? MAP(f, walk) : null
-      ];
-    },
-    "throw": function(expr) {
-      return [ this[0], walk(expr) ];
-    },
-    "new": function(ctor, args) {
-      return [ this[0], walk(ctor), MAP(args, walk) ];
-    },
-    "switch": function(expr, body) {
-      return [ this[0], walk(expr), MAP(body, function(branch){
-        return [ branch[0] ? walk(branch[0]) : null,
-          MAP(branch[1], walk) ];
-      }) ];
-    },
-    "break": function(label) {
-      return [ this[0], label ];
-    },
-    "continue": function(label) {
-      return [ this[0], label ];
-    },
-    "conditional": function(cond, t, e) {
-      return [ this[0], walk(cond), walk(t), walk(e) ];
-    },
-    "assign": function(op, lvalue, rvalue) {
-      return [ this[0], op, walk(lvalue), walk(rvalue) ];
-    },
-    "dot": function(expr) {
-      return [ this[0], walk(expr) ].concat(slice(arguments, 1));
-    },
-    "call": function(expr, args) {
-      return [ this[0], walk(expr), MAP(args, walk) ];
-    },
-    "function": function(name, args, body) {
-      return [ this[0], name, args.slice(), MAP(body, walk) ];
-    },
-    "defun": function(name, args, body) {
-      return [ this[0], name, args.slice(), MAP(body, walk) ];
-    },
-    "if": function(conditional, t, e) {
-      return [ this[0], walk(conditional), walk(t), walk(e) ];
-    },
-    "for": function(init, cond, step, block) {
-      return [ this[0], walk(init), walk(cond), walk(step), walk(block) ];
-    },
-    "for-in": function(vvar, key, hash, block) {
-      return [ this[0], walk(vvar), walk(key), walk(hash), walk(block) ];
-    },
-    "while": function(cond, block) {
-      return [ this[0], walk(cond), walk(block) ];
-    },
-    "do": function(cond, block) {
-      return [ this[0], walk(cond), walk(block) ];
-    },
-    "return": function(expr) {
-      return [ this[0], walk(expr) ];
-    },
-    "binary": function(op, left, right) {
-      return [ this[0], op, walk(left), walk(right) ];
-    },
-    "unary-prefix": function(op, expr) {
-      return [ this[0], op, walk(expr) ];
-    },
-    "unary-postfix": function(op, expr) {
-      return [ this[0], op, walk(expr) ];
-    },
-    "sub": function(expr, subscript) {
-      return [ this[0], walk(expr), walk(subscript) ];
-    },
-    "object": function(props) {
-      return [ this[0], MAP(props, function(p){
-        return p.length == 2
-        ? [ p[0], walk(p[1]) ]
-        : [ p[0], walk(p[1]), p[2] ]; // get/set-ter
-      }) ];
-    },
-    "regexp": function(rx, mods) {
-      return [ this[0], rx, mods ];
-    },
-    "array": function(elements) {
-      return [ this[0], MAP(elements, walk) ];
-    },
-    "stat": function(stat) {
-      return [ this[0], walk(stat) ];
-    },
-    "seq": function() {
-      return [ this[0] ].concat(MAP(slice(arguments), walk));
-    },
-    "label": function(name, block) {
-      return [ this[0], name, walk(block) ];
-    },
-    "with": function(expr, block) {
-      return [ this[0], walk(expr), walk(block) ];
-    },
-    "atom": function(name) {
-      return [ this[0], name ];
-    }
-  };
-
-  var user = {};
-  var stack = [];
-  function walk(ast) {
-    if (ast == null)
-      return null;
-    try {
-      stack.push(ast);
-      var type = ast[0];
-      var gen = user[type];
-      if (gen) {
-        var ret = gen.apply(ast, ast.slice(1));
-        if (ret != null)
-          return ret;
-      }
-      gen = walkers[type];
-      return gen.apply(ast, ast.slice(1));
-    } finally {
-      stack.pop();
-    }
-  };
-
-  function with_walkers(walkers, cont){
-    var save = {}, i;
-    for (i in walkers) if (HOP(walkers, i)) {
-      save[i] = user[i];
-      user[i] = walkers[i];
-    }
-    var ret = cont();
-    for (i in save) if (HOP(save, i)) {
-      if (!save[i]) delete user[i];
-      else user[i] = save[i];
-    }
-    return ret;
-  };
-
-  return {
-    walk: walk,
-    with_walkers: with_walkers,
-    parent: function() {
-      return stack[stack.length - 2]; // last one is current node
-    },
-    stack: function() {
-      return stack;
-    }
-  };
+        function _vardefs(defs) {
+                return [ this[0], MAP(defs, function(def){
+                        var a = [ def[0] ];
+                        if (def.length > 1)
+                                a[1] = walk(def[1]);
+                        return a;
+                }) ];
+        };
+        function _block(statements) {
+                var out = [ this[0] ];
+                if (statements != null)
+                        out.push(MAP(statements, walk));
+                return out;
+        };
+        var walkers = {
+                "string": function(str) {
+                        return [ this[0], str ];
+                },
+                "num": function(num) {
+                        return [ this[0], num ];
+                },
+                "name": function(name) {
+                        return [ this[0], name ];
+                },
+                "toplevel": function(statements) {
+                        return [ this[0], MAP(statements, walk) ];
+                },
+                "block": _block,
+                "splice": _block,
+                "var": _vardefs,
+                "const": _vardefs,
+                "try": function(t, c, f) {
+                        return [
+                                this[0],
+                                MAP(t, walk),
+                                c != null ? [ c[0], MAP(c[1], walk) ] : null,
+                                f != null ? MAP(f, walk) : null
+                        ];
+                },
+                "throw": function(expr) {
+                        return [ this[0], walk(expr) ];
+                },
+                "new": function(ctor, args) {
+                        return [ this[0], walk(ctor), MAP(args, walk) ];
+                },
+                "switch": function(expr, body) {
+                        return [ this[0], walk(expr), MAP(body, function(branch){
+                                return [ branch[0] ? walk(branch[0]) : null,
+                                         MAP(branch[1], walk) ];
+                        }) ];
+                },
+                "break": function(label) {
+                        return [ this[0], label ];
+                },
+                "continue": function(label) {
+                        return [ this[0], label ];
+                },
+                "conditional": function(cond, t, e) {
+                        return [ this[0], walk(cond), walk(t), walk(e) ];
+                },
+                "assign": function(op, lvalue, rvalue) {
+                        return [ this[0], op, walk(lvalue), walk(rvalue) ];
+                },
+                "dot": function(expr) {
+                        return [ this[0], walk(expr) ].concat(slice(arguments, 1));
+                },
+                "call": function(expr, args) {
+                        return [ this[0], walk(expr), MAP(args, walk) ];
+                },
+                "function": function(name, args, body) {
+                        return [ this[0], name, args.slice(), MAP(body, walk) ];
+                },
+                "defun": function(name, args, body) {
+                        return [ this[0], name, args.slice(), MAP(body, walk) ];
+                },
+                "if": function(conditional, t, e) {
+                        return [ this[0], walk(conditional), walk(t), walk(e) ];
+                },
+                "for": function(init, cond, step, block) {
+                        return [ this[0], walk(init), walk(cond), walk(step), walk(block) ];
+                },
+                "for-in": function(vvar, key, hash, block) {
+                        return [ this[0], walk(vvar), walk(key), walk(hash), walk(block) ];
+                },
+                "while": function(cond, block) {
+                        return [ this[0], walk(cond), walk(block) ];
+                },
+                "do": function(cond, block) {
+                        return [ this[0], walk(cond), walk(block) ];
+                },
+                "return": function(expr) {
+                        return [ this[0], walk(expr) ];
+                },
+                "binary": function(op, left, right) {
+                        return [ this[0], op, walk(left), walk(right) ];
+                },
+                "unary-prefix": function(op, expr) {
+                        return [ this[0], op, walk(expr) ];
+                },
+                "unary-postfix": function(op, expr) {
+                        return [ this[0], op, walk(expr) ];
+                },
+                "sub": function(expr, subscript) {
+                        return [ this[0], walk(expr), walk(subscript) ];
+                },
+                "object": function(props) {
+                        return [ this[0], MAP(props, function(p){
+                                return p.length == 2
+                                        ? [ p[0], walk(p[1]) ]
+                                        : [ p[0], walk(p[1]), p[2] ]; // get/set-ter
+                        }) ];
+                },
+                "regexp": function(rx, mods) {
+                        return [ this[0], rx, mods ];
+                },
+                "array": function(elements) {
+                        return [ this[0], MAP(elements, walk) ];
+                },
+                "stat": function(stat) {
+                        return [ this[0], walk(stat) ];
+                },
+                "seq": function() {
+                        return [ this[0] ].concat(MAP(slice(arguments), walk));
+                },
+                "label": function(name, block) {
+                        return [ this[0], name, walk(block) ];
+                },
+                "with": function(expr, block) {
+                        return [ this[0], walk(expr), walk(block) ];
+                },
+                "atom": function(name) {
+                        return [ this[0], name ];
+                }
+        };
+
+        var user = {};
+        var stack = [];
+        function walk(ast) {
+                if (ast == null)
+                        return null;
+                try {
+                        stack.push(ast);
+                        var type = ast[0];
+                        var gen = user[type];
+                        if (gen) {
+                                var ret = gen.apply(ast, ast.slice(1));
+                                if (ret != null)
+                                        return ret;
+                        }
+                        gen = walkers[type];
+                        return gen.apply(ast, ast.slice(1));
+                } finally {
+                        stack.pop();
+                }
+        };
+
+        function with_walkers(walkers, cont){
+                var save = {}, i;
+                for (i in walkers) if (HOP(walkers, i)) {
+                        save[i] = user[i];
+                        user[i] = walkers[i];
+                }
+                var ret = cont();
+                for (i in save) if (HOP(save, i)) {
+                        if (!save[i]) delete user[i];
+                        else user[i] = save[i];
+                }
+                return ret;
+        };
+
+        return {
+                walk: walk,
+                with_walkers: with_walkers,
+                parent: function() {
+                        return stack[stack.length - 2]; // last one is current node
+                },
+                stack: function() {
+                        return stack;
+                }
+        };
+};
+
+/* -----[ Scope and mangling ]----- */
+
+function Scope(parent) {
+        this.names = {};        // names defined in this scope
+        this.mangled = {};      // mangled names (orig.name => mangled)
+        this.rev_mangled = {};  // reverse lookup (mangled => orig.name)
+        this.cname = -1;        // current mangled name
+        this.refs = {};         // names referenced from this scope
+        this.uses_with = false; // will become TRUE if with() is detected in this or any subscopes
+        this.uses_eval = false; // will become TRUE if eval() is detected in this or any subscopes
+        this.parent = parent;   // parent scope
+        this.children = [];     // sub-scopes
+        if (parent) {
+                this.level = parent.level + 1;
+                parent.children.push(this);
+        } else {
+                this.level = 0;
+        }
+};
+
+var base54 = (function(){
+        var DIGITS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$_";
+        return function(num) {
+                var ret = "";
+                do {
+                        ret = DIGITS.charAt(num % 54) + ret;
+                        num = Math.floor(num / 54);
+                } while (num > 0);
+                return ret;
+        };
+})();
+
+Scope.prototype = {
+        has: function(name) {
+                for (var s = this; s; s = s.parent)
+                        if (HOP(s.names, name))
+                                return s;
+        },
+        has_mangled: function(mname) {
+                for (var s = this; s; s = s.parent)
+                        if (HOP(s.rev_mangled, mname))
+                                return s;
+        },
+        toJSON: function() {
+                return {
+                        names: this.names,
+                        uses_eval: this.uses_eval,
+                        uses_with: this.uses_with
+                };
+        },
+
+        next_mangled: function() {
+                // we must be careful that the new mangled name:
+                //
+                // 1. doesn't shadow a mangled name from a parent
+                //    scope, unless we don't reference the original
+                //    name from this scope OR from any sub-scopes!
+                //    This will get slow.
+                //
+                // 2. doesn't shadow an original name from a parent
+                //    scope, in the event that the name is not mangled
+                //    in the parent scope and we reference that name
+                //    here OR IN ANY SUBSCOPES!
+                //
+                // 3. doesn't shadow a name that is referenced but not
+                //    defined (possibly global defined elsewhere).
+                for (;;) {
+                        var m = base54(++this.cname), prior;
+
+                        // case 1.
+                        prior = this.has_mangled(m);
+                        if (prior && this.refs[prior.rev_mangled[m]] === prior)
+                                continue;
+
+                        // case 2.
+                        prior = this.has(m);
+                        if (prior && prior !== this && this.refs[m] === prior && !prior.has_mangled(m))
+                                continue;
+
+                        // case 3.
+                        if (HOP(this.refs, m) && this.refs[m] == null)
+                                continue;
+
+                        // I got "do" once. :-/
+                        if (!is_identifier(m))
+                                continue;
+
+                        return m;
+                }
+        },
+        set_mangle: function(name, m) {
+                this.rev_mangled[m] = name;
+                return this.mangled[name] = m;
+        },
+        get_mangled: function(name, newMangle) {
+                if (this.uses_eval || this.uses_with) return name; // no mangle if eval or with is in use
+                var s = this.has(name);
+                if (!s) return name; // not in visible scope, no mangle
+                if (HOP(s.mangled, name)) return s.mangled[name]; // already mangled in this scope
+                if (!newMangle) return name;                      // not found and no mangling requested
+                return s.set_mangle(name, s.next_mangled());
+        },
+        references: function(name) {
+                return name && !this.parent || this.uses_with || this.uses_eval || this.refs[name];
+        },
+        define: function(name, type) {
+                if (name != null) {
+                        if (type == "var" || !HOP(this.names, name))
+                                this.names[name] = type || "var";
+                        return name;
+                }
+        }
+};
+
+function ast_add_scope(ast) {
+
+        var current_scope = null;
+        var w = ast_walker(), walk = w.walk;
+        var having_eval = [];
+
+        function with_new_scope(cont) {
+                current_scope = new Scope(current_scope);
+                var ret = current_scope.body = cont();
+                ret.scope = current_scope;
+                current_scope = current_scope.parent;
+                return ret;
+        };
+
+        function define(name, type) {
+                return current_scope.define(name, type);
+        };
+
+        function reference(name) {
+                current_scope.refs[name] = true;
+        };
+
+        function _lambda(name, args, body) {
+                var is_defun = this[0] == "defun";
+                return [ this[0], is_defun ? define(name, "defun") : name, args, with_new_scope(function(){
+                        if (!is_defun) define(name, "lambda");
+                        MAP(args, function(name){ define(name, "arg") });
+                        return MAP(body, walk);
+                })];
+        };
+
+        function _vardefs(type) {
+                return function(defs) {
+                        MAP(defs, function(d){
+                                define(d[0], type);
+                                if (d[1]) reference(d[0]);
+                        });
+                };
+        };
+
+        return with_new_scope(function(){
+                // process AST
+                var ret = w.with_walkers({
+                        "function": _lambda,
+                        "defun": _lambda,
+                        "label": function(name, stat) { define(name, "label") },
+                        "break": function(label) { if (label) reference(label) },
+                        "continue": function(label) { if (label) reference(label) },
+                        "with": function(expr, block) {
+                                for (var s = current_scope; s; s = s.parent)
+                                        s.uses_with = true;
+                        },
+                        "var": _vardefs("var"),
+                        "const": _vardefs("const"),
+                        "try": function(t, c, f) {
+                                if (c != null) return [
+                                        this[0],
+                                        MAP(t, walk),
+                                        [ define(c[0], "catch"), MAP(c[1], walk) ],
+                                        f != null ? MAP(f, walk) : null
+                                ];
+                        },
+                        "name": function(name) {
+                                if (name == "eval")
+                                        having_eval.push(current_scope);
+                                reference(name);
+                        }
+                }, function(){
+                        return walk(ast);
+                });
+
+                // the reason why we need an additional pass here is
+                // that names can be used prior to their definition.
+
+                // scopes where eval was detected and their parents
+                // are marked with uses_eval, unless they define the
+                // "eval" name.
+                MAP(having_eval, function(scope){
+                        if (!scope.has("eval")) while (scope) {
+                                scope.uses_eval = true;
+                                scope = scope.parent;
+                        }
+                });
+
+                // for referenced names it might be useful to know
+                // their origin scope.  current_scope here is the
+                // toplevel one.
+                function fixrefs(scope, i) {
+                        // do children first; order shouldn't matter
+                        for (i = scope.children.length; --i >= 0;)
+                                fixrefs(scope.children[i]);
+                        for (i in scope.refs) if (HOP(scope.refs, i)) {
+                                // find origin scope and propagate the reference to origin
+                                for (var origin = scope.has(i), s = scope; s; s = s.parent) {
+                                        s.refs[i] = origin;
+                                        if (s === origin) break;
+                                }
+                        }
+                };
+                fixrefs(current_scope);
+
+                return ret;
+        });
+
+};
+
+/* -----[ mangle names ]----- */
+
+function ast_mangle(ast, options) {
+        var w = ast_walker(), walk = w.walk, scope;
+        options = options || {};
+
+        function get_mangled(name, newMangle) {
+                if (!options.toplevel && !scope.parent) return name; // don't mangle toplevel
+                if (options.except && member(name, options.except))
+                        return name;
+                return scope.get_mangled(name, newMangle);
+        };
+
+        function get_define(name) {
+                if (options.defines) {
+                        // we always lookup a defined symbol for the current scope FIRST, so declared
+                        // vars trump a DEFINE symbol, but if no such var is found, then match a DEFINE value
+                        if (!scope.has(name)) {
+                                if (HOP(options.defines, name)) {
+                                        return options.defines[name];
+                                }
+                        }
+                        return null;
+                }
+        };
+
+        function _lambda(name, args, body) {
+                var is_defun = this[0] == "defun", extra;
+                if (name) {
+                        if (is_defun) name = get_mangled(name);
+                        else {
+                                extra = {};
+                                if (!(scope.uses_eval || scope.uses_with))
+                                        name = extra[name] = scope.next_mangled();
+                                else
+                                        extra[name] = name;
+                        }
+                }
+                body = with_scope(body.scope, function(){
+                        args = MAP(args, function(name){ return get_mangled(name) });
+                        return MAP(body, walk);
+                }, extra);
+                return [ this[0], name, args, body ];
+        };
+
+        function with_scope(s, cont, extra) {
+                var _scope = scope;
+                scope = s;
+                if (extra) for (var i in extra) if (HOP(extra, i)) {
+                        s.set_mangle(i, extra[i]);
+                }
+                for (var i in s.names) if (HOP(s.names, i)) {
+                        get_mangled(i, true);
+                }
+                var ret = cont();
+                ret.scope = s;
+                scope = _scope;
+                return ret;
+        };
+
+        function _vardefs(defs) {
+                return [ this[0], MAP(defs, function(d){
+                        return [ get_mangled(d[0]), walk(d[1]) ];
+                }) ];
+        };
+
+        return w.with_walkers({
+                "function": _lambda,
+                "defun": function() {
+                        // move function declarations to the top when
+                        // they are not in some block.
+                        var ast = _lambda.apply(this, arguments);
+                        switch (w.parent()[0]) {
+                            case "toplevel":
+                            case "function":
+                            case "defun":
+                                return MAP.at_top(ast);
+                        }
+                        return ast;
+                },
+                "label": function(label, stat) { return [ this[0], get_mangled(label), walk(stat) ] },
+                "break": function(label) { if (label) return [ this[0], get_mangled(label) ] },
+                "continue": function(label) { if (label) return [ this[0], get_mangled(label) ] },
+                "var": _vardefs,
+                "const": _vardefs,
+                "name": function(name) {
+                        return get_define(name) || [ this[0], get_mangled(name) ];
+                },
+                "try": function(t, c, f) {
+                        return [ this[0],
+                                 MAP(t, walk),
+                                 c != null ? [ get_mangled(c[0]), MAP(c[1], walk) ] : null,
+                                 f != null ? MAP(f, walk) : null ];
+                },
+                "toplevel": function(body) {
+                        var self = this;
+                        return with_scope(self.scope, function(){
+                                return [ self[0], MAP(body, walk) ];
+                        });
+                }
+        }, function() {
+                return walk(ast_add_scope(ast));
+        });
 };
 
+/* -----[
+   - compress foo["bar"] into foo.bar,
+   - remove block brackets {} where possible
+   - join consecutive var declarations
+   - various optimizations for IFs:
+     - if (cond) foo(); else bar();  ==>  cond?foo():bar();
+     - if (cond) foo();  ==>  cond&&foo();
+     - if (foo) return bar(); else return baz();  ==> return foo?bar():baz(); // also for throw
+     - if (foo) return bar(); else something();  ==> {if(foo)return bar();something()}
+   ]----- */
+
 var warn = function(){};
 
 function best_of(ast1, ast2) {
-  return gen_code(ast1).length > gen_code(ast2[0] == "stat" ? ast2[1] : ast2).length ? ast2 : ast1;
+        return gen_code(ast1).length > gen_code(ast2[0] == "stat" ? ast2[1] : ast2).length ? ast2 : ast1;
 };
 
 function last_stat(b) {
-  if (b[0] == "block" && b[1] && b[1].length > 0)
-    return b[1][b[1].length - 1];
-  return b;
+        if (b[0] == "block" && b[1] && b[1].length > 0)
+                return b[1][b[1].length - 1];
+        return b;
 }
 
 function aborts(t) {
-  if (t) switch (last_stat(t)[0]) {
-    case "return":
-    case "break":
-    case "continue":
-    case "throw":
-      return true;
-  }
+        if (t) switch (last_stat(t)[0]) {
+            case "return":
+            case "break":
+            case "continue":
+            case "throw":
+                return true;
+        }
 };
 
 function boolean_expr(expr) {
-  return ((expr[0] == "unary-prefix"
-      && member(expr[1], [ "!", "delete" ])) ||
+        return ( (expr[0] == "unary-prefix"
+                  && member(expr[1], [ "!", "delete" ])) ||
 
-     (expr[0] == "binary"
-      && member(expr[1], [ "in", "instanceof", "==", "!=", "===", "!==", "<", "<=", ">=", ">" ])) ||
+                 (expr[0] == "binary"
+                  && member(expr[1], [ "in", "instanceof", "==", "!=", "===", "!==", "<", "<=", ">=", ">" ])) ||
 
-     (expr[0] == "binary"
-      && member(expr[1], [ "&&", "||" ])
-      && boolean_expr(expr[2])
-      && boolean_expr(expr[3])) ||
+                 (expr[0] == "binary"
+                  && member(expr[1], [ "&&", "||" ])
+                  && boolean_expr(expr[2])
+                  && boolean_expr(expr[3])) ||
 
-     (expr[0] == "conditional"
-      && boolean_expr(expr[2])
-      && boolean_expr(expr[3])) ||
+                 (expr[0] == "conditional"
+                  && boolean_expr(expr[2])
+                  && boolean_expr(expr[3])) ||
 
-     (expr[0] == "assign"
-      && expr[1] === true
-      && boolean_expr(expr[3])) ||
+                 (expr[0] == "assign"
+                  && expr[1] === true
+                  && boolean_expr(expr[3])) ||
 
-     (expr[0] == "seq"
-      && boolean_expr(expr[expr.length - 1])));
+                 (expr[0] == "seq"
+                  && boolean_expr(expr[expr.length - 1]))
+               );
+};
+
+function make_conditional(c, t, e) {
+    var make_real_conditional = function() {
+        if (c[0] == "unary-prefix" && c[1] == "!") {
+            return e ? [ "conditional", c[2], e, t ] : [ "binary", "||", c[2], t ];
+        } else {
+            return e ? [ "conditional", c, t, e ] : [ "binary", "&&", c, t ];
+        }
+    };
+    // shortcut the conditional if the expression has a constant value
+    return when_constant(c, function(ast, val){
+        warn_unreachable(val ? e : t);
+        return          (val ? t : e);
+    }, make_real_conditional);
 };
 
 function empty(b) {
-  return !b || (b[0] == "block" && (!b[1] || b[1].length == 0));
+        return !b || (b[0] == "block" && (!b[1] || b[1].length == 0));
 };
 
 function is_string(node) {
-  return (node[0] == "string" ||
-          node[0] == "unary-prefix" && node[1] == "typeof" ||
-          node[0] == "binary" && node[1] == "+" &&
-          (is_string(node[2]) || is_string(node[3])));
+        return (node[0] == "string" ||
+                node[0] == "unary-prefix" && node[1] == "typeof" ||
+                node[0] == "binary" && node[1] == "+" &&
+                (is_string(node[2]) || is_string(node[3])));
+};
+
+var when_constant = (function(){
+
+        var $NOT_CONSTANT = {};
+
+        // this can only evaluate constant expressions.  If it finds anything
+        // not constant, it throws $NOT_CONSTANT.
+        function evaluate(expr) {
+                switch (expr[0]) {
+                    case "string":
+                    case "num":
+                        return expr[1];
+                    case "name":
+                    case "atom":
+                        switch (expr[1]) {
+                            case "true": return true;
+                            case "false": return false;
+                        }
+                        break;
+                    case "unary-prefix":
+                        switch (expr[1]) {
+                            case "!": return !evaluate(expr[2]);
+                            case "typeof": return typeof evaluate(expr[2]);
+                            case "~": return ~evaluate(expr[2]);
+                            case "-": return -evaluate(expr[2]);
+                            case "+": return +evaluate(expr[2]);
+                        }
+                        break;
+                    case "binary":
+                        var left = expr[2], right = expr[3];
+                        switch (expr[1]) {
+                            case "&&"         : return evaluate(left) &&         evaluate(right);
+                            case "||"         : return evaluate(left) ||         evaluate(right);
+                            case "|"          : return evaluate(left) |          evaluate(right);
+                            case "&"          : return evaluate(left) &          evaluate(right);
+                            case "^"          : return evaluate(left) ^          evaluate(right);
+                            case "+"          : return evaluate(left) +          evaluate(right);
+                            case "*"          : return evaluate(left) *          evaluate(right);
+                            case "/"          : return evaluate(left) /          evaluate(right);
+                            case "-"          : return evaluate(left) -          evaluate(right);
+                            case "<<"         : return evaluate(left) <<         evaluate(right);
+                            case ">>"         : return evaluate(left) >>         evaluate(right);
+                            case ">>>"        : return evaluate(left) >>>        evaluate(right);
+                            case "=="         : return evaluate(left) ==         evaluate(right);
+                            case "==="        : return evaluate(left) ===        evaluate(right);
+                            case "!="         : return evaluate(left) !=         evaluate(right);
+                            case "!=="        : return evaluate(left) !==        evaluate(right);
+                            case "<"          : return evaluate(left) <          evaluate(right);
+                            case "<="         : return evaluate(left) <=         evaluate(right);
+                            case ">"          : return evaluate(left) >          evaluate(right);
+                            case ">="         : return evaluate(left) >=         evaluate(right);
+                            case "in"         : return evaluate(left) in         evaluate(right);
+                            case "instanceof" : return evaluate(left) instanceof evaluate(right);
+                        }
+                }
+                throw $NOT_CONSTANT;
+        };
+
+        return function(expr, yes, no) {
+                try {
+                        var val = evaluate(expr), ast;
+                        switch (typeof val) {
+                            case "string": ast =  [ "string", val ]; break;
+                            case "number": ast =  [ "num", val ]; break;
+                            case "boolean": ast =  [ "name", String(val) ]; break;
+                            default: throw new Error("Can't handle constant of type: " + (typeof val));
+                        }
+                        return yes.call(expr, ast, val);
+                } catch(ex) {
+                        if (ex === $NOT_CONSTANT) {
+                                if (expr[0] == "binary"
+                                    && (expr[1] == "===" || expr[1] == "!==")
+                                    && ((is_string(expr[2]) && is_string(expr[3]))
+                                        || (boolean_expr(expr[2]) && boolean_expr(expr[3])))) {
+                                        expr[1] = expr[1].substr(0, 2);
+                                }
+                                else if (no && expr[0] == "binary"
+                                         && (expr[1] == "||" || expr[1] == "&&")) {
+                                    // the whole expression is not constant but the lval may be...
+                                    try {
+                                        var lval = evaluate(expr[2]);
+                                        expr = ((expr[1] == "&&" && (lval ? expr[3] : lval))    ||
+                                                (expr[1] == "||" && (lval ? lval    : expr[3])) ||
+                                                expr);
+                                    } catch(ex2) {
+                                        // IGNORE... lval is not constant
+                                    }
+                                }
+                                return no ? no.call(expr, expr) : null;
+                        }
+                        else throw ex;
+                }
+        };
+
+})();
+
+function warn_unreachable(ast) {
+        if (!empty(ast))
+