Mercurial > repo
diff ply-3.8/CHANGES @ 7267:343ff337a19b
<ais523> ` tar -xf ply-3.8.tar.gz
| author | HackBot |
|---|---|
| date | Wed, 23 Mar 2016 02:40:16 +0000 |
| parents | |
| children |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/ply-3.8/CHANGES Wed Mar 23 02:40:16 2016 +0000 @@ -0,0 +1,1343 @@ +Version 3.8 +--------------------- +10/02/15: beazley + Fixed issues related to Python 3.5. Patch contributed by Barry Warsaw. + +Version 3.7 +--------------------- +08/25/15: beazley + Fixed problems when reading table files from pickled data. + +05/07/15: beazley + Fixed regression in handling of table modules if specified as module + objects. See https://github.com/dabeaz/ply/issues/63 + +Version 3.6 +--------------------- +04/25/15: beazley + If PLY is unable to create the 'parser.out' or 'parsetab.py' files due + to permission issues, it now just issues a warning message and + continues to operate. This could happen if a module using PLY + is installed in a funny way where tables have to be regenerated, but + for whatever reason, the user doesn't have write permission on + the directory where PLY wants to put them. + +04/24/15: beazley + Fixed some issues related to use of packages and table file + modules. Just to emphasize, PLY now generates its special + files such as 'parsetab.py' and 'lextab.py' in the *SAME* + directory as the source file that uses lex() and yacc(). + + If for some reason, you want to change the name of the table + module, use the tabmodule and lextab options: + + lexer = lex.lex(lextab='spamlextab') + parser = yacc.yacc(tabmodule='spamparsetab') + + If you specify a simple name as shown, the module will still be + created in the same directory as the file invoking lex() or yacc(). + If you want the table files to be placed into a different package, + then give a fully qualified package name. For example: + + lexer = lex.lex(lextab='pkgname.files.lextab') + parser = yacc.yacc(tabmodule='pkgname.files.parsetab') + + For this to work, 'pkgname.files' must already exist as a valid + Python package (i.e., the directories must already exist and be + set up with the proper __init__.py files, etc.). + +Version 3.5 +--------------------- +04/21/15: beazley + Added support for defaulted_states in the parser. A + defaulted_state is a state where the only legal action is a + reduction of a single grammar rule across all valid input + tokens. For such states, the rule is reduced and the + reading of the next lookahead token is delayed until it is + actually needed at a later point in time. + + This delay in consuming the next lookahead token is a + potentially important feature in advanced parsing + applications that require tight interaction between the + lexer and the parser. For example, a grammar rule change + modify the lexer state upon reduction and have such changes + take effect before the next input token is read. + + *** POTENTIAL INCOMPATIBILITY *** + One potential danger of defaulted_states is that syntax + errors might be deferred to a a later point of processing + than where they were detected in past versions of PLY. + Thus, it's possible that your error handling could change + slightly on the same inputs. defaulted_states do not change + the overall parsing of the input (i.e., the same grammar is + accepted). + + If for some reason, you need to disable defaulted states, + you can do this: + + parser = yacc.yacc() + parser.defaulted_states = {} + +04/21/15: beazley + Fixed debug logging in the parser. It wasn't properly reporting goto states + on grammar rule reductions. + +04/20/15: beazley + Added actions to be defined to character literals (Issue #32). For example: + + literals = [ '{', '}' ] + + def t_lbrace(t): + r'\{' + # Some action + t.type = '{' + return t + + def t_rbrace(t): + r'\}' + # Some action + t.type = '}' + return t + +04/19/15: beazley + Import of the 'parsetab.py' file is now constrained to only consider the + directory specified by the outputdir argument to yacc(). If not supplied, + the import will only consider the directory in which the grammar is defined. + This should greatly reduce problems with the wrong parsetab.py file being + imported by mistake. For example, if it's found somewhere else on the path + by accident. + + *** POTENTIAL INCOMPATIBILITY *** It's possible that this might break some + packaging/deployment setup if PLY was instructed to place its parsetab.py + in a different location. You'll have to specify a proper outputdir= argument + to yacc() to fix this if needed. + +04/19/15: beazley + Changed default output directory to be the same as that in which the + yacc grammar is defined. If your grammar is in a file 'calc.py', + then the parsetab.py and parser.out files should be generated in the + same directory as that file. The destination directory can be changed + using the outputdir= argument to yacc(). + +04/19/15: beazley + Changed the parsetab.py file signature slightly so that the parsetab won't + regenerate if created on a different major version of Python (ie., a + parsetab created on Python 2 will work with Python 3). + +04/16/15: beazley + Fixed Issue #44 call_errorfunc() should return the result of errorfunc() + +04/16/15: beazley + Support for versions of Python <2.7 is officially dropped. PLY may work, but + the unit tests requires Python 2.7 or newer. + +04/16/15: beazley + Fixed bug related to calling yacc(start=...). PLY wasn't regenerating the + table file correctly for this case. + +04/16/15: beazley + Added skipped tests for PyPy and Java. Related to use of Python's -O option. + +05/29/13: beazley + Added filter to make unit tests pass under 'python -3'. + Reported by Neil Muller. + +05/29/13: beazley + Fixed CPP_INTEGER regex in ply/cpp.py (Issue 21). + Reported by @vbraun. + +05/29/13: beazley + Fixed yacc validation bugs when from __future__ import unicode_literals + is being used. Reported by Kenn Knowles. + +05/29/13: beazley + Added support for Travis-CI. Contributed by Kenn Knowles. + +05/29/13: beazley + Added a .gitignore file. Suggested by Kenn Knowles. + +05/29/13: beazley + Fixed validation problems for source files that include a + different source code encoding specifier. Fix relies on + the inspect module. Should work on Python 2.6 and newer. + Not sure about older versions of Python. + Contributed by Michael Droettboom + +05/21/13: beazley + Fixed unit tests for yacc to eliminate random failures due to dict hash value + randomization in Python 3.3 + Reported by Arfrever + +10/15/12: beazley + Fixed comment whitespace processing bugs in ply/cpp.py. + Reported by Alexei Pososin. + +10/15/12: beazley + Fixed token names in ply/ctokens.py to match rule names. + Reported by Alexei Pososin. + +04/26/12: beazley + Changes to functions available in panic mode error recover. In previous versions + of PLY, the following global functions were available for use in the p_error() rule: + + yacc.errok() # Reset error state + yacc.token() # Get the next token + yacc.restart() # Reset the parsing stack + + The use of global variables was problematic for code involving multiple parsers + and frankly was a poor design overall. These functions have been moved to methods + of the parser instance created by the yacc() function. You should write code like + this: + + def p_error(p): + ... + parser.errok() + + parser = yacc.yacc() + + *** POTENTIAL INCOMPATIBILITY *** The original global functions now issue a + DeprecationWarning. + +04/19/12: beazley + Fixed some problems with line and position tracking and the use of error + symbols. If you have a grammar rule involving an error rule like this: + + def p_assignment_bad(p): + '''assignment : location EQUALS error SEMI''' + ... + + You can now do line and position tracking on the error token. For example: + + def p_assignment_bad(p): + '''assignment : location EQUALS error SEMI''' + start_line = p.lineno(3) + start_pos = p.lexpos(3) + + If the trackng=True option is supplied to parse(), you can additionally get + spans: + + def p_assignment_bad(p): + '''assignment : location EQUALS error SEMI''' + start_line, end_line = p.linespan(3) + start_pos, end_pos = p.lexspan(3) + + Note that error handling is still a hairy thing in PLY. This won't work + unless your lexer is providing accurate information. Please report bugs. + Suggested by a bug reported by Davis Herring. + +04/18/12: beazley + Change to doc string handling in lex module. Regex patterns are now first + pulled from a function's .regex attribute. If that doesn't exist, then + .doc is checked as a fallback. The @TOKEN decorator now sets the .regex + attribute of a function instead of its doc string. + Changed suggested by Kristoffer Ellersgaard Koch. + +04/18/12: beazley + Fixed issue #1: Fixed _tabversion. It should use __tabversion__ instead of __version__ + Reported by Daniele Tricoli + +04/18/12: beazley + Fixed issue #8: Literals empty list causes IndexError + Reported by Walter Nissen. + +04/18/12: beazley + Fixed issue #12: Typo in code snippet in documentation + Reported by florianschanda. + +04/18/12: beazley + Fixed issue #10: Correctly escape t_XOREQUAL pattern. + Reported by Andy Kittner. + +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, the following methods can be used to change states + + def t_TOKNAME(t): + t.lexer.begin('foo') # Begin state 'foo' + t.lexer.push_state('foo') # Begin state 'foo', push old state + # onto a stack + t.lexer.pop_state() # Restore previous state + t.lexer.current_state() # Returns name of current state + + These methods mirror the BEGIN(), yy_push_state(), yy_pop_state(), and + yy_top_state() functions in flex. + + The use of start states can be used as one way to write sub-lexers. + For example, the lexer or parser might instruct the lexer to start + generating a different set of tokens depending on the context. + + example/yply/ylex.py shows the use of start states to grab C/C++ + code fragments out of traditional yacc specification files. + + *** NEW FEATURE *** Suggested by Daniel Larraz with whom I also + discussed various aspects of the design. + +10/19/06: beazley + Minor change to the way in which yacc.py was reporting shift/reduce + conflicts. Although the underlying LALR(1) algorithm was correct, + PLY was under-reporting the number of conflicts compared to yacc/bison + when precedence rules were in effect. This change should make PLY + report the same number of conflicts as yacc. + +10/19/06: beazley + Modified yacc so that grammar rules could also include the '-' + character. For example: + + def p_expr_list(p): + 'expression-list : expression-list expression' + + Suggested by Oldrich Jedlicka. + +10/18/06: beazley + Attribute lexer.lexmatch added so that token rules can access the re + match object that was generated. For example: + + def t_FOO(t): + r'some regex' + m = t.lexer.lexmatch + # Do something with m + + + This may be useful if you want to access named groups specified within + the regex for a specific token. Suggested by Oldrich Jedlicka. + +10/16/06: beazley + Changed the error message that results if an illegal character + is encountered and no default error function is defined in lex. + The exception is now more informative about the actual cause of + the error. + +Version 2.1 +------------------------------ +10/02/06: beazley + The last Lexer object built by lex() can be found in lex.lexer. + The last Parser object built by yacc() can be found in yacc.parser. + +10/02/06: beazley + New example added: examples/yply + + This example uses PLY to convert Unix-yacc specification files to + PLY programs with the same grammar. This may be useful if you + want to convert a grammar from bison/yacc to use with PLY. + +10/02/06: beazley + Added support for a start symbol to be specified in the yacc + input file itself. Just do this: + + start = 'name' + + where 'name' matches some grammar rule. For example: + + def p_name(p): + 'name : A B C' + ... + + This mirrors the functionality of the yacc %start specifier. + +09/30/06: beazley + Some new examples added.: + + examples/GardenSnake : A simple indentation based language similar + to Python. Shows how you might handle + whitespace. Contributed by Andrew Dalke. + + examples/BASIC : An implementation of 1964 Dartmouth BASIC. + Contributed by Dave against his better + judgement. + +09/28/06: beazley + Minor patch to allow named groups to be used in lex regular + expression rules. For example: + + t_QSTRING = r'''(?P<quote>['"]).*?(?P=quote)''' + + Patch submitted by Adam Ring. + +09/28/06: beazley + LALR(1) is now the default parsing method. To use SLR, use + yacc.yacc(method="SLR"). Note: there is no performance impact + on parsing when using LALR(1) instead of SLR. However, constructing + the parsing tables will take a little longer. + +09/26/06: beazley + Change to line number tracking. To modify line numbers, modify + the line number of the lexer itself. For example: + + def t_NEWLINE(t): + r'\n' + t.lexer.lineno += 1 + + This modification is both cleanup and a performance optimization. + In past versions, lex was monitoring every token for changes in + the line number. This extra processing is unnecessary for a vast + majority of tokens. Thus, this new approach cleans it up a bit. + + *** POTENTIAL INCOMPATIBILITY *** + You will need to change code in your lexer that updates the line + number. For example, "t.lineno += 1" becomes "t.lexer.lineno += 1" + +09/26/06: beazley + Added the lexing position to tokens as an attribute lexpos. This + is the raw index into the input text at which a token appears. + This information can be used to compute column numbers and other + details (e.g., scan backwards from lexpos to the first newline + to get a column position). + +09/25/06: beazley + Changed the name of the __copy__() method on the Lexer class + to clone(). This is used to clone a Lexer object (e.g., if + you're running different lexers at the same time). + +09/21/06: beazley + Limitations related to the use of the re module have been eliminated. + Several users reported problems with regular expressions exceeding + more than 100 named groups. To solve this, lex.py is now capable + of automatically splitting its master regular regular expression into + smaller expressions as needed. This should, in theory, make it + possible to specify an arbitrarily large number of tokens. + +09/21/06: beazley + Improved error checking in lex.py. Rules that match the empty string + are now rejected (otherwise they cause the lexer to enter an infinite + loop). An extra check for rules containing '#' has also been added. + Since lex compiles regular expressions in verbose mode, '#' is interpreted + as a regex comment, it is critical to use '\#' instead. + +09/18/06: beazley + Added a @TOKEN decorator function to lex.py that can be used to + define token rules where the documentation string might be computed + in some way. + + digit = r'([0-9])' + nondigit = r'([_A-Za-z])' + identifier = r'(' + nondigit + r'(' + digit + r'|' + nondigit + r')*)' + + from ply.lex import TOKEN + + @TOKEN(identifier) + def t_ID(t): + # Do whatever + + The @TOKEN decorator merely sets the documentation string of the + associated token function as needed for lex to work. + + Note: An alternative solution is the following: + + def t_ID(t): + # Do whatever + + t_ID.__doc__ = identifier + + Note: Decorators require the use of Python 2.4 or later. If compatibility + with old versions is needed, use the latter solution. + + The need for this feature was suggested by Cem Karan. + +09/14/06: beazley + Support for single-character literal tokens has been added to yacc. + These literals must be enclosed in quotes. For example: + + def p_expr(p): + "expr : expr '+' expr" + ... + + def p_expr(p): + 'expr : expr "-" expr' + ... + + In addition to this, it is necessary to tell the lexer module about + literal characters. This is done by defining the variable 'literals' + as a list of characters. This should be defined in the module that + invokes the lex.lex() function. For example: + + literals = ['+','-','*','/','(',')','='] + + or simply + + literals = '+=*/()=' + + It is important to note that literals can only be a single character. + When the lexer fails to match a token using its normal regular expression + rules, it will check the current character against the literal list. + If found, it will be returned with a token type set to match the literal + character. Otherwise, an illegal character will be signalled. + + +09/14/06: beazley + Modified PLY to install itself as a proper Python package called 'ply'. + This will make it a little more friendly to other modules. This + changes the usage of PLY only slightly. Just do this to import the + modules + + import ply.lex as lex + import ply.yacc as yacc + + Alternatively, you can do this: + + from ply import * + + Which imports both the lex and yacc modules. + Change suggested by Lee June. + +09/13/06: beazley + Changed the handling of negative indices when used in production rules. + A negative production index now accesses already parsed symbols on the + parsing stack. For example, + + def p_foo(p): + "foo: A B C D" + print p[1] # Value of 'A' symbol + print p[2] # Value of 'B' symbol + print p[-1] # Value of whatever symbol appears before A + # on the parsing stack. + + p[0] = some_val # Sets the value of the 'foo' grammer symbol + + This behavior makes it easier to work with embedded actions within the + parsing rules. For example, in C-yacc, it is possible to write code like + this: + + bar: A { printf("seen an A = %d\n", $1); } B { do_stuff; } + + In this example, the printf() code executes immediately after A has been + parsed. Within the embedded action code, $1 refers to the A symbol on + the stack. + + To perform this equivalent action in PLY, you need to write a pair + of rules like this: + + def p_bar(p): + "bar : A seen_A B" + do_stuff + + def p_seen_A(p): + "seen_A :" + print "seen an A =", p[-1] + + The second rule "seen_A" is merely a empty production which should be + reduced as soon as A is parsed in the "bar" rule above. The use + of the negative index p[-1] is used to access whatever symbol appeared + before the seen_A symbol. + + This feature also makes it possible to support inherited attributes. + For example: + + def p_decl(p): + "decl : scope name" + + def p_scope(p): + """scope : GLOBAL + | LOCAL""" + p[0] = p[1] + + def p_name(p): + "name : ID" + if p[-1] == "GLOBAL": + # ... + else if p[-1] == "LOCAL": + #... + + In this case, the name rule is inheriting an attribute from the + scope declaration that precedes it. + + *** POTENTIAL INCOMPATIBILITY *** + If you are currently using negative indices within existing grammar rules, + your code will break. This should be extremely rare if non-existent in + most cases. The argument to various grammar rules is not usually not + processed in the same way as a list of items. + +Version 2.0 +------------------------------ +09/07/06: beazley + Major cleanup and refactoring of the LR table generation code. Both SLR + and LALR(1) table generation is now performed by the same code base with + only minor extensions for extra LALR(1) processing. + +09/07/06: beazley + Completely reimplemented the entire LALR(1) parsing engine to use the + DeRemer and Pennello algorithm for calculating lookahead sets. This + significantly improves the performance of generating LALR(1) tables + and has the added feature of actually working correctly! If you + experienced weird behavior with LALR(1) in prior releases, this should + hopefully resolve all of those problems. Many thanks to + Andrew Waters and Markus Schoepflin for submitting bug reports + and helping me test out the revised LALR(1) support. + +Version 1.8 +------------------------------ +08/02/06: beazley + Fixed a problem related to the handling of default actions in LALR(1) + parsing. If you experienced subtle and/or bizarre behavior when trying + to use the LALR(1) engine, this may correct those problems. Patch + contributed by Russ Cox. Note: This patch has been superceded by + revisions for LALR(1) parsing in Ply-2.0. + +08/02/06: beazley + Added support for slicing of productions in yacc. + Patch contributed by Patrick Mezard. + +Version 1.7 +------------------------------ +03/02/06: beazley + Fixed infinite recursion problem ReduceToTerminals() function that + would sometimes come up in LALR(1) table generation. Reported by + Markus Schoepflin. + +03/01/06: beazley + Added "reflags" argument to lex(). For example: + + lex.lex(reflags=re.UNICODE) + + This can be used to specify optional flags to the re.compile() function + used inside the lexer. This may be necessary for special situations such + as processing Unicode (e.g., if you want escapes like \w and \b to consult + the Unicode character property database). The need for this suggested by + Andreas Jung. + +03/01/06: beazley + Fixed a bug with an uninitialized variable on repeated instantiations of parser + objects when the write_tables=0 argument was used. Reported by Michael Brown. + +03/01/06: beazley + Modified lex.py to accept Unicode strings both as the regular expressions for + tokens and as input. Hopefully this is the only change needed for Unicode support. + Patch contributed by Johan Dahl. + +03/01/06: beazley + Modified the class-based interface to work with new-style or old-style classes. + Patch contributed by Michael Brown (although I tweaked it slightly so it would work + with older versions of Python). + +Version 1.6 +------------------------------ +05/27/05: beazley + Incorporated patch contributed by Christopher Stawarz to fix an extremely + devious bug in LALR(1) parser generation. This patch should fix problems + numerous people reported with LALR parsing. + +05/27/05: beazley + Fixed problem with lex.py copy constructor. Reported by Dave Aitel, Aaron Lav, + and Thad Austin. + +05/27/05: beazley + Added outputdir option to yacc() to control output directory. Contributed + by Christopher Stawarz. + +05/27/05: beazley + Added rununit.py test script to run tests using the Python unittest module. + Contributed by Miki Tebeka. + +Version 1.5 +------------------------------ +05/26/04: beazley + Major enhancement. LALR(1) parsing support is now working. + This feature was implemented by Elias Ioup (ezioup@alumni.uchicago.edu) + and optimized by David Beazley. To use LALR(1) parsing do + the following: + + yacc.yacc(method="LALR") + + Computing LALR(1) parsing tables takes about twice as long as + the default SLR method. However, LALR(1) allows you to handle + more complex grammars. For example, the ANSI C grammar + (in example/ansic) has 13 shift-reduce conflicts with SLR, but + only has 1 shift-reduce conflict with LALR(1). + +05/20/04: beazley + Added a __len__ method to parser production lists. Can + be used in parser rules like this: + + def p_somerule(p): + """a : B C D + | E F" + if (len(p) == 3): + # Must have been first rule + elif (len(p) == 2): + # Must be second rule + + Suggested by Joshua Gerth and others. + +Version 1.4 +------------------------------ +04/23/04: beazley + Incorporated a variety of patches contributed by Eric Raymond. + These include: + + 0. Cleans up some comments so they don't wrap on an 80-column display. + 1. Directs compiler errors to stderr where they belong. + 2. Implements and documents automatic line counting when \n is ignored. + 3. Changes the way progress messages are dumped when debugging is on. + The new format is both less verbose and conveys more information than + the old, including shift and reduce actions. + +04/23/04: beazley + Added a Python setup.py file to simply installation. Contributed + by Adam Kerrison. + +04/23/04: beazley + Added patches contributed by Adam Kerrison. + + - Some output is now only shown when debugging is enabled. This + means that PLY will be completely silent when not in debugging mode. + + - An optional parameter "write_tables" can be passed to yacc() to + control whether or not parsing tables are written. By default, + it is true, but it can be turned off if you don't want the yacc + table file. Note: disabling this will cause yacc() to regenerate + the parsing table each time. + +04/23/04: beazley + Added patches contributed by David McNab. This patch addes two + features: + + - The parser can be supplied as a class instead of a module. + For an example of this, see the example/classcalc directory. + + - Debugging output can be directed to a filename of the user's + choice. Use + + yacc(debugfile="somefile.out") + + +Version 1.3 +------------------------------ +12/10/02: jmdyck + Various minor adjustments to the code that Dave checked in today. + Updated test/yacc_{inf,unused}.exp to reflect today's changes. + +12/10/02: beazley + Incorporated a variety of minor bug fixes to empty production + handling and infinite recursion checking. Contributed by + Michael Dyck. + +12/10/02: beazley + Removed bogus recover() method call in yacc.restart() + +Version 1.2 +------------------------------ +11/27/02: beazley + Lexer and parser objects are now available as an attribute + of tokens and slices respectively. For example: + + def t_NUMBER(t): + r'\d+' + print t.lexer + + def p_expr_plus(t): + 'expr: expr PLUS expr' + print t.lexer + print t.parser + + This can be used for state management (if needed). + +10/31/02: beazley + Modified yacc.py to work with Python optimize mode. To make + this work, you need to use + + yacc.yacc(optimize=1) + + Furthermore, you need to first run Python in normal mode + to generate the necessary parsetab.py files. After that, + you can use python -O or python -OO. + + Note: optimized mode turns off a lot of error checking. + Only use when you are sure that your grammar is working. + Make sure parsetab.py is up to date! + +10/30/02: beazley + Added cloning of Lexer objects. For example: + + import copy + l = lex.lex() + lc = copy.copy(l) + + l.input("Some text") + lc.input("Some other text") + ... + + This might be useful if the same "lexer" is meant to + be used in different contexts---or if multiple lexers + are running concurrently. + +10/30/02: beazley + Fixed subtle bug with first set computation and empty productions. + Patch submitted by Michael Dyck. + +10/30/02: beazley + Fixed error messages to use "filename:line: message" instead + of "filename:line. message". This makes error reporting more + friendly to emacs. Patch submitted by François Pinard. + +10/30/02: beazley + Improvements to parser.out file. Terminals and nonterminals + are sorted instead of being printed in random order. + Patch submitted by François Pinard. + +10/30/02: beazley + Improvements to parser.out file output. Rules are now printed + in a way that's easier to understand. Contributed by Russ Cox. + +10/30/02: beazley + Added 'nonassoc' associativity support. This can be used + to disable the chaining of operators like a < b < c. + To use, simply specify 'nonassoc' in the precedence table + + precedence = ( + ('nonassoc', 'LESSTHAN', 'GREATERTHAN'), # Nonassociative operators + ('left', 'PLUS', 'MINUS'), + ('left', 'TIMES', 'DIVIDE'), + ('right', 'UMINUS'), # Unary minus operator + ) + + Patch contributed by Russ Cox. + +10/30/02: beazley + Modified the lexer to provide optional support for Python -O and -OO + modes. To make this work, Python *first* needs to be run in + unoptimized mode. This reads the lexing information and creates a + file "lextab.py". Then, run lex like this: + + # module foo.py + ... + ... + lex.lex(optimize=1) + + Once the lextab file has been created, subsequent calls to + lex.lex() will read data from the lextab file instead of using + introspection. In optimized mode (-O, -OO) everything should + work normally despite the loss of doc strings. + + To change the name of the file 'lextab.py' use the following: + + lex.lex(lextab="footab") + + (this creates a file footab.py) + + +Version 1.1 October 25, 2001 +------------------------------ + +10/25/01: beazley + Modified the table generator to produce much more compact data. + This should greatly reduce the size of the parsetab.py[c] file. + Caveat: the tables still need to be constructed so a little more + work is done in parsetab on import. + +10/25/01: beazley + There may be a possible bug in the cycle detector that reports errors + about infinite recursion. I'm having a little trouble tracking it + down, but if you get this problem, you can disable the cycle + detector as follows: + + yacc.yacc(check_recursion = 0) + +10/25/01: beazley + Fixed a bug in lex.py that sometimes caused illegal characters to be + reported incorrectly. Reported by Sverre Jørgensen. + +7/8/01 : beazley + Added a reference to the underlying lexer object when tokens are handled by + functions. The lexer is available as the 'lexer' attribute. This + was added to provide better lexing support for languages such as Fortran + where certain types of tokens can't be conveniently expressed as regular + expressions (and where the tokenizing function may want to perform a + little backtracking). Suggested by Pearu Peterson. + +6/20/01 : beazley + Modified yacc() function so that an optional starting symbol can be specified. + For example: + + yacc.yacc(start="statement") + + Normally yacc always treats the first production rule as the starting symbol. + However, if you are debugging your grammar it may be useful to specify + an alternative starting symbol. Idea suggested by Rich Salz. + +Version 1.0 June 18, 2001 +-------------------------- +Initial public offering +