Squashed 'yocto-poky/' content from commit ea562de
git-subtree-dir: yocto-poky
git-subtree-split: ea562de57590c966cd5a75fda8defecd397e6436
diff --git a/bitbake/lib/ply/yacc.py b/bitbake/lib/ply/yacc.py
new file mode 100644
index 0000000..6168fd9
--- /dev/null
+++ b/bitbake/lib/ply/yacc.py
@@ -0,0 +1,3276 @@
+# -----------------------------------------------------------------------------
+# ply: yacc.py
+#
+# Copyright (C) 2001-2009,
+# David M. Beazley (Dabeaz LLC)
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright notice,
+# this list of conditions and the following disclaimer.
+# * Redistributions in binary form must reproduce the above copyright notice,
+# this list of conditions and the following disclaimer in the documentation
+# and/or other materials provided with the distribution.
+# * Neither the name of the David Beazley or Dabeaz LLC may be used to
+# endorse or promote products derived from this software without
+# specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+# -----------------------------------------------------------------------------
+#
+# This implements an LR parser that is constructed from grammar rules defined
+# as Python functions. The grammer is specified by supplying the BNF inside
+# Python documentation strings. The inspiration for this technique was borrowed
+# from John Aycock's Spark parsing system. PLY might be viewed as cross between
+# Spark and the GNU bison utility.
+#
+# The current implementation is only somewhat object-oriented. The
+# LR parser itself is defined in terms of an object (which allows multiple
+# parsers to co-exist). However, most of the variables used during table
+# construction are defined in terms of global variables. Users shouldn't
+# notice unless they are trying to define multiple parsers at the same
+# time using threads (in which case they should have their head examined).
+#
+# This implementation supports both SLR and LALR(1) parsing. LALR(1)
+# support was originally implemented by Elias Ioup (ezioup@alumni.uchicago.edu),
+# using the algorithm found in Aho, Sethi, and Ullman "Compilers: Principles,
+# Techniques, and Tools" (The Dragon Book). LALR(1) has since been replaced
+# by the more efficient DeRemer and Pennello algorithm.
+#
+# :::::::: WARNING :::::::
+#
+# Construction of LR parsing tables is fairly complicated and expensive.
+# To make this module run fast, a *LOT* of work has been put into
+# optimization---often at the expensive of readability and what might
+# consider to be good Python "coding style." Modify the code at your
+# own risk!
+# ----------------------------------------------------------------------------
+
+__version__ = "3.3"
+__tabversion__ = "3.2" # Table version
+
+#-----------------------------------------------------------------------------
+# === User configurable parameters ===
+#
+# Change these to modify the default behavior of yacc (if you wish)
+#-----------------------------------------------------------------------------
+
+yaccdebug = 0 # Debugging mode. If set, yacc generates a
+ # a 'parser.out' file in the current directory
+
+debug_file = 'parser.out' # Default name of the debugging file
+tab_module = 'parsetab' # Default name of the table module
+default_lr = 'LALR' # Default LR table generation method
+
+error_count = 3 # Number of symbols that must be shifted to leave recovery mode
+
+yaccdevel = 0 # Set to True if developing yacc. This turns off optimized
+ # implementations of certain functions.
+
+resultlimit = 40 # Size limit of results when running in debug mode.
+
+pickle_protocol = 0 # Protocol to use when writing pickle files
+
+import re, types, sys, os.path
+
+# Compatibility function for python 2.6/3.0
+if sys.version_info[0] < 3:
+ def func_code(f):
+ return f.func_code
+else:
+ def func_code(f):
+ return f.__code__
+
+# Compatibility
+try:
+ MAXINT = sys.maxint
+except AttributeError:
+ MAXINT = sys.maxsize
+
+# Python 2.x/3.0 compatibility.
+def load_ply_lex():
+ if sys.version_info[0] < 3:
+ import lex
+ else:
+ import ply.lex as lex
+ return lex
+
+# This object is a stand-in for a logging object created by the
+# logging module. PLY will use this by default to create things
+# such as the parser.out file. If a user wants more detailed
+# information, they can create their own logging object and pass
+# it into PLY.
+
+class PlyLogger(object):
+ def __init__(self,f):
+ self.f = f
+ def debug(self,msg,*args,**kwargs):
+ self.f.write((msg % args) + "\n")
+ info = debug
+
+ def warning(self,msg,*args,**kwargs):
+ self.f.write("WARNING: "+ (msg % args) + "\n")
+
+ def error(self,msg,*args,**kwargs):
+ self.f.write("ERROR: " + (msg % args) + "\n")
+
+ critical = debug
+
+# Null logger is used when no output is generated. Does nothing.
+class NullLogger(object):
+ def __getattribute__(self,name):
+ return self
+ def __call__(self,*args,**kwargs):
+ return self
+
+# Exception raised for yacc-related errors
+class YaccError(Exception): pass
+
+# Format the result message that the parser produces when running in debug mode.
+def format_result(r):
+ repr_str = repr(r)
+ if '\n' in repr_str: repr_str = repr(repr_str)
+ if len(repr_str) > resultlimit:
+ repr_str = repr_str[:resultlimit]+" ..."
+ result = "<%s @ 0x%x> (%s)" % (type(r).__name__,id(r),repr_str)
+ return result
+
+
+# Format stack entries when the parser is running in debug mode
+def format_stack_entry(r):
+ repr_str = repr(r)
+ if '\n' in repr_str: repr_str = repr(repr_str)
+ if len(repr_str) < 16:
+ return repr_str
+ else:
+ return "<%s @ 0x%x>" % (type(r).__name__,id(r))
+
+#-----------------------------------------------------------------------------
+# === LR Parsing Engine ===
+#
+# The following classes are used for the LR parser itself. These are not
+# used during table construction and are independent of the actual LR
+# table generation algorithm
+#-----------------------------------------------------------------------------
+
+# This class is used to hold non-terminal grammar symbols during parsing.
+# It normally has the following attributes set:
+# .type = Grammar symbol type
+# .value = Symbol value
+# .lineno = Starting line number
+# .endlineno = Ending line number (optional, set automatically)
+# .lexpos = Starting lex position
+# .endlexpos = Ending lex position (optional, set automatically)
+
+class YaccSymbol:
+ def __str__(self): return self.type
+ def __repr__(self): return str(self)
+
+# This class is a wrapper around the objects actually passed to each
+# grammar rule. Index lookup and assignment actually assign the
+# .value attribute of the underlying YaccSymbol object.
+# The lineno() method returns the line number of a given
+# item (or 0 if not defined). The linespan() method returns
+# a tuple of (startline,endline) representing the range of lines
+# for a symbol. The lexspan() method returns a tuple (lexpos,endlexpos)
+# representing the range of positional information for a symbol.
+
+class YaccProduction:
+ def __init__(self,s,stack=None):
+ self.slice = s
+ self.stack = stack
+ self.lexer = None
+ self.parser= None
+ def __getitem__(self,n):
+ if n >= 0: return self.slice[n].value
+ else: return self.stack[n].value
+
+ def __setitem__(self,n,v):
+ self.slice[n].value = v
+
+ def __getslice__(self,i,j):
+ return [s.value for s in self.slice[i:j]]
+
+ def __len__(self):
+ return len(self.slice)
+
+ def lineno(self,n):
+ return getattr(self.slice[n],"lineno",0)
+
+ def set_lineno(self,n,lineno):
+ self.slice[n].lineno = lineno
+
+ def linespan(self,n):
+ startline = getattr(self.slice[n],"lineno",0)
+ endline = getattr(self.slice[n],"endlineno",startline)
+ return startline,endline
+
+ def lexpos(self,n):
+ return getattr(self.slice[n],"lexpos",0)
+
+ def lexspan(self,n):
+ startpos = getattr(self.slice[n],"lexpos",0)
+ endpos = getattr(self.slice[n],"endlexpos",startpos)
+ return startpos,endpos
+
+ def error(self):
+ raise SyntaxError
+
+
+# -----------------------------------------------------------------------------
+# == LRParser ==
+#
+# The LR Parsing engine.
+# -----------------------------------------------------------------------------
+
+class LRParser:
+ def __init__(self,lrtab,errorf):
+ self.productions = lrtab.lr_productions
+ self.action = lrtab.lr_action
+ self.goto = lrtab.lr_goto
+ self.errorfunc = errorf
+
+ def errok(self):
+ self.errorok = 1
+
+ def restart(self):
+ del self.statestack[:]
+ del self.symstack[:]
+ sym = YaccSymbol()
+ sym.type = '$end'
+ self.symstack.append(sym)
+ self.statestack.append(0)
+
+ def parse(self,input=None,lexer=None,debug=0,tracking=0,tokenfunc=None):
+ if debug or yaccdevel:
+ if isinstance(debug,int):
+ debug = PlyLogger(sys.stderr)
+ return self.parsedebug(input,lexer,debug,tracking,tokenfunc)
+ elif tracking:
+ return self.parseopt(input,lexer,debug,tracking,tokenfunc)
+ else:
+ return self.parseopt_notrack(input,lexer,debug,tracking,tokenfunc)
+
+
+ # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+ # parsedebug().
+ #
+ # This is the debugging enabled version of parse(). All changes made to the
+ # parsing engine should be made here. For the non-debugging version,
+ # copy this code to a method parseopt() and delete all of the sections
+ # enclosed in:
+ #
+ # #--! DEBUG
+ # statements
+ # #--! DEBUG
+ #
+ # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+ def parsedebug(self,input=None,lexer=None,debug=None,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
+
+ # --! DEBUG
+ debug.info("PLY: PARSE DEBUG START")
+ # --! DEBUG
+
+ # 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 = "$end"
+ symstack.append(sym)
+ state = 0
+ while 1:
+ # Get the next symbol on the input. If a lookahead symbol
+ # is already set, we just use that. Otherwise, we'll pull
+ # the next token off of the lookaheadstack or from the lexer
+
+ # --! DEBUG
+ debug.debug('')
+ debug.debug('State : %s', state)
+ # --! DEBUG
+
+ if not lookahead:
+ if not lookaheadstack:
+ lookahead = get_token() # Get the next token
+ else:
+ lookahead = lookaheadstack.pop()
+ if not lookahead:
+ lookahead = YaccSymbol()
+ lookahead.type = "$end"
+
+ # --! DEBUG
+ debug.debug('Stack : %s',
+ ("%s . %s" % (" ".join([xx.type for xx in symstack][1:]), str(lookahead))).lstrip())
+ # --! DEBUG
+
+ # 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
+
+ # --! DEBUG
+ debug.debug("Action : Shift and goto state %s", t)
+ # --! DEBUG
+
+ 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
+
+ # --! DEBUG
+ if plen:
+ 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)
+ else:
+ debug.info("Action : Reduce rule [%s] with %s and goto state %d", p.str, [],-t)
+
+ # --! DEBUG
+
+ 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)
+ # --! DEBUG
+ debug.info("Result : %s", format_result(pslice[0]))
+ # --! DEBUG
+ 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)
+ # --! DEBUG
+ debug.info("Result : %s", format_result(pslice[0]))
+ # --! DEBUG
+ 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]
+ result = getattr(n,"value",None)
+ # --! DEBUG
+ debug.info("Done : Returning %s", format_result(result))
+ debug.info("PLY: PARSE DEBUG END")
+ # --! DEBUG
+ return result
+
+ if t == None:
+
+ # --! DEBUG
+ debug.error('Error : %s',
+ ("%s . %s" % (" ".join([xx.type for xx in symstack][1:]), str(lookahead))).lstrip())
+ # --! DEBUG
+
+ # 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().
+ #
+ # 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