3276 lines
126 KiB
Python
3276 lines
126 KiB
Python
# -----------------------------------------------------------------------------
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# ply: yacc.py
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#
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# Copyright (C) 2001-2011,
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# David M. Beazley (Dabeaz LLC)
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are
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# met:
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#
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# * Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above copyright notice,
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# this list of conditions and the following disclaimer in the documentation
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# and/or other materials provided with the distribution.
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# * Neither the name of the David Beazley or Dabeaz LLC may be used to
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# endorse or promote products derived from this software without
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# specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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# -----------------------------------------------------------------------------
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#
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# This implements an LR parser that is constructed from grammar rules defined
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# as Python functions. The grammer is specified by supplying the BNF inside
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# Python documentation strings. The inspiration for this technique was borrowed
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# from John Aycock's Spark parsing system. PLY might be viewed as cross between
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# Spark and the GNU bison utility.
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#
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# The current implementation is only somewhat object-oriented. The
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# LR parser itself is defined in terms of an object (which allows multiple
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# parsers to co-exist). However, most of the variables used during table
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# construction are defined in terms of global variables. Users shouldn't
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# notice unless they are trying to define multiple parsers at the same
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# time using threads (in which case they should have their head examined).
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#
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# This implementation supports both SLR and LALR(1) parsing. LALR(1)
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# support was originally implemented by Elias Ioup (ezioup@alumni.uchicago.edu),
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# using the algorithm found in Aho, Sethi, and Ullman "Compilers: Principles,
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# Techniques, and Tools" (The Dragon Book). LALR(1) has since been replaced
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# by the more efficient DeRemer and Pennello algorithm.
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#
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# :::::::: WARNING :::::::
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#
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# Construction of LR parsing tables is fairly complicated and expensive.
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# To make this module run fast, a *LOT* of work has been put into
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# optimization---often at the expensive of readability and what might
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# consider to be good Python "coding style." Modify the code at your
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# own risk!
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# ----------------------------------------------------------------------------
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__version__ = "3.4"
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__tabversion__ = "3.2" # Table version
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#-----------------------------------------------------------------------------
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# === User configurable parameters ===
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#
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# Change these to modify the default behavior of yacc (if you wish)
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#-----------------------------------------------------------------------------
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yaccdebug = 1 # Debugging mode. If set, yacc generates a
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# a 'parser.out' file in the current directory
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debug_file = 'parser.out' # Default name of the debugging file
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tab_module = 'parsetab' # Default name of the table module
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default_lr = 'LALR' # Default LR table generation method
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error_count = 3 # Number of symbols that must be shifted to leave recovery mode
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yaccdevel = 0 # Set to True if developing yacc. This turns off optimized
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# implementations of certain functions.
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resultlimit = 40 # Size limit of results when running in debug mode.
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pickle_protocol = 0 # Protocol to use when writing pickle files
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import re, types, sys, os.path
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# Compatibility function for python 2.6/3.0
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if sys.version_info[0] < 3:
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def func_code(f):
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return f.func_code
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else:
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def func_code(f):
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return f.__code__
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# Compatibility
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try:
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MAXINT = sys.maxint
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except AttributeError:
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MAXINT = sys.maxsize
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# Python 2.x/3.0 compatibility.
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def load_ply_lex():
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if sys.version_info[0] < 3:
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import lex
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else:
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import ply.lex as lex
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return lex
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# This object is a stand-in for a logging object created by the
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# logging module. PLY will use this by default to create things
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# such as the parser.out file. If a user wants more detailed
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# information, they can create their own logging object and pass
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# it into PLY.
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class PlyLogger(object):
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def __init__(self,f):
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self.f = f
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def debug(self,msg,*args,**kwargs):
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self.f.write((msg % args) + "\n")
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info = debug
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def warning(self,msg,*args,**kwargs):
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self.f.write("WARNING: "+ (msg % args) + "\n")
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def error(self,msg,*args,**kwargs):
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self.f.write("ERROR: " + (msg % args) + "\n")
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critical = debug
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# Null logger is used when no output is generated. Does nothing.
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class NullLogger(object):
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def __getattribute__(self,name):
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return self
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def __call__(self,*args,**kwargs):
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return self
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# Exception raised for yacc-related errors
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class YaccError(Exception): pass
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# Format the result message that the parser produces when running in debug mode.
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def format_result(r):
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repr_str = repr(r)
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if '\n' in repr_str: repr_str = repr(repr_str)
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if len(repr_str) > resultlimit:
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repr_str = repr_str[:resultlimit]+" ..."
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result = "<%s @ 0x%x> (%s)" % (type(r).__name__,id(r),repr_str)
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return result
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# Format stack entries when the parser is running in debug mode
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def format_stack_entry(r):
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repr_str = repr(r)
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if '\n' in repr_str: repr_str = repr(repr_str)
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if len(repr_str) < 16:
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return repr_str
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else:
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return "<%s @ 0x%x>" % (type(r).__name__,id(r))
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#-----------------------------------------------------------------------------
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# === LR Parsing Engine ===
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#
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# The following classes are used for the LR parser itself. These are not
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# used during table construction and are independent of the actual LR
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# table generation algorithm
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#-----------------------------------------------------------------------------
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# This class is used to hold non-terminal grammar symbols during parsing.
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# It normally has the following attributes set:
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# .type = Grammar symbol type
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# .value = Symbol value
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# .lineno = Starting line number
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# .endlineno = Ending line number (optional, set automatically)
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# .lexpos = Starting lex position
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# .endlexpos = Ending lex position (optional, set automatically)
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class YaccSymbol:
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def __str__(self): return self.type
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def __repr__(self): return str(self)
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# This class is a wrapper around the objects actually passed to each
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# grammar rule. Index lookup and assignment actually assign the
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# .value attribute of the underlying YaccSymbol object.
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# The lineno() method returns the line number of a given
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# item (or 0 if not defined). The linespan() method returns
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# a tuple of (startline,endline) representing the range of lines
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# for a symbol. The lexspan() method returns a tuple (lexpos,endlexpos)
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# representing the range of positional information for a symbol.
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class YaccProduction:
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def __init__(self,s,stack=None):
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self.slice = s
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self.stack = stack
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self.lexer = None
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self.parser= None
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def __getitem__(self,n):
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if n >= 0: return self.slice[n].value
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else: return self.stack[n].value
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def __setitem__(self,n,v):
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self.slice[n].value = v
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def __getslice__(self,i,j):
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return [s.value for s in self.slice[i:j]]
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def __len__(self):
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return len(self.slice)
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def lineno(self,n):
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return getattr(self.slice[n],"lineno",0)
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def set_lineno(self,n,lineno):
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self.slice[n].lineno = lineno
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def linespan(self,n):
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startline = getattr(self.slice[n],"lineno",0)
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endline = getattr(self.slice[n],"endlineno",startline)
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return startline,endline
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def lexpos(self,n):
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return getattr(self.slice[n],"lexpos",0)
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def lexspan(self,n):
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startpos = getattr(self.slice[n],"lexpos",0)
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endpos = getattr(self.slice[n],"endlexpos",startpos)
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return startpos,endpos
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def error(self):
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raise SyntaxError
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# -----------------------------------------------------------------------------
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# == LRParser ==
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#
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# The LR Parsing engine.
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# -----------------------------------------------------------------------------
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class LRParser:
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def __init__(self,lrtab,errorf):
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self.productions = lrtab.lr_productions
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self.action = lrtab.lr_action
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self.goto = lrtab.lr_goto
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self.errorfunc = errorf
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def errok(self):
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self.errorok = 1
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def restart(self):
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del self.statestack[:]
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del self.symstack[:]
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sym = YaccSymbol()
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sym.type = '$end'
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self.symstack.append(sym)
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self.statestack.append(0)
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def parse(self,input=None,lexer=None,debug=0,tracking=0,tokenfunc=None):
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if debug or yaccdevel:
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if isinstance(debug,int):
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debug = PlyLogger(sys.stderr)
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return self.parsedebug(input,lexer,debug,tracking,tokenfunc)
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elif tracking:
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return self.parseopt(input,lexer,debug,tracking,tokenfunc)
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else:
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return self.parseopt_notrack(input,lexer,debug,tracking,tokenfunc)
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# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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# parsedebug().
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#
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# This is the debugging enabled version of parse(). All changes made to the
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# parsing engine should be made here. For the non-debugging version,
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# copy this code to a method parseopt() and delete all of the sections
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# enclosed in:
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#
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# #--! DEBUG
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# statements
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# #--! DEBUG
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#
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# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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def parsedebug(self,input=None,lexer=None,debug=None,tracking=0,tokenfunc=None):
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lookahead = None # Current lookahead symbol
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lookaheadstack = [ ] # Stack of lookahead symbols
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actions = self.action # Local reference to action table (to avoid lookup on self.)
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goto = self.goto # Local reference to goto table (to avoid lookup on self.)
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prod = self.productions # Local reference to production list (to avoid lookup on self.)
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pslice = YaccProduction(None) # Production object passed to grammar rules
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errorcount = 0 # Used during error recovery
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# --! DEBUG
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debug.info("PLY: PARSE DEBUG START")
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# --! DEBUG
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# If no lexer was given, we will try to use the lex module
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if not lexer:
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lex = load_ply_lex()
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lexer = lex.lexer
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# Set up the lexer and parser objects on pslice
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pslice.lexer = lexer
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pslice.parser = self
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# If input was supplied, pass to lexer
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if input is not None:
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lexer.input(input)
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if tokenfunc is None:
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# Tokenize function
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get_token = lexer.token
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else:
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get_token = tokenfunc
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# Set up the state and symbol stacks
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statestack = [ ] # Stack of parsing states
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self.statestack = statestack
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symstack = [ ] # Stack of grammar symbols
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self.symstack = symstack
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pslice.stack = symstack # Put in the production
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errtoken = None # Err token
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# The start state is assumed to be (0,$end)
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statestack.append(0)
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sym = YaccSymbol()
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sym.type = "$end"
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symstack.append(sym)
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state = 0
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while 1:
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# Get the next symbol on the input. If a lookahead symbol
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# is already set, we just use that. Otherwise, we'll pull
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# the next token off of the lookaheadstack or from the lexer
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# --! DEBUG
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debug.debug('')
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debug.debug('State : %s', state)
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# --! DEBUG
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if not lookahead:
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if not lookaheadstack:
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lookahead = get_token() # Get the next token
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else:
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lookahead = lookaheadstack.pop()
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if not lookahead:
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lookahead = YaccSymbol()
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lookahead.type = "$end"
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# --! DEBUG
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debug.debug('Stack : %s',
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("%s . %s" % (" ".join([xx.type for xx in symstack][1:]), str(lookahead))).lstrip())
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# --! DEBUG
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# Check the action table
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ltype = lookahead.type
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t = actions[state].get(ltype)
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if t is not None:
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if t > 0:
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# shift a symbol on the stack
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statestack.append(t)
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state = t
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# --! DEBUG
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debug.debug("Action : Shift and goto state %s", t)
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# --! DEBUG
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symstack.append(lookahead)
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lookahead = None
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# Decrease error count on successful shift
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if errorcount: errorcount -=1
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continue
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if t < 0:
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# reduce a symbol on the stack, emit a production
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p = prod[-t]
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pname = p.name
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plen = p.len
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# Get production function
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sym = YaccSymbol()
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sym.type = pname # Production name
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sym.value = None
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# --! DEBUG
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if plen:
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debug.info("Action : Reduce rule [%s] with %s and goto state %d", p.str, "["+",".join([format_stack_entry(_v.value) for _v in symstack[-plen:]])+"]",-t)
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else:
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debug.info("Action : Reduce rule [%s] with %s and goto state %d", p.str, [],-t)
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# --! DEBUG
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if plen:
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targ = symstack[-plen-1:]
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targ[0] = sym
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# --! TRACKING
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if tracking:
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t1 = targ[1]
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sym.lineno = t1.lineno
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sym.lexpos = t1.lexpos
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t1 = targ[-1]
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sym.endlineno = getattr(t1,"endlineno",t1.lineno)
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sym.endlexpos = getattr(t1,"endlexpos",t1.lexpos)
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# --! TRACKING
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# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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# The code enclosed in this section is duplicated
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# below as a performance optimization. Make sure
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# changes get made in both locations.
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pslice.slice = targ
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try:
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# Call the grammar rule with our special slice object
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del symstack[-plen:]
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del statestack[-plen:]
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p.callable(pslice)
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# --! DEBUG
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debug.info("Result : %s", format_result(pslice[0]))
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# --! DEBUG
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symstack.append(sym)
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state = goto[statestack[-1]][pname]
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statestack.append(state)
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except SyntaxError:
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# If an error was set. Enter error recovery state
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lookaheadstack.append(lookahead)
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symstack.pop()
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statestack.pop()
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state = statestack[-1]
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sym.type = 'error'
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lookahead = sym
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errorcount = error_count
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self.errorok = 0
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continue
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# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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else:
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# --! TRACKING
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if tracking:
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sym.lineno = lexer.lineno
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sym.lexpos = lexer.lexpos
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# --! TRACKING
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targ = [ sym ]
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# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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# The code enclosed in this section is duplicated
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# above as a performance optimization. Make sure
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# changes get made in both locations.
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pslice.slice = targ
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try:
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# Call the grammar rule with our special slice object
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p.callable(pslice)
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# --! DEBUG
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debug.info("Result : %s", format_result(pslice[0]))
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# --! DEBUG
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symstack.append(sym)
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state = goto[statestack[-1]][pname]
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statestack.append(state)
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except SyntaxError:
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# If an error was set. Enter error recovery state
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lookaheadstack.append(lookahead)
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symstack.pop()
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statestack.pop()
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state = statestack[-1]
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sym.type = 'error'
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lookahead = sym
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errorcount = error_count
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self.errorok = 0
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continue
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# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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if t == 0:
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n = symstack[-1]
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result = getattr(n,"value",None)
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# --! DEBUG
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debug.info("Done : Returning %s", format_result(result))
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debug.info("PLY: PARSE DEBUG END")
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# --! DEBUG
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return result
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if t == None:
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# --! DEBUG
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debug.error('Error : %s',
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("%s . %s" % (" ".join([xx.type for xx in symstack][1:]), str(lookahead))).lstrip())
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# --! DEBUG
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# We have some kind of parsing error here. To handle
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# this, we are going to push the current token onto
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# the tokenstack and replace it with an 'error' token.
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# If there are any synchronization rules, they may
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# catch it.
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#
|
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# In addition to pushing the error token, we call call
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# the user defined p_error() function if this is the
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# first syntax error. This function is only called if
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# errorcount == 0.
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if errorcount == 0 or self.errorok:
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errorcount = error_count
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self.errorok = 0
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errtoken = lookahead
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if errtoken.type == "$end":
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errtoken = None # End of file!
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if self.errorfunc:
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global errok,token,restart
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errok = self.errok # Set some special functions available in error recovery
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token = get_token
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restart = self.restart
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if errtoken and not hasattr(errtoken,'lexer'):
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errtoken.lexer = lexer
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tok = self.errorfunc(errtoken)
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del errok, token, restart # Delete special functions
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if self.errorok:
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# User must have done some kind of panic
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|
# mode recovery on their own. The
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# returned token is the next lookahead
|
|
lookahead = tok
|
|
errtoken = None
|
|
continue
|
|
else:
|
|
if errtoken:
|
|
if hasattr(errtoken,"lineno"): lineno = lookahead.lineno
|
|
else: lineno = 0
|
|
if lineno:
|
|
sys.stderr.write("yacc: Syntax error at line %d, token=%s\n" % (lineno, errtoken.type))
|
|
else:
|
|
sys.stderr.write("yacc: Syntax error, token=%s" % errtoken.type)
|
|
else:
|
|
sys.stderr.write("yacc: Parse error in input. EOF\n")
|
|
return
|
|
|
|
else:
|
|
errorcount = error_count
|
|
|
|
# case 1: the statestack only has 1 entry on it. If we're in this state, the
|
|
# entire parse has been rolled back and we're completely hosed. The token is
|
|
# discarded and we just keep going.
|
|
|
|
if len(statestack) <= 1 and lookahead.type != "$end":
|
|
lookahead = None
|
|
errtoken = None
|
|
state = 0
|
|
# Nuke the pushback stack
|
|
del lookaheadstack[:]
|
|
continue
|
|
|
|
# case 2: the statestack has a couple of entries on it, but we're
|
|
# at the end of the file. nuke the top entry and generate an error token
|
|
|
|
# Start nuking entries on the stack
|
|
if lookahead.type == "$end":
|
|
# Whoa. We're really hosed here. Bail out
|
|
return
|
|
|
|
if lookahead.type != 'error':
|
|
sym = symstack[-1]
|
|
if sym.type == 'error':
|
|
# Hmmm. Error is on top of stack, we'll just nuke input
|
|
# symbol and continue
|
|
lookahead = None
|
|
continue
|
|
t = YaccSymbol()
|
|
t.type = 'error'
|
|
if hasattr(lookahead,"lineno"):
|
|
t.lineno = lookahead.lineno
|
|
t.value = lookahead
|
|
lookaheadstack.append(lookahead)
|
|
lookahead = t
|
|
else:
|
|
symstack.pop()
|
|
statestack.pop()
|
|
state = statestack[-1] # Potential bug fix
|
|
|
|
continue
|
|
|
|
# Call an error function here
|
|
raise RuntimeError("yacc: internal parser error!!!\n")
|
|
|
|
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
# parseopt().
|
|
#
|
|
# Optimized version of parse() method. DO NOT EDIT THIS CODE DIRECTLY.
|
|
# Edit the debug version above, then copy any modifications to the method
|
|
# below while removing #--! DEBUG sections.
|
|
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
|
|
|
|
def parseopt(self,input=None,lexer=None,debug=0,tracking=0,tokenfunc=None):
|
|
lookahead = None # Current lookahead symbol
|
|
lookaheadstack = [ ] # Stack of lookahead symbols
|
|
actions = self.action # Local reference to action table (to avoid lookup on self.)
|
|
goto = self.goto # Local reference to goto table (to avoid lookup on self.)
|
|
prod = self.productions # Local reference to production list (to avoid lookup on self.)
|
|
pslice = YaccProduction(None) # Production object passed to grammar rules
|
|
errorcount = 0 # Used during error recovery
|
|
|
|
# If no lexer was given, we will try to use the lex module
|
|
if not lexer:
|
|
lex = load_ply_lex()
|
|
lexer = lex.lexer
|
|
|
|
# Set up the lexer and parser objects on pslice
|
|
pslice.lexer = lexer
|
|
pslice.parser = self
|
|
|
|
# If input was supplied, pass to lexer
|
|
if input is not None:
|
|
lexer.input(input)
|
|
|
|
if tokenfunc is None:
|
|
# Tokenize function
|
|
get_token = lexer.token
|
|
else:
|
|
get_token = tokenfunc
|
|
|
|
# Set up the state and symbol stacks
|
|
|
|
statestack = [ ] # Stack of parsing states
|
|
self.statestack = statestack
|
|
symstack = [ ] # Stack of grammar symbols
|
|
self.symstack = symstack
|
|
|
|
pslice.stack = symstack # Put in the production
|
|
errtoken = None # Err token
|
|
|
|
# The start state is assumed to be (0,$end)
|
|
|
|
statestack.append(0)
|
|
sym = YaccSymbol()
|
|
sym.type = '$end'
|
|
symstack.append(sym)
|
|
state = 0
|
|
while 1:
|
|
# Get the next symbol on the input. If a lookahead symbol
|
|
# is already set, we just use that. Otherwise, we'll pull
|
|
# the next token off of the lookaheadstack or from the lexer
|
|
|
|
if not lookahead:
|
|
if not lookaheadstack:
|
|
lookahead = get_token() # Get the next token
|
|
else:
|
|
lookahead = lookaheadstack.pop()
|
|
if not lookahead:
|
|
lookahead = YaccSymbol()
|
|
lookahead.type = '$end'
|
|
|
|
# Check the action table
|
|
ltype = lookahead.type
|
|
t = actions[state].get(ltype)
|
|
|
|
if t is not None:
|
|
if t > 0:
|
|
# shift a symbol on the stack
|
|
statestack.append(t)
|
|
state = t
|
|
|
|
symstack.append(lookahead)
|
|
lookahead = None
|
|
|
|
# Decrease error count on successful shift
|
|
if errorcount: errorcount -=1
|
|
continue
|
|
|
|
if t < 0:
|
|
# reduce a symbol on the stack, emit a production
|
|
p = prod[-t]
|
|
pname = p.name
|
|
plen = p.len
|
|
|
|
# Get production function
|
|
sym = YaccSymbol()
|
|
sym.type = pname # Production name
|
|
sym.value = None
|
|
|
|
if plen:
|
|
targ = symstack[-plen-1:]
|
|
targ[0] = sym
|
|
|
|
# --! TRACKING
|
|
if tracking:
|
|
t1 = targ[1]
|
|
sym.lineno = t1.lineno
|
|
sym.lexpos = t1.lexpos
|
|
t1 = targ[-1]
|
|
sym.endlineno = getattr(t1,"endlineno",t1.lineno)
|
|
sym.endlexpos = getattr(t1,"endlexpos",t1.lexpos)
|
|
|
|
# --! TRACKING
|
|
|
|
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
# The code enclosed in this section is duplicated
|
|
# below as a performance optimization. Make sure
|
|
# changes get made in both locations.
|
|
|
|
pslice.slice = targ
|
|
|
|
try:
|
|
# Call the grammar rule with our special slice object
|
|
del symstack[-plen:]
|
|
del statestack[-plen:]
|
|
p.callable(pslice)
|
|
symstack.append(sym)
|
|
state = goto[statestack[-1]][pname]
|
|
statestack.append(state)
|
|
except SyntaxError:
|
|
# If an error was set. Enter error recovery state
|
|
lookaheadstack.append(lookahead)
|
|
symstack.pop()
|
|
statestack.pop()
|
|
state = statestack[-1]
|
|
sym.type = 'error'
|
|
lookahead = sym
|
|
errorcount = error_count
|
|
self.errorok = 0
|
|
continue
|
|
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
|
|
else:
|
|
|
|
# --! TRACKING
|
|
if tracking:
|
|
sym.lineno = lexer.lineno
|
|
sym.lexpos = lexer.lexpos
|
|
# --! TRACKING
|
|
|
|
targ = [ sym ]
|
|
|
|
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
# The code enclosed in this section is duplicated
|
|
# above as a performance optimization. Make sure
|
|
# changes get made in both locations.
|
|
|
|
pslice.slice = targ
|
|
|
|
try:
|
|
# Call the grammar rule with our special slice object
|
|
p.callable(pslice)
|
|
symstack.append(sym)
|
|
state = goto[statestack[-1]][pname]
|
|
statestack.append(state)
|
|
except SyntaxError:
|
|
# If an error was set. Enter error recovery state
|
|
lookaheadstack.append(lookahead)
|
|
symstack.pop()
|
|
statestack.pop()
|
|
state = statestack[-1]
|
|
sym.type = 'error'
|
|
lookahead = sym
|
|
errorcount = error_count
|
|
self.errorok = 0
|
|
continue
|
|
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
|
|
if t == 0:
|
|
n = symstack[-1]
|
|
return getattr(n,"value",None)
|
|
|
|
if t == None:
|
|
|
|
# We have some kind of parsing error here. To handle
|
|
# this, we are going to push the current token onto
|
|
# the tokenstack and replace it with an 'error' token.
|
|
# If there are any synchronization rules, they may
|
|
# catch it.
|
|
#
|
|
# In addition to pushing the error token, we call call
|
|
# the user defined p_error() function if this is the
|
|
# first syntax error. This function is only called if
|
|
# errorcount == 0.
|
|
if errorcount == 0 or self.errorok:
|
|
errorcount = error_count
|
|
self.errorok = 0
|
|
errtoken = lookahead
|
|
if errtoken.type == '$end':
|
|
errtoken = None # End of file!
|
|
if self.errorfunc:
|
|
global errok,token,restart
|
|
errok = self.errok # Set some special functions available in error recovery
|
|
token = get_token
|
|
restart = self.restart
|
|
if errtoken and not hasattr(errtoken,'lexer'):
|
|
errtoken.lexer = lexer
|
|
tok = self.errorfunc(errtoken)
|
|
del errok, token, restart # Delete special functions
|
|
|
|
if self.errorok:
|
|
# User must have done some kind of panic
|
|
# mode recovery on their own. The
|
|
# returned token is the next lookahead
|
|
lookahead = tok
|
|
errtoken = None
|
|
continue
|
|
else:
|
|
if errtoken:
|
|
if hasattr(errtoken,"lineno"): lineno = lookahead.lineno
|
|
else: lineno = 0
|
|
if lineno:
|
|
sys.stderr.write("yacc: Syntax error at line %d, token=%s\n" % (lineno, errtoken.type))
|
|
else:
|
|
sys.stderr.write("yacc: Syntax error, token=%s" % errtoken.type)
|
|
else:
|
|
sys.stderr.write("yacc: Parse error in input. EOF\n")
|
|
return
|
|
|
|
else:
|
|
errorcount = error_count
|
|
|
|
# case 1: the statestack only has 1 entry on it. If we're in this state, the
|
|
# entire parse has been rolled back and we're completely hosed. The token is
|
|
# discarded and we just keep going.
|
|
|
|
if len(statestack) <= 1 and lookahead.type != '$end':
|
|
lookahead = None
|
|
errtoken = None
|
|
state = 0
|
|
# Nuke the pushback stack
|
|
del lookaheadstack[:]
|
|
continue
|
|
|
|
# case 2: the statestack has a couple of entries on it, but we're
|
|
# at the end of the file. nuke the top entry and generate an error token
|
|
|
|
# Start nuking entries on the stack
|
|
if lookahead.type == '$end':
|
|
# Whoa. We're really hosed here. Bail out
|
|
return
|
|
|
|
if lookahead.type != 'error':
|
|
sym = symstack[-1]
|
|
if sym.type == 'error':
|
|
# Hmmm. Error is on top of stack, we'll just nuke input
|
|
# symbol and continue
|
|
lookahead = None
|
|
continue
|
|
t = YaccSymbol()
|
|
t.type = 'error'
|
|
if hasattr(lookahead,"lineno"):
|
|
t.lineno = lookahead.lineno
|
|
t.value = lookahead
|
|
lookaheadstack.append(lookahead)
|
|
lookahead = t
|
|
else:
|
|
symstack.pop()
|
|
statestack.pop()
|
|
state = statestack[-1] # Potential bug fix
|
|
|
|
continue
|
|
|
|
# Call an error function here
|
|
raise RuntimeError("yacc: internal parser error!!!\n")
|
|
|
|
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
# parseopt_notrack().
|
|
#
|
|
# Optimized version of parseopt() with line number tracking removed.
|
|
# DO NOT EDIT THIS CODE DIRECTLY. Copy the optimized version and remove
|
|
# code in the #--! TRACKING sections
|
|
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
|
|
def parseopt_notrack(self,input=None,lexer=None,debug=0,tracking=0,tokenfunc=None):
|
|
lookahead = None # Current lookahead symbol
|
|
lookaheadstack = [ ] # Stack of lookahead symbols
|
|
actions = self.action # Local reference to action table (to avoid lookup on self.)
|
|
goto = self.goto # Local reference to goto table (to avoid lookup on self.)
|
|
prod = self.productions # Local reference to production list (to avoid lookup on self.)
|
|
pslice = YaccProduction(None) # Production object passed to grammar rules
|
|
errorcount = 0 # Used during error recovery
|
|
|
|
# If no lexer was given, we will try to use the lex module
|
|
if not lexer:
|
|
lex = load_ply_lex()
|
|
lexer = lex.lexer
|
|
|
|
# Set up the lexer and parser objects on pslice
|
|
pslice.lexer = lexer
|
|
pslice.parser = self
|
|
|
|
# If input was supplied, pass to lexer
|
|
if input is not None:
|
|
lexer.input(input)
|
|
|
|
if tokenfunc is None:
|
|
# Tokenize function
|
|
get_token = lexer.token
|
|
else:
|
|
get_token = tokenfunc
|
|
|
|
# Set up the state and symbol stacks
|
|
|
|
statestack = [ ] # Stack of parsing states
|
|
self.statestack = statestack
|
|
symstack = [ ] # Stack of grammar symbols
|
|
self.symstack = symstack
|
|
|
|
pslice.stack = symstack # Put in the production
|
|
errtoken = None # Err token
|
|
|
|
# The start state is assumed to be (0,$end)
|
|
|
|
statestack.append(0)
|
|
sym = YaccSymbol()
|
|
sym.type = '$end'
|
|
symstack.append(sym)
|
|
state = 0
|
|
while 1:
|
|
# Get the next symbol on the input. If a lookahead symbol
|
|
# is already set, we just use that. Otherwise, we'll pull
|
|
# the next token off of the lookaheadstack or from the lexer
|
|
|
|
if not lookahead:
|
|
if not lookaheadstack:
|
|
lookahead = get_token() # Get the next token
|
|
else:
|
|
lookahead = lookaheadstack.pop()
|
|
if not lookahead:
|
|
lookahead = YaccSymbol()
|
|
lookahead.type = '$end'
|
|
|
|
# Check the action table
|
|
ltype = lookahead.type
|
|
t = actions[state].get(ltype)
|
|
|
|
if t is not None:
|
|
if t > 0:
|
|
# shift a symbol on the stack
|
|
statestack.append(t)
|
|
state = t
|
|
|
|
symstack.append(lookahead)
|
|
lookahead = None
|
|
|
|
# Decrease error count on successful shift
|
|
if errorcount: errorcount -=1
|
|
continue
|
|
|
|
if t < 0:
|
|
# reduce a symbol on the stack, emit a production
|
|
p = prod[-t]
|
|
pname = p.name
|
|
plen = p.len
|
|
|
|
# Get production function
|
|
sym = YaccSymbol()
|
|
sym.type = pname # Production name
|
|
sym.value = None
|
|
|
|
if plen:
|
|
targ = symstack[-plen-1:]
|
|
targ[0] = sym
|
|
|
|
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
# The code enclosed in this section is duplicated
|
|
# below as a performance optimization. Make sure
|
|
# changes get made in both locations.
|
|
|
|
pslice.slice = targ
|
|
|
|
try:
|
|
# Call the grammar rule with our special slice object
|
|
del symstack[-plen:]
|
|
del statestack[-plen:]
|
|
p.callable(pslice)
|
|
symstack.append(sym)
|
|
state = goto[statestack[-1]][pname]
|
|
statestack.append(state)
|
|
except SyntaxError:
|
|
# If an error was set. Enter error recovery state
|
|
lookaheadstack.append(lookahead)
|
|
symstack.pop()
|
|
statestack.pop()
|
|
state = statestack[-1]
|
|
sym.type = 'error'
|
|
lookahead = sym
|
|
errorcount = error_count
|
|
self.errorok = 0
|
|
continue
|
|
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
|
|
else:
|
|
|
|
targ = [ sym ]
|
|
|
|
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
# The code enclosed in this section is duplicated
|
|
# above as a performance optimization. Make sure
|
|
# changes get made in both locations.
|
|
|
|
pslice.slice = targ
|
|
|
|
try:
|
|
# Call the grammar rule with our special slice object
|
|
p.callable(pslice)
|
|
symstack.append(sym)
|
|
state = goto[statestack[-1]][pname]
|
|
statestack.append(state)
|
|
except SyntaxError:
|
|
# If an error was set. Enter error recovery state
|
|
lookaheadstack.append(lookahead)
|
|
symstack.pop()
|
|
statestack.pop()
|
|
state = statestack[-1]
|
|
sym.type = 'error'
|
|
lookahead = sym
|
|
errorcount = error_count
|
|
self.errorok = 0
|
|
continue
|
|
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
|
|
if t == 0:
|
|
n = symstack[-1]
|
|
return getattr(n,"value",None)
|
|
|
|
if t == None:
|
|
|
|
# We have some kind of parsing error here. To handle
|
|
# this, we are going to push the current token onto
|
|
# the tokenstack and replace it with an 'error' token.
|
|
# If there are any synchronization rules, they may
|
|
# catch it.
|
|
#
|
|
# In addition to pushing the error token, we call call
|
|
# the user defined p_error() function if this is the
|
|
# first syntax error. This function is only called if
|
|
# errorcount == 0.
|
|
if errorcount == 0 or self.errorok:
|
|
errorcount = error_count
|
|
self.errorok = 0
|
|
errtoken = lookahead
|
|
if errtoken.type == '$end':
|
|
errtoken = None # End of file!
|
|
if self.errorfunc:
|
|
global errok,token,restart
|
|
errok = self.errok # Set some special functions available in error recovery
|
|
token = get_token
|
|
restart = self.restart
|
|
if errtoken and not hasattr(errtoken,'lexer'):
|
|
errtoken.lexer = lexer
|
|
tok = self.errorfunc(errtoken)
|
|
del errok, token, restart # Delete special functions
|
|
|
|
if self.errorok:
|
|
# User must have done some kind of panic
|
|
# mode recovery on their own. The
|
|
# returned token is the next lookahead
|
|
lookahead = tok
|
|
errtoken = None
|
|
continue
|
|
else:
|
|
if errtoken:
|
|
if hasattr(errtoken,"lineno"): lineno = lookahead.lineno
|
|
else: lineno = 0
|
|
if lineno:
|
|
sys.stderr.write("yacc: Syntax error at line %d, token=%s\n" % (lineno, errtoken.type))
|
|
else:
|
|
sys.stderr.write("yacc: Syntax error, token=%s" % errtoken.type)
|
|
else:
|
|
sys.stderr.write("yacc: Parse error in input. EOF\n")
|
|
return
|
|
|
|
else:
|
|
errorcount = error_count
|
|
|
|
# case 1: the statestack only has 1 entry on it. If we're in this state, the
|
|
# entire parse has been rolled back and we're completely hosed. The token is
|
|
# discarded and we just keep going.
|
|
|
|
if len(statestack) <= 1 and lookahead.type != '$end':
|
|
lookahead = None
|
|
errtoken = None
|
|
state = 0
|
|
# Nuke the pushback stack
|
|
del lookaheadstack[:]
|
|
continue
|
|
|
|
# case 2: the statestack has a couple of entries on it, but we're
|
|
# at the end of the file. nuke the top entry and generate an error token
|
|
|
|
# Start nuking entries on the stack
|
|
if lookahead.type == '$end':
|
|
# Whoa. We're really hosed here. Bail out
|
|
return
|
|
|
|
if lookahead.type != 'error':
|
|
sym = symstack[-1]
|
|
if sym.type == 'error':
|
|
# Hmmm. Error is on top of stack, we'll just nuke input
|
|
# symbol and continue
|
|
lookahead = None
|
|
continue
|
|
t = YaccSymbol()
|
|
t.type = 'error'
|
|
if hasattr(lookahead,"lineno"):
|
|
t.lineno = lookahead.lineno
|
|
t.value = lookahead
|
|
lookaheadstack.append(lookahead)
|
|
lookahead = t
|
|
else:
|
|
symstack.pop()
|
|
statestack.pop()
|
|
state = statestack[-1] # Potential bug fix
|
|
|
|
continue
|
|
|
|
# Call an error function here
|
|
raise RuntimeError("yacc: internal parser error!!!\n")
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# === Grammar Representation ===
|
|
#
|
|
# The following functions, classes, and variables are used to represent and
|
|
# manipulate the rules that make up a grammar.
|
|
# -----------------------------------------------------------------------------
|
|
|
|
import re
|
|
|
|
# regex matching identifiers
|
|
_is_identifier = re.compile(r'^[a-zA-Z0-9_-]+$')
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# class Production:
|
|
#
|
|
# This class stores the raw information about a single production or grammar rule.
|
|
# A grammar rule refers to a specification such as this:
|
|
#
|
|
# expr : expr PLUS term
|
|
#
|
|
# Here are the basic attributes defined on all productions
|
|
#
|
|
# name - Name of the production. For example 'expr'
|
|
# prod - A list of symbols on the right side ['expr','PLUS','term']
|
|
# prec - Production precedence level
|
|
# number - Production number.
|
|
# func - Function that executes on reduce
|
|
# file - File where production function is defined
|
|
# lineno - Line number where production function is defined
|
|
#
|
|
# The following attributes are defined or optional.
|
|
#
|
|
# len - Length of the production (number of symbols on right hand side)
|
|
# usyms - Set of unique symbols found in the production
|
|
# -----------------------------------------------------------------------------
|
|
|
|
class Production(object):
|
|
reduced = 0
|
|
def __init__(self,number,name,prod,precedence=('right',0),func=None,file='',line=0):
|
|
self.name = name
|
|
self.prod = tuple(prod)
|
|
self.number = number
|
|
self.func = func
|
|
self.callable = None
|
|
self.file = file
|
|
self.line = line
|
|
self.prec = precedence
|
|
|
|
# Internal settings used during table construction
|
|
|
|
self.len = len(self.prod) # Length of the production
|
|
|
|
# Create a list of unique production symbols used in the production
|
|
self.usyms = [ ]
|
|
for s in self.prod:
|
|
if s not in self.usyms:
|
|
self.usyms.append(s)
|
|
|
|
# List of all LR items for the production
|
|
self.lr_items = []
|
|
self.lr_next = None
|
|
|
|
# Create a string representation
|
|
if self.prod:
|
|
self.str = "%s -> %s" % (self.name," ".join(self.prod))
|
|
else:
|
|
self.str = "%s -> <empty>" % self.name
|
|
|
|
def __str__(self):
|
|
return self.str
|
|
|
|
def __repr__(self):
|
|
return "Production("+str(self)+")"
|
|
|
|
def __len__(self):
|
|
return len(self.prod)
|
|
|
|
def __nonzero__(self):
|
|
return 1
|
|
|
|
def __getitem__(self,index):
|
|
return self.prod[index]
|
|
|
|
# Return the nth lr_item from the production (or None if at the end)
|
|
def lr_item(self,n):
|
|
if n > len(self.prod): return None
|
|
p = LRItem(self,n)
|
|
|
|
# Precompute the list of productions immediately following. Hack. Remove later
|
|
try:
|
|
p.lr_after = Prodnames[p.prod[n+1]]
|
|
except (IndexError,KeyError):
|
|
p.lr_after = []
|
|
try:
|
|
p.lr_before = p.prod[n-1]
|
|
except IndexError:
|
|
p.lr_before = None
|
|
|
|
return p
|
|
|
|
# Bind the production function name to a callable
|
|
def bind(self,pdict):
|
|
if self.func:
|
|
self.callable = pdict[self.func]
|
|
|
|
# This class serves as a minimal standin for Production objects when
|
|
# reading table data from files. It only contains information
|
|
# actually used by the LR parsing engine, plus some additional
|
|
# debugging information.
|
|
class MiniProduction(object):
|
|
def __init__(self,str,name,len,func,file,line):
|
|
self.name = name
|
|
self.len = len
|
|
self.func = func
|
|
self.callable = None
|
|
self.file = file
|
|
self.line = line
|
|
self.str = str
|
|
def __str__(self):
|
|
return self.str
|
|
def __repr__(self):
|
|
return "MiniProduction(%s)" % self.str
|
|
|
|
# Bind the production function name to a callable
|
|
def bind(self,pdict):
|
|
if self.func:
|
|
self.callable = pdict[self.func]
|
|
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# class LRItem
|
|
#
|
|
# This class represents a specific stage of parsing a production rule. For
|
|
# example:
|
|
#
|
|
# expr : expr . PLUS term
|
|
#
|
|
# In the above, the "." represents the current location of the parse. Here
|
|
# basic attributes:
|
|
#
|
|
# name - Name of the production. For example 'expr'
|
|
# prod - A list of symbols on the right side ['expr','.', 'PLUS','term']
|
|
# number - Production number.
|
|
#
|
|
# lr_next Next LR item. Example, if we are ' expr -> expr . PLUS term'
|
|
# then lr_next refers to 'expr -> expr PLUS . term'
|
|
# lr_index - LR item index (location of the ".") in the prod list.
|
|
# lookaheads - LALR lookahead symbols for this item
|
|
# len - Length of the production (number of symbols on right hand side)
|
|
# lr_after - List of all productions that immediately follow
|
|
# lr_before - Grammar symbol immediately before
|
|
# -----------------------------------------------------------------------------
|
|
|
|
class LRItem(object):
|
|
def __init__(self,p,n):
|
|
self.name = p.name
|
|
self.prod = list(p.prod)
|
|
self.number = p.number
|
|
self.lr_index = n
|
|
self.lookaheads = { }
|
|
self.prod.insert(n,".")
|
|
self.prod = tuple(self.prod)
|
|
self.len = len(self.prod)
|
|
self.usyms = p.usyms
|
|
|
|
def __str__(self):
|
|
if self.prod:
|
|
s = "%s -> %s" % (self.name," ".join(self.prod))
|
|
else:
|
|
s = "%s -> <empty>" % self.name
|
|
return s
|
|
|
|
def __repr__(self):
|
|
return "LRItem("+str(self)+")"
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# rightmost_terminal()
|
|
#
|
|
# Return the rightmost terminal from a list of symbols. Used in add_production()
|
|
# -----------------------------------------------------------------------------
|
|
def rightmost_terminal(symbols, terminals):
|
|
i = len(symbols) - 1
|
|
while i >= 0:
|
|
if symbols[i] in terminals:
|
|
return symbols[i]
|
|
i -= 1
|
|
return None
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# === GRAMMAR CLASS ===
|
|
#
|
|
# The following class represents the contents of the specified grammar along
|
|
# with various computed properties such as first sets, follow sets, LR items, etc.
|
|
# This data is used for critical parts of the table generation process later.
|
|
# -----------------------------------------------------------------------------
|
|
|
|
class GrammarError(YaccError): pass
|
|
|
|
class Grammar(object):
|
|
def __init__(self,terminals):
|
|
self.Productions = [None] # A list of all of the productions. The first
|
|
# entry is always reserved for the purpose of
|
|
# building an augmented grammar
|
|
|
|
self.Prodnames = { } # A dictionary mapping the names of nonterminals to a list of all
|
|
# productions of that nonterminal.
|
|
|
|
self.Prodmap = { } # A dictionary that is only used to detect duplicate
|
|
# productions.
|
|
|
|
self.Terminals = { } # A dictionary mapping the names of terminal symbols to a
|
|
# list of the rules where they are used.
|
|
|
|
for term in terminals:
|
|
self.Terminals[term] = []
|
|
|
|
self.Terminals['error'] = []
|
|
|
|
self.Nonterminals = { } # A dictionary mapping names of nonterminals to a list
|
|
# of rule numbers where they are used.
|
|
|
|
self.First = { } # A dictionary of precomputed FIRST(x) symbols
|
|
|
|
self.Follow = { } # A dictionary of precomputed FOLLOW(x) symbols
|
|
|
|
self.Precedence = { } # Precedence rules for each terminal. Contains tuples of the
|
|
# form ('right',level) or ('nonassoc', level) or ('left',level)
|
|
|
|
self.UsedPrecedence = { } # Precedence rules that were actually used by the grammer.
|
|
# This is only used to provide error checking and to generate
|
|
# a warning about unused precedence rules.
|
|
|
|
self.Start = None # Starting symbol for the grammar
|
|
|
|
|
|
def __len__(self):
|
|
return len(self.Productions)
|
|
|
|
def __getitem__(self,index):
|
|
return self.Productions[index]
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# set_precedence()
|
|
#
|
|
# Sets the precedence for a given terminal. assoc is the associativity such as
|
|
# 'left','right', or 'nonassoc'. level is a numeric level.
|
|
#
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def set_precedence(self,term,assoc,level):
|
|
assert self.Productions == [None],"Must call set_precedence() before add_production()"
|
|
if term in self.Precedence:
|
|
raise GrammarError("Precedence already specified for terminal '%s'" % term)
|
|
if assoc not in ['left','right','nonassoc']:
|
|
raise GrammarError("Associativity must be one of 'left','right', or 'nonassoc'")
|
|
self.Precedence[term] = (assoc,level)
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# add_production()
|
|
#
|
|
# Given an action function, this function assembles a production rule and
|
|
# computes its precedence level.
|
|
#
|
|
# The production rule is supplied as a list of symbols. For example,
|
|
# a rule such as 'expr : expr PLUS term' has a production name of 'expr' and
|
|
# symbols ['expr','PLUS','term'].
|
|
#
|
|
# Precedence is determined by the precedence of the right-most non-terminal
|
|
# or the precedence of a terminal specified by %prec.
|
|
#
|
|
# A variety of error checks are performed to make sure production symbols
|
|
# are valid and that %prec is used correctly.
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def add_production(self,prodname,syms,func=None,file='',line=0):
|
|
|
|
if prodname in self.Terminals:
|
|
raise GrammarError("%s:%d: Illegal rule name '%s'. Already defined as a token" % (file,line,prodname))
|
|
if prodname == 'error':
|
|
raise GrammarError("%s:%d: Illegal rule name '%s'. error is a reserved word" % (file,line,prodname))
|
|
if not _is_identifier.match(prodname):
|
|
raise GrammarError("%s:%d: Illegal rule name '%s'" % (file,line,prodname))
|
|
|
|
# Look for literal tokens
|
|
for n,s in enumerate(syms):
|
|
if s[0] in "'\"":
|
|
try:
|
|
c = eval(s)
|
|
if (len(c) > 1):
|
|
raise GrammarError("%s:%d: Literal token %s in rule '%s' may only be a single character" % (file,line,s, prodname))
|
|
if not c in self.Terminals:
|
|
self.Terminals[c] = []
|
|
syms[n] = c
|
|
continue
|
|
except SyntaxError:
|
|
pass
|
|
if not _is_identifier.match(s) and s != '%prec':
|
|
raise GrammarError("%s:%d: Illegal name '%s' in rule '%s'" % (file,line,s, prodname))
|
|
|
|
# Determine the precedence level
|
|
if '%prec' in syms:
|
|
if syms[-1] == '%prec':
|
|
raise GrammarError("%s:%d: Syntax error. Nothing follows %%prec" % (file,line))
|
|
if syms[-2] != '%prec':
|
|
raise GrammarError("%s:%d: Syntax error. %%prec can only appear at the end of a grammar rule" % (file,line))
|
|
precname = syms[-1]
|
|
prodprec = self.Precedence.get(precname,None)
|
|
if not prodprec:
|
|
raise GrammarError("%s:%d: Nothing known about the precedence of '%s'" % (file,line,precname))
|
|
else:
|
|
self.UsedPrecedence[precname] = 1
|
|
del syms[-2:] # Drop %prec from the rule
|
|
else:
|
|
# If no %prec, precedence is determined by the rightmost terminal symbol
|
|
precname = rightmost_terminal(syms,self.Terminals)
|
|
prodprec = self.Precedence.get(precname,('right',0))
|
|
|
|
# See if the rule is already in the rulemap
|
|
map = "%s -> %s" % (prodname,syms)
|
|
if map in self.Prodmap:
|
|
m = self.Prodmap[map]
|
|
raise GrammarError("%s:%d: Duplicate rule %s. " % (file,line, m) +
|
|
"Previous definition at %s:%d" % (m.file, m.line))
|
|
|
|
# From this point on, everything is valid. Create a new Production instance
|
|
pnumber = len(self.Productions)
|
|
if not prodname in self.Nonterminals:
|
|
self.Nonterminals[prodname] = [ ]
|
|
|
|
# Add the production number to Terminals and Nonterminals
|
|
for t in syms:
|
|
if t in self.Terminals:
|
|
self.Terminals[t].append(pnumber)
|
|
else:
|
|
if not t in self.Nonterminals:
|
|
self.Nonterminals[t] = [ ]
|
|
self.Nonterminals[t].append(pnumber)
|
|
|
|
# Create a production and add it to the list of productions
|
|
p = Production(pnumber,prodname,syms,prodprec,func,file,line)
|
|
self.Productions.append(p)
|
|
self.Prodmap[map] = p
|
|
|
|
# Add to the global productions list
|
|
try:
|
|
self.Prodnames[prodname].append(p)
|
|
except KeyError:
|
|
self.Prodnames[prodname] = [ p ]
|
|
return 0
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# set_start()
|
|
#
|
|
# Sets the starting symbol and creates the augmented grammar. Production
|
|
# rule 0 is S' -> start where start is the start symbol.
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def set_start(self,start=None):
|
|
if not start:
|
|
start = self.Productions[1].name
|
|
if start not in self.Nonterminals:
|
|
raise GrammarError("start symbol %s undefined" % start)
|
|
self.Productions[0] = Production(0,"S'",[start])
|
|
self.Nonterminals[start].append(0)
|
|
self.Start = start
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# find_unreachable()
|
|
#
|
|
# Find all of the nonterminal symbols that can't be reached from the starting
|
|
# symbol. Returns a list of nonterminals that can't be reached.
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def find_unreachable(self):
|
|
|
|
# Mark all symbols that are reachable from a symbol s
|
|
def mark_reachable_from(s):
|
|
if reachable[s]:
|
|
# We've already reached symbol s.
|
|
return
|
|
reachable[s] = 1
|
|
for p in self.Prodnames.get(s,[]):
|
|
for r in p.prod:
|
|
mark_reachable_from(r)
|
|
|
|
reachable = { }
|
|
for s in list(self.Terminals) + list(self.Nonterminals):
|
|
reachable[s] = 0
|
|
|
|
mark_reachable_from( self.Productions[0].prod[0] )
|
|
|
|
return [s for s in list(self.Nonterminals)
|
|
if not reachable[s]]
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# infinite_cycles()
|
|
#
|
|
# This function looks at the various parsing rules and tries to detect
|
|
# infinite recursion cycles (grammar rules where there is no possible way
|
|
# to derive a string of only terminals).
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def infinite_cycles(self):
|
|
terminates = {}
|
|
|
|
# Terminals:
|
|
for t in self.Terminals:
|
|
terminates[t] = 1
|
|
|
|
terminates['$end'] = 1
|
|
|
|
# Nonterminals:
|
|
|
|
# Initialize to false:
|
|
for n in self.Nonterminals:
|
|
terminates[n] = 0
|
|
|
|
# Then propagate termination until no change:
|
|
while 1:
|
|
some_change = 0
|
|
for (n,pl) in self.Prodnames.items():
|
|
# Nonterminal n terminates iff any of its productions terminates.
|
|
for p in pl:
|
|
# Production p terminates iff all of its rhs symbols terminate.
|
|
for s in p.prod:
|
|
if not terminates[s]:
|
|
# The symbol s does not terminate,
|
|
# so production p does not terminate.
|
|
p_terminates = 0
|
|
break
|
|
else:
|
|
# didn't break from the loop,
|
|
# so every symbol s terminates
|
|
# so production p terminates.
|
|
p_terminates = 1
|
|
|
|
if p_terminates:
|
|
# symbol n terminates!
|
|
if not terminates[n]:
|
|
terminates[n] = 1
|
|
some_change = 1
|
|
# Don't need to consider any more productions for this n.
|
|
break
|
|
|
|
if not some_change:
|
|
break
|
|
|
|
infinite = []
|
|
for (s,term) in terminates.items():
|
|
if not term:
|
|
if not s in self.Prodnames and not s in self.Terminals and s != 'error':
|
|
# s is used-but-not-defined, and we've already warned of that,
|
|
# so it would be overkill to say that it's also non-terminating.
|
|
pass
|
|
else:
|
|
infinite.append(s)
|
|
|
|
return infinite
|
|
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# undefined_symbols()
|
|
#
|
|
# Find all symbols that were used the grammar, but not defined as tokens or
|
|
# grammar rules. Returns a list of tuples (sym, prod) where sym in the symbol
|
|
# and prod is the production where the symbol was used.
|
|
# -----------------------------------------------------------------------------
|
|
def undefined_symbols(self):
|
|
result = []
|
|
for p in self.Productions:
|
|
if not p: continue
|
|
|
|
for s in p.prod:
|
|
if not s in self.Prodnames and not s in self.Terminals and s != 'error':
|
|
result.append((s,p))
|
|
return result
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# unused_terminals()
|
|
#
|
|
# Find all terminals that were defined, but not used by the grammar. Returns
|
|
# a list of all symbols.
|
|
# -----------------------------------------------------------------------------
|
|
def unused_terminals(self):
|
|
unused_tok = []
|
|
for s,v in self.Terminals.items():
|
|
if s != 'error' and not v:
|
|
unused_tok.append(s)
|
|
|
|
return unused_tok
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# unused_rules()
|
|
#
|
|
# Find all grammar rules that were defined, but not used (maybe not reachable)
|
|
# Returns a list of productions.
|
|
# ------------------------------------------------------------------------------
|
|
|
|
def unused_rules(self):
|
|
unused_prod = []
|
|
for s,v in self.Nonterminals.items():
|
|
if not v:
|
|
p = self.Prodnames[s][0]
|
|
unused_prod.append(p)
|
|
return unused_prod
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# unused_precedence()
|
|
#
|
|
# Returns a list of tuples (term,precedence) corresponding to precedence
|
|
# rules that were never used by the grammar. term is the name of the terminal
|
|
# on which precedence was applied and precedence is a string such as 'left' or
|
|
# 'right' corresponding to the type of precedence.
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def unused_precedence(self):
|
|
unused = []
|
|
for termname in self.Precedence:
|
|
if not (termname in self.Terminals or termname in self.UsedPrecedence):
|
|
unused.append((termname,self.Precedence[termname][0]))
|
|
|
|
return unused
|
|
|
|
# -------------------------------------------------------------------------
|
|
# _first()
|
|
#
|
|
# Compute the value of FIRST1(beta) where beta is a tuple of symbols.
|
|
#
|
|
# During execution of compute_first1, the result may be incomplete.
|
|
# Afterward (e.g., when called from compute_follow()), it will be complete.
|
|
# -------------------------------------------------------------------------
|
|
def _first(self,beta):
|
|
|
|
# We are computing First(x1,x2,x3,...,xn)
|
|
result = [ ]
|
|
for x in beta:
|
|
x_produces_empty = 0
|
|
|
|
# Add all the non-<empty> symbols of First[x] to the result.
|
|
for f in self.First[x]:
|
|
if f == '<empty>':
|
|
x_produces_empty = 1
|
|
else:
|
|
if f not in result: result.append(f)
|
|
|
|
if x_produces_empty:
|
|
# We have to consider the next x in beta,
|
|
# i.e. stay in the loop.
|
|
pass
|
|
else:
|
|
# We don't have to consider any further symbols in beta.
|
|
break
|
|
else:
|
|
# There was no 'break' from the loop,
|
|
# so x_produces_empty was true for all x in beta,
|
|
# so beta produces empty as well.
|
|
result.append('<empty>')
|
|
|
|
return result
|
|
|
|
# -------------------------------------------------------------------------
|
|
# compute_first()
|
|
#
|
|
# Compute the value of FIRST1(X) for all symbols
|
|
# -------------------------------------------------------------------------
|
|
def compute_first(self):
|
|
if self.First:
|
|
return self.First
|
|
|
|
# Terminals:
|
|
for t in self.Terminals:
|
|
self.First[t] = [t]
|
|
|
|
self.First['$end'] = ['$end']
|
|
|
|
# Nonterminals:
|
|
|
|
# Initialize to the empty set:
|
|
for n in self.Nonterminals:
|
|
self.First[n] = []
|
|
|
|
# Then propagate symbols until no change:
|
|
while 1:
|
|
some_change = 0
|
|
for n in self.Nonterminals:
|
|
for p in self.Prodnames[n]:
|
|
for f in self._first(p.prod):
|
|
if f not in self.First[n]:
|
|
self.First[n].append( f )
|
|
some_change = 1
|
|
if not some_change:
|
|
break
|
|
|
|
return self.First
|
|
|
|
# ---------------------------------------------------------------------
|
|
# compute_follow()
|
|
#
|
|
# Computes all of the follow sets for every non-terminal symbol. The
|
|
# follow set is the set of all symbols that might follow a given
|
|
# non-terminal. See the Dragon book, 2nd Ed. p. 189.
|
|
# ---------------------------------------------------------------------
|
|
def compute_follow(self,start=None):
|
|
# If already computed, return the result
|
|
if self.Follow:
|
|
return self.Follow
|
|
|
|
# If first sets not computed yet, do that first.
|
|
if not self.First:
|
|
self.compute_first()
|
|
|
|
# Add '$end' to the follow list of the start symbol
|
|
for k in self.Nonterminals:
|
|
self.Follow[k] = [ ]
|
|
|
|
if not start:
|
|
start = self.Productions[1].name
|
|
|
|
self.Follow[start] = [ '$end' ]
|
|
|
|
while 1:
|
|
didadd = 0
|
|
for p in self.Productions[1:]:
|
|
# Here is the production set
|
|
for i in range(len(p.prod)):
|
|
B = p.prod[i]
|
|
if B in self.Nonterminals:
|
|
# Okay. We got a non-terminal in a production
|
|
fst = self._first(p.prod[i+1:])
|
|
hasempty = 0
|
|
for f in fst:
|
|
if f != '<empty>' and f not in self.Follow[B]:
|
|
self.Follow[B].append(f)
|
|
didadd = 1
|
|
if f == '<empty>':
|
|
hasempty = 1
|
|
if hasempty or i == (len(p.prod)-1):
|
|
# Add elements of follow(a) to follow(b)
|
|
for f in self.Follow[p.name]:
|
|
if f not in self.Follow[B]:
|
|
self.Follow[B].append(f)
|
|
didadd = 1
|
|
if not didadd: break
|
|
return self.Follow
|
|
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# build_lritems()
|
|
#
|
|
# This function walks the list of productions and builds a complete set of the
|
|
# LR items. The LR items are stored in two ways: First, they are uniquely
|
|
# numbered and placed in the list _lritems. Second, a linked list of LR items
|
|
# is built for each production. For example:
|
|
#
|
|
# E -> E PLUS E
|
|
#
|
|
# Creates the list
|
|
#
|
|
# [E -> . E PLUS E, E -> E . PLUS E, E -> E PLUS . E, E -> E PLUS E . ]
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def build_lritems(self):
|
|
for p in self.Productions:
|
|
lastlri = p
|
|
i = 0
|
|
lr_items = []
|
|
while 1:
|
|
if i > len(p):
|
|
lri = None
|
|
else:
|
|
lri = LRItem(p,i)
|
|
# Precompute the list of productions immediately following
|
|
try:
|
|
lri.lr_after = self.Prodnames[lri.prod[i+1]]
|
|
except (IndexError,KeyError):
|
|
lri.lr_after = []
|
|
try:
|
|
lri.lr_before = lri.prod[i-1]
|
|
except IndexError:
|
|
lri.lr_before = None
|
|
|
|
lastlri.lr_next = lri
|
|
if not lri: break
|
|
lr_items.append(lri)
|
|
lastlri = lri
|
|
i += 1
|
|
p.lr_items = lr_items
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# == Class LRTable ==
|
|
#
|
|
# This basic class represents a basic table of LR parsing information.
|
|
# Methods for generating the tables are not defined here. They are defined
|
|
# in the derived class LRGeneratedTable.
|
|
# -----------------------------------------------------------------------------
|
|
|
|
class VersionError(YaccError): pass
|
|
|
|
class LRTable(object):
|
|
def __init__(self):
|
|
self.lr_action = None
|
|
self.lr_goto = None
|
|
self.lr_productions = None
|
|
self.lr_method = None
|
|
|
|
def read_table(self,module):
|
|
if isinstance(module,types.ModuleType):
|
|
parsetab = module
|
|
else:
|
|
if sys.version_info[0] < 3:
|
|
exec("import %s as parsetab" % module)
|
|
else:
|
|
env = { }
|
|
exec("import %s as parsetab" % module, env, env)
|
|
parsetab = env['parsetab']
|
|
|
|
if parsetab._tabversion != __tabversion__:
|
|
raise VersionError("yacc table file version is out of date")
|
|
|
|
self.lr_action = parsetab._lr_action
|
|
self.lr_goto = parsetab._lr_goto
|
|
|
|
self.lr_productions = []
|
|
for p in parsetab._lr_productions:
|
|
self.lr_productions.append(MiniProduction(*p))
|
|
|
|
self.lr_method = parsetab._lr_method
|
|
return parsetab._lr_signature
|
|
|
|
def read_pickle(self,filename):
|
|
try:
|
|
import cPickle as pickle
|
|
except ImportError:
|
|
import pickle
|
|
|
|
in_f = open(filename,"rb")
|
|
|
|
tabversion = pickle.load(in_f)
|
|
if tabversion != __tabversion__:
|
|
raise VersionError("yacc table file version is out of date")
|
|
self.lr_method = pickle.load(in_f)
|
|
signature = pickle.load(in_f)
|
|
self.lr_action = pickle.load(in_f)
|
|
self.lr_goto = pickle.load(in_f)
|
|
productions = pickle.load(in_f)
|
|
|
|
self.lr_productions = []
|
|
for p in productions:
|
|
self.lr_productions.append(MiniProduction(*p))
|
|
|
|
in_f.close()
|
|
return signature
|
|
|
|
# Bind all production function names to callable objects in pdict
|
|
def bind_callables(self,pdict):
|
|
for p in self.lr_productions:
|
|
p.bind(pdict)
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# === LR Generator ===
|
|
#
|
|
# The following classes and functions are used to generate LR parsing tables on
|
|
# a grammar.
|
|
# -----------------------------------------------------------------------------
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# digraph()
|
|
# traverse()
|
|
#
|
|
# The following two functions are used to compute set valued functions
|
|
# of the form:
|
|
#
|
|
# F(x) = F'(x) U U{F(y) | x R y}
|
|
#
|
|
# This is used to compute the values of Read() sets as well as FOLLOW sets
|
|
# in LALR(1) generation.
|
|
#
|
|
# Inputs: X - An input set
|
|
# R - A relation
|
|
# FP - Set-valued function
|
|
# ------------------------------------------------------------------------------
|
|
|
|
def digraph(X,R,FP):
|
|
N = { }
|
|
for x in X:
|
|
N[x] = 0
|
|
stack = []
|
|
F = { }
|
|
for x in X:
|
|
if N[x] == 0: traverse(x,N,stack,F,X,R,FP)
|
|
return F
|
|
|
|
def traverse(x,N,stack,F,X,R,FP):
|
|
stack.append(x)
|
|
d = len(stack)
|
|
N[x] = d
|
|
F[x] = FP(x) # F(X) <- F'(x)
|
|
|
|
rel = R(x) # Get y's related to x
|
|
for y in rel:
|
|
if N[y] == 0:
|
|
traverse(y,N,stack,F,X,R,FP)
|
|
N[x] = min(N[x],N[y])
|
|
for a in F.get(y,[]):
|
|
if a not in F[x]: F[x].append(a)
|
|
if N[x] == d:
|
|
N[stack[-1]] = MAXINT
|
|
F[stack[-1]] = F[x]
|
|
element = stack.pop()
|
|
while element != x:
|
|
N[stack[-1]] = MAXINT
|
|
F[stack[-1]] = F[x]
|
|
element = stack.pop()
|
|
|
|
class LALRError(YaccError): pass
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# == LRGeneratedTable ==
|
|
#
|
|
# This class implements the LR table generation algorithm. There are no
|
|
# public methods except for write()
|
|
# -----------------------------------------------------------------------------
|
|
|
|
class LRGeneratedTable(LRTable):
|
|
def __init__(self,grammar,method='LALR',log=None):
|
|
if method not in ['SLR','LALR']:
|
|
raise LALRError("Unsupported method %s" % method)
|
|
|
|
self.grammar = grammar
|
|
self.lr_method = method
|
|
|
|
# Set up the logger
|
|
if not log:
|
|
log = NullLogger()
|
|
self.log = log
|
|
|
|
# Internal attributes
|
|
self.lr_action = {} # Action table
|
|
self.lr_goto = {} # Goto table
|
|
self.lr_productions = grammar.Productions # Copy of grammar Production array
|
|
self.lr_goto_cache = {} # Cache of computed gotos
|
|
self.lr0_cidhash = {} # Cache of closures
|
|
|
|
self._add_count = 0 # Internal counter used to detect cycles
|
|
|
|
# Diagonistic information filled in by the table generator
|
|
self.sr_conflict = 0
|
|
self.rr_conflict = 0
|
|
self.conflicts = [] # List of conflicts
|
|
|
|
self.sr_conflicts = []
|
|
self.rr_conflicts = []
|
|
|
|
# Build the tables
|
|
self.grammar.build_lritems()
|
|
self.grammar.compute_first()
|
|
self.grammar.compute_follow()
|
|
self.lr_parse_table()
|
|
|
|
# Compute the LR(0) closure operation on I, where I is a set of LR(0) items.
|
|
|
|
def lr0_closure(self,I):
|
|
self._add_count += 1
|
|
|
|
# Add everything in I to J
|
|
J = I[:]
|
|
didadd = 1
|
|
while didadd:
|
|
didadd = 0
|
|
for j in J:
|
|
for x in j.lr_after:
|
|
if getattr(x,"lr0_added",0) == self._add_count: continue
|
|
# Add B --> .G to J
|
|
J.append(x.lr_next)
|
|
x.lr0_added = self._add_count
|
|
didadd = 1
|
|
|
|
return J
|
|
|
|
# Compute the LR(0) goto function goto(I,X) where I is a set
|
|
# of LR(0) items and X is a grammar symbol. This function is written
|
|
# in a way that guarantees uniqueness of the generated goto sets
|
|
# (i.e. the same goto set will never be returned as two different Python
|
|
# objects). With uniqueness, we can later do fast set comparisons using
|
|
# id(obj) instead of element-wise comparison.
|
|
|
|
def lr0_goto(self,I,x):
|
|
# First we look for a previously cached entry
|
|
g = self.lr_goto_cache.get((id(I),x),None)
|
|
if g: return g
|
|
|
|
# Now we generate the goto set in a way that guarantees uniqueness
|
|
# of the result
|
|
|
|
s = self.lr_goto_cache.get(x,None)
|
|
if not s:
|
|
s = { }
|
|
self.lr_goto_cache[x] = s
|
|
|
|
gs = [ ]
|
|
for p in I:
|
|
n = p.lr_next
|
|
if n and n.lr_before == x:
|
|
s1 = s.get(id(n),None)
|
|
if not s1:
|
|
s1 = { }
|
|
s[id(n)] = s1
|
|
gs.append(n)
|
|
s = s1
|
|
g = s.get('$end',None)
|
|
if not g:
|
|
if gs:
|
|
g = self.lr0_closure(gs)
|
|
s['$end'] = g
|
|
else:
|
|
s['$end'] = gs
|
|
self.lr_goto_cache[(id(I),x)] = g
|
|
return g
|
|
|
|
# Compute the LR(0) sets of item function
|
|
def lr0_items(self):
|
|
|
|
C = [ self.lr0_closure([self.grammar.Productions[0].lr_next]) ]
|
|
i = 0
|
|
for I in C:
|
|
self.lr0_cidhash[id(I)] = i
|
|
i += 1
|
|
|
|
# Loop over the items in C and each grammar symbols
|
|
i = 0
|
|
while i < len(C):
|
|
I = C[i]
|
|
i += 1
|
|
|
|
# Collect all of the symbols that could possibly be in the goto(I,X) sets
|
|
asyms = { }
|
|
for ii in I:
|
|
for s in ii.usyms:
|
|
asyms[s] = None
|
|
|
|
for x in asyms:
|
|
g = self.lr0_goto(I,x)
|
|
if not g: continue
|
|
if id(g) in self.lr0_cidhash: continue
|
|
self.lr0_cidhash[id(g)] = len(C)
|
|
C.append(g)
|
|
|
|
return C
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# ==== LALR(1) Parsing ====
|
|
#
|
|
# LALR(1) parsing is almost exactly the same as SLR except that instead of
|
|
# relying upon Follow() sets when performing reductions, a more selective
|
|
# lookahead set that incorporates the state of the LR(0) machine is utilized.
|
|
# Thus, we mainly just have to focus on calculating the lookahead sets.
|
|
#
|
|
# The method used here is due to DeRemer and Pennelo (1982).
|
|
#
|
|
# DeRemer, F. L., and T. J. Pennelo: "Efficient Computation of LALR(1)
|
|
# Lookahead Sets", ACM Transactions on Programming Languages and Systems,
|
|
# Vol. 4, No. 4, Oct. 1982, pp. 615-649
|
|
#
|
|
# Further details can also be found in:
|
|
#
|
|
# J. Tremblay and P. Sorenson, "The Theory and Practice of Compiler Writing",
|
|
# McGraw-Hill Book Company, (1985).
|
|
#
|
|
# -----------------------------------------------------------------------------
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# compute_nullable_nonterminals()
|
|
#
|
|
# Creates a dictionary containing all of the non-terminals that might produce
|
|
# an empty production.
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def compute_nullable_nonterminals(self):
|
|
nullable = {}
|
|
num_nullable = 0
|
|
while 1:
|
|
for p in self.grammar.Productions[1:]:
|
|
if p.len == 0:
|
|
nullable[p.name] = 1
|
|
continue
|
|
for t in p.prod:
|
|
if not t in nullable: break
|
|
else:
|
|
nullable[p.name] = 1
|
|
if len(nullable) == num_nullable: break
|
|
num_nullable = len(nullable)
|
|
return nullable
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# find_nonterminal_trans(C)
|
|
#
|
|
# Given a set of LR(0) items, this functions finds all of the non-terminal
|
|
# transitions. These are transitions in which a dot appears immediately before
|
|
# a non-terminal. Returns a list of tuples of the form (state,N) where state
|
|
# is the state number and N is the nonterminal symbol.
|
|
#
|
|
# The input C is the set of LR(0) items.
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def find_nonterminal_transitions(self,C):
|
|
trans = []
|
|
for state in range(len(C)):
|
|
for p in C[state]:
|
|
if p.lr_index < p.len - 1:
|
|
t = (state,p.prod[p.lr_index+1])
|
|
if t[1] in self.grammar.Nonterminals:
|
|
if t not in trans: trans.append(t)
|
|
state = state + 1
|
|
return trans
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# dr_relation()
|
|
#
|
|
# Computes the DR(p,A) relationships for non-terminal transitions. The input
|
|
# is a tuple (state,N) where state is a number and N is a nonterminal symbol.
|
|
#
|
|
# Returns a list of terminals.
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def dr_relation(self,C,trans,nullable):
|
|
dr_set = { }
|
|
state,N = trans
|
|
terms = []
|
|
|
|
g = self.lr0_goto(C[state],N)
|
|
for p in g:
|
|
if p.lr_index < p.len - 1:
|
|
a = p.prod[p.lr_index+1]
|
|
if a in self.grammar.Terminals:
|
|
if a not in terms: terms.append(a)
|
|
|
|
# This extra bit is to handle the start state
|
|
if state == 0 and N == self.grammar.Productions[0].prod[0]:
|
|
terms.append('$end')
|
|
|
|
return terms
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# reads_relation()
|
|
#
|
|
# Computes the READS() relation (p,A) READS (t,C).
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def reads_relation(self,C, trans, empty):
|
|
# Look for empty transitions
|
|
rel = []
|
|
state, N = trans
|
|
|
|
g = self.lr0_goto(C[state],N)
|
|
j = self.lr0_cidhash.get(id(g),-1)
|
|
for p in g:
|
|
if p.lr_index < p.len - 1:
|
|
a = p.prod[p.lr_index + 1]
|
|
if a in empty:
|
|
rel.append((j,a))
|
|
|
|
return rel
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# compute_lookback_includes()
|
|
#
|
|
# Determines the lookback and includes relations
|
|
#
|
|
# LOOKBACK:
|
|
#
|
|
# This relation is determined by running the LR(0) state machine forward.
|
|
# For example, starting with a production "N : . A B C", we run it forward
|
|
# to obtain "N : A B C ." We then build a relationship between this final
|
|
# state and the starting state. These relationships are stored in a dictionary
|
|
# lookdict.
|
|
#
|
|
# INCLUDES:
|
|
#
|
|
# Computes the INCLUDE() relation (p,A) INCLUDES (p',B).
|
|
#
|
|
# This relation is used to determine non-terminal transitions that occur
|
|
# inside of other non-terminal transition states. (p,A) INCLUDES (p', B)
|
|
# if the following holds:
|
|
#
|
|
# B -> LAT, where T -> epsilon and p' -L-> p
|
|
#
|
|
# L is essentially a prefix (which may be empty), T is a suffix that must be
|
|
# able to derive an empty string. State p' must lead to state p with the string L.
|
|
#
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def compute_lookback_includes(self,C,trans,nullable):
|
|
|
|
lookdict = {} # Dictionary of lookback relations
|
|
includedict = {} # Dictionary of include relations
|
|
|
|
# Make a dictionary of non-terminal transitions
|
|
dtrans = {}
|
|
for t in trans:
|
|
dtrans[t] = 1
|
|
|
|
# Loop over all transitions and compute lookbacks and includes
|
|
for state,N in trans:
|
|
lookb = []
|
|
includes = []
|
|
for p in C[state]:
|
|
if p.name != N: continue
|
|
|
|
# Okay, we have a name match. We now follow the production all the way
|
|
# through the state machine until we get the . on the right hand side
|
|
|
|
lr_index = p.lr_index
|
|
j = state
|
|
while lr_index < p.len - 1:
|
|
lr_index = lr_index + 1
|
|
t = p.prod[lr_index]
|
|
|
|
# Check to see if this symbol and state are a non-terminal transition
|
|
if (j,t) in dtrans:
|
|
# Yes. Okay, there is some chance that this is an includes relation
|
|
# the only way to know for certain is whether the rest of the
|
|
# production derives empty
|
|
|
|
li = lr_index + 1
|
|
while li < p.len:
|
|
if p.prod[li] in self.grammar.Terminals: break # No forget it
|
|
if not p.prod[li] in nullable: break
|
|
li = li + 1
|
|
else:
|
|
# Appears to be a relation between (j,t) and (state,N)
|
|
includes.append((j,t))
|
|
|
|
g = self.lr0_goto(C[j],t) # Go to next set
|
|
j = self.lr0_cidhash.get(id(g),-1) # Go to next state
|
|
|
|
# When we get here, j is the final state, now we have to locate the production
|
|
for r in C[j]:
|
|
if r.name != p.name: continue
|
|
if r.len != p.len: continue
|
|
i = 0
|
|
# This look is comparing a production ". A B C" with "A B C ."
|
|
while i < r.lr_index:
|
|
if r.prod[i] != p.prod[i+1]: break
|
|
i = i + 1
|
|
else:
|
|
lookb.append((j,r))
|
|
for i in includes:
|
|
if not i in includedict: includedict[i] = []
|
|
includedict[i].append((state,N))
|
|
lookdict[(state,N)] = lookb
|
|
|
|
return lookdict,includedict
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# compute_read_sets()
|
|
#
|
|
# Given a set of LR(0) items, this function computes the read sets.
|
|
#
|
|
# Inputs: C = Set of LR(0) items
|
|
# ntrans = Set of nonterminal transitions
|
|
# nullable = Set of empty transitions
|
|
#
|
|
# Returns a set containing the read sets
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def compute_read_sets(self,C, ntrans, nullable):
|
|
FP = lambda x: self.dr_relation(C,x,nullable)
|
|
R = lambda x: self.reads_relation(C,x,nullable)
|
|
F = digraph(ntrans,R,FP)
|
|
return F
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# compute_follow_sets()
|
|
#
|
|
# Given a set of LR(0) items, a set of non-terminal transitions, a readset,
|
|
# and an include set, this function computes the follow sets
|
|
#
|
|
# Follow(p,A) = Read(p,A) U U {Follow(p',B) | (p,A) INCLUDES (p',B)}
|
|
#
|
|
# Inputs:
|
|
# ntrans = Set of nonterminal transitions
|
|
# readsets = Readset (previously computed)
|
|
# inclsets = Include sets (previously computed)
|
|
#
|
|
# Returns a set containing the follow sets
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def compute_follow_sets(self,ntrans,readsets,inclsets):
|
|
FP = lambda x: readsets[x]
|
|
R = lambda x: inclsets.get(x,[])
|
|
F = digraph(ntrans,R,FP)
|
|
return F
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# add_lookaheads()
|
|
#
|
|
# Attaches the lookahead symbols to grammar rules.
|
|
#
|
|
# Inputs: lookbacks - Set of lookback relations
|
|
# followset - Computed follow set
|
|
#
|
|
# This function directly attaches the lookaheads to productions contained
|
|
# in the lookbacks set
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def add_lookaheads(self,lookbacks,followset):
|
|
for trans,lb in lookbacks.items():
|
|
# Loop over productions in lookback
|
|
for state,p in lb:
|
|
if not state in p.lookaheads:
|
|
p.lookaheads[state] = []
|
|
f = followset.get(trans,[])
|
|
for a in f:
|
|
if a not in p.lookaheads[state]: p.lookaheads[state].append(a)
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# add_lalr_lookaheads()
|
|
#
|
|
# This function does all of the work of adding lookahead information for use
|
|
# with LALR parsing
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def add_lalr_lookaheads(self,C):
|
|
# Determine all of the nullable nonterminals
|
|
nullable = self.compute_nullable_nonterminals()
|
|
|
|
# Find all non-terminal transitions
|
|
trans = self.find_nonterminal_transitions(C)
|
|
|
|
# Compute read sets
|
|
readsets = self.compute_read_sets(C,trans,nullable)
|
|
|
|
# Compute lookback/includes relations
|
|
lookd, included = self.compute_lookback_includes(C,trans,nullable)
|
|
|
|
# Compute LALR FOLLOW sets
|
|
followsets = self.compute_follow_sets(trans,readsets,included)
|
|
|
|
# Add all of the lookaheads
|
|
self.add_lookaheads(lookd,followsets)
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# lr_parse_table()
|
|
#
|
|
# This function constructs the parse tables for SLR or LALR
|
|
# -----------------------------------------------------------------------------
|
|
def lr_parse_table(self):
|
|
Productions = self.grammar.Productions
|
|
Precedence = self.grammar.Precedence
|
|
goto = self.lr_goto # Goto array
|
|
action = self.lr_action # Action array
|
|
log = self.log # Logger for output
|
|
|
|
actionp = { } # Action production array (temporary)
|
|
|
|
log.info("Parsing method: %s", self.lr_method)
|
|
|
|
# Step 1: Construct C = { I0, I1, ... IN}, collection of LR(0) items
|
|
# This determines the number of states
|
|
|
|
C = self.lr0_items()
|
|
|
|
if self.lr_method == 'LALR':
|
|
self.add_lalr_lookaheads(C)
|
|
|
|
# Build the parser table, state by state
|
|
st = 0
|
|
for I in C:
|
|
# Loop over each production in I
|
|
actlist = [ ] # List of actions
|
|
st_action = { }
|
|
st_actionp = { }
|
|
st_goto = { }
|
|
log.info("")
|
|
log.info("state %d", st)
|
|
log.info("")
|
|
for p in I:
|
|
log.info(" (%d) %s", p.number, str(p))
|
|
log.info("")
|
|
|
|
for p in I:
|
|
if p.len == p.lr_index + 1:
|
|
if p.name == "S'":
|
|
# Start symbol. Accept!
|
|
st_action["$end"] = 0
|
|
st_actionp["$end"] = p
|
|
else:
|
|
# We are at the end of a production. Reduce!
|
|
if self.lr_method == 'LALR':
|
|
laheads = p.lookaheads[st]
|
|
else:
|
|
laheads = self.grammar.Follow[p.name]
|
|
for a in laheads:
|
|
actlist.append((a,p,"reduce using rule %d (%s)" % (p.number,p)))
|
|
r = st_action.get(a,None)
|
|
if r is not None:
|
|
# Whoa. Have a shift/reduce or reduce/reduce conflict
|
|
if r > 0:
|
|
# Need to decide on shift or reduce here
|
|
# By default we favor shifting. Need to add
|
|
# some precedence rules here.
|
|
sprec,slevel = Productions[st_actionp[a].number].prec
|
|
rprec,rlevel = Precedence.get(a,('right',0))
|
|
if (slevel < rlevel) or ((slevel == rlevel) and (rprec == 'left')):
|
|
# We really need to reduce here.
|
|
st_action[a] = -p.number
|
|
st_actionp[a] = p
|
|
if not slevel and not rlevel:
|
|
log.info(" ! shift/reduce conflict for %s resolved as reduce",a)
|
|
self.sr_conflicts.append((st,a,'reduce'))
|
|
Productions[p.number].reduced += 1
|
|
elif (slevel == rlevel) and (rprec == 'nonassoc'):
|
|
st_action[a] = None
|
|
else:
|
|
# Hmmm. Guess we'll keep the shift
|
|
if not rlevel:
|
|
log.info(" ! shift/reduce conflict for %s resolved as shift",a)
|
|
self.sr_conflicts.append((st,a,'shift'))
|
|
elif r < 0:
|
|
# Reduce/reduce conflict. In this case, we favor the rule
|
|
# that was defined first in the grammar file
|
|
oldp = Productions[-r]
|
|
pp = Productions[p.number]
|
|
if oldp.line > pp.line:
|
|
st_action[a] = -p.number
|
|
st_actionp[a] = p
|
|
chosenp,rejectp = pp,oldp
|
|
Productions[p.number].reduced += 1
|
|
Productions[oldp.number].reduced -= 1
|
|
else:
|
|
chosenp,rejectp = oldp,pp
|
|
self.rr_conflicts.append((st,chosenp,rejectp))
|
|
log.info(" ! reduce/reduce conflict for %s resolved using rule %d (%s)", a,st_actionp[a].number, st_actionp[a])
|
|
else:
|
|
raise LALRError("Unknown conflict in state %d" % st)
|
|
else:
|
|
st_action[a] = -p.number
|
|
st_actionp[a] = p
|
|
Productions[p.number].reduced += 1
|
|
else:
|
|
i = p.lr_index
|
|
a = p.prod[i+1] # Get symbol right after the "."
|
|
if a in self.grammar.Terminals:
|
|
g = self.lr0_goto(I,a)
|
|
j = self.lr0_cidhash.get(id(g),-1)
|
|
if j >= 0:
|
|
# We are in a shift state
|
|
actlist.append((a,p,"shift and go to state %d" % j))
|
|
r = st_action.get(a,None)
|
|
if r is not None:
|
|
# Whoa have a shift/reduce or shift/shift conflict
|
|
if r > 0:
|
|
if r != j:
|
|
raise LALRError("Shift/shift conflict in state %d" % st)
|
|
elif r < 0:
|
|
# Do a precedence check.
|
|
# - if precedence of reduce rule is higher, we reduce.
|
|
# - if precedence of reduce is same and left assoc, we reduce.
|
|
# - otherwise we shift
|
|
rprec,rlevel = Productions[st_actionp[a].number].prec
|
|
sprec,slevel = Precedence.get(a,('right',0))
|
|
if (slevel > rlevel) or ((slevel == rlevel) and (rprec == 'right')):
|
|
# We decide to shift here... highest precedence to shift
|
|
Productions[st_actionp[a].number].reduced -= 1
|
|
st_action[a] = j
|
|
st_actionp[a] = p
|
|
if not rlevel:
|
|
log.info(" ! shift/reduce conflict for %s resolved as shift",a)
|
|
self.sr_conflicts.append((st,a,'shift'))
|
|
elif (slevel == rlevel) and (rprec == 'nonassoc'):
|
|
st_action[a] = None
|
|
else:
|
|
# Hmmm. Guess we'll keep the reduce
|
|
if not slevel and not rlevel:
|
|
log.info(" ! shift/reduce conflict for %s resolved as reduce",a)
|
|
self.sr_conflicts.append((st,a,'reduce'))
|
|
|
|
else:
|
|
raise LALRError("Unknown conflict in state %d" % st)
|
|
else:
|
|
st_action[a] = j
|
|
st_actionp[a] = p
|
|
|
|
# Print the actions associated with each terminal
|
|
_actprint = { }
|
|
for a,p,m in actlist:
|
|
if a in st_action:
|
|
if p is st_actionp[a]:
|
|
log.info(" %-15s %s",a,m)
|
|
_actprint[(a,m)] = 1
|
|
log.info("")
|
|
# Print the actions that were not used. (debugging)
|
|
not_used = 0
|
|
for a,p,m in actlist:
|
|
if a in st_action:
|
|
if p is not st_actionp[a]:
|
|
if not (a,m) in _actprint:
|
|
log.debug(" ! %-15s [ %s ]",a,m)
|
|
not_used = 1
|
|
_actprint[(a,m)] = 1
|
|
if not_used:
|
|
log.debug("")
|
|
|
|
# Construct the goto table for this state
|
|
|
|
nkeys = { }
|
|
for ii in I:
|
|
for s in ii.usyms:
|
|
if s in self.grammar.Nonterminals:
|
|
nkeys[s] = None
|
|
for n in nkeys:
|
|
g = self.lr0_goto(I,n)
|
|
j = self.lr0_cidhash.get(id(g),-1)
|
|
if j >= 0:
|
|
st_goto[n] = j
|
|
log.info(" %-30s shift and go to state %d",n,j)
|
|
|
|
action[st] = st_action
|
|
actionp[st] = st_actionp
|
|
goto[st] = st_goto
|
|
st += 1
|
|
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# write()
|
|
#
|
|
# This function writes the LR parsing tables to a file
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def write_table(self,modulename,outputdir='',signature=""):
|
|
basemodulename = modulename.split(".")[-1]
|
|
filename = os.path.join(outputdir,basemodulename) + ".py"
|
|
try:
|
|
f = open(filename,"w")
|
|
|
|
f.write("""
|
|
# %s
|
|
# This file is automatically generated. Do not edit.
|
|
_tabversion = %r
|
|
|
|
_lr_method = %r
|
|
|
|
_lr_signature = %r
|
|
""" % (filename, __tabversion__, self.lr_method, signature))
|
|
|
|
# Change smaller to 0 to go back to original tables
|
|
smaller = 1
|
|
|
|
# Factor out names to try and make smaller
|
|
if smaller:
|
|
items = { }
|
|
|
|
for s,nd in self.lr_action.items():
|
|
for name,v in nd.items():
|
|
i = items.get(name)
|
|
if not i:
|
|
i = ([],[])
|
|
items[name] = i
|
|
i[0].append(s)
|
|
i[1].append(v)
|
|
|
|
f.write("\n_lr_action_items = {")
|
|
for k,v in items.items():
|
|
f.write("%r:([" % k)
|
|
for i in v[0]:
|
|
f.write("%r," % i)
|
|
f.write("],[")
|
|
for i in v[1]:
|
|
f.write("%r," % i)
|
|
|
|
f.write("]),")
|
|
f.write("}\n")
|
|
|
|
f.write("""
|
|
_lr_action = { }
|
|
for _k, _v in _lr_action_items.items():
|
|
for _x,_y in zip(_v[0],_v[1]):
|
|
if not _x in _lr_action: _lr_action[_x] = { }
|
|
_lr_action[_x][_k] = _y
|
|
del _lr_action_items
|
|
""")
|
|
|
|
else:
|
|
f.write("\n_lr_action = { ");
|
|
for k,v in self.lr_action.items():
|
|
f.write("(%r,%r):%r," % (k[0],k[1],v))
|
|
f.write("}\n");
|
|
|
|
if smaller:
|
|
# Factor out names to try and make smaller
|
|
items = { }
|
|
|
|
for s,nd in self.lr_goto.items():
|
|
for name,v in nd.items():
|
|
i = items.get(name)
|
|
if not i:
|
|
i = ([],[])
|
|
items[name] = i
|
|
i[0].append(s)
|
|
i[1].append(v)
|
|
|
|
f.write("\n_lr_goto_items = {")
|
|
for k,v in items.items():
|
|
f.write("%r:([" % k)
|
|
for i in v[0]:
|
|
f.write("%r," % i)
|
|
f.write("],[")
|
|
for i in v[1]:
|
|
f.write("%r," % i)
|
|
|
|
f.write("]),")
|
|
f.write("}\n")
|
|
|
|
f.write("""
|
|
_lr_goto = { }
|
|
for _k, _v in _lr_goto_items.items():
|
|
for _x,_y in zip(_v[0],_v[1]):
|
|
if not _x in _lr_goto: _lr_goto[_x] = { }
|
|
_lr_goto[_x][_k] = _y
|
|
del _lr_goto_items
|
|
""")
|
|
else:
|
|
f.write("\n_lr_goto = { ");
|
|
for k,v in self.lr_goto.items():
|
|
f.write("(%r,%r):%r," % (k[0],k[1],v))
|
|
f.write("}\n");
|
|
|
|
# Write production table
|
|
f.write("_lr_productions = [\n")
|
|
for p in self.lr_productions:
|
|
if p.func:
|
|
f.write(" (%r,%r,%d,%r,%r,%d),\n" % (p.str,p.name, p.len, p.func,p.file,p.line))
|
|
else:
|
|
f.write(" (%r,%r,%d,None,None,None),\n" % (str(p),p.name, p.len))
|
|
f.write("]\n")
|
|
f.close()
|
|
|
|
except IOError:
|
|
e = sys.exc_info()[1]
|
|
sys.stderr.write("Unable to create '%s'\n" % filename)
|
|
sys.stderr.write(str(e)+"\n")
|
|
return
|
|
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# pickle_table()
|
|
#
|
|
# This function pickles the LR parsing tables to a supplied file object
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def pickle_table(self,filename,signature=""):
|
|
try:
|
|
import cPickle as pickle
|
|
except ImportError:
|
|
import pickle
|
|
outf = open(filename,"wb")
|
|
pickle.dump(__tabversion__,outf,pickle_protocol)
|
|
pickle.dump(self.lr_method,outf,pickle_protocol)
|
|
pickle.dump(signature,outf,pickle_protocol)
|
|
pickle.dump(self.lr_action,outf,pickle_protocol)
|
|
pickle.dump(self.lr_goto,outf,pickle_protocol)
|
|
|
|
outp = []
|
|
for p in self.lr_productions:
|
|
if p.func:
|
|
outp.append((p.str,p.name, p.len, p.func,p.file,p.line))
|
|
else:
|
|
outp.append((str(p),p.name,p.len,None,None,None))
|
|
pickle.dump(outp,outf,pickle_protocol)
|
|
outf.close()
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# === INTROSPECTION ===
|
|
#
|
|
# The following functions and classes are used to implement the PLY
|
|
# introspection features followed by the yacc() function itself.
|
|
# -----------------------------------------------------------------------------
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# get_caller_module_dict()
|
|
#
|
|
# This function returns a dictionary containing all of the symbols defined within
|
|
# a caller further down the call stack. This is used to get the environment
|
|
# associated with the yacc() call if none was provided.
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def get_caller_module_dict(levels):
|
|
try:
|
|
raise RuntimeError
|
|
except RuntimeError:
|
|
e,b,t = sys.exc_info()
|
|
f = t.tb_frame
|
|
while levels > 0:
|
|
f = f.f_back
|
|
levels -= 1
|
|
ldict = f.f_globals.copy()
|
|
if f.f_globals != f.f_locals:
|
|
ldict.update(f.f_locals)
|
|
|
|
return ldict
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# parse_grammar()
|
|
#
|
|
# This takes a raw grammar rule string and parses it into production data
|
|
# -----------------------------------------------------------------------------
|
|
def parse_grammar(doc,file,line):
|
|
grammar = []
|
|
# Split the doc string into lines
|
|
pstrings = doc.splitlines()
|
|
lastp = None
|
|
dline = line
|
|
for ps in pstrings:
|
|
dline += 1
|
|
p = ps.split()
|
|
if not p: continue
|
|
try:
|
|
if p[0] == '|':
|
|
# This is a continuation of a previous rule
|
|
if not lastp:
|
|
raise SyntaxError("%s:%d: Misplaced '|'" % (file,dline))
|
|
prodname = lastp
|
|
syms = p[1:]
|
|
else:
|
|
prodname = p[0]
|
|
lastp = prodname
|
|
syms = p[2:]
|
|
assign = p[1]
|
|
if assign != ':' and assign != '::=':
|
|
raise SyntaxError("%s:%d: Syntax error. Expected ':'" % (file,dline))
|
|
|
|
grammar.append((file,dline,prodname,syms))
|
|
except SyntaxError:
|
|
raise
|
|
except Exception:
|
|
raise SyntaxError("%s:%d: Syntax error in rule '%s'" % (file,dline,ps.strip()))
|
|
|
|
return grammar
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# ParserReflect()
|
|
#
|
|
# This class represents information extracted for building a parser including
|
|
# start symbol, error function, tokens, precedence list, action functions,
|
|
# etc.
|
|
# -----------------------------------------------------------------------------
|
|
class ParserReflect(object):
|
|
def __init__(self,pdict,log=None):
|
|
self.pdict = pdict
|
|
self.start = None
|
|
self.error_func = None
|
|
self.tokens = None
|
|
self.files = {}
|
|
self.grammar = []
|
|
self.error = 0
|
|
|
|
if log is None:
|
|
self.log = PlyLogger(sys.stderr)
|
|
else:
|
|
self.log = log
|
|
|
|
# Get all of the basic information
|
|
def get_all(self):
|
|
self.get_start()
|
|
self.get_error_func()
|
|
self.get_tokens()
|
|
self.get_precedence()
|
|
self.get_pfunctions()
|
|
|
|
# Validate all of the information
|
|
def validate_all(self):
|
|
self.validate_start()
|
|
self.validate_error_func()
|
|
self.validate_tokens()
|
|
self.validate_precedence()
|
|
self.validate_pfunctions()
|
|
self.validate_files()
|
|
return self.error
|
|
|
|
# Compute a signature over the grammar
|
|
def signature(self):
|
|
try:
|
|
from hashlib import md5
|
|
except ImportError:
|
|
from md5 import md5
|
|
try:
|
|
sig = md5()
|
|
if self.start:
|
|
sig.update(self.start.encode('latin-1'))
|
|
if self.prec:
|
|
sig.update("".join(["".join(p) for p in self.prec]).encode('latin-1'))
|
|
if self.tokens:
|
|
sig.update(" ".join(self.tokens).encode('latin-1'))
|
|
for f in self.pfuncs:
|
|
if f[3]:
|
|
sig.update(f[3].encode('latin-1'))
|
|
except (TypeError,ValueError):
|
|
pass
|
|
return sig.digest()
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# validate_file()
|
|
#
|
|
# This method checks to see if there are duplicated p_rulename() functions
|
|
# in the parser module file. Without this function, it is really easy for
|
|
# users to make mistakes by cutting and pasting code fragments (and it's a real
|
|
# bugger to try and figure out why the resulting parser doesn't work). Therefore,
|
|
# we just do a little regular expression pattern matching of def statements
|
|
# to try and detect duplicates.
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def validate_files(self):
|
|
# Match def p_funcname(
|
|
fre = re.compile(r'\s*def\s+(p_[a-zA-Z_0-9]*)\(')
|
|
|
|
for filename in self.files.keys():
|
|
base,ext = os.path.splitext(filename)
|
|
if ext != '.py': return 1 # No idea. Assume it's okay.
|
|
|
|
try:
|
|
f = open(filename)
|
|
lines = f.readlines()
|
|
f.close()
|
|
except IOError:
|
|
continue
|
|
|
|
counthash = { }
|
|
for linen,l in enumerate(lines):
|
|
linen += 1
|
|
m = fre.match(l)
|
|
if m:
|
|
name = m.group(1)
|
|
prev = counthash.get(name)
|
|
if not prev:
|
|
counthash[name] = linen
|
|
else:
|
|
self.log.warning("%s:%d: Function %s redefined. Previously defined on line %d", filename,linen,name,prev)
|
|
|
|
# Get the start symbol
|
|
def get_start(self):
|
|
self.start = self.pdict.get('start')
|
|
|
|
# Validate the start symbol
|
|
def validate_start(self):
|
|
if self.start is not None:
|
|
if not isinstance(self.start,str):
|
|
self.log.error("'start' must be a string")
|
|
|
|
# Look for error handler
|
|
def get_error_func(self):
|
|
self.error_func = self.pdict.get('p_error')
|
|
|
|
# Validate the error function
|
|
def validate_error_func(self):
|
|
if self.error_func:
|
|
if isinstance(self.error_func,types.FunctionType):
|
|
ismethod = 0
|
|
elif isinstance(self.error_func, types.MethodType):
|
|
ismethod = 1
|
|
else:
|
|
self.log.error("'p_error' defined, but is not a function or method")
|
|
self.error = 1
|
|
return
|
|
|
|
eline = func_code(self.error_func).co_firstlineno
|
|
efile = func_code(self.error_func).co_filename
|
|
self.files[efile] = 1
|
|
|
|
if (func_code(self.error_func).co_argcount != 1+ismethod):
|
|
self.log.error("%s:%d: p_error() requires 1 argument",efile,eline)
|
|
self.error = 1
|
|
|
|
# Get the tokens map
|
|
def get_tokens(self):
|
|
tokens = self.pdict.get("tokens",None)
|
|
if not tokens:
|
|
self.log.error("No token list is defined")
|
|
self.error = 1
|
|
return
|
|
|
|
if not isinstance(tokens,(list, tuple)):
|
|
self.log.error("tokens must be a list or tuple")
|
|
self.error = 1
|
|
return
|
|
|
|
if not tokens:
|
|
self.log.error("tokens is empty")
|
|
self.error = 1
|
|
return
|
|
|
|
self.tokens = tokens
|
|
|
|
# Validate the tokens
|
|
def validate_tokens(self):
|
|
# Validate the tokens.
|
|
if 'error' in self.tokens:
|
|
self.log.error("Illegal token name 'error'. Is a reserved word")
|
|
self.error = 1
|
|
return
|
|
|
|
terminals = {}
|
|
for n in self.tokens:
|
|
if n in terminals:
|
|
self.log.warning("Token '%s' multiply defined", n)
|
|
terminals[n] = 1
|
|
|
|
# Get the precedence map (if any)
|
|
def get_precedence(self):
|
|
self.prec = self.pdict.get("precedence",None)
|
|
|
|
# Validate and parse the precedence map
|
|
def validate_precedence(self):
|
|
preclist = []
|
|
if self.prec:
|
|
if not isinstance(self.prec,(list,tuple)):
|
|
self.log.error("precedence must be a list or tuple")
|
|
self.error = 1
|
|
return
|
|
for level,p in enumerate(self.prec):
|
|
if not isinstance(p,(list,tuple)):
|
|
self.log.error("Bad precedence table")
|
|
self.error = 1
|
|
return
|
|
|
|
if len(p) < 2:
|
|
self.log.error("Malformed precedence entry %s. Must be (assoc, term, ..., term)",p)
|
|
self.error = 1
|
|
return
|
|
assoc = p[0]
|
|
if not isinstance(assoc,str):
|
|
self.log.error("precedence associativity must be a string")
|
|
self.error = 1
|
|
return
|
|
for term in p[1:]:
|
|
if not isinstance(term,str):
|
|
self.log.error("precedence items must be strings")
|
|
self.error = 1
|
|
return
|
|
preclist.append((term,assoc,level+1))
|
|
self.preclist = preclist
|
|
|
|
# Get all p_functions from the grammar
|
|
def get_pfunctions(self):
|
|
p_functions = []
|
|
for name, item in self.pdict.items():
|
|
if name[:2] != 'p_': continue
|
|
if name == 'p_error': continue
|
|
if isinstance(item,(types.FunctionType,types.MethodType)):
|
|
line = func_code(item).co_firstlineno
|
|
file = func_code(item).co_filename
|
|
p_functions.append((line,file,name,item.__doc__))
|
|
|
|
# Sort all of the actions by line number
|
|
p_functions.sort()
|
|
self.pfuncs = p_functions
|
|
|
|
|
|
# Validate all of the p_functions
|
|
def validate_pfunctions(self):
|
|
grammar = []
|
|
# Check for non-empty symbols
|
|
if len(self.pfuncs) == 0:
|
|
self.log.error("no rules of the form p_rulename are defined")
|
|
self.error = 1
|
|
return
|
|
|
|
for line, file, name, doc in self.pfuncs:
|
|
func = self.pdict[name]
|
|
if isinstance(func, types.MethodType):
|
|
reqargs = 2
|
|
else:
|
|
reqargs = 1
|
|
if func_code(func).co_argcount > reqargs:
|
|
self.log.error("%s:%d: Rule '%s' has too many arguments",file,line,func.__name__)
|
|
self.error = 1
|
|
elif func_code(func).co_argcount < reqargs:
|
|
self.log.error("%s:%d: Rule '%s' requires an argument",file,line,func.__name__)
|
|
self.error = 1
|
|
elif not func.__doc__:
|
|
self.log.warning("%s:%d: No documentation string specified in function '%s' (ignored)",file,line,func.__name__)
|
|
else:
|
|
try:
|
|
parsed_g = parse_grammar(doc,file,line)
|
|
for g in parsed_g:
|
|
grammar.append((name, g))
|
|
except SyntaxError:
|
|
e = sys.exc_info()[1]
|
|
self.log.error(str(e))
|
|
self.error = 1
|
|
|
|
# Looks like a valid grammar rule
|
|
# Mark the file in which defined.
|
|
self.files[file] = 1
|
|
|
|
# Secondary validation step that looks for p_ definitions that are not functions
|
|
# or functions that look like they might be grammar rules.
|
|
|
|
for n,v in self.pdict.items():
|
|
if n[0:2] == 'p_' and isinstance(v, (types.FunctionType, types.MethodType)): continue
|
|
if n[0:2] == 't_': continue
|
|
if n[0:2] == 'p_' and n != 'p_error':
|
|
self.log.warning("'%s' not defined as a function", n)
|
|
if ((isinstance(v,types.FunctionType) and func_code(v).co_argcount == 1) or
|
|
(isinstance(v,types.MethodType) and func_code(v).co_argcount == 2)):
|
|
try:
|
|
doc = v.__doc__.split(" ")
|
|
if doc[1] == ':':
|
|
self.log.warning("%s:%d: Possible grammar rule '%s' defined without p_ prefix",
|
|
func_code(v).co_filename, func_code(v).co_firstlineno,n)
|
|
except Exception:
|
|
pass
|
|
|
|
self.grammar = grammar
|
|
|
|
# -----------------------------------------------------------------------------
|
|
# yacc(module)
|
|
#
|
|
# Build a parser
|
|
# -----------------------------------------------------------------------------
|
|
|
|
def yacc(method='LALR', debug=yaccdebug, module=None, tabmodule=tab_module, start=None,
|
|
check_recursion=1, optimize=0, write_tables=1, debugfile=debug_file,outputdir='',
|
|
debuglog=None, errorlog = None, picklefile=None):
|
|
|
|
global parse # Reference to the parsing method of the last built parser
|
|
|
|
# If pickling is enabled, table files are not created
|
|
|
|
if picklefile:
|
|
write_tables = 0
|
|
|
|
if errorlog is None:
|
|
errorlog = PlyLogger(sys.stderr)
|
|
|
|
# Get the module dictionary used for the parser
|
|
if module:
|
|
_items = [(k,getattr(module,k)) for k in dir(module)]
|
|
pdict = dict(_items)
|
|
else:
|
|
pdict = get_caller_module_dict(2)
|
|
|
|
# Collect parser information from the dictionary
|
|
pinfo = ParserReflect(pdict,log=errorlog)
|
|
pinfo.get_all()
|
|
|
|
if pinfo.error:
|
|
raise YaccError("Unable to build parser")
|
|
|
|
# Check signature against table files (if any)
|
|
signature = pinfo.signature()
|
|
|
|
# Read the tables
|
|
try:
|
|
lr = LRTable()
|
|
if picklefile:
|
|
read_signature = lr.read_pickle(picklefile)
|
|
else:
|
|
read_signature = lr.read_table(tabmodule)
|
|
if optimize or (read_signature == signature):
|
|
try:
|
|
lr.bind_callables(pinfo.pdict)
|
|
parser = LRParser(lr,pinfo.error_func)
|
|
parse = parser.parse
|
|
return parser
|
|
except Exception:
|
|
e = sys.exc_info()[1]
|
|
errorlog.warning("There was a problem loading the table file: %s", repr(e))
|
|
except VersionError:
|
|
e = sys.exc_info()
|
|
errorlog.warning(str(e))
|
|
except Exception:
|
|
pass
|
|
|
|
if debuglog is None:
|
|
if debug:
|
|
debuglog = PlyLogger(open(debugfile,"w"))
|
|
else:
|
|
debuglog = NullLogger()
|
|
|
|
debuglog.info("Created by PLY version %s (http://www.dabeaz.com/ply)", __version__)
|
|
|
|
|
|
errors = 0
|
|
|
|
# Validate the parser information
|
|
if pinfo.validate_all():
|
|
raise YaccError("Unable to build parser")
|
|
|
|
if not pinfo.error_func:
|
|
errorlog.warning("no p_error() function is defined")
|
|
|
|
# Create a grammar object
|
|
grammar = Grammar(pinfo.tokens)
|
|
|
|
# Set precedence level for terminals
|
|
for term, assoc, level in pinfo.preclist:
|
|
try:
|
|
grammar.set_precedence(term,assoc,level)
|
|
except GrammarError:
|
|
e = sys.exc_info()[1]
|
|
errorlog.warning("%s",str(e))
|
|
|
|
# Add productions to the grammar
|
|
for funcname, gram in pinfo.grammar:
|
|
file, line, prodname, syms = gram
|
|
try:
|
|
grammar.add_production(prodname,syms,funcname,file,line)
|
|
except GrammarError:
|
|
e = sys.exc_info()[1]
|
|
errorlog.error("%s",str(e))
|
|
errors = 1
|
|
|
|
# Set the grammar start symbols
|
|
try:
|
|
if start is None:
|
|
grammar.set_start(pinfo.start)
|
|
else:
|
|
grammar.set_start(start)
|
|
except GrammarError:
|
|
e = sys.exc_info()[1]
|
|
errorlog.error(str(e))
|
|
errors = 1
|
|
|
|
if errors:
|
|
raise YaccError("Unable to build parser")
|
|
|
|
# Verify the grammar structure
|
|
undefined_symbols = grammar.undefined_symbols()
|
|
for sym, prod in undefined_symbols:
|
|
errorlog.error("%s:%d: Symbol '%s' used, but not defined as a token or a rule",prod.file,prod.line,sym)
|
|
errors = 1
|
|
|
|
unused_terminals = grammar.unused_terminals()
|
|
if unused_terminals:
|
|
debuglog.info("")
|
|
debuglog.info("Unused terminals:")
|
|
debuglog.info("")
|
|
for term in unused_terminals:
|
|
errorlog.warning("Token '%s' defined, but not used", term)
|
|
debuglog.info(" %s", term)
|
|
|
|
# Print out all productions to the debug log
|
|
if debug:
|
|
debuglog.info("")
|
|
debuglog.info("Grammar")
|
|
debuglog.info("")
|
|
for n,p in enumerate(grammar.Productions):
|
|
debuglog.info("Rule %-5d %s", n, p)
|
|
|
|
# Find unused non-terminals
|
|
unused_rules = grammar.unused_rules()
|
|
for prod in unused_rules:
|
|
errorlog.warning("%s:%d: Rule '%s' defined, but not used", prod.file, prod.line, prod.name)
|
|
|
|
if len(unused_terminals) == 1:
|
|
errorlog.warning("There is 1 unused token")
|
|
if len(unused_terminals) > 1:
|
|
errorlog.warning("There are %d unused tokens", len(unused_terminals))
|
|
|
|
if len(unused_rules) == 1:
|
|
errorlog.warning("There is 1 unused rule")
|
|
if len(unused_rules) > 1:
|
|
errorlog.warning("There are %d unused rules", len(unused_rules))
|
|
|
|
if debug:
|
|
debuglog.info("")
|
|
debuglog.info("Terminals, with rules where they appear")
|
|
debuglog.info("")
|
|
terms = list(grammar.Terminals)
|
|
terms.sort()
|
|
for term in terms:
|
|
debuglog.info("%-20s : %s", term, " ".join([str(s) for s in grammar.Terminals[term]]))
|
|
|
|
debuglog.info("")
|
|
debuglog.info("Nonterminals, with rules where they appear")
|
|
debuglog.info("")
|
|
nonterms = list(grammar.Nonterminals)
|
|
nonterms.sort()
|
|
for nonterm in nonterms:
|
|
debuglog.info("%-20s : %s", nonterm, " ".join([str(s) for s in grammar.Nonterminals[nonterm]]))
|
|
debuglog.info("")
|
|
|
|
if check_recursion:
|
|
unreachable = grammar.find_unreachable()
|
|
for u in unreachable:
|
|
errorlog.warning("Symbol '%s' is unreachable",u)
|
|
|
|
infinite = grammar.infinite_cycles()
|
|
for inf in infinite:
|
|
errorlog.error("Infinite recursion detected for symbol '%s'", inf)
|
|
errors = 1
|
|
|
|
unused_prec = grammar.unused_precedence()
|
|
for term, assoc in unused_prec:
|
|
errorlog.error("Precedence rule '%s' defined for unknown symbol '%s'", assoc, term)
|
|
errors = 1
|
|
|
|
if errors:
|
|
raise YaccError("Unable to build parser")
|
|
|
|
# Run the LRGeneratedTable on the grammar
|
|
if debug:
|
|
errorlog.debug("Generating %s tables", method)
|
|
|
|
lr = LRGeneratedTable(grammar,method,debuglog)
|
|
|
|
if debug:
|
|
num_sr = len(lr.sr_conflicts)
|
|
|
|
# Report shift/reduce and reduce/reduce conflicts
|
|
if num_sr == 1:
|
|
errorlog.warning("1 shift/reduce conflict")
|
|
elif num_sr > 1:
|
|
errorlog.warning("%d shift/reduce conflicts", num_sr)
|
|
|
|
num_rr = len(lr.rr_conflicts)
|
|
if num_rr == 1:
|
|
errorlog.warning("1 reduce/reduce conflict")
|
|
elif num_rr > 1:
|
|
errorlog.warning("%d reduce/reduce conflicts", num_rr)
|
|
|
|
# Write out conflicts to the output file
|
|
if debug and (lr.sr_conflicts or lr.rr_conflicts):
|
|
debuglog.warning("")
|
|
debuglog.warning("Conflicts:")
|
|
debuglog.warning("")
|
|
|
|
for state, tok, resolution in lr.sr_conflicts:
|
|
debuglog.warning("shift/reduce conflict for %s in state %d resolved as %s", tok, state, resolution)
|
|
|
|
already_reported = {}
|
|
for state, rule, rejected in lr.rr_conflicts:
|
|
if (state,id(rule),id(rejected)) in already_reported:
|
|
continue
|
|
debuglog.warning("reduce/reduce conflict in state %d resolved using rule (%s)", state, rule)
|
|
debuglog.warning("rejected rule (%s) in state %d", rejected,state)
|
|
errorlog.warning("reduce/reduce conflict in state %d resolved using rule (%s)", state, rule)
|
|
errorlog.warning("rejected rule (%s) in state %d", rejected, state)
|
|
already_reported[state,id(rule),id(rejected)] = 1
|
|
|
|
warned_never = []
|
|
for state, rule, rejected in lr.rr_conflicts:
|
|
if not rejected.reduced and (rejected not in warned_never):
|
|
debuglog.warning("Rule (%s) is never reduced", rejected)
|
|
errorlog.warning("Rule (%s) is never reduced", rejected)
|
|
warned_never.append(rejected)
|
|
|
|
# Write the table file if requested
|
|
if write_tables:
|
|
lr.write_table(tabmodule,outputdir,signature)
|
|
|
|
# Write a pickled version of the tables
|
|
if picklefile:
|
|
lr.pickle_table(picklefile,signature)
|
|
|
|
# Build the parser
|
|
lr.bind_callables(pinfo.pdict)
|
|
parser = LRParser(lr,pinfo.error_func)
|
|
|
|
parse = parser.parse
|
|
return parser
|