forked from osmocom/wireshark
![Ronnie Sahlberg](/assets/img/avatar_default.png)
ASN2ETH compiler and support script for lexical and syntactic analysis. Will later be used for all those ASN.1 protocols we havent implemented yet svn path=/trunk/; revision=10983
1845 lines
66 KiB
Python
1845 lines
66 KiB
Python
#-----------------------------------------------------------------------------
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# ply: yacc.py
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#
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# Author: David M. Beazley (beazley@cs.uchicago.edu)
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# Department of Computer Science
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# University of Chicago
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# Chicago, IL 60637
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#
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# Copyright (C) 2001, David M. Beazley
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#
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# $Header: /svn/cvsroot/ethereal/tools/yacc.py,v 1.1 2004/05/24 08:33:09 sahlberg Exp $
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#
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# See the file COPYING for a complete copy of the LGPL.
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#
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#
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# This implements an LR parser that is constructed from grammar rules defined
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# as Python functions. Roughly speaking, this module is a cross between
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# John Aycock's Spark system and the GNU bison utility.
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#
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# Disclaimer: This is a work in progress. SLR parsing seems to work fairly
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# well and there is extensive error checking. LALR(1) is in progress. The
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# rest of this file is a bit of a mess. Please pardon the dust.
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#
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# The current implementation is only somewhat object-oriented. The
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# LR parser itself is defined in terms of an object (which allows multiple
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# parsers to co-exist). However, most of the variables used during table
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# construction are defined in terms of global variables. Users shouldn't
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# notice unless they are trying to define multiple parsers at the same
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# time using threads (in which case they should have their head examined).
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#-----------------------------------------------------------------------------
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__version__ = "1.3"
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#-----------------------------------------------------------------------------
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# === User configurable parameters ===
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#
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# Change these to modify the default behavior of yacc (if you wish)
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#-----------------------------------------------------------------------------
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yaccdebug = 1 # Debugging mode. If set, yacc generates a
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# a 'parser.out' file in the current directory
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debug_file = 'parser.out' # Default name of the debugging file
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tab_module = 'parsetab' # Default name of the table module
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default_lr = 'SLR' # Default LR table generation method
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error_count = 3 # Number of symbols that must be shifted to leave recovery mode
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import re, types, sys, cStringIO, md5, os.path
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# Exception raised for yacc-related errors
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class YaccError(Exception): pass
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#-----------------------------------------------------------------------------
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# === LR Parsing Engine ===
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#
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# The following classes are used for the LR parser itself. These are not
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# used during table construction and are independent of the actual LR
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# table generation algorithm
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#-----------------------------------------------------------------------------
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# This class is used to hold non-terminal grammar symbols during parsing.
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# It normally has the following attributes set:
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# .type = Grammar symbol type
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# .value = Symbol value
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# .lineno = Starting line number
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# .endlineno = Ending line number (optional, set automatically)
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class YaccSymbol:
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def __str__(self): return self.type
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def __repr__(self): return str(self)
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# This class is a wrapper around the objects actually passed to each
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# grammar rule. Index lookup and assignment actually assign the
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# .value attribute of the underlying YaccSymbol object.
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# The lineno() method returns the line number of a given
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# item (or 0 if not defined). The linespan() method returns
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# a tuple of (startline,endline) representing the range of lines
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# for a symbol.
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class YaccSlice:
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def __init__(self,s):
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self.slice = s
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self.pbstack = []
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def __getitem__(self,n):
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return self.slice[n].value
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def __setitem__(self,n,v):
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self.slice[n].value = v
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def lineno(self,n):
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return getattr(self.slice[n],"lineno",0)
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def linespan(self,n):
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startline = getattr(self.slice[n],"lineno",0)
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endline = getattr(self.slice[n],"endlineno",startline)
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return startline,endline
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def pushback(self,n):
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if n <= 0:
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raise ValueError, "Expected a positive value"
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if n > (len(self.slice)-1):
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raise ValueError, "Can't push %d tokens. Only %d are available." % (n,len(self.slice)-1)
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for i in range(0,n):
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self.pbstack.append(self.slice[-i-1])
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# The LR Parsing engine. This is defined as a class so that multiple parsers
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# can exist in the same process. A user never instantiates this directly.
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# Instead, the global yacc() function should be used to create a suitable Parser
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# object.
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class Parser:
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def __init__(self,magic=None):
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# This is a hack to keep users from trying to instantiate a Parser
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# object directly.
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if magic != "xyzzy":
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raise YaccError, "Can't instantiate Parser. Use yacc() instead."
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# Reset internal state
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self.productions = None # List of productions
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self.errorfunc = None # Error handling function
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self.action = { } # LR Action table
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self.goto = { } # LR goto table
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self.require = { } # Attribute require table
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self.method = "Unknown LR" # Table construction method used
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def errok(self):
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self.errorcount = 0
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def restart(self):
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del self.statestack[:]
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del self.symstack[:]
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sym = YaccSymbol()
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sym.type = '$'
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self.symstack.append(sym)
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self.statestack.append(0)
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def parse(self,input=None,lexer=None,debug=0):
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lookahead = None # Current lookahead symbol
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lookaheadstack = [ ] # Stack of lookahead symbols
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actions = self.action # Local reference to action table
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goto = self.goto # Local reference to goto table
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prod = self.productions # Local reference to production list
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pslice = YaccSlice(None) # Slice object passed to grammar rules
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pslice.parser = self # Parser object
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self.errorcount = 0 # Used during error recovery
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# If no lexer was given, we will try to use the lex module
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if not lexer:
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import lex as lexer
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pslice.lexer = lexer
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# If input was supplied, pass to lexer
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if input:
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lexer.input(input)
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# Tokenize function
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get_token = lexer.token
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statestack = [ ] # Stack of parsing states
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self.statestack = statestack
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symstack = [ ] # Stack of grammar symbols
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self.symstack = symstack
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errtoken = None # Err token
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# The start state is assumed to be (0,$)
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statestack.append(0)
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sym = YaccSymbol()
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sym.type = '$'
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symstack.append(sym)
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while 1:
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# Get the next symbol on the input. If a lookahead symbol
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# is already set, we just use that. Otherwise, we'll pull
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# the next token off of the lookaheadstack or from the lexer
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if not lookahead:
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if not lookaheadstack:
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lookahead = get_token() # Get the next token
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else:
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lookahead = lookaheadstack.pop()
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if not lookahead:
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lookahead = YaccSymbol()
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lookahead.type = '$'
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if debug:
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print "%-20s : %s" % (lookahead, [xx.type for xx in symstack])
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# Check the action table
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s = statestack[-1]
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ltype = lookahead.type
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t = actions.get((s,ltype),None)
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if t is not None:
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if t > 0:
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# shift a symbol on the stack
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if ltype == '$':
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# Error, end of input
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print "yacc: Parse error. EOF"
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return
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statestack.append(t)
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symstack.append(lookahead)
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lookahead = None
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# Decrease error count on successful shift
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if self.errorcount > 0:
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self.errorcount -= 1
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continue
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if t < 0:
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# reduce a symbol on the stack, emit a production
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p = prod[-t]
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pname = p.name
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plen = p.len
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# Get production function
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sym = YaccSymbol()
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sym.type = pname # Production name
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sym.value = None
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if plen:
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targ = symstack[-plen-1:]
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targ[0] = sym
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try:
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sym.lineno = targ[1].lineno
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sym.endlineno = getattr(targ[-1],"endlineno",targ[-1].lineno)
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except AttributeError:
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sym.lineno = 0
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del symstack[-plen:]
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del statestack[-plen:]
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else:
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sym.lineno = 0
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targ = [ sym ]
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pslice.slice = targ
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pslice.pbstack = []
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# Call the grammar rule with our special slice object
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p.func(pslice)
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# Validate attributes of the resulting value attribute
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# if require:
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# try:
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# t0 = targ[0]
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# r = Requires.get(t0.type,None)
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# t0d = t0.__dict__
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# if r:
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# for field in r:
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# tn = t0
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# for fname in field:
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# try:
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# tf = tn.__dict__
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# tn = tf.get(fname)
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# except StandardError:
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# tn = None
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# if not tn:
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# print "%s:%d: Rule %s doesn't set required attribute '%s'" % \
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# (p.file,p.line,p.name,".".join(field))
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# except TypeError,LookupError:
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# print "Bad requires directive " % r
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# pass
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# If there was a pushback, put that on the stack
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if pslice.pbstack:
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lookaheadstack.append(lookahead)
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for _t in pslice.pbstack:
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lookaheadstack.append(_t)
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lookahead = None
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symstack.append(sym)
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statestack.append(goto[statestack[-1],pname])
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continue
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if t == 0:
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n = symstack[-1]
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return getattr(n,"value",None)
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if t == None:
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# We have some kind of parsing error here. To handle this,
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# we are going to push the current token onto the tokenstack
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# and replace it with an 'error' token. If there are any synchronization
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# rules, they may catch it.
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#
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# In addition to pushing the error token, we call call the user defined p_error()
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# function if this is the first syntax error. This function is only called
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# if errorcount == 0.
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if not self.errorcount:
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self.errorcount = error_count
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errtoken = lookahead
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if errtoken.type == '$':
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errtoken = None # End of file!
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if self.errorfunc:
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global errok,token,restart
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errok = self.errok # Set some special functions available in error recovery
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token = get_token
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restart = self.restart
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tok = self.errorfunc(errtoken)
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del errok, token, restart # Delete special functions
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if not self.errorcount:
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# User must have done some kind of panic mode recovery on their own. The returned token
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# is the next lookahead
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lookahead = tok
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errtoken = None
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continue
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else:
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if errtoken:
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if hasattr(errtoken,"lineno"): lineno = lookahead.lineno
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else: lineno = 0
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if lineno:
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print "yacc: Syntax error at line %d, token=%s" % (lineno, errtoken.type)
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else:
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print "yacc: Syntax error, token=%s" % errtoken.type
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else:
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print "yacc: Parse error in input. EOF"
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return
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else:
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self.errorcount = error_count
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# case 1: the statestack only has 1 entry on it. If we're in this state, the
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# entire parse has been rolled back and we're completely hosed. The token is
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# discarded and we just keep going.
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if len(statestack) <= 1 and lookahead.type != '$':
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lookahead = None
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errtoken = None
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# Nuke the pushback stack
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del lookaheadstack[:]
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continue
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# case 2: the statestack has a couple of entries on it, but we're
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# at the end of the file. nuke the top entry and generate an error token
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# Start nuking entries on the stack
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if lookahead.type == '$':
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# Whoa. We're really hosed here. Bail out
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return
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if lookahead.type != 'error':
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sym = symstack[-1]
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if sym.type == 'error':
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# Hmmm. Error is on top of stack, we'll just nuke input
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# symbol and continue
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lookahead = None
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continue
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t = YaccSymbol()
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t.type = 'error'
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if hasattr(lookahead,"lineno"):
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t.lineno = lookahead.lineno
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t.value = lookahead
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lookaheadstack.append(lookahead)
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lookahead = t
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else:
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symstack.pop()
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statestack.pop()
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continue
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# Call an error function here
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raise RuntimeError, "yacc: internal parser error!!!\n"
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# -----------------------------------------------------------------------------
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# === Parser Construction ===
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#
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# The following functions and variables are used to implement the yacc() function
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# itself. This is pretty hairy stuff involving lots of error checking,
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# construction of LR items, kernels, and so forth. Although a lot of
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# this work is done using global variables, the resulting Parser object
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# is completely self contained--meaning that it is safe to repeatedly
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# call yacc() with different grammars in the same application.
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# -----------------------------------------------------------------------------
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# -----------------------------------------------------------------------------
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# validate_file()
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#
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# This function checks to see if there are duplicated p_rulename() functions
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# in the parser module file. Without this function, it is really easy for
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# users to make mistakes by cutting and pasting code fragments (and it's a real
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# bugger to try and figure out why the resulting parser doesn't work). Therefore,
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# we just do a little regular expression pattern matching of def statements
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# to try and detect duplicates.
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# -----------------------------------------------------------------------------
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def validate_file(filename):
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base,ext = os.path.splitext(filename)
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if ext != '.py': return 1 # No idea. Assume it's okay.
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try:
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f = open(filename)
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lines = f.readlines()
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f.close()
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except IOError:
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return 1 # Oh well
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# Match def p_funcname(
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fre = re.compile(r'\s*def\s+(p_[a-zA-Z_0-9]*)\(')
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counthash = { }
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linen = 1
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noerror = 1
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for l in lines:
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m = fre.match(l)
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if m:
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name = m.group(1)
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prev = counthash.get(name)
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if not prev:
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counthash[name] = linen
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else:
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print "%s:%d: Function %s redefined. Previously defined on line %d" % (filename,linen,name,prev)
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noerror = 0
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linen += 1
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return noerror
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# This function looks for functions that might be grammar rules, but which don't have the proper p_suffix.
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def validate_dict(d):
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for n,v in d.items():
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if n[0:2] == 'p_' and isinstance(v,types.FunctionType): continue
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if n[0:2] == 't_': continue
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if n[0:2] == 'p_':
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print "yacc: Warning. '%s' not defined as a function" % n
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if isinstance(v,types.FunctionType) and v.func_code.co_argcount == 1:
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try:
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doc = v.__doc__.split(" ")
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if doc[1] == ':':
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print "%s:%d: Warning. Possible grammar rule '%s' defined without p_ prefix." % (v.func_code.co_filename, v.func_code.co_firstlineno,n)
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except StandardError:
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pass
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# -----------------------------------------------------------------------------
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# === GRAMMAR FUNCTIONS ===
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#
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# The following global variables and functions are used to store, manipulate,
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# and verify the grammar rules specified by the user.
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# -----------------------------------------------------------------------------
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# Initialize all of the global variables used during grammar construction
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def initialize_vars():
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global Productions, Prodnames, Prodmap, Terminals
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global Nonterminals, First, Follow, Precedence, LRitems
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global Errorfunc, Signature, Requires
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Productions = [None] # A list of all of the productions. The first
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# entry is always reserved for the purpose of
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# building an augmented grammar
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Prodnames = { } # A dictionary mapping the names of nonterminals to a list of all
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# productions of that nonterminal.
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Prodmap = { } # A dictionary that is only used to detect duplicate
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# productions.
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Terminals = { } # A dictionary mapping the names of terminal symbols to a
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# list of the rules where they are used.
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Nonterminals = { } # A dictionary mapping names of nonterminals to a list
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# of rule numbers where they are used.
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First = { } # A dictionary of precomputed FIRST(x) symbols
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Follow = { } # A dictionary of precomputed FOLLOW(x) symbols
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Precedence = { } # Precedence rules for each terminal. Contains tuples of the
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# form ('right',level) or ('nonassoc', level) or ('left',level)
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LRitems = [ ] # A list of all LR items for the grammar. These are the
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# productions with the "dot" like E -> E . PLUS E
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Errorfunc = None # User defined error handler
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Signature = md5.new() # Digital signature of the grammar rules, precedence
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# and other information. Used to determined when a
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# parsing table needs to be regenerated.
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Requires = { } # Requires list
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# File objects used when creating the parser.out debugging file
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global _vf, _vfc
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_vf = cStringIO.StringIO()
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_vfc = cStringIO.StringIO()
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# -----------------------------------------------------------------------------
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# class Production:
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#
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# This class stores the raw information about a single production or grammar rule.
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# It has a few required attributes:
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#
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# name - Name of the production (nonterminal)
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# prod - A list of symbols making up its production
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# number - Production number.
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#
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# In addition, a few additional attributes are used to help with debugging or
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# optimization of table generation.
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#
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# file - File where production action is defined.
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# lineno - Line number where action is defined
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# func - Action function
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# prec - Precedence level
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# 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()"
|
|
|