path: root/third_party/ply/CHANGES

Version 3.4
---------------------
02/17/11: beazley
          Minor patch to make cpp.py compatible with Python 3.  Note: This
          is an experimental file not currently used by the rest of PLY.

02/17/11: beazley
          Fixed setup.py trove classifiers to properly list PLY as
          Python 3 compatible.

01/02/11: beazley
          Migration of repository to github.

Version 3.3
-----------------------------
08/25/09: beazley
          Fixed issue 15 related to the set_lineno() method in yacc.  Reported by
	  mdsherry.

08/25/09: beazley
          Fixed a bug related to regular expression compilation flags not being
          properly stored in lextab.py files created by the lexer when running
          in optimize mode.  Reported by Bruce Frederiksen.


Version 3.2
-----------------------------
03/24/09: beazley
          Added an extra check to not print duplicated warning messages
          about reduce/reduce conflicts.

03/24/09: beazley
          Switched PLY over to a BSD-license.

03/23/09: beazley
          Performance optimization.  Discovered a few places to make
          speedups in LR table generation.

03/23/09: beazley
          New warning message.  PLY now warns about rules never 
          reduced due to reduce/reduce conflicts.  Suggested by
          Bruce Frederiksen.

03/23/09: beazley
          Some clean-up of warning messages related to reduce/reduce errors.

03/23/09: beazley
          Added a new picklefile option to yacc() to write the parsing
          tables to a filename using the pickle module.   Here is how
          it works:

              yacc(picklefile="parsetab.p")

          This option can be used if the normal parsetab.py file is
          extremely large.  For example, on jython, it is impossible
          to read parsing tables if the parsetab.py exceeds a certain
          threshold.

          The filename supplied to the picklefile option is opened
          relative to the current working directory of the Python 
          interpreter.  If you need to refer to the file elsewhere,
          you will need to supply an absolute or relative path.

          For maximum portability, the pickle file is written
          using protocol 0. 
 
03/13/09: beazley
          Fixed a bug in parser.out generation where the rule numbers
          where off by one.

03/13/09: beazley
          Fixed a string formatting bug with one of the error messages.
          Reported by Richard Reitmeyer

Version 3.1
-----------------------------
02/28/09: beazley
          Fixed broken start argument to yacc().  PLY-3.0 broke this
          feature by accident.

02/28/09: beazley
          Fixed debugging output. yacc() no longer reports shift/reduce
          or reduce/reduce conflicts if debugging is turned off.  This
          restores similar behavior in PLY-2.5.   Reported by Andrew Waters.

Version 3.0
-----------------------------
02/03/09: beazley
          Fixed missing lexer attribute on certain tokens when
          invoking the parser p_error() function.  Reported by 
          Bart Whiteley.

02/02/09: beazley
          The lex() command now does all error-reporting and diagonistics
          using the logging module interface.   Pass in a Logger object
          using the errorlog parameter to specify a different logger.

02/02/09: beazley
          Refactored ply.lex to use a more object-oriented and organized
          approach to collecting lexer information.

02/01/09: beazley
          Removed the nowarn option from lex().  All output is controlled
          by passing in a logger object.   Just pass in a logger with a high
          level setting to suppress output.   This argument was never 
          documented to begin with so hopefully no one was relying upon it.

02/01/09: beazley
          Discovered and removed a dead if-statement in the lexer.  This
          resulted in a 6-7% speedup in lexing when I tested it.

01/13/09: beazley
          Minor change to the procedure for signalling a syntax error in a
          production rule.  A normal SyntaxError exception should be raised
          instead of yacc.SyntaxError.

01/13/09: beazley
          Added a new method p.set_lineno(n,lineno) that can be used to set the
          line number of symbol n in grammar rules.   This simplifies manual
          tracking of line numbers.

01/11/09: beazley
          Vastly improved debugging support for yacc.parse().   Instead of passing
          debug as an integer, you can supply a Logging object (see the logging
          module). Messages will be generated at the ERROR, INFO, and DEBUG
	  logging levels, each level providing progressively more information.
          The debugging trace also shows states, grammar rule, values passed
          into grammar rules, and the result of each reduction.

01/09/09: beazley
          The yacc() command now does all error-reporting and diagnostics using
          the interface of the logging module.  Use the errorlog parameter to
          specify a logging object for error messages.  Use the debuglog parameter
          to specify a logging object for the 'parser.out' output.

01/09/09: beazley
          *HUGE* refactoring of the the ply.yacc() implementation.   The high-level
	  user interface is backwards compatible, but the internals are completely
          reorganized into classes.  No more global variables.    The internals
          are also more extensible.  For example, you can use the classes to 
          construct a LALR(1) parser in an entirely different manner than 
          what is currently the case.  Documentation is forthcoming.

01/07/09: beazley
          Various cleanup and refactoring of yacc internals.  

01/06/09: beazley
          Fixed a bug with precedence assignment.  yacc was assigning the precedence
          each rule based on the left-most token, when in fact, it should have been
          using the right-most token.  Reported by Bruce Frederiksen.

11/27/08: beazley
          Numerous changes to support Python 3.0 including removal of deprecated 
          statements (e.g., has_key) and the additional of compatibility code
          to emulate features from Python 2 that have been removed, but which
          are needed.   Fixed the unit testing suite to work with Python 3.0.
          The code should be backwards compatible with Python 2.

11/26/08: beazley
          Loosened the rules on what kind of objects can be passed in as the
          "module" parameter to lex() and yacc().  Previously, you could only use
          a module or an instance.  Now, PLY just uses dir() to get a list of
          symbols on whatever the object is without regard for its type.

11/26/08: beazley
          Changed all except: statements to be compatible with Python2.x/3.x syntax.

11/26/08: beazley
          Changed all raise Exception, value statements to raise Exception(value) for
          forward compatibility.

11/26/08: beazley
          Removed all print statements from lex and yacc, using sys.stdout and sys.stderr
          directly.  Preparation for Python 3.0 support.

11/04/08: beazley
          Fixed a bug with referring to symbols on the the parsing stack using negative
          indices.

05/29/08: beazley
          Completely revamped the testing system to use the unittest module for everything.
          Added additional tests to cover new errors/warnings.

Version 2.5
-----------------------------
05/28/08: beazley
          Fixed a bug with writing lex-tables in optimized mode and start states.
          Reported by Kevin Henry.

Version 2.4
-----------------------------
05/04/08: beazley
          A version number is now embedded in the table file signature so that 
          yacc can more gracefully accomodate changes to the output format
          in the future.

05/04/08: beazley
          Removed undocumented .pushback() method on grammar productions.  I'm
          not sure this ever worked and can't recall ever using it.  Might have
          been an abandoned idea that never really got fleshed out.  This
          feature was never described or tested so removing it is hopefully
          harmless.

05/04/08: beazley
          Added extra error checking to yacc() to detect precedence rules defined
          for undefined terminal symbols.   This allows yacc() to detect a potential
          problem that can be really tricky to debug if no warning message or error
          message is generated about it.

05/04/08: beazley
          lex() now has an outputdir that can specify the output directory for
          tables when running in optimize mode.  For example:

             lexer = lex.lex(optimize=True, lextab="ltab", outputdir="foo/bar")
 
          The behavior of specifying a table module and output directory are
          more aligned with the behavior of yacc().
          
05/04/08: beazley
          [Issue 9]
          Fixed filename bug in when specifying the modulename in lex() and yacc(). 
          If you specified options such as the following:

             parser = yacc.yacc(tabmodule="foo.bar.parsetab",outputdir="foo/bar")

          yacc would create a file "foo.bar.parsetab.py" in the given directory.
          Now, it simply generates a file "parsetab.py" in that directory. 
          Bug reported by cptbinho.

05/04/08: beazley
          Slight modification to lex() and yacc() to allow their table files
	  to be loaded from a previously loaded module.   This might make
	  it easier to load the parsing tables from a complicated package
          structure.  For example:

	       import foo.bar.spam.parsetab as parsetab
               parser = yacc.yacc(tabmodule=parsetab)

          Note:  lex and yacc will never regenerate the table file if used
          in the form---you will get a warning message instead. 
          This idea suggested by Brian Clapper.


04/28/08: beazley
          Fixed a big with p_error() functions being picked up correctly
          when running in yacc(optimize=1) mode.  Patch contributed by
          Bart Whiteley.

02/28/08: beazley
          Fixed a bug with 'nonassoc' precedence rules.   Basically the
          non-precedence was being ignored and not producing the correct
          run-time behavior in the parser.

02/16/08: beazley
          Slight relaxation of what the input() method to a lexer will
          accept as a string.   Instead of testing the input to see
          if the input is a string or unicode string, it checks to see
          if the input object looks like it contains string data.
          This change makes it possible to pass string-like objects
          in as input.  For example, the object returned by mmap.

              import mmap, os
              data = mmap.mmap(os.open(filename,os.O_RDONLY),
                               os.path.getsize(filename),
                               access=mmap.ACCESS_READ)
              lexer.input(data)
           

11/29/07: beazley
          Modification of ply.lex to allow token functions to aliased.
          This is subtle, but it makes it easier to create libraries and
          to reuse token specifications.  For example, suppose you defined
          a function like this:

               def number(t):
                    r'\d+'
                    t.value = int(t.value)
                    return t

          This change would allow you to define a token rule as follows:

              t_NUMBER = number

          In this case, the token type will be set to 'NUMBER' and use
          the associated number() function to process tokens.   
           
11/28/07: beazley
          Slight modification to lex and yacc to grab symbols from both
          the local and global dictionaries of the caller.   This
          modification allows lexers and parsers to be defined using
          inner functions and closures.

11/28/07: beazley
          Performance optimization:  The lexer.lexmatch and t.lexer
          attributes are no longer set for lexer tokens that are not
          defined by functions.   The only normal use of these attributes
          would be in lexer rules that need to perform some kind of 
          special processing.  Thus, it doesn't make any sense to set
          them on every token.

          *** POTENTIAL INCOMPATIBILITY ***  This might break code
          that is mucking around with internal lexer state in some
          sort of magical way.

11/27/07: beazley
          Added the ability to put the parser into error-handling mode
          from within a normal production.   To do this, simply raise
          a yacc.SyntaxError exception like this:

          def p_some_production(p):
              'some_production : prod1 prod2'
              ...
              raise yacc.SyntaxError      # Signal an error

          A number of things happen after this occurs:

          - The last symbol shifted onto the symbol stack is discarded
            and parser state backed up to what it was before the
            the rule reduction.

          - The current lookahead symbol is saved and replaced by
            the 'error' symbol.

          - The parser enters error recovery mode where it tries
            to either reduce the 'error' rule or it starts 
            discarding items off of the stack until the parser
            resets.

          When an error is manually set, the parser does *not* call 
          the p_error() function (if any is defined).
          *** NEW FEATURE *** Suggested on the mailing list

11/27/07: beazley
          Fixed structure bug in examples/ansic.  Reported by Dion Blazakis.

11/27/07: beazley
          Fixed a bug in the lexer related to start conditions and ignored
          token rules.  If a rule was defined that changed state, but
          returned no token, the lexer could be left in an inconsistent
          state.  Reported by 
          
11/27/07: beazley
          Modified setup.py to support Python Eggs.   Patch contributed by
          Simon Cross.

11/09/07: beazely
          Fixed a bug in error handling in yacc.  If a syntax error occurred and the
          parser rolled the entire parse stack back, the parser would be left in in
          inconsistent state that would cause it to trigger incorrect actions on
          subsequent input.  Reported by Ton Biegstraaten, Justin King, and others.

11/09/07: beazley
          Fixed a bug when passing empty input strings to yacc.parse().   This 
          would result in an error message about "No input given".  Reported
          by Andrew Dalke.

Version 2.3
-----------------------------
02/20/07: beazley
          Fixed a bug with character literals if the literal '.' appeared as the
          last symbol of a grammar rule.  Reported by Ales Smrcka.

02/19/07: beazley
          Warning messages are now redirected to stderr instead of being printed
          to standard output.

02/19/07: beazley
          Added a warning message to lex.py if it detects a literal backslash
          character inside the t_ignore declaration.  This is to help
          problems that might occur if someone accidentally defines t_ignore
          as a Python raw string.  For example:

              t_ignore = r' \t'

          The idea for this is from an email I received from David Cimimi who
          reported bizarre behavior in lexing as a result of defining t_ignore
          as a raw string by accident.

02/18/07: beazley
          Performance improvements.  Made some changes to the internal
          table organization and LR parser to improve parsing performance.

02/18/07: beazley
          Automatic tracking of line number and position information must now be 
          enabled by a special flag to parse().  For example:

              yacc.parse(data,tracking=True)

          In many applications, it's just not that important to have the
          parser automatically track all line numbers.  By making this an 
          optional feature, it allows the parser to run significantly faster
          (more than a 20% speed increase in many cases).    Note: positional
          information is always available for raw tokens---this change only
          applies to positional information associated with nonterminal
          grammar symbols.
          *** POTENTIAL INCOMPATIBILITY ***
	  
02/18/07: beazley
          Yacc no longer supports extended slices of grammar productions.
          However, it does support regular slices.  For example:

          def p_foo(p):
              '''foo: a b c d e'''
              p[0] = p[1:3]

          This change is a performance improvement to the parser--it streamlines
          normal access to the grammar values since slices are now handled in
          a __getslice__() method as opposed to __getitem__().

02/12/07: beazley
          Fixed a bug in the handling of token names when combined with
          start conditions.   Bug reported by Todd O'Bryan.

Version 2.2
------------------------------
11/01/06: beazley
          Added lexpos() and lexspan() methods to grammar symbols.  These
          mirror the same functionality of lineno() and linespan().  For
          example:

          def p_expr(p):
              'expr : expr PLUS expr'
               p.lexpos(1)     # Lexing position of left-hand-expression
               p.lexpos(1)     # Lexing position of PLUS
               start,end = p.lexspan(3)  # Lexing range of right hand expression

11/01/06: beazley
          Minor change to error handling.  The recommended way to skip characters
          in the input is to use t.lexer.skip() as shown here:

             def t_error(t):
                 print "Illegal character '%s'" % t.value[0]
                 t.lexer.skip(1)
          
          The old approach of just using t.skip(1) will still work, but won't
          be documented.

10/31/06: beazley
          Discarded tokens can now be specified as simple strings instead of
          functions.  To do this, simply include the text "ignore_" in the
          token declaration.  For example:

              t_ignore_cppcomment = r'//.*'
          
          Previously, this had to be done with a function.  For example:

              def t_ignore_cppcomment(t):
                  r'//.*'
                  pass

          If start conditions/states are being used, state names should appear
          before the "ignore_" text.

10/19/06: beazley
          The Lex module now provides support for flex-style start conditions
          as described at http://www.gnu.org/software/flex/manual/html_chapter/flex_11.html.
          Please refer to this document to understand this change note.  Refer to
          the PLY documentation for PLY-specific explanation of how this works.

          To use start conditions, you first need to declare a set of states in
          your lexer file:

          states = (
                    ('foo','exclusive'),
                    ('bar','inclusive')
          )

          This serves the same role as the %s and %x specifiers in flex.

          One a state has been declared, tokens for that state can be 
          declared by defining rules of the form t_state_TOK.  For example:

            t_PLUS = '\+'          # Rule defined in INITIAL state
            t_foo_NUM = '\d+'      # Rule defined in foo state
            t_bar_NUM = '\d+'      # Rule defined in bar state

            t_foo_bar_NUM = '\d+'  # Rule defined in both foo and bar
            t_ANY_NUM = '\d+'      # Rule defined in all states

          In addition to defining tokens for each state, the t_ignore and t_error
          specifications can be customized for specific states.  For example:

            t_foo_ignore = " "     # Ignored characters for foo state
            def t_bar_error(t):   
                # Handle errors in bar state

          With token rules