--- /dev/null
+#-----------------------------------------------------------------------------
+# ply: yacc.py
+#
+# Author: David M. Beazley (beazley@cs.uchicago.edu)
+# Department of Computer Science
+# University of Chicago
+# Chicago, IL 60637
+#
+# Copyright (C) 2001, David M. Beazley
+#
+# $Header: /cvsroot/ply/ply/yacc.py,v 1.15 2002/12/12 21:16:18 beazley Exp $
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+#
+# See the file COPYING for a complete copy of the LGPL.
+#
+#
+# This implements an LR parser that is constructed from grammar rules defined
+# as Python functions. Roughly speaking, this module is a cross between
+# John Aycock's Spark system and the GNU bison utility.
+#
+# Disclaimer: This is a work in progress. SLR parsing seems to work fairly
+# well and there is extensive error checking. LALR(1) is in progress. The
+# rest of this file is a bit of a mess. Please pardon the dust.
+#
+# 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).
+#-----------------------------------------------------------------------------
+
+__version__ = "1.3"
+
+#-----------------------------------------------------------------------------
+# === User configurable parameters ===
+#
+# Change these to modify the default behavior of yacc (if you wish)
+#-----------------------------------------------------------------------------
+
+yaccdebug = 1 # 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 = 'SLR' # Default LR table generation method
+
+error_count = 3 # Number of symbols that must be shifted to leave recovery mode
+
+import re, types, sys, cStringIO, md5, os.path
+
+# Exception raised for yacc-related errors
+class YaccError(Exception): pass
+
+#-----------------------------------------------------------------------------
+# === 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)
+
+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.
+
+class YaccSlice:
+ def __init__(self,s):
+ self.slice = s
+ self.pbstack = []
+
+ def __getitem__(self,n):
+ return self.slice[n].value
+
+ def __setitem__(self,n,v):
+ self.slice[n].value = v
+
+ def lineno(self,n):
+ return getattr(self.slice[n],"lineno",0)
+
+ def linespan(self,n):
+ startline = getattr(self.slice[n],"lineno",0)
+ endline = getattr(self.slice[n],"endlineno",startline)
+ return startline,endline
+
+ def pushback(self,n):
+ if n <= 0:
+ raise ValueError, "Expected a positive value"
+ if n > (len(self.slice)-1):
+ raise ValueError, "Can't push %d tokens. Only %d are available." % (n,len(self.slice)-1)
+ for i in range(0,n):
+ self.pbstack.append(self.slice[-i-1])
+
+# The LR Parsing engine. This is defined as a class so that multiple parsers
+# can exist in the same process. A user never instantiates this directly.
+# Instead, the global yacc() function should be used to create a suitable Parser
+# object.
+
+class Parser:
+ def __init__(self,magic=None):
+
+ # This is a hack to keep users from trying to instantiate a Parser
+ # object directly.
+
+ if magic != "xyzzy":
+ raise YaccError, "Can't instantiate Parser. Use yacc() instead."
+
+ # Reset internal state
+ self.productions = None # List of productions
+ self.errorfunc = None # Error handling function
+ self.action = { } # LR Action table
+ self.goto = { } # LR goto table
+ self.require = { } # Attribute require table
+ self.method = "Unknown LR" # Table construction method used
+
+ def errok(self):
+ self.errorcount = 0
+
+ def restart(self):
+ del self.statestack[:]
+ del self.symstack[:]
+ sym = YaccSymbol()
+ sym.type = '$'
+ self.symstack.append(sym)
+ self.statestack.append(0)
+
+ def parse(self,input=None,lexer=None,debug=0):
+ lookahead = None # Current lookahead symbol
+ lookaheadstack = [ ] # Stack of lookahead symbols
+ actions = self.action # Local reference to action table
+ goto = self.goto # Local reference to goto table
+ prod = self.productions # Local reference to production list
+ pslice = YaccSlice(None) # Slice object passed to grammar rules
+ pslice.parser = self # Parser object
+ self.errorcount = 0 # Used during error recovery
+
+ # If no lexer was given, we will try to use the lex module
+ if not lexer:
+ import lex as lexer
+
+ pslice.lexer = lexer
+
+ # If input was supplied, pass to lexer
+ if input:
+ lexer.input(input)
+
+ # Tokenize function
+ get_token = lexer.token
+
+ statestack = [ ] # Stack of parsing states
+ self.statestack = statestack
+ symstack = [ ] # Stack of grammar symbols
+ self.symstack = symstack
+
+ errtoken = None # Err token
+
+ # The start state is assumed to be (0,$)
+ statestack.append(0)
+ sym = YaccSymbol()
+ sym.type = '$'
+ symstack.append(sym)
+
+ while 1:
+ # Get the next symbol on the input. If a lookahead symbol
+ # is already set, we just use that. Otherwise, we'll pull
+ # the next token off of the lookaheadstack or from the lexer
+ if not lookahead:
+ if not lookaheadstack:
+ lookahead = get_token() # Get the next token
+ else:
+ lookahead = lookaheadstack.pop()
+ if not lookahead:
+ lookahead = YaccSymbol()
+ lookahead.type = '$'
+ if debug:
+ print "%-20s : %s" % (lookahead, [xx.type for xx in symstack])
+
+ # Check the action table
+ s = statestack[-1]
+ ltype = lookahead.type
+ t = actions.get((s,ltype),None)
+
+ if t is not None:
+ if t > 0:
+ # shift a symbol on the stack
+ if ltype == '$':
+ # Error, end of input
+ print "yacc: Parse error. EOF"
+ return
+ statestack.append(t)
+ symstack.append(lookahead)
+ lookahead = None
+
+ # Decrease error count on successful shift
+ if self.errorcount > 0:
+ self.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
+ try:
+ sym.lineno = targ[1].lineno
+ sym.endlineno = getattr(targ[-1],"endlineno",targ[-1].lineno)
+ except AttributeError:
+ sym.lineno = 0
+ del symstack[-plen:]
+ del statestack[-plen:]
+ else:
+ sym.lineno = 0
+ targ = [ sym ]
+ pslice.slice = targ
+ pslice.pbstack = []
+ # Call the grammar rule with our special slice object
+ p.func(pslice)
+
+ # Validate attributes of the resulting value attribute
+# if require:
+# try:
+# t0 = targ[0]
+# r = Requires.get(t0.type,None)
+# t0d = t0.__dict__
+# if r:
+# for field in r:
+# tn = t0
+# for fname in field:
+# try:
+# tf = tn.__dict__
+# tn = tf.get(fname)
+# except StandardError:
+# tn = None
+# if not tn:
+# print "%s:%d: Rule %s doesn't set required attribute '%s'" % \
+# (p.file,p.line,p.name,".".join(field))
+# except TypeError,LookupError:
+# print "Bad requires directive " % r
+# pass
+
+
+ # If there was a pushback, put that on the stack
+ if pslice.pbstack:
+ lookaheadstack.append(lookahead)
+ for _t in pslice.pbstack:
+ lookaheadstack.append(_t)
+ lookahead = None
+
+ symstack.append(sym)
+ statestack.append(goto[statestack[-1],pname])
+ 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 not self.errorcount:
+ self.errorcount = error_count
+ errtoken = lookahead
+ if errtoken.type == '$':
+ 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
+ tok = self.errorfunc(errtoken)
+ del errok, token, restart # Delete special functions
+
+ if not self.errorcount:
+ # 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:
+ print "yacc: Syntax error at line %d, token=%s" % (lineno, errtoken.type)
+ else:
+ print "yacc: Syntax error, token=%s" % errtoken.type
+ else:
+ print "yacc: Parse error in input. EOF"
+ return
+
+ else:
+ self.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 != '$':
+ lookahead = None
+ errtoken = None
+ # Nuke the pushback stack
+ del lookaheadstack[:]
+ continue
+
+ # case 2: the statestack has a couple of entries on it, but we're
+ # at the end of the file. nuke the top entry and generate an error token
+
+ # Start nuking entries on the stack
+ if lookahead.type == '$':
+ # 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()
+
+ continue
+
+ # Call an error function here
+ raise RuntimeError, "yacc: internal parser error!!!\n"
+
+# -----------------------------------------------------------------------------
+# === Parser Construction ===
+#
+# The following functions and variables are used to implement the yacc() function
+# itself. This is pretty hairy stuff involving lots of error checking,
+# construction of LR items, kernels, and so forth. Although a lot of
+# this work is done using global variables, the resulting Parser object
+# is completely self contained--meaning that it is safe to repeatedly
+# call yacc() with different grammars in the same application.
+# -----------------------------------------------------------------------------
+
+# -----------------------------------------------------------------------------
+# validate_file()
+#
+# This function 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_file(filename):
+ 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:
+ return 1 # Oh well
+
+ # Match def p_funcname(
+ fre = re.compile(r'\s*def\s+(p_[a-zA-Z_0-9]*)\(')
+ counthash = { }
+ linen = 1
+ noerror = 1
+ for l in lines:
+ m = fre.match(l)
+ if m:
+ name = m.group(1)
+ prev = counthash.get(name)
+ if not prev:
+ counthash[name] = linen
+ else:
+ print "%s:%d: Function %s redefined. Previously defined on line %d" % (filename,linen,name,prev)
+ noerror = 0
+ linen += 1
+ return noerror
+
+# This function looks for functions that might be grammar rules, but which don't have the proper p_suffix.
+def validate_dict(d):
+ for n,v in d.items():
+ if n[0:2] == 'p_' and isinstance(v,types.FunctionType): continue
+ if n[0:2] == 't_': continue
+
+ if n[0:2] == 'p_':
+ print "yacc: Warning. '%s' not defined as a function" % n
+ if isinstance(v,types.FunctionType) and v.func_code.co_argcount == 1:
+ try:
+ doc = v.__doc__.split(" ")
+ if doc[1] == ':':
+ print "%s:%d: Warning. Possible grammar rule '%s' defined without p_ prefix." % (v.func_code.co_filename, v.func_code.co_firstlineno,n)
+ except StandardError:
+ pass
+
+# -----------------------------------------------------------------------------
+# === GRAMMAR FUNCTIONS ===
+#
+# The following global variables and functions are used to store, manipulate,
+# and verify the grammar rules specified by the user.
+# -----------------------------------------------------------------------------
+
+# Initialize all of the global variables used during grammar construction
+def initialize_vars():
+ global Productions, Prodnames, Prodmap, Terminals
+ global Nonterminals, First, Follow, Precedence, LRitems
+ global Errorfunc, Signature, Requires
+
+ Productions = [None] # A list of all of the productions. The first
+ # entry is always reserved for the purpose of
+ # building an augmented grammar
+
+ Prodnames = { } # A dictionary mapping the names of nonterminals to a list of all
+ # productions of that nonterminal.
+
+ Prodmap = { } # A dictionary that is only used to detect duplicate
+ # productions.
+
+ Terminals = { } # A dictionary mapping the names of terminal symbols to a
+ # list of the rules where they are used.
+
+ Nonterminals = { } # A dictionary mapping names of nonterminals to a list
+ # of rule numbers where they are used.
+
+ First = { } # A dictionary of precomputed FIRST(x) symbols
+
+ Follow = { } # A dictionary of precomputed FOLLOW(x) symbols
+
+ Precedence = { } # Precedence rules for each terminal. Contains tuples of the
+ # form ('right',level) or ('nonassoc', level) or ('left',level)
+
+ LRitems = [ ] # A list of all LR items for the grammar. These are the
+ # productions with the "dot" like E -> E . PLUS E
+
+ Errorfunc = None # User defined error handler
+
+ Signature = md5.new() # Digital signature of the grammar rules, precedence
+ # and other information. Used to determined when a
+ # parsing table needs to be regenerated.
+
+ Requires = { } # Requires list
+
+ # File objects used when creating the parser.out debugging file
+ global _vf, _vfc
+ _vf = cStringIO.StringIO()
+ _vfc = cStringIO.StringIO()
+
+# -----------------------------------------------------------------------------
+# class Production:
+#
+# This class stores the raw information about a single production or grammar rule.
+# It has a few required attributes:
+#
+# name - Name of the production (nonterminal)
+# prod - A list of symbols making up its production
+# number - Production number.
+#
+# In addition, a few additional attributes are used to help with debugging or
+# optimization of table generation.
+#
+# file - File where production action is defined.
+# lineno - Line number where action is defined
+# func - Action function
+# prec - Precedence level
+# lr_next - Next LR item. Example, if we are ' E -> E . PLUS E'
+# then lr_next refers to 'E -> E PLUS . E'
+# lr_index - LR item index (location of the ".") in the prod list.
+# len - Length of the production (number of symbols on right hand side)
+# -----------------------------------------------------------------------------
+
+class Production:
+ def __init__(self,**kw):
+ for k,v in kw.items():
+ setattr(self,k,v)
+ self.lr_index = -1
+ self.lr0_added = 0 # Flag indicating whether or not added to LR0 closure
+ self.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 str(self)
+
+ # Compute lr_items from the production
+ def lr_item(self,n):
+ if n > len(self.prod): return None
+ p = Production()
+ p.name = self.name
+ p.prod = list(self.prod)
+ p.number = self.number
+ p.lr_index = n
+ p.prod.insert(n,".")
+ p.prod = tuple(p.prod)
+ p.len = len(p.prod)
+ p.usyms = self.usyms
+
+ # Precompute list of productions immediately following
+ try:
+ p.lrafter = Prodnames[p.prod[n+1]]
+ except (IndexError,KeyError),e:
+ p.lrafter = []
+ try:
+ p.lrbefore = p.prod[n-1]
+ except IndexError:
+ p.lrbefore = None
+
+ return p
+
+class MiniProduction:
+ pass
+
+# Utility function
+def is_identifier(s):
+ for c in s:
+ if not (c.isalnum() or c == '_'): return 0
+ return 1
+
+# -----------------------------------------------------------------------------
+# add_production()
+#
+# Given an action function, this function assembles a production rule.
+# The production rule is assumed to be found in the function's docstring.
+# This rule has the general syntax:
+#
+# name1 ::= production1
+# | production2
+# | production3
+# ...
+# | productionn
+# name2 ::= production1
+# | production2
+# ...
+# -----------------------------------------------------------------------------
+
+def add_production(f,file,line,prodname,syms):
+
+ if Terminals.has_key(prodname):
+ print "%s:%d: Illegal rule name '%s'. Already defined as a token." % (file,line,prodname)
+ return -1
+ if prodname == 'error':
+ print "%s:%d: Illegal rule name '%s'. error is a reserved word." % (file,line,prodname)
+ return -1
+
+ if not is_identifier(prodname):
+ print "%s:%d: Illegal rule name '%s'" % (file,line,prodname)
+ return -1
+
+ for s in syms:
+ if not is_identifier(s) and s != '%prec':
+ print "%s:%d: Illegal name '%s' in rule '%s'" % (file,line,s, prodname)
+ return -1
+
+ # See if the rule is already in the rulemap
+ map = "%s -> %s" % (prodname,syms)
+ if Prodmap.has_key(map):
+ m = Prodmap[map]
+ print "%s:%d: Duplicate rule %s." % (file,line, m)
+ print "%s:%d: Previous definition at %s:%d" % (file,line, m.file, m.line)
+ return -1
+
+ p = Production()
+ p.name = prodname
+ p.prod = syms
+ p.file = file
+ p.line = line
+ p.func = f
+ p.number = len(Productions)
+
+
+ Productions.append(p)
+ Prodmap[map] = p
+ if not Nonterminals.has_key(prodname):
+ Nonterminals[prodname] = [ ]
+
+ # Add all terminals to Terminals
+ i = 0
+ while i < len(p.prod):
+ t = p.prod[i]
+ if t == '%prec':
+ try:
+ precname = p.prod[i+1]
+ except IndexError:
+ print "%s:%d: Syntax error. Nothing follows %%prec." % (p.file,p.line)
+ return -1
+
+ prec = Precedence.get(precname,None)
+ if not prec:
+ print "%s:%d: Nothing known about the precedence of '%s'" % (p.file,p.line,precname)
+ return -1
+ else:
+ p.prec = prec
+ del p.prod[i]
+ del p.prod[i]
+ continue
+
+ if Terminals.has_key(t):
+ Terminals[t].append(p.number)
+ # Is a terminal. We'll assign a precedence to p based on this
+ if not hasattr(p,"prec"):
+ p.prec = Precedence.get(t,('right',0))
+ else:
+ if not Nonterminals.has_key(t):
+ Nonterminals[t] = [ ]
+ Nonterminals[t].append(p.number)
+ i += 1
+
+ if not hasattr(p,"prec"):
+ p.prec = ('right',0)
+
+ # Set final length of productions
+ p.len = len(p.prod)
+ p.prod = tuple(p.prod)
+
+ # Calculate unique syms in the production
+ p.usyms = [ ]
+ for s in p.prod:
+ if s not in p.usyms:
+ p.usyms.append(s)
+
+ # Add to the global productions list
+ try:
+ Prodnames[p.name].append(p)
+ except KeyError:
+ Prodnames[p.name] = [ p ]
+ return 0
+
+# Given a raw rule function, this function rips out its doc string
+# and adds rules to the grammar
+
+def add_function(f):
+ line = f.func_code.co_firstlineno
+ file = f.func_code.co_filename
+ error = 0
+
+ if f.func_code.co_argcount > 1:
+ print "%s:%d: Rule '%s' has too many arguments." % (file,line,f.__name__)
+ return -1
+
+ if f.func_code.co_argcount < 1:
+ print "%s:%d: Rule '%s' requires an argument." % (file,line,f.__name__)
+ return -1
+
+ if f.__doc__:
+ # Split the doc string into lines
+ pstrings = f.__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:
+ print "%s:%d: Misplaced '|'." % (file,dline)
+ return -1
+ prodname = lastp
+ if len(p) > 1:
+ syms = p[1:]
+ else:
+ syms = [ ]
+ else:
+ prodname = p[0]
+ lastp = prodname
+ assign = p[1]
+ if len(p) > 2:
+ syms = p[2:]
+ else:
+ syms = [ ]
+ if assign != ':' and assign != '::=':
+ print "%s:%d: Syntax error. Expected ':'" % (file,dline)
+ return -1
+ e = add_production(f,file,dline,prodname,syms)
+ error += e
+ except StandardError:
+ print "%s:%d: Syntax error in rule '%s'" % (file,dline,ps)
+ error -= 1
+ else:
+ print "%s:%d: No documentation string specified in function '%s'" % (file,line,f.__name__)
+ return error
+
+
+# Cycle checking code (Michael Dyck)
+
+def compute_reachable():
+ '''
+ Find each symbol that can be reached from the start symbol.
+ Print a warning for any nonterminals that can't be reached.
+ (Unused terminals have already had their warning.)
+ '''
+ Reachable = { }
+ for s in Terminals.keys() + Nonterminals.keys():
+ Reachable[s] = 0
+
+ mark_reachable_from( Productions[0].prod[0], Reachable )
+
+ for s in Nonterminals.keys():
+ if not Reachable[s]:
+ print "yacc: Symbol '%s' is unreachable." % s
+
+def mark_reachable_from(s, Reachable):
+ '''
+ Mark all symbols that are reachable from symbol s.
+ '''
+ if Reachable[s]:
+ # We've already reached symbol s.
+ return
+ Reachable[s] = 1
+ for p in Prodnames.get(s,[]):
+ for r in p.prod:
+ mark_reachable_from(r, Reachable)
+
+# -----------------------------------------------------------------------------
+# compute_terminates()
+#
+# 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 compute_terminates():
+ '''
+ Raise an error for any symbols that don't terminate.
+ '''
+ Terminates = {}
+
+ # Terminals:
+ for t in Terminals.keys():
+ Terminates[t] = 1
+
+ Terminates['$'] = 1
+
+ # Nonterminals:
+
+ # Initialize to false:
+ for n in Nonterminals.keys():
+ Terminates[n] = 0
+
+ # Then propagate termination until no change:
+ while 1:
+ some_change = 0
+ for (n,pl) in 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
+
+ some_error = 0
+ for (s,terminates) in Terminates.items():
+ if not terminates:
+ if not Prodnames.has_key(s) and not Terminals.has_key(s) 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:
+ print "yacc: Infinite recursion detected for symbol '%s'." % s
+ some_error = 1
+
+ return some_error
+
+# -----------------------------------------------------------------------------
+# verify_productions()
+#
+# This function examines all of the supplied rules to see if they seem valid.
+# -----------------------------------------------------------------------------
+def verify_productions(cycle_check=1):
+ error = 0
+ for p in Productions:
+ if not p: continue
+
+ for s in p.prod:
+ if not Prodnames.has_key(s) and not Terminals.has_key(s) and s != 'error':
+ print "%s:%d: Symbol '%s' used, but not defined as a token or a rule." % (p.file,p.line,s)
+ error = 1
+ continue
+
+ unused_tok = 0
+ # Now verify all of the tokens
+ if yaccdebug:
+ _vf.write("Unused terminals:\n\n")
+ for s,v in Terminals.items():
+ if s != 'error' and not v:
+ print "yacc: Warning. Token '%s' defined, but not used." % s
+ if yaccdebug: _vf.write(" %s\n"% s)
+ unused_tok += 1
+
+ # Print out all of the productions
+ if yaccdebug:
+ _vf.write("\nGrammar\n\n")
+ for i in range(1,len(Productions)):
+ _vf.write("Rule %-5d %s\n" % (i, Productions[i]))
+
+ unused_prod = 0
+ # Verify the use of all productions
+ for s,v in Nonterminals.items():
+ if not v:
+ p = Prodnames[s][0]
+ print "%s:%d: Warning. Rule '%s' defined, but not used." % (p.file,p.line, s)
+ unused_prod += 1
+
+
+ if unused_tok == 1:
+ print "yacc: Warning. There is 1 unused token."
+ if unused_tok > 1:
+ print "yacc: Warning. There are %d unused tokens." % unused_tok
+
+ if unused_prod == 1:
+ print "yacc: Warning. There is 1 unused rule."
+ if unused_prod > 1:
+ print "yacc: Warning. There are %d unused rules." % unused_prod
+
+ if yaccdebug:
+ _vf.write("\nTerminals, with rules where they appear\n\n")
+ ks = Terminals.keys()
+ ks.sort()
+ for k in ks:
+ _vf.write("%-20s : %s\n" % (k, " ".join([str(s) for s in Terminals[k]])))
+ _vf.write("\nNonterminals, with rules where they appear\n\n")
+ ks = Nonterminals.keys()
+ ks.sort()
+ for k in ks:
+ _vf.write("%-20s : %s\n" % (k, " ".join([str(s) for s in Nonterminals[k]])))
+
+ if (cycle_check):
+ compute_reachable()
+ error += compute_terminates()
+# error += check_cycles()
+ return error
+
+# -----------------------------------------------------------------------------
+# 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():
+ for p in Productions:
+ lastlri = p
+ lri = p.lr_item(0)
+ i = 0
+ while 1:
+ lri = p.lr_item(i)
+ lastlri.lr_next = lri
+ if not lri: break
+ lri.lr_num = len(LRitems)
+ LRitems.append(lri)
+ lastlri = lri
+ i += 1
+
+ # In order for the rest of the parser generator to work, we need to
+ # guarantee that no more lritems are generated. Therefore, we nuke
+ # the p.lr_item method. (Only used in debugging)
+ # Production.lr_item = None
+
+# -----------------------------------------------------------------------------
+# add_precedence()
+#
+# Given a list of precedence rules, add to the precedence table.
+# -----------------------------------------------------------------------------
+
+def add_precedence(plist):
+ plevel = 0
+ error = 0
+ for p in plist:
+ plevel += 1
+ try:
+ prec = p[0]
+ terms = p[1:]
+ if prec != 'left' and prec != 'right' and prec != 'nonassoc':
+ print "yacc: Invalid precedence '%s'" % prec
+ return -1
+ for t in terms:
+ if Precedence.has_key(t):
+ print "yacc: Precedence already specified for terminal '%s'" % t
+ error += 1
+ continue
+ Precedence[t] = (prec,plevel)
+ except:
+ print "yacc: Invalid precedence table."
+ error += 1
+
+ return error
+
+# -----------------------------------------------------------------------------
+# augment_grammar()
+#
+# Compute the augmented grammar. This is just a rule S' -> start where start
+# is the starting symbol.
+# -----------------------------------------------------------------------------
+
+def augment_grammar(start=None):
+ if not start:
+ start = Productions[1].name
+ Productions[0] = Production(name="S'",prod=[start],number=0,len=1,prec=('right',0),func=None)
+ Productions[0].usyms = [ start ]
+ Nonterminals[start].append(0)
+
+
+# -------------------------------------------------------------------------
+# 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(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 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
+
+
+# FOLLOW(x)
+# Given a non-terminal. This function computes the set of all symbols
+# that might follow it. Dragon book, p. 189.
+
+def compute_follow(start=None):
+ # Add '$' to the follow list of the start symbol
+ for k in Nonterminals.keys():
+ Follow[k] = [ ]
+
+ if not start:
+ start = Productions[1].name
+
+ Follow[start] = [ '$' ]
+
+ while 1:
+ didadd = 0
+ for p in Productions[1:]:
+ # Here is the production set
+ for i in range(len(p.prod)):
+ B = p.prod[i]
+ if Nonterminals.has_key(B):
+ # Okay. We got a non-terminal in a production
+ fst = first(p.prod[i+1:])
+ hasempty = 0
+ for f in fst:
+ if f != '<empty>' and f not in Follow[B]:
+ Follow[B].append(f)
+ didadd = 1
+ if f == '<empty>':
+ hasempty = 1
+ if hasempty or i == (len(p.prod)-1):
+ # Add elements of follow(a) to follow(b)
+ for f in Follow[p.name]:
+ if f not in Follow[B]:
+ Follow[B].append(f)
+ didadd = 1
+ if not didadd: break
+
+ if 0 and yaccdebug:
+ _vf.write('\nFollow:\n')
+ for k in Nonterminals.keys():
+ _vf.write("%-20s : %s\n" % (k, " ".join([str(s) for s in Follow[k]])))
+
+# -------------------------------------------------------------------------
+# compute_first1()
+#
+# Compute the value of FIRST1(X) for all symbols
+# -------------------------------------------------------------------------
+def compute_first1():
+
+ # Terminals:
+ for t in Terminals.keys():
+ First[t] = [t]
+
+ First['$'] = ['$']
+ First['#'] = ['#'] # what's this for?
+
+ # Nonterminals:
+
+ # Initialize to the empty set:
+ for n in Nonterminals.keys():
+ First[n] = []
+
+ # Then propagate symbols until no change:
+ while 1:
+ some_change = 0
+ for n in Nonterminals.keys():
+ for p in Prodnames[n]:
+ for f in first(p.prod):
+ if f not in First[n]:
+ First[n].append( f )
+ some_change = 1
+ if not some_change:
+ break
+
+ if 0 and yaccdebug:
+ _vf.write('\nFirst:\n')
+ for k in Nonterminals.keys():
+ _vf.write("%-20s : %s\n" %
+ (k, " ".join([str(s) for s in First[k]])))
+
+# -----------------------------------------------------------------------------
+# === SLR Generation ===
+#
+# The following functions are used to construct SLR (Simple LR) parsing tables
+# as described on p.221-229 of the dragon book.
+# -----------------------------------------------------------------------------
+
+# Global variables for the LR parsing engine
+def lr_init_vars():
+ global _lr_action, _lr_goto, _lr_method
+ global _lr_goto_cache
+
+ _lr_action = { } # Action table
+ _lr_goto = { } # Goto table
+ _lr_method = "Unknown" # LR method used
+ _lr_goto_cache = { }
+
+# Compute the LR(0) closure operation on I, where I is a set of LR(0) items.
+# prodlist is a list of productions.
+
+_add_count = 0 # Counter used to detect cycles
+
+def lr0_closure(I):
+ global _add_count
+
+ _add_count += 1
+ prodlist = Productions
+
+ # Add everything in I to J
+ J = I[:]
+ didadd = 1
+ while didadd:
+ didadd = 0
+ for j in J:
+ for x in j.lrafter:
+ if x.lr0_added == _add_count: continue
+ # Add B --> .G to J
+ J.append(x.lr_next)
+ x.lr0_added = _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(I,x):
+ # First we look for a previously cached entry
+ g = _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 = _lr_goto_cache.get(x,None)
+ if not s:
+ s = { }
+ _lr_goto_cache[x] = s
+
+ gs = [ ]
+ for p in I:
+ n = p.lr_next
+ if n and n.lrbefore == x:
+ s1 = s.get(id(n),None)
+ if not s1:
+ s1 = { }
+ s[id(n)] = s1
+ gs.append(n)
+ s = s1
+ g = s.get('$',None)
+ if not g:
+ if gs:
+ g = lr0_closure(gs)
+ s['$'] = g
+ else:
+ s['$'] = gs
+ _lr_goto_cache[(id(I),x)] = g
+ return g
+
+# Compute the kernel of a set of LR(0) items
+def lr0_kernel(I):
+ KI = [ ]
+ for p in I:
+ if p.name == "S'" or p.lr_index > 0 or p.len == 0:
+ KI.append(p)
+
+ return KI
+
+_lr0_cidhash = { }
+
+# Compute the LR(0) sets of item function
+def lr0_items():
+
+ C = [ lr0_closure([Productions[0].lr_next]) ]
+ i = 0
+ for I in C:
+ _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.keys():
+ g = lr0_goto(I,x)
+ if not g: continue
+ if _lr0_cidhash.has_key(id(g)): continue
+ _lr0_cidhash[id(g)] = len(C)
+ C.append(g)
+
+ return C
+
+# -----------------------------------------------------------------------------
+# slr_parse_table()
+#
+# This function constructs an SLR table.
+# -----------------------------------------------------------------------------
+def slr_parse_table():
+ global _lr_method
+ goto = _lr_goto # Goto array
+ action = _lr_action # Action array
+ actionp = { } # Action production array (temporary)
+
+ _lr_method = "SLR"
+
+ n_srconflict = 0
+ n_rrconflict = 0
+
+ print "yacc: Generating SLR parsing table..."
+ if yaccdebug:
+ _vf.write("\n\nParsing method: SLR\n\n")
+
+ # Step 1: Construct C = { I0, I1, ... IN}, collection of LR(0) items
+ # This determines the number of states
+
+ C = lr0_items()
+
+ # Build the parser table, state by state
+ st = 0
+ for I in C:
+ # Loop over each production in I
+ actlist = [ ] # List of actions
+
+ if yaccdebug:
+ _vf.write("\nstate %d\n\n" % st)
+ for p in I:
+ _vf.write(" (%d) %s\n" % (p.number, str(p)))
+ _vf.write("\n")
+
+ for p in I:
+ try:
+ if p.prod[-1] == ".":
+ if p.name == "S'":
+ # Start symbol. Accept!
+ action[st,"$"] = 0
+ actionp[st,"$"] = p
+ else:
+ # We are at the end of a production. Reduce!
+ for a in Follow[p.name]:
+ actlist.append((a,p,"reduce using rule %d (%s)" % (p.number,p)))
+ r = action.get((st,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[actionp[st,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.
+ action[st,a] = -p.number
+ actionp[st,a] = p
+ if not slevel and not rlevel:
+ _vfc.write("shift/reduce conflict in state %d resolved as reduce.\n" % st)
+ _vf.write(" ! shift/reduce conflict for %s resolved as reduce.\n" % a)
+ n_srconflict += 1
+ elif (slevel == rlevel) and (rprec == 'nonassoc'):
+ action[st,a] = None
+ else:
+ # Hmmm. Guess we'll keep the shift
+ if not slevel and not rlevel:
+ _vfc.write("shift/reduce conflict in state %d resolved as shift.\n" % st)
+ _vf.write(" ! shift/reduce conflict for %s resolved as shift.\n" % a)
+ n_srconflict +=1
+ 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:
+ action[st,a] = -p.number
+ actionp[st,a] = p
+ # print "Reduce/reduce conflict in state %d" % st
+ n_rrconflict += 1
+ _vfc.write("reduce/reduce conflict in state %d resolved using rule %d (%s).\n" % (st, actionp[st,a].number, actionp[st,a]))
+ _vf.write(" ! reduce/reduce conflict for %s resolved using rule %d (%s).\n" % (a,actionp[st,a].number, actionp[st,a]))
+ else:
+ print "Unknown conflict in state %d" % st
+ else:
+ action[st,a] = -p.number
+ actionp[st,a] = p
+ else:
+ i = p.lr_index
+ a = p.prod[i+1] # Get symbol right after the "."
+ if Terminals.has_key(a):
+ g = lr0_goto(I,a)
+ j = _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 = action.get((st,a),None)
+ if r is not None:
+ # Whoa have a shift/reduce or shift/shift conflict
+ if r > 0:
+ if r != j:
+ print "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[actionp[st,a].number].prec
+ sprec,slevel = Precedence.get(a,('right',0))
+ if (slevel > rlevel) or ((slevel == rlevel) and (rprec != 'left')):
+ # We decide to shift here... highest precedence to shift
+ action[st,a] = j
+ actionp[st,a] = p
+ if not slevel and not rlevel:
+ n_srconflict += 1
+ _vfc.write("shift/reduce conflict in state %d resolved as shift.\n" % st)
+ _vf.write(" ! shift/reduce conflict for %s resolved as shift.\n" % a)
+ elif (slevel == rlevel) and (rprec == 'nonassoc'):
+ action[st,a] = None
+ else:
+ # Hmmm. Guess we'll keep the reduce
+ if not slevel and not rlevel:
+ n_srconflict +=1
+ _vfc.write("shift/reduce conflict in state %d resolved as reduce.\n" % st)
+ _vf.write(" ! shift/reduce conflict for %s resolved as reduce.\n" % a)
+
+ else:
+ print "Unknown conflict in state %d" % st
+ else:
+ action[st,a] = j
+ actionp[st,a] = p
+
+ except StandardError,e:
+ raise YaccError, "Hosed in slr_parse_table", e
+
+ # Print the actions associated with each terminal
+ if yaccdebug:
+ for a,p,m in actlist:
+ if action.has_key((st,a)):
+ if p is actionp[st,a]:
+ _vf.write(" %-15s %s\n" % (a,m))
+ _vf.write("\n")
+ for a,p,m in actlist:
+ if action.has_key((st,a)):
+ if p is not actionp[st,a]:
+ _vf.write(" ! %-15s [ %s ]\n" % (a,m))
+
+ # Construct the goto table for this state
+ if yaccdebug:
+ _vf.write("\n")
+ nkeys = { }
+ for ii in I:
+ for s in ii.usyms:
+ if Nonterminals.has_key(s):
+ nkeys[s] = None
+ for n in nkeys.keys():
+ g = lr0_goto(I,n)
+ j = _lr0_cidhash.get(id(g),-1)
+ if j >= 0:
+ goto[st,n] = j
+ if yaccdebug:
+ _vf.write(" %-15s shift and go to state %d\n" % (n,j))
+
+ st += 1
+
+ if n_srconflict == 1:
+ print "yacc: %d shift/reduce conflict" % n_srconflict
+ if n_srconflict > 1:
+ print "yacc: %d shift/reduce conflicts" % n_srconflict
+ if n_rrconflict == 1:
+ print "yacc: %d reduce/reduce conflict" % n_rrconflict
+ if n_rrconflict > 1:
+ print "yacc: %d reduce/reduce conflicts" % n_rrconflict
+
+
+# -----------------------------------------------------------------------------
+# ==== LALR(1) Parsing ====
+# **** UNFINISHED! 6/16/01
+# -----------------------------------------------------------------------------
+
+
+# Compute the lr1_closure of a set I. I is a list of tuples (p,a) where
+# p is a LR0 item and a is a terminal
+
+_lr1_add_count = 0
+
+def lr1_closure(I):
+ global _lr1_add_count
+
+ _lr1_add_count += 1
+
+ J = I[:]
+
+ # Loop over items (p,a) in I.
+ ji = 0
+ while ji < len(J):
+ p,a = J[ji]
+ # p = [ A -> alpha . B beta]
+
+ # For each production B -> gamma
+ for B in p.lr1_after:
+ f = tuple(p.lr1_beta + (a,))
+
+ # For each terminal b in first(Beta a)
+ for b in first(f):
+ # Check if (B -> . gamma, b) is in J
+ # Only way this can happen is if the add count mismatches
+ pn = B.lr_next
+ if pn.lr_added.get(b,0) == _lr1_add_count: continue
+ pn.lr_added[b] = _lr1_add_count
+ J.append((pn,b))
+ ji += 1
+
+ return J
+
+def lalr_parse_table():
+
+ # Compute some lr1 information about all of the productions
+ for p in LRitems:
+ try:
+ after = p.prod[p.lr_index + 1]
+ p.lr1_after = Prodnames[after]
+ p.lr1_beta = p.prod[p.lr_index + 2:]
+ except LookupError:
+ p.lr1_after = [ ]
+ p.lr1_beta = [ ]
+ p.lr_added = { }
+
+ # Compute the LR(0) items
+ C = lr0_items()
+ CK = []
+ for I in C:
+ CK.append(lr0_kernel(I))
+
+ print CK
+
+# -----------------------------------------------------------------------------
+# ==== LR Utility functions ====
+# -----------------------------------------------------------------------------
+
+# -----------------------------------------------------------------------------
+# _lr_write_tables()
+#
+# This function writes the LR parsing tables to a file
+# -----------------------------------------------------------------------------
+
+def lr_write_tables(modulename=tab_module):
+ filename = modulename + ".py"
+ try:
+ f = open(filename,"w")
+
+ f.write("""
+# %s
+# This file is automatically generated. Do not edit.
+
+_lr_method = %s
+
+_lr_signature = %s
+""" % (filename, repr(_lr_method), repr(Signature.digest())))
+
+ # Change smaller to 0 to go back to original tables
+ smaller = 1
+
+ # Factor out names to try and make smaller
+ if smaller:
+ items = { }
+
+ for k,v in _lr_action.items():
+ i = items.get(k[1])
+ if not i:
+ i = ([],[])
+ items[k[1]] = i
+ i[0].append(k[0])
+ 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]):
+ _lr_action[(_x,_k)] = _y
+del _lr_action_items
+""")
+
+ else:
+ f.write("\n_lr_action = { ");
+ for k,v in _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 k,v in _lr_goto.items():
+ i = items.get(k[1])
+ if not i:
+ i = ([],[])
+ items[k[1]] = i
+ i[0].append(k[0])
+ 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]):
+ _lr_goto[(_x,_k)] = _y
+del _lr_goto_items
+""")
+ else:
+ f.write("\n_lr_goto = { ");
+ for k,v in _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 Productions:
+ if p:
+ if (p.func):
+ f.write(" (%r,%d,%r,%r,%d),\n" % (p.name, p.len, p.func.__name__,p.file,p.line))
+ else:
+ f.write(" (%r,%d,None,None,None),\n" % (p.name, p.len))
+ else:
+ f.write(" None,\n")
+ f.write("]\n")
+ f.close()
+
+ except IOError,e:
+ print "Unable to create '%s'" % filename
+ print e
+ return
+
+def lr_read_tables(module=tab_module,optimize=0):
+ global _lr_action, _lr_goto, _lr_productions, _lr_method
+ try:
+ exec "import %s as parsetab" % module
+
+ if (optimize) or (Signature.digest() == parsetab._lr_signature):
+ _lr_action = parsetab._lr_action
+ _lr_goto = parsetab._lr_goto
+ _lr_productions = parsetab._lr_productions
+ _lr_method = parsetab._lr_method
+ return 1
+ else:
+ return 0
+
+ except (ImportError,AttributeError):
+ return 0
+
+# -----------------------------------------------------------------------------
+# yacc(module)
+#
+# Build the parser module
+# -----------------------------------------------------------------------------
+
+def yacc(method=default_lr, debug=yaccdebug, module=None, tabmodule=tab_module, start=None, check_recursion=1, optimize=0):
+ global yaccdebug
+ yaccdebug = debug
+
+ initialize_vars()
+ files = { }
+ error = 0
+
+ # Add starting symbol to signature
+ if start:
+ Signature.update(start)
+
+ # Try to figure out what module we are working with
+ if module:
+ # User supplied a module object.
+ if not isinstance(module, types.ModuleType):
+ raise ValueError,"Expected a module"
+
+ ldict = module.__dict__
+
+ else:
+ # No module given. We might be able to get information from the caller.
+ # Throw an exception and unwind the traceback to get the globals
+
+ try:
+ raise RuntimeError
+ except RuntimeError:
+ e,b,t = sys.exc_info()
+ f = t.tb_frame
+ f = f.f_back # Walk out to our calling function
+ ldict = f.f_globals # Grab its globals dictionary
+
+ # If running in optimized mode. We're going to
+
+ if (optimize and lr_read_tables(tabmodule,1)):
+ # Read parse table
+ del Productions[:]
+ for p in _lr_productions:
+ if not p:
+ Productions.append(None)
+ else:
+ m = MiniProduction()
+ m.name = p[0]
+ m.len = p[1]
+ m.file = p[3]
+ m.line = p[4]
+ if p[2]:
+ m.func = ldict[p[2]]
+ Productions.append(m)
+
+ else:
+ # Get the tokens map
+ tokens = ldict.get("tokens",None)
+
+ if not tokens:
+ raise YaccError,"module does not define a list 'tokens'"
+ if not (isinstance(tokens,types.ListType) or isinstance(tokens,types.TupleType)):
+ raise YaccError,"tokens must be a list or tuple."
+
+ # Check to see if a requires dictionary is defined.
+ requires = ldict.get("require",None)
+ if requires:
+ if not (isinstance(requires,types.DictType)):
+ raise YaccError,"require must be a dictionary."
+
+ for r,v in requires.items():
+ try:
+ if not (isinstance(v,types.ListType)):
+ raise TypeError
+ v1 = [x.split(".") for x in v]
+ Requires[r] = v1
+ except StandardError:
+ print "Invalid specification for rule '%s' in require. Expected a list of strings" % r
+
+
+ # Build the dictionary of terminals. We a record a 0 in the
+ # dictionary to track whether or not a terminal is actually
+ # used in the grammar
+
+ if 'error' in tokens:
+ print "yacc: Illegal token 'error'. Is a reserved word."
+ raise YaccError,"Illegal token name"
+
+ for n in tokens:
+ if Terminals.has_key(n):
+ print "yacc: Warning. Token '%s' multiply defined." % n
+ Terminals[n] = [ ]
+
+ Terminals['error'] = [ ]
+
+ # Get the precedence map (if any)
+ prec = ldict.get("precedence",None)
+ if prec:
+ if not (isinstance(prec,types.ListType) or isinstance(prec,types.TupleType)):
+ raise YaccError,"precedence must be a list or tuple."
+ add_precedence(prec)
+ Signature.update(repr(prec))
+
+ for n in tokens:
+ if not Precedence.has_key(n):
+ Precedence[n] = ('right',0) # Default, right associative, 0 precedence
+
+ # Look for error handler
+ ef = ldict.get('p_error',None)
+ if ef:
+ if not isinstance(ef,types.FunctionType):
+ raise YaccError,"'p_error' defined, but is not a function."
+ eline = ef.func_code.co_firstlineno
+ efile = ef.func_code.co_filename
+ files[efile] = None
+
+ if (ef.func_code.co_argcount != 1):
+ raise YaccError,"%s:%d: p_error() requires 1 argument." % (efile,eline)
+ global Errorfunc
+ Errorfunc = ef
+ else:
+ print "yacc: Warning. no p_error() function is defined."
+
+ # Get the list of built-in functions with p_ prefix
+ symbols = [ldict[f] for f in ldict.keys()
+ if (isinstance(ldict[f],types.FunctionType) and ldict[f].__name__[:2] == 'p_'
+ and ldict[f].__name__ != 'p_error')]
+
+ # Check for non-empty symbols
+ if len(symbols) == 0:
+ raise YaccError,"no rules of the form p_rulename are defined."
+
+ # Sort the symbols by line number
+ symbols.sort(lambda x,y: cmp(x.func_code.co_firstlineno,y.func_code.co_firstlineno))
+
+ # Add all of the symbols to the grammar
+ for f in symbols:
+ if (add_function(f)) < 0:
+ error += 1
+ else:
+ files[f.func_code.co_filename] = None
+
+ # Make a signature of the docstrings
+ for f in symbols:
+ if f.__doc__:
+ Signature.update(f.__doc__)
+
+ lr_init_vars()
+
+ if error:
+ raise YaccError,"Unable to construct parser."
+
+ if not lr_read_tables(tabmodule):
+
+ # Validate files
+ for filename in files.keys():
+ if not validate_file(filename):
+ error = 1
+
+ # Validate dictionary
+ validate_dict(ldict)
+
+ if start and not Prodnames.has_key(start):
+ raise YaccError,"Bad starting symbol '%s'" % start
+
+ augment_grammar(start)
+ error = verify_productions(cycle_check=check_recursion)
+ otherfunc = [ldict[f] for f in ldict.keys()
+ if (isinstance(ldict[f],types.FunctionType) and ldict[f].__name__[:2] != 'p_')]
+
+ if error:
+ raise YaccError,"Unable to construct parser."
+
+ build_lritems()
+ compute_first1()
+ compute_follow(start)
+
+ if method == 'SLR':
+ slr_parse_table()
+ elif method == 'LALR1':
+ lalr_parse_table()
+ return
+ else:
+ raise YaccError, "Unknown parsing method '%s'" % method
+
+ lr_write_tables(tabmodule)
+
+ if yaccdebug:
+ try:
+ f = open(debug_file,"w")
+ f.write(_vfc.getvalue())
+ f.write("\n\n")
+ f.write(_vf.getvalue())
+ f.close()
+ except IOError,e:
+ print "yacc: can't create '%s'" % debug_file,e
+
+ # Made it here. Create a parser object and set up its internal state.
+ # Set global parse() method to bound method of parser object.
+
+ p = Parser("xyzzy")
+ p.productions = Productions
+ p.errorfunc = Errorfunc
+ p.action = _lr_action
+ p.goto = _lr_goto
+ p.method = _lr_method
+ p.require = Requires
+
+ global parse
+ parse = p.parse
+
+ # Clean up all of the globals we created
+ if (not optimize):
+ yacc_cleanup()
+ return p
+
+# yacc_cleanup function. Delete all of the global variables
+# used during table construction
+
+def yacc_cleanup():
+ global _lr_action, _lr_goto, _lr_method, _lr_goto_cache
+ del _lr_action, _lr_goto, _lr_method, _lr_goto_cache
+
+ global Productions, Prodnames, Prodmap, Terminals
+ global Nonterminals, First, Follow, Precedence, LRitems
+ global Errorfunc, Signature, Requires
+
+ del Productions, Prodnames, Prodmap, Terminals
+ del Nonterminals, First, Follow, Precedence, LRitems
+ del Errorfunc, Signature, Requires
+
+ global _vf, _vfc
+ del _vf, _vfc
+
+
+# Stub that raises an error if parsing is attempted without first calling yacc()
+def parse(*args,**kwargs):
+ raise YaccError, "yacc: No parser built with yacc()"
+
projects / mad.git / commitdiff