Rename to solve

1 files changed, 0 insertions, 2209 deletions

diff --git a/chall/ply-2.2/ply/yacc.py b/chall/ply-2.2/ply/yacc.py
deleted file mode 100644
index caf98af..0000000
--- a/chall/ply-2.2/ply/yacc.py
+++ /dev/null
@@ -1,2209 +0,0 @@
-#-----------------------------------------------------------------------------
-# ply: yacc.py
-#
-# Author(s): David M. Beazley (dave@dabeaz.com)
-#
-# Copyright (C) 2001-2006, David M. Beazley
-#
-# 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. 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__ = "2.2"
-
-#-----------------------------------------------------------------------------
-#                     === 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  = 'LALR'           # 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)
-#        .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.pbstack = []
-        self.stack = stack
-
-    def __getitem__(self,n):
-        if type(n) == types.IntType:
-             if n >= 0: return self.slice[n].value
-             else: return self.stack[n].value
-        else:
-             return [s.value for s in self.slice[n.start:n.stop:n.step]]
-
-    def __setitem__(self,n,v):
-        self.slice[n].value = v
-
-    def __len__(self):
-        return len(self.slice)
-    
-    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 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 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 = '$end'
-        self.symstack.append(sym)
-        self.statestack.append(0)
-        
-    def parse(self,input=None,lexer=None,debug=0):
-        lookahead = None                 # Current lookahead symbol
-        lookaheadstack = [ ]             # Stack of lookahead symbols
-        actions = self.action            # Local reference to action table
-        goto    = self.goto              # Local reference to goto table
-        prod    = self.productions       # Local reference to production list
-        pslice  = YaccProduction(None)   # Production object passed to grammar rules
-        pslice.parser = self             # Parser object
-        self.errorcount = 0              # Used during error recovery
-
-        # If no lexer was given, we will try to use the lex module
-        if not lexer:
-            import lex
-            lexer = lex.lexer
-
-        pslice.lexer = lexer
-        
-        # If input was supplied, pass to lexer
-        if input:
-            lexer.input(input)
-
-        # Tokenize function
-        get_token = lexer.token
-
-        statestack = [ ]                # Stack of parsing states
-        self.statestack = statestack
-        symstack   = [ ]                # Stack of grammar symbols
-        self.symstack = symstack
-
-        pslice.stack = symstack         # Put in the production
-        errtoken   = None               # Err token
-
-        # The start state is assumed to be (0,$end)
-        statestack.append(0)
-        sym = YaccSymbol()
-        sym.type = '$end'
-        symstack.append(sym)
-        
-        while 1:
-            # Get the next symbol on the input.  If a lookahead symbol
-            # is already set, we just use that. Otherwise, we'll pull
-            # the next token off of the lookaheadstack or from the lexer
-            if debug > 1:
-                print 'state', statestack[-1]
-            if not lookahead:
-                if not lookaheadstack:
-                    lookahead = get_token()     # Get the next token
-                else:
-                    lookahead = lookaheadstack.pop()
-                if not lookahead:
-                    lookahead = YaccSymbol()
-                    lookahead.type = '$end'
-            if debug:
-                errorlead = ("%s . %s" % (" ".join([xx.type for xx in symstack][1:]), str(lookahead))).lstrip()
-
-            # Check the action table
-            s = statestack[-1]
-            ltype = lookahead.type
-            t = actions.get((s,ltype),None)
-
-            if debug > 1:
-                print 'action', t
-            if t is not None:
-                if t > 0:
-                    # shift a symbol on the stack
-                    if ltype == '$end':
-                        # Error, end of input
-                        sys.stderr.write("yacc: Parse error. EOF\n")
-                        return
-                    statestack.append(t)
-                    if debug > 1:
-                        sys.stderr.write("%-60s shift state %s\n" % (errorlead, 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 debug > 1:
-                        sys.stderr.write("%-60s reduce %d\n" % (errorlead, -t))
-
-                    if plen:
-                        targ = symstack[-plen-1:]
-                        targ[0] = sym
-                        try:
-                            sym.lineno = targ[1].lineno
-                            sym.endlineno = getattr(targ[-1],"endlineno",targ[-1].lineno)
-                            sym.lexpos = targ[1].lexpos
-                            sym.endlexpos = getattr(targ[-1],"endlexpos",targ[-1].lexpos)
-                        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)
-
-                    # 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)
-                    sys.stderr.write(errorlead, "\n")
-
-            if t == None:
-                if debug:
-                    sys.stderr.write(errorlead + "\n")
-                # 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 == '$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
-                        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:
-                                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:
-                    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 != '$end':
-                    lookahead = None
-                    errtoken = None
-                    # Nuke the pushback stack
-                    del lookaheadstack[:]
-                    continue
-
-                # case 2: the statestack has a couple of entries on it, but we're
-                # at the end of the file. nuke the top entry and generate an error token
-
-                # Start nuking entries on the stack
-                if lookahead.type == '$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()
-
-                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:
-                sys.stderr.write("%s:%d: Function %s redefined. Previously defined on line %d\n" % (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 type(v) in (types.FunctionType, types.MethodType): continue
-        if n[0:2] == 't_': continue
-
-        if n[0:2] == 'p_':
-            sys.stderr.write("yacc: Warning. '%s' not defined as a function\n" % n)
-        if 1 and isinstance(v,types.FunctionType) and v.func_code.co_argcount == 1:
-            try:
-                doc = v.__doc__.split(" ")
-                if doc[1] == ':':
-                    sys.stderr.write("%s:%d: Warning. Possible grammar rule '%s' defined without p_ prefix.\n" % (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.
-#       lookaheads - LALR lookahead symbols for this item
-#       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.lr1_added = 0    # Flag indicating whether or not added to LR1
-        self.usyms = [ ]
-        self.lookaheads = { }
-        self.lk_added = { }
-        self.setnumbers = [ ]
-        
-    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.lookaheads = { }
-        p.setnumbers = self.setnumbers
-        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
-
-# regex matching identifiers
-_is_identifier = re.compile(r'^[a-zA-Z0-9_-]+$')
-
-# -----------------------------------------------------------------------------
-# 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):
-        sys.stderr.write("%s:%d: Illegal rule name '%s'. Already defined as a token.\n" % (file,line,prodname))
-        return -1
-    if prodname == 'error':
-        sys.stderr.write("%s:%d: Illegal rule name '%s'. error is a reserved word.\n" % (file,line,prodname))
-        return -1
-                
-    if not _is_identifier.match(prodname):
-        sys.stderr.write("%s:%d: Illegal rule name '%s'\n" % (file,line,prodname))
-        return -1
-
-    for x in range(len(syms)):
-        s = syms[x]
-        if s[0] in "'\"":
-             try:
-                 c = eval(s)
-                 if (len(c) > 1):
-                      sys.stderr.write("%s:%d: Literal token %s in rule '%s' may only be a single character\n" % (file,line,s, prodname)) 
-                      return -1
-                 if not Terminals.has_key(c):
-                      Terminals[c] = []
-                 syms[x] = c
-                 continue
-             except SyntaxError:
-                 pass
-        if not _is_identifier.match(s) and s != '%prec':
-            sys.stderr.write("%s:%d: Illegal name '%s' in rule '%s'\n" % (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]
-        sys.stderr.write("%s:%d: Duplicate rule %s.\n" % (file,line, m))
-        sys.stderr.write("%s:%d: Previous definition at %s:%d\n" % (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:
-                sys.stderr.write("%s:%d: Syntax error. Nothing follows %%prec.\n" % (p.file,p.line))
-                return -1
-
-            prec = Precedence.get(precname,None)
-            if not prec:
-                sys.stderr.write("%s:%d: Nothing known about the precedence of '%s'\n" % (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 isinstance(f,types.MethodType):
-        reqdargs = 2
-    else:
-        reqdargs = 1
-        
-    if f.func_code.co_argcount > reqdargs:
-        sys.stderr.write("%s:%d: Rule '%s' has too many arguments.\n" % (file,line,f.__name__))
-        return -1
-
-    if f.func_code.co_argcount < reqdargs:
-        sys.stderr.write("%s:%d: Rule '%s' requires an argument.\n" % (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:
-                        sys.stderr.write("%s:%d: Misplaced '|'.\n" % (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 != '::=':
-                        sys.stderr.write("%s:%d: Syntax error. Expected ':'\n" % (file,dline))
-                        return -1
-                         
- 
-                e = add_production(f,file,dline,prodname,syms)
-                error += e
-
-                
-            except StandardError:
-                sys.stderr.write("%s:%d: Syntax error in rule '%s'\n" % (file,dline,ps))
-                error -= 1
-    else:
-        sys.stderr.write("%s:%d: No documentation string specified in function '%s'\n" % (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]:
-            sys.stderr.write("yacc: Symbol '%s' is unreachable.\n" % 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['$end'] = 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:
-                sys.stderr.write("yacc: Infinite recursion detected for symbol '%s'.\n" % 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':
-                sys.stderr.write("%s:%d: Symbol '%s' used, but not defined as a token or a rule.\n" % (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:
-            sys.stderr.write("yacc: Warning. Token '%s' defined, but not used.\n" % 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]
-            sys.stderr.write("%s:%d: Warning. Rule '%s' defined, but not used.\n" % (p.file,p.line, s))
-            unused_prod += 1
-
-    
-    if unused_tok == 1:
-        sys.stderr.write("yacc: Warning. There is 1 unused token.\n")
-    if unused_tok > 1:
-        sys.stderr.write("yacc: Warning. There are %d unused tokens.\n" % unused_tok)
-
-    if unused_prod == 1:
-        sys.stderr.write("yacc: Warning. There is 1 unused rule.\n")
-    if unused_prod > 1:
-        sys.stderr.write("yacc: Warning. There are %d unused rules.\n" % 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':
-                sys.stderr.write("yacc: Invalid precedence '%s'\n" % prec)
-                return -1
-            for t in terms:
-                if Precedence.has_key(t):
-                    sys.stderr.write("yacc: Precedence already specified for terminal '%s'\n" % t)
-                    error += 1
-                    continue
-                Precedence[t] = (prec,plevel)
-        except:
-            sys.stderr.write("yacc: Invalid precedence table.\n")
-            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 '$end' to the follow list of the start symbol
-    for k in Nonterminals.keys():
-        Follow[k] = [ ]
-
-    if not start:
-        start = Productions[1].name
-        
-    Follow[start] = [ '$end' ]
-        
-    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['$end'] = ['$end']
-    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, _lr0_cidhash
-    
-    _lr_action       = { }        # Action table
-    _lr_goto         = { }        # Goto table
-    _lr_method       = "Unknown"  # LR method used
-    _lr_goto_cache   = { }
-    _lr0_cidhash     = { }
-
-
-# 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('$end',None)
-    if not g:
-        if gs:
-            g = lr0_closure(gs)
-            s['$end'] = g
-        else:
-            s['$end'] = gs
-    _lr_goto_cache[(id(I),x)] = g
-    return g
-
-_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
-
-# -----------------------------------------------------------------------------
-#                       ==== 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).
-#
-# Note:  This implementation is a complete replacement of the LALR(1) 
-#        implementation in PLY-1.x releases.   That version was based on
-#        a less efficient algorithm and it had bugs in its implementation.
-# -----------------------------------------------------------------------------
-
-# -----------------------------------------------------------------------------
-# compute_nullable_nonterminals()
-#
-# Creates a dictionary containing all of the non-terminals that might produce
-# an empty production.   
-# -----------------------------------------------------------------------------
-
-def compute_nullable_nonterminals():
-    nullable = {}
-    num_nullable = 0
-    while 1:
-       for p in Productions[1:]:
-           if p.len == 0:
-                nullable[p.name] = 1
-                continue
-           for t in p.prod:
-                if not nullable.has_key(t): 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(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 Nonterminals.has_key(t[1]):
-                        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(C,trans,nullable):
-    dr_set = { }
-    state,N = trans
-    terms = []
-
-    g = lr0_goto(C[state],N)
-    for p in g:
-       if p.lr_index < p.len - 1:
-           a = p.prod[p.lr_index+1]
-           if Terminals.has_key(a):
-               if a not in terms: terms.append(a)
-
-    # This extra bit is to handle the start state
-    if state == 0 and N == Productions[0].prod[0]:
-       terms.append('$end')
- 
-    return terms
-
-# -----------------------------------------------------------------------------
-# reads_relation()
-#
-# Computes the READS() relation (p,A) READS (t,C).
-# -----------------------------------------------------------------------------
-
-def reads_relation(C, trans, empty):
-    # Look for empty transitions
-    rel = []
-    state, N = trans
-
-    g = lr0_goto(C[state],N)
-    j = _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 empty.has_key(a):
-                  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(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 dtrans.has_key((j,t)):
-                       # 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 Terminals.has_key(p.prod[li]): break      # No forget it
-                            if not nullable.has_key(p.prod[li]): break
-                            li = li + 1
-                       else:
-                            # Appears to be a relation between (j,t) and (state,N)
-                            includes.append((j,t))
-
-                 g = lr0_goto(C[j],t)               # Go to next set             
-                 j = _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 includedict.has_key(i): includedict[i] = []
-             includedict[i].append((state,N))
-        lookdict[(state,N)] = lookb
-
-    return lookdict,includedict
-
-# -----------------------------------------------------------------------------
-# 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]] = sys.maxint
-       F[stack[-1]] = F[x]
-       element = stack.pop()
-       while element != x:
-           N[stack[-1]] = sys.maxint
-           F[stack[-1]] = F[x]
-           element = stack.pop()
-
-# -----------------------------------------------------------------------------
-# 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(C, ntrans, nullable):
-    FP = lambda x: dr_relation(C,x,nullable)
-    R =  lambda x: 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(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(lookbacks,followset):
-    for trans,lb in lookbacks.items():
-        # Loop over productions in lookback
-        for state,p in lb:
-             if not p.lookaheads.has_key(state):
-                  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(C):
-    # Determine all of the nullable nonterminals
-    nullable = compute_nullable_nonterminals()
-
-    # Find all non-terminal transitions
-    trans = find_nonterminal_transitions(C)
-
-    # Compute read sets
-    readsets = compute_read_sets(C,trans,nullable)
-
-    # Compute lookback/includes relations
-    lookd, included = compute_lookback_includes(C,trans,nullable)
-
-    # Compute LALR FOLLOW sets
-    followsets = compute_follow_sets(trans,readsets,included)
-    
-    # Add all of the lookaheads
-    add_lookaheads(lookd,followsets)
-
-# -----------------------------------------------------------------------------
-# lr_parse_table()
-#
-# This function constructs the parse tables for SLR or LALR
-# -----------------------------------------------------------------------------
-def lr_parse_table(method):
-    global _lr_method
-    goto = _lr_goto           # Goto array
-    action = _lr_action       # Action array
-    actionp = { }             # Action production array (temporary)
-
-    _lr_method = method
-    
-    n_srconflict = 0
-    n_rrconflict = 0
-
-    if yaccdebug:
-        sys.stderr.write("yacc: Generating %s parsing table...\n" % method)        
-        _vf.write("\n\nParsing method: %s\n\n" % method)
-        
-    # Step 1: Construct C = { I0, I1, ... IN}, collection of LR(0) items
-    # This determines the number of states
-    
-    C = lr0_items()
-
-    if method == 'LALR':
-        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
-        
-        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,"$end"] = 0
-                        actionp[st,"$end"] = p
-                    else:
-                        # We are at the end of a production.  Reduce!
-                        if method == 'LALR':
-                            laheads = p.lookaheads[st]
-                        else:
-                            laheads = Follow[p.name]
-                        for a in laheads:
-                            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 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
-                                    # sys.stderr.write("Reduce/reduce conflict in state %d\n" % 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:
-                                    sys.stderr.write("Unknown conflict in state %d\n" % 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:
-                                        sys.stderr.write("Shift/shift conflict in state %d\n" % 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 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:
-                                    sys.stderr.write("Unknown conflict in state %d\n" % st)
-                            else:
-                                action[st,a] = j
-                                actionp[st,a] = p
-                                
-            except StandardError,e:
-                raise YaccError, "Hosed in lr_parse_table", e
-
-        # Print the actions associated with each terminal
-        if yaccdebug:
-          _actprint = { }
-          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))
-                    _actprint[(a,m)] = 1
-          _vf.write("\n")
-          for a,p,m in actlist:
-            if action.has_key((st,a)):
-                if p is not actionp[st,a]:
-                    if not _actprint.has_key((a,m)):
-                        _vf.write("  ! %-15s [ %s ]\n" % (a,m))
-                        _actprint[(a,m)] = 1
-            
-        # 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("    %-30s shift and go to state %d\n" % (n,j))
-
-        st += 1
-
-    if yaccdebug:
-        if n_srconflict == 1:
-            sys.stderr.write("yacc: %d shift/reduce conflict\n" % n_srconflict)
-        if n_srconflict > 1:
-            sys.stderr.write("yacc: %d shift/reduce conflicts\n" % n_srconflict)
-        if n_rrconflict == 1:
-            sys.stderr.write("yacc: %d reduce/reduce conflict\n" % n_rrconflict)
-        if n_rrconflict > 1:
-            sys.stderr.write("yacc: %d reduce/reduce conflicts\n" % n_rrconflict)
-
-# -----------------------------------------------------------------------------
-#                          ==== LR Utility functions ====
-# -----------------------------------------------------------------------------
-
-# -----------------------------------------------------------------------------
-# _lr_write_tables()
-#
-# This function writes the LR parsing tables to a file
-# -----------------------------------------------------------------------------
-
-def lr_write_tables(modulename=tab_module,outputdir=''):
-    filename = os.path.join(outputdir,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
-
-
-# Available instance types.  This is used when parsers are defined by a class.
-# it's a little funky because I want to preserve backwards compatibility
-# with Python 2.0 where types.ObjectType is undefined.
-
-try:
-   _INSTANCETYPE = (types.InstanceType, types.ObjectType)
-except AttributeError:
-   _INSTANCETYPE = types.InstanceType
-
-# -----------------------------------------------------------------------------
-# 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,write_tables=1,debugfile=debug_file,outputdir=''):
-    global yaccdebug
-    yaccdebug = debug
-    
-    initialize_vars()
-    files = { }
-    error = 0
-
-
-    # Add parsing method to signature
-    Signature.update(method)
-    
-    # If a "module" parameter was supplied, extract its dictionary.
-    # Note: a module may in fact be an instance as well.
-    
-    if module:
-        # User supplied a module object.
-        if isinstance(module, types.ModuleType):
-            ldict = module.__dict__
-        elif isinstance(module, _INSTANCETYPE):
-            _items = [(k,getattr(module,k)) for k in dir(module)]
-            ldict = { }
-            for i in _items:
-                ldict[i[0]] = i[1]
-        else:
-            raise ValueError,"Expected a module"
-        
-    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
-
-    # Add starting symbol to signature
-    if not start:
-        start = ldict.get("start",None)
-    if start:
-        Signature.update(start)
-
-    # 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
-        if (module and isinstance(module,_INSTANCETYPE)):
-            tokens = getattr(module,"tokens",None)
-        else:
-            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 isinstance(ef,types.FunctionType):
-                ismethod = 0
-            elif isinstance(ef, types.MethodType):
-                ismethod = 1
-            else:
-                raise YaccError,"'p_error' defined, but is not a function or method."                
-            eline = ef.func_code.co_firstlineno
-            efile = ef.func_code.co_filename
-            files[efile] = None
-
-            if (ef.func_code.co_argcount != 1+ismethod):
-                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 (type(ldict[f]) in (types.FunctionType, types.MethodType) 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 (type(f) in (types.FunctionType,types.MethodType) and ldict[f].__name__[:2] != 'p_')]
-
-            if error:
-                raise YaccError,"Unable to construct parser."
-            
-            build_lritems()
-            compute_first1()
-            compute_follow(start)
-        
-            if method in ['SLR','LALR']:
-                lr_parse_table(method)
-            else:
-                raise YaccError, "Unknown parsing method '%s'" % method
-
-            if write_tables:
-                lr_write_tables(tabmodule,outputdir)        
-    
-            if yaccdebug:
-                try:
-                    f = open(os.path.join(outputdir,debugfile),"w")
-                    f.write(_vfc.getvalue())
-                    f.write("\n\n")
-                    f.write(_vf.getvalue())
-                    f.close()
-                except IOError,e:
-                    print "yacc: can't create '%s'" % debugfile,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
-
-    global parser
-    parser = p
-
-    # 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()"
-