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<moon__> mkx bin/hfs//erro You have discovered an eerie caven. The air above the dark stone floor is alive with vorices of purple light and dark, boiling clouds. Seemingly bottomless glowing pit mark the surface.
author | HackBot |
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date | Sat, 07 May 2016 00:41:47 +0000 |
parents | a1845676eaa0 |
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# ----------------------------------------------------------------------------- # ply: yacc.py # # Copyright (C) 2001-2015, # David M. Beazley (Dabeaz LLC) # All rights reserved. # # Redistribution and use in source and binary forms, with or without # modification, are permitted provided that the following conditions are # met: # # * Redistributions of source code must retain the above copyright notice, # this list of conditions and the following disclaimer. # * Redistributions in binary form must reproduce the above copyright notice, # this list of conditions and the following disclaimer in the documentation # and/or other materials provided with the distribution. # * Neither the name of the David Beazley or Dabeaz LLC may be used to # endorse or promote products derived from this software without # specific prior written permission. # # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. # ----------------------------------------------------------------------------- # # This implements an LR parser that is constructed from grammar rules defined # as Python functions. The grammer is specified by supplying the BNF inside # Python documentation strings. The inspiration for this technique was borrowed # from John Aycock's Spark parsing system. PLY might be viewed as cross between # Spark and the GNU bison utility. # # The current implementation is only somewhat object-oriented. The # LR parser itself is defined in terms of an object (which allows multiple # parsers to co-exist). However, most of the variables used during table # construction are defined in terms of global variables. Users shouldn't # notice unless they are trying to define multiple parsers at the same # time using threads (in which case they should have their head examined). # # This implementation supports both SLR and LALR(1) parsing. LALR(1) # support was originally implemented by Elias Ioup (ezioup@alumni.uchicago.edu), # using the algorithm found in Aho, Sethi, and Ullman "Compilers: Principles, # Techniques, and Tools" (The Dragon Book). LALR(1) has since been replaced # by the more efficient DeRemer and Pennello algorithm. # # :::::::: WARNING ::::::: # # Construction of LR parsing tables is fairly complicated and expensive. # To make this module run fast, a *LOT* of work has been put into # optimization---often at the expensive of readability and what might # consider to be good Python "coding style." Modify the code at your # own risk! # ---------------------------------------------------------------------------- import re import types import sys import os.path import inspect import base64 import warnings __version__ = '3.8' __tabversion__ = '3.8' #----------------------------------------------------------------------------- # === User configurable parameters === # # Change these to modify the default behavior of yacc (if you wish) #----------------------------------------------------------------------------- yaccdebug = True # Debugging mode. If set, yacc generates a # a 'parser.out' file in the current directory debug_file = 'parser.out' # Default name of the debugging file tab_module = 'parsetab' # Default name of the table module default_lr = 'LALR' # Default LR table generation method error_count = 3 # Number of symbols that must be shifted to leave recovery mode yaccdevel = False # Set to True if developing yacc. This turns off optimized # implementations of certain functions. resultlimit = 40 # Size limit of results when running in debug mode. pickle_protocol = 0 # Protocol to use when writing pickle files # String type-checking compatibility if sys.version_info[0] < 3: string_types = basestring else: string_types = str MAXINT = sys.maxsize # This object is a stand-in for a logging object created by the # logging module. PLY will use this by default to create things # such as the parser.out file. If a user wants more detailed # information, they can create their own logging object and pass # it into PLY. class PlyLogger(object): def __init__(self, f): self.f = f def debug(self, msg, *args, **kwargs): self.f.write((msg % args) + '\n') info = debug def warning(self, msg, *args, **kwargs): self.f.write('WARNING: ' + (msg % args) + '\n') def error(self, msg, *args, **kwargs): self.f.write('ERROR: ' + (msg % args) + '\n') critical = debug # Null logger is used when no output is generated. Does nothing. class NullLogger(object): def __getattribute__(self, name): return self def __call__(self, *args, **kwargs): return self # Exception raised for yacc-related errors class YaccError(Exception): pass # Format the result message that the parser produces when running in debug mode. def format_result(r): repr_str = repr(r) if '\n' in repr_str: repr_str = repr(repr_str) if len(repr_str) > resultlimit: repr_str = repr_str[:resultlimit] + ' ...' result = '<%s @ 0x%x> (%s)' % (type(r).__name__, id(r), repr_str) return result # Format stack entries when the parser is running in debug mode def format_stack_entry(r): repr_str = repr(r) if '\n' in repr_str: repr_str = repr(repr_str) if len(repr_str) < 16: return repr_str else: return '<%s @ 0x%x>' % (type(r).__name__, id(r)) # Panic mode error recovery support. This feature is being reworked--much of the # code here is to offer a deprecation/backwards compatible transition _errok = None _token = None _restart = None _warnmsg = '''PLY: Don't use global functions errok(), token(), and restart() in p_error(). Instead, invoke the methods on the associated parser instance: def p_error(p): ... # Use parser.errok(), parser.token(), parser.restart() ... parser = yacc.yacc() ''' def errok(): warnings.warn(_warnmsg) return _errok() def restart(): warnings.warn(_warnmsg) return _restart() def token(): warnings.warn(_warnmsg) return _token() # Utility function to call the p_error() function with some deprecation hacks def call_errorfunc(errorfunc, token, parser): global _errok, _token, _restart _errok = parser.errok _token = parser.token _restart = parser.restart r = errorfunc(token) try: del _errok, _token, _restart except NameError: pass return r #----------------------------------------------------------------------------- # === LR Parsing Engine === # # The following classes are used for the LR parser itself. These are not # used during table construction and are independent of the actual LR # table generation algorithm #----------------------------------------------------------------------------- # This class is used to hold non-terminal grammar symbols during parsing. # It normally has the following attributes set: # .type = Grammar symbol type # .value = Symbol value # .lineno = Starting line number # .endlineno = Ending line number (optional, set automatically) # .lexpos = Starting lex position # .endlexpos = Ending lex position (optional, set automatically) class YaccSymbol: def __str__(self): return self.type def __repr__(self): return str(self) # This class is a wrapper around the objects actually passed to each # grammar rule. Index lookup and assignment actually assign the # .value attribute of the underlying YaccSymbol object. # The lineno() method returns the line number of a given # item (or 0 if not defined). The linespan() method returns # a tuple of (startline,endline) representing the range of lines # for a symbol. The lexspan() method returns a tuple (lexpos,endlexpos) # representing the range of positional information for a symbol. class YaccProduction: def __init__(self, s, stack=None): self.slice = s self.stack = stack self.lexer = None self.parser = None def __getitem__(self, n): if isinstance(n, slice): return [s.value for s in self.slice[n]] elif n >= 0: return self.slice[n].value else: return self.stack[n].value def __setitem__(self, n, v): self.slice[n].value = v def __getslice__(self, i, j): return [s.value for s in self.slice[i:j]] def __len__(self): return len(self.slice) def lineno(self, n): return getattr(self.slice[n], 'lineno', 0) def set_lineno(self, n, lineno): self.slice[n].lineno = lineno def linespan(self, n): startline = getattr(self.slice[n], 'lineno', 0) endline = getattr(self.slice[n], 'endlineno', startline) return startline, endline def lexpos(self, n): return getattr(self.slice[n], 'lexpos', 0) def lexspan(self, n): startpos = getattr(self.slice[n], 'lexpos', 0) endpos = getattr(self.slice[n], 'endlexpos', startpos) return startpos, endpos def error(self): raise SyntaxError # ----------------------------------------------------------------------------- # == LRParser == # # The LR Parsing engine. # ----------------------------------------------------------------------------- class LRParser: def __init__(self, lrtab, errorf): self.productions = lrtab.lr_productions self.action = lrtab.lr_action self.goto = lrtab.lr_goto self.errorfunc = errorf self.set_defaulted_states() self.errorok = True def errok(self): self.errorok = True def restart(self): del self.statestack[:] del self.symstack[:] sym = YaccSymbol() sym.type = '$end' self.symstack.append(sym) self.statestack.append(0) # Defaulted state support. # This method identifies parser states where there is only one possible reduction action. # For such states, the parser can make a choose to make a rule reduction without consuming # the next look-ahead token. This delayed invocation of the tokenizer can be useful in # certain kinds of advanced parsing situations where the lexer and parser interact with # each other or change states (i.e., manipulation of scope, lexer states, etc.). # # See: http://www.gnu.org/software/bison/manual/html_node/Default-Reductions.html#Default-Reductions def set_defaulted_states(self): self.defaulted_states = {} for state, actions in self.action.items(): rules = list(actions.values()) if len(rules) == 1 and rules[0] < 0: self.defaulted_states[state] = rules[0] def disable_defaulted_states(self): self.defaulted_states = {} def parse(self, input=None, lexer=None, debug=False, tracking=False, tokenfunc=None): if debug or yaccdevel: if isinstance(debug, int): debug = PlyLogger(sys.stderr) return self.parsedebug(input, lexer, debug, tracking, tokenfunc) elif tracking: return self.parseopt(input, lexer, debug, tracking, tokenfunc) else: return self.parseopt_notrack(input, lexer, debug, tracking, tokenfunc) # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! # parsedebug(). # # This is the debugging enabled version of parse(). All changes made to the # parsing engine should be made here. Optimized versions of this function # are automatically created by the ply/ygen.py script. This script cuts out # sections enclosed in markers such as this: # # #--! DEBUG # statements # #--! DEBUG # # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! def parsedebug(self, input=None, lexer=None, debug=False, tracking=False, tokenfunc=None): #--! parsedebug-start lookahead = None # Current lookahead symbol lookaheadstack = [] # Stack of lookahead symbols actions = self.action # Local reference to action table (to avoid lookup on self.) goto = self.goto # Local reference to goto table (to avoid lookup on self.) prod = self.productions # Local reference to production list (to avoid lookup on self.) defaulted_states = self.defaulted_states # Local reference to defaulted states pslice = YaccProduction(None) # Production object passed to grammar rules errorcount = 0 # Used during error recovery #--! DEBUG debug.info('PLY: PARSE DEBUG START') #--! DEBUG # If no lexer was given, we will try to use the lex module if not lexer: from . import lex lexer = lex.lexer # Set up the lexer and parser objects on pslice pslice.lexer = lexer pslice.parser = self # If input was supplied, pass to lexer if input is not None: lexer.input(input) if tokenfunc is None: # Tokenize function get_token = lexer.token else: get_token = tokenfunc # Set the parser() token method (sometimes used in error recovery) self.token = get_token # Set up the state and symbol stacks statestack = [] # Stack of parsing states self.statestack = statestack symstack = [] # Stack of grammar symbols self.symstack = symstack pslice.stack = symstack # Put in the production errtoken = None # Err token # The start state is assumed to be (0,$end) statestack.append(0) sym = YaccSymbol() sym.type = '$end' symstack.append(sym) state = 0 while True: # Get the next symbol on the input. If a lookahead symbol # is already set, we just use that. Otherwise, we'll pull # the next token off of the lookaheadstack or from the lexer #--! DEBUG debug.debug('') debug.debug('State : %s', state) #--! DEBUG if state not in defaulted_states: if not lookahead: if not lookaheadstack: lookahead = get_token() # Get the next token else: lookahead = lookaheadstack.pop() if not lookahead: lookahead = YaccSymbol() lookahead.type = '$end' # Check the action table ltype = lookahead.type t = actions[state].get(ltype) else: t = defaulted_states[state] #--! DEBUG debug.debug('Defaulted state %s: Reduce using %d', state, -t) #--! DEBUG #--! DEBUG debug.debug('Stack : %s', ('%s . %s' % (' '.join([xx.type for xx in symstack][1:]), str(lookahead))).lstrip()) #--! DEBUG if t is not None: if t > 0: # shift a symbol on the stack statestack.append(t) state = t #--! DEBUG debug.debug('Action : Shift and goto state %s', t) #--! DEBUG symstack.append(lookahead) lookahead = None # Decrease error count on successful shift if errorcount: errorcount -= 1 continue if t < 0: # reduce a symbol on the stack, emit a production p = prod[-t] pname = p.name plen = p.len # Get production function sym = YaccSymbol() sym.type = pname # Production name sym.value = None #--! DEBUG if plen: debug.info('Action : Reduce rule [%s] with %s and goto state %d', p.str, '['+','.join([format_stack_entry(_v.value) for _v in symstack[-plen:]])+']', goto[statestack[-1-plen]][pname]) else: debug.info('Action : Reduce rule [%s] with %s and goto state %d', p.str, [], goto[statestack[-1]][pname]) #--! DEBUG if plen: targ = symstack[-plen-1:] targ[0] = sym #--! TRACKING if tracking: t1 = targ[1] sym.lineno = t1.lineno sym.lexpos = t1.lexpos t1 = targ[-1] sym.endlineno = getattr(t1, 'endlineno', t1.lineno) sym.endlexpos = getattr(t1, 'endlexpos', t1.lexpos) #--! TRACKING # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! # The code enclosed in this section is duplicated # below as a performance optimization. Make sure # changes get made in both locations. pslice.slice = targ try: # Call the grammar rule with our special slice object del symstack[-plen:] del statestack[-plen:] p.callable(pslice) #--! DEBUG debug.info('Result : %s', format_result(pslice[0])) #--! DEBUG symstack.append(sym) state = goto[statestack[-1]][pname] statestack.append(state) except SyntaxError: # If an error was set. Enter error recovery state lookaheadstack.append(lookahead) symstack.pop() statestack.pop() state = statestack[-1] sym.type = 'error' lookahead = sym errorcount = error_count self.errorok = False continue # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! else: #--! TRACKING if tracking: sym.lineno = lexer.lineno sym.lexpos = lexer.lexpos #--! TRACKING targ = [sym] # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! # The code enclosed in this section is duplicated # above as a performance optimization. Make sure # changes get made in both locations. pslice.slice = targ try: # Call the grammar rule with our special slice object p.callable(pslice) #--! DEBUG debug.info('Result : %s', format_result(pslice[0])) #--! DEBUG symstack.append(sym) state = goto[statestack[-1]][pname] statestack.append(state) except SyntaxError: # If an error was set. Enter error recovery state lookaheadstack.append(lookahead) symstack.pop() statestack.pop() state = statestack[-1] sym.type = 'error' lookahead = sym errorcount = error_count self.errorok = False continue # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! if t == 0: n = symstack[-1] result = getattr(n, 'value', None) #--! DEBUG debug.info('Done : Returning %s', format_result(result)) debug.info('PLY: PARSE DEBUG END') #--! DEBUG return result if t is None: #--! DEBUG debug.error('Error : %s', ('%s . %s' % (' '.join([xx.type for xx in symstack][1:]), str(lookahead))).lstrip()) #--! DEBUG # We have some kind of parsing error here. To handle # this, we are going to push the current token onto # the tokenstack and replace it with an 'error' token. # If there are any synchronization rules, they may # catch it. # # In addition to pushing the error token, we call call # the user defined p_error() function if this is the # first syntax error. This function is only called if # errorcount == 0. if errorcount == 0 or self.errorok: errorcount = error_count self.errorok = False errtoken = lookahead if errtoken.type == '$end': errtoken = None # End of file! if self.errorfunc: if errtoken and not hasattr(errtoken, 'lexer'): errtoken.lexer = lexer tok = call_errorfunc(self.errorfunc, errtoken, self) if self.errorok: # User must have done some kind of panic # mode recovery on their own. The # returned token is the next lookahead lookahead = tok errtoken = None continue else: if errtoken: if hasattr(errtoken, 'lineno'): lineno = lookahead.lineno else: lineno = 0 if lineno: sys.stderr.write('yacc: Syntax error at line %d, token=%s\n' % (lineno, errtoken.type)) else: sys.stderr.write('yacc: Syntax error, token=%s' % errtoken.type) else: sys.stderr.write('yacc: Parse error in input. EOF\n') return else: errorcount = error_count # case 1: the statestack only has 1 entry on it. If we're in this state, the # entire parse has been rolled back and we're completely hosed. The token is # discarded and we just keep going. if len(statestack) <= 1 and lookahead.type != '$end': lookahead = None errtoken = None state = 0 # Nuke the pushback stack del lookaheadstack[:] continue # case 2: the statestack has a couple of entries on it, but we're # at the end of the file. nuke the top entry and generate an error token # Start nuking entries on the stack if lookahead.type == '$end': # Whoa. We're really hosed here. Bail out return if lookahead.type != 'error': sym = symstack[-1] if sym.type == 'error': # Hmmm. Error is on top of stack, we'll just nuke input # symbol and continue #--! TRACKING if tracking: sym.endlineno = getattr(lookahead, 'lineno', sym.lineno) sym.endlexpos = getattr(lookahead, 'lexpos', sym.lexpos) #--! TRACKING lookahead = None continue # Create the error symbol for the first time and make it the new lookahead symbol t = YaccSymbol() t.type = 'error' if hasattr(lookahead, 'lineno'): t.lineno = t.endlineno = lookahead.lineno if hasattr(lookahead, 'lexpos'): t.lexpos = t.endlexpos = lookahead.lexpos t.value = lookahead lookaheadstack.append(lookahead) lookahead = t else: sym = symstack.pop() #--! TRACKING if tracking: lookahead.lineno = sym.lineno lookahead.lexpos = sym.lexpos #--! TRACKING statestack.pop() state = statestack[-1] continue # Call an error function here raise RuntimeError('yacc: internal parser error!!!\n') #--! parsedebug-end # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! # parseopt(). # # Optimized version of parse() method. DO NOT EDIT THIS CODE DIRECTLY! # This code is automatically generated by the ply/ygen.py script. Make # changes to the parsedebug() method instead. # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! def parseopt(self, input=None, lexer=None, debug=False, tracking=False, tokenfunc=None): #--! parseopt-start lookahead = None # Current lookahead symbol lookaheadstack = [] # Stack of lookahead symbols actions = self.action # Local reference to action table (to avoid lookup on self.) goto = self.goto # Local reference to goto table (to avoid lookup on self.) prod = self.productions # Local reference to production list (to avoid lookup on self.) defaulted_states = self.defaulted_states # Local reference to defaulted states pslice = YaccProduction(None) # Production object passed to grammar rules errorcount = 0 # Used during error recovery # If no lexer was given, we will try to use the lex module if not lexer: from . import lex lexer = lex.lexer # Set up the lexer and parser objects on pslice pslice.lexer = lexer pslice.parser = self # If input was supplied, pass to lexer if input is not None: lexer.input(input) if tokenfunc is None: # Tokenize function get_token = lexer.token else: get_token = tokenfunc # Set the parser() token method (sometimes used in error recovery) self.token = get_token # Set up the state and symbol stacks statestack = [] # Stack of parsing states self.statestack = statestack symstack = [] # Stack of grammar symbols self.symstack = symstack pslice.stack = symstack # Put in the production errtoken = None # Err token # The start state is assumed to be (0,$end) statestack.append(0) sym = YaccSymbol() sym.type = '$end' symstack.append(sym) state = 0 while True: # Get the next symbol on the input. If a lookahead symbol # is already set, we just use that. Otherwise, we'll pull # the next token off of the lookaheadstack or from the lexer if state not in defaulted_states: if not lookahead: if not lookaheadstack: lookahead = get_token() # Get the next token else: lookahead = lookaheadstack.pop() if not lookahead: lookahead = YaccSymbol() lookahead.type = '$end' # Check the action table ltype = lookahead.type t = actions[state].get(ltype) else: t = defaulted_states[state] if t is not None: if t > 0: # shift a symbol on the stack statestack.append(t) state = t symstack.append(lookahead) lookahead = None # Decrease error count on successful shift if errorcount: errorcount -= 1 continue if t < 0: # reduce a symbol on the stack, emit a production p = prod[-t] pname = p.name plen = p.len # Get production function sym = YaccSymbol() sym.type = pname # Production name sym.value = None if plen: targ = symstack[-plen-1:] targ[0] = sym #--! TRACKING if tracking: t1 = targ[1] sym.lineno = t1.lineno sym.lexpos = t1.lexpos t1 = targ[-1] sym.endlineno = getattr(t1, 'endlineno', t1.lineno) sym.endlexpos = getattr(t1, 'endlexpos', t1.lexpos) #--! TRACKING # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! # The code enclosed in this section is duplicated # below as a performance optimization. Make sure # changes get made in both locations. pslice.slice = targ try: # Call the grammar rule with our special slice object del symstack[-plen:] del statestack[-plen:] p.callable(pslice) symstack.append(sym) state = goto[statestack[-1]][pname] statestack.append(state) except SyntaxError: # If an error was set. Enter error recovery state lookaheadstack.append(lookahead) symstack.pop() statestack.pop() state = statestack[-1] sym.type = 'error' lookahead = sym errorcount = error_count self.errorok = False continue # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! else: #--! TRACKING if tracking: sym.lineno = lexer.lineno sym.lexpos = lexer.lexpos #--! TRACKING targ = [sym] # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! # The code enclosed in this section is duplicated # above as a performance optimization. Make sure # changes get made in both locations. pslice.slice = targ try: # Call the grammar rule with our special slice object p.callable(pslice) symstack.append(sym) state = goto[statestack[-1]][pname] statestack.append(state) except SyntaxError: # If an error was set. Enter error recovery state lookaheadstack.append(lookahead) symstack.pop() statestack.pop() state = statestack[-1] sym.type = 'error' lookahead = sym errorcount = error_count self.errorok = False continue # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! if t == 0: n = symstack[-1] result = getattr(n, 'value', None) return result if t is None: # We have some kind of parsing error here. To handle # this, we are going to push the current token onto # the tokenstack and replace it with an 'error' token. # If there are any synchronization rules, they may # catch it. # # In addition to pushing the error token, we call call # the user defined p_error() function if this is the # first syntax error. This function is only called if # errorcount == 0. if errorcount == 0 or self.errorok: errorcount = error_count self.errorok = False errtoken = lookahead if errtoken.type == '$end': errtoken = None # End of file! if self.errorfunc: if errtoken and not hasattr(errtoken, 'lexer'): errtoken.lexer = lexer tok = call_errorfunc(self.errorfunc, errtoken, self) if self.errorok: # User must have done some kind of panic # mode recovery on their own. The # returned token is the next lookahead lookahead = tok errtoken = None continue else: if errtoken: if hasattr(errtoken, 'lineno'): lineno = lookahead.lineno else: lineno = 0 if lineno: sys.stderr.write('yacc: Syntax error at line %d, token=%s\n' % (lineno, errtoken.type)) else: sys.stderr.write('yacc: Syntax error, token=%s' % errtoken.type) else: sys.stderr.write('yacc: Parse error in input. EOF\n') return else: errorcount = error_count # case 1: the statestack only has 1 entry on it. If we're in this state, the # entire parse has been rolled back and we're completely hosed. The token is # discarded and we just keep going. if len(statestack) <= 1 and lookahead.type != '$end': lookahead = None errtoken = None state = 0 # Nuke the pushback stack del lookaheadstack[:] continue # case 2: the statestack has a couple of entries on it, but we're # at the end of the file. nuke the top entry and generate an error token # Start nuking entries on the stack if lookahead.type == '$end': # Whoa. We're really hosed here. Bail out return if lookahead.type != 'error': sym = symstack[-1] if sym.type == 'error': # Hmmm. Error is on top of stack, we'll just nuke input # symbol and continue #--! TRACKING if tracking: sym.endlineno = getattr(lookahead, 'lineno', sym.lineno) sym.endlexpos = getattr(lookahead, 'lexpos', sym.lexpos) #--! TRACKING lookahead = None continue # Create the error symbol for the first time and make it the new lookahead symbol t = YaccSymbol() t.type = 'error' if hasattr(lookahead, 'lineno'): t.lineno = t.endlineno = lookahead.lineno if hasattr(lookahead, 'lexpos'): t.lexpos = t.endlexpos = lookahead.lexpos t.value = lookahead lookaheadstack.append(lookahead) lookahead = t else: sym = symstack.pop() #--! TRACKING if tracking: lookahead.lineno = sym.lineno lookahead.lexpos = sym.lexpos #--! TRACKING statestack.pop() state = statestack[-1] continue # Call an error function here raise RuntimeError('yacc: internal parser error!!!\n') #--! parseopt-end # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! # parseopt_notrack(). # # Optimized version of parseopt() with line number tracking removed. # DO NOT EDIT THIS CODE DIRECTLY. This code is automatically generated # by the ply/ygen.py script. Make changes to the parsedebug() method instead. # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! def parseopt_notrack(self, input=None, lexer=None, debug=False, tracking=False, tokenfunc=None): #--! parseopt-notrack-start lookahead = None # Current lookahead symbol lookaheadstack = [] # Stack of lookahead symbols actions = self.action # Local reference to action table (to avoid lookup on self.) goto = self.goto # Local reference to goto table (to avoid lookup on self.) prod = self.productions # Local reference to production list (to avoid lookup on self.) defaulted_states = self.defaulted_states # Local reference to defaulted states pslice = YaccProduction(None) # Production object passed to grammar rules errorcount = 0 # Used during error recovery # If no lexer was given, we will try to use the lex module if not lexer: from . import lex lexer = lex.lexer # Set up the lexer and parser objects on pslice pslice.lexer = lexer pslice.parser = self # If input was supplied, pass to lexer if input is not None: lexer.input(input) if tokenfunc is None: # Tokenize function get_token = lexer.token else: get_token = tokenfunc # Set the parser() token method (sometimes used in error recovery) self.token = get_token # Set up the state and symbol stacks statestack = [] # Stack of parsing states self.statestack = statestack symstack = [] # Stack of grammar symbols self.symstack = symstack pslice.stack = symstack # Put in the production errtoken = None # Err token # The start state is assumed to be (0,$end) statestack.append(0) sym = YaccSymbol() sym.type = '$end' symstack.append(sym) state = 0 while True: # Get the next symbol on the input. If a lookahead symbol # is already set, we just use that. Otherwise, we'll pull # the next token off of the lookaheadstack or from the lexer if state not in defaulted_states: if not lookahead: if not lookaheadstack: lookahead = get_token() # Get the next token else: lookahead = lookaheadstack.pop() if not lookahead: lookahead = YaccSymbol() lookahead.type = '$end' # Check the action table ltype = lookahead.type t = actions[state].get(ltype) else: t = defaulted_states[state] if t is not None: if t > 0: # shift a symbol on the stack statestack.append(t) state = t symstack.append(lookahead) lookahead = None # Decrease error count on successful shift if errorcount: errorcount -= 1 continue if t < 0: # reduce a symbol on the stack, emit a production p = prod[-t] pname = p.name plen = p.len # Get production function sym = YaccSymbol() sym.type = pname # Production name sym.value = None if plen: targ = symstack[-plen-1:] targ[0] = sym # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! # The code enclosed in this section is duplicated # below as a performance optimization. Make sure # changes get made in both locations. pslice.slice = targ try: # Call the grammar rule with our special slice object del symstack[-plen:] del statestack[-plen:] p.callable(pslice) symstack.append(sym) state = goto[statestack[-1]][pname] statestack.append(state) except SyntaxError: # If an error was set. Enter error recovery state lookaheadstack.append(lookahead) symstack.pop() statestack.pop() state = statestack[-1] sym.type = 'error' lookahead = sym errorcount = error_count self.errorok = False continue # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! else: targ = [sym] # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! # The code enclosed in this section is duplicated # above as a performance optimization. Make sure # changes get made in both locations. pslice.slice = targ try: # Call the grammar rule with our special slice object p.callable(pslice) symstack.append(sym) state = goto[statestack[-1]][pname] statestack.append(state) except SyntaxError: # If an error was set. Enter error recovery state lookaheadstack.append(lookahead) symstack.pop() statestack.pop() state = statestack[-1] sym.type = 'error' lookahead = sym errorcount = error_count self.errorok = False continue # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! if t == 0: n = symstack[-1] result = getattr(n, 'value', None) return result if t is None: # We have some kind of parsing error here. To handle # this, we are going to push the current token onto # the tokenstack and replace it with an 'error' token. # If there are any synchronization rules, they may # catch it. # # In addition to pushing the error token, we call call # the user defined p_error() function if this is the # first syntax error. This function is only called if # errorcount == 0. if errorcount == 0 or self.errorok: errorcount = error_count self.errorok = False errtoken = lookahead if errtoken.type == '$end': errtoken = None # End of file! if self.errorfunc: if errtoken and not hasattr(errtoken, 'lexer'): errtoken.lexer = lexer tok = call_errorfunc(self.errorfunc, errtoken, self) if self.errorok: # User must have done some kind of panic # mode recovery on their own. The # returned token is the next lookahead lookahead = tok errtoken = None continue else: if errtoken: if hasattr(errtoken, 'lineno'): lineno = lookahead.lineno else: lineno = 0 if lineno: sys.stderr.write('yacc: Syntax error at line %d, token=%s\n' % (lineno, errtoken.type)) else: sys.stderr.write('yacc: Syntax error, token=%s' % errtoken.type) else: sys.stderr.write('yacc: Parse error in input. EOF\n') return else: errorcount = error_count # case 1: the statestack only has 1 entry on it. If we're in this state, the # entire parse has been rolled back and we're completely hosed. The token is # discarded and we just keep going. if len(statestack) <= 1 and lookahead.type != '$end': lookahead = None errtoken = None state = 0 # Nuke the pushback stack del lookaheadstack[:] continue # case 2: the statestack has a couple of entries on it, but we're # at the end of the file. nuke the top entry and generate an error token # Start nuking entries on the stack if lookahead.type == '$end': # Whoa. We're really hosed here. Bail out return if lookahead.type != 'error': sym = symstack[-1] if sym.type == 'error': # Hmmm. Error is on top of stack, we'll just nuke input # symbol and continue lookahead = None continue # Create the error symbol for the first time and make it the new lookahead symbol t = YaccSymbol() t.type = 'error' if hasattr(lookahead, 'lineno'): t.lineno = t.endlineno = lookahead.lineno if hasattr(lookahead, 'lexpos'): t.lexpos = t.endlexpos = lookahead.lexpos t.value = lookahead lookaheadstack.append(lookahead) lookahead = t else: sym = symstack.pop() statestack.pop() state = statestack[-1] continue # Call an error function here raise RuntimeError('yacc: internal parser error!!!\n') #--! parseopt-notrack-end # ----------------------------------------------------------------------------- # === Grammar Representation === # # The following functions, classes, and variables are used to represent and # manipulate the rules that make up a grammar. # ----------------------------------------------------------------------------- # regex matching identifiers _is_identifier = re.compile(r'^[a-zA-Z0-9_-]+$') # ----------------------------------------------------------------------------- # class Production: # # This class stores the raw information about a single production or grammar rule. # A grammar rule refers to a specification such as this: # # expr : expr PLUS term # # Here are the basic attributes defined on all productions # # name - Name of the production. For example 'expr' # prod - A list of symbols on the right side ['expr','PLUS','term'] # prec - Production precedence level # number - Production number. # func - Function that executes on reduce # file - File where production function is defined # lineno - Line number where production function is defined # # The following attributes are defined or optional. # # len - Length of the production (number of symbols on right hand side) # usyms - Set of unique symbols found in the production # ----------------------------------------------------------------------------- class Production(object): reduced = 0 def __init__(self, number, name, prod, precedence=('right', 0), func=None, file='', line=0): self.name = name self.prod = tuple(prod) self.number = number self.func = func self.callable = None self.file = file self.line = line self.prec = precedence # Internal settings used during table construction self.len = len(self.prod) # Length of the production # Create a list of unique production symbols used in the production self.usyms = [] for s in self.prod: if s not in self.usyms: self.usyms.append(s) # List of all LR items for the production self.lr_items = [] self.lr_next = None # Create a string representation if self.prod: self.str = '%s -> %s' % (self.name, ' '.join(self.prod)) else: self.str = '%s -> <empty>' % self.name def __str__(self): return self.str def __repr__(self): return 'Production(' + str(self) + ')' def __len__(self): return len(self.prod) def __nonzero__(self): return 1 def __getitem__(self, index): return self.prod[index] # Return the nth lr_item from the production (or None if at the end) def lr_item(self, n): if n > len(self.prod): return None p = LRItem(self, n) # Precompute the list of productions immediately following. try: p.lr_after = Prodnames[p.prod[n+1]] except (IndexError, KeyError): p.lr_after = [] try: p.lr_before = p.prod[n-1] except IndexError: p.lr_before = None return p # Bind the production function name to a callable def bind(self, pdict): if self.func: self.callable = pdict[self.func] # This class serves as a minimal standin for Production objects when # reading table data from files. It only contains information # actually used by the LR parsing engine, plus some additional # debugging information. class MiniProduction(object): def __init__(self, str, name, len, func, file, line): self.name = name self.len = len self.func = func self.callable = None self.file = file self.line = line self.str = str def __str__(self): return self.str def __repr__(self): return 'MiniProduction(%s)' % self.str # Bind the production function name to a callable def bind(self, pdict): if self.func: self.callable = pdict[self.func] # ----------------------------------------------------------------------------- # class LRItem # # This class represents a specific stage of parsing a production rule. For # example: # # expr : expr . PLUS term # # In the above, the "." represents the current location of the parse. Here # basic attributes: # # name - Name of the production. For example 'expr' # prod - A list of symbols on the right side ['expr','.', 'PLUS','term'] # number - Production number. # # lr_next Next LR item. Example, if we are ' expr -> expr . PLUS term' # then lr_next refers to 'expr -> expr PLUS . term' # lr_index - LR item index (location of the ".") in the prod list. # lookaheads - LALR lookahead symbols for this item # len - Length of the production (number of symbols on right hand side) # lr_after - List of all productions that immediately follow # lr_before - Grammar symbol immediately before # ----------------------------------------------------------------------------- class LRItem(object): def __init__(self, p, n): self.name = p.name self.prod = list(p.prod) self.number = p.number self.lr_index = n self.lookaheads = {} self.prod.insert(n, '.') self.prod = tuple(self.prod) self.len = len(self.prod) self.usyms = p.usyms def __str__(self): if self.prod: s = '%s -> %s' % (self.name, ' '.join(self.prod)) else: s = '%s -> <empty>' % self.name return s def __repr__(self): return 'LRItem(' + str(self) + ')' # ----------------------------------------------------------------------------- # rightmost_terminal() # # Return the rightmost terminal from a list of symbols. Used in add_production() # ----------------------------------------------------------------------------- def rightmost_terminal(symbols, terminals): i = len(symbols) - 1 while i >= 0: if symbols[i] in terminals: return symbols[i] i -= 1 return None # ----------------------------------------------------------------------------- # === GRAMMAR CLASS === # # The following class represents the contents of the specified grammar along # with various computed properties such as first sets, follow sets, LR items, etc. # This data is used for critical parts of the table generation process later. # ----------------------------------------------------------------------------- class GrammarError(YaccError): pass class Grammar(object): def __init__(self, terminals): self.Productions = [None] # A list of all of the productions. The first # entry is always reserved for the purpose of # building an augmented grammar self.Prodnames = {} # A dictionary mapping the names of nonterminals to a list of all # productions of that nonterminal. self.Prodmap = {} # A dictionary that is only used to detect duplicate # productions. self.Terminals = {} # A dictionary mapping the names of terminal symbols to a # list of the rules where they are used. for term in terminals: self.Terminals[term] = [] self.Terminals['error'] = [] self.Nonterminals = {} # A dictionary mapping names of nonterminals to a list # of rule numbers where they are used. self.First = {} # A dictionary of precomputed FIRST(x) symbols self.Follow = {} # A dictionary of precomputed FOLLOW(x) symbols self.Precedence = {} # Precedence rules for each terminal. Contains tuples of the # form ('right',level) or ('nonassoc', level) or ('left',level) self.UsedPrecedence = set() # Precedence rules that were actually used by the grammer. # This is only used to provide error checking and to generate # a warning about unused precedence rules. self.Start = None # Starting symbol for the grammar def __len__(self): return len(self.Productions) def __getitem__(self, index): return self.Productions[index] # ----------------------------------------------------------------------------- # set_precedence() # # Sets the precedence for a given terminal. assoc is the associativity such as # 'left','right', or 'nonassoc'. level is a numeric level. # # ----------------------------------------------------------------------------- def set_precedence(self, term, assoc, level): assert self.Productions == [None], 'Must call set_precedence() before add_production()' if term in self.Precedence: raise GrammarError('Precedence already specified for terminal %r' % term) if assoc not in ['left', 'right', 'nonassoc']: raise GrammarError("Associativity must be one of 'left','right', or 'nonassoc'") self.Precedence[term] = (assoc, level) # ----------------------------------------------------------------------------- # add_production() # # Given an action function, this function assembles a production rule and # computes its precedence level. # # The production rule is supplied as a list of symbols. For example, # a rule such as 'expr : expr PLUS term' has a production name of 'expr' and # symbols ['expr','PLUS','term']. # # Precedence is determined by the precedence of the right-most non-terminal # or the precedence of a terminal specified by %prec. # # A variety of error checks are performed to make sure production symbols # are valid and that %prec is used correctly. # ----------------------------------------------------------------------------- def add_production(self, prodname, syms, func=None, file='', line=0): if prodname in self.Terminals: raise GrammarError('%s:%d: Illegal rule name %r. Already defined as a token' % (file, line, prodname)) if prodname == 'error': raise GrammarError('%s:%d: Illegal rule name %r. error is a reserved word' % (file, line, prodname)) if not _is_identifier.match(prodname): raise GrammarError('%s:%d: Illegal rule name %r' % (file, line, prodname)) # Look for literal tokens for n, s in enumerate(syms): if s[0] in "'\"": try: c = eval(s) if (len(c) > 1): raise GrammarError('%s:%d: Literal token %s in rule %r may only be a single character' % (file, line, s, prodname)) if c not in self.Terminals: self.Terminals[c] = [] syms[n] = c continue except SyntaxError: pass if not _is_identifier.match(s) and s != '%prec': raise GrammarError('%s:%d: Illegal name %r in rule %r' % (file, line, s, prodname)) # Determine the precedence level if '%prec' in syms: if syms[-1] == '%prec': raise GrammarError('%s:%d: Syntax error. Nothing follows %%prec' % (file, line)) if syms[-2] != '%prec': raise GrammarError('%s:%d: Syntax error. %%prec can only appear at the end of a grammar rule' % (file, line)) precname = syms[-1] prodprec = self.Precedence.get(precname) if not prodprec: raise GrammarError('%s:%d: Nothing known about the precedence of %r' % (file, line, precname)) else: self.UsedPrecedence.add(precname) del syms[-2:] # Drop %prec from the rule else: # If no %prec, precedence is determined by the rightmost terminal symbol precname = rightmost_terminal(syms, self.Terminals) prodprec = self.Precedence.get(precname, ('right', 0)) # See if the rule is already in the rulemap map = '%s -> %s' % (prodname, syms) if map in self.Prodmap: m = self.Prodmap[map] raise GrammarError('%s:%d: Duplicate rule %s. ' % (file, line, m) + 'Previous definition at %s:%d' % (m.file, m.line)) # From this point on, everything is valid. Create a new Production instance pnumber = len(self.Productions) if prodname not in self.Nonterminals: self.Nonterminals[prodname] = [] # Add the production number to Terminals and Nonterminals for t in syms: if t in self.Terminals: self.Terminals[t].append(pnumber) else: if t not in self.Nonterminals: self.Nonterminals[t] = [] self.Nonterminals[t].append(pnumber) # Create a production and add it to the list of productions p = Production(pnumber, prodname, syms, prodprec, func, file, line) self.Productions.append(p) self.Prodmap[map] = p # Add to the global productions list try: self.Prodnames[prodname].append(p) except KeyError: self.Prodnames[prodname] = [p] # ----------------------------------------------------------------------------- # set_start() # # Sets the starting symbol and creates the augmented grammar. Production # rule 0 is S' -> start where start is the start symbol. # ----------------------------------------------------------------------------- def set_start(self, start=None): if not start: start = self.Productions[1].name if start not in self.Nonterminals: raise GrammarError('start symbol %s undefined' % start) self.Productions[0] = Production(0, "S'", [start]) self.Nonterminals[start].append(0) self.Start = start # ----------------------------------------------------------------------------- # find_unreachable() # # Find all of the nonterminal symbols that can't be reached from the starting # symbol. Returns a list of nonterminals that can't be reached. # ----------------------------------------------------------------------------- def find_unreachable(self): # Mark all symbols that are reachable from a symbol s def mark_reachable_from(s): if s in reachable: return reachable.add(s) for p in self.Prodnames.get(s, []): for r in p.prod: mark_reachable_from(r) reachable = set() mark_reachable_from(self.Productions[0].prod[0]) return [s for s in self.Nonterminals if s not in reachable] # ----------------------------------------------------------------------------- # infinite_cycles() # # This function looks at the various parsing rules and tries to detect # infinite recursion cycles (grammar rules where there is no possible way # to derive a string of only terminals). # ----------------------------------------------------------------------------- def infinite_cycles(self): terminates = {} # Terminals: for t in self.Terminals: terminates[t] = True terminates['$end'] = True # Nonterminals: # Initialize to false: for n in self.Nonterminals: terminates[n] = False # Then propagate termination until no change: while True: some_change = False for (n, pl) in self.Prodnames.items(): # Nonterminal n terminates iff any of its productions terminates. for p in pl: # Production p terminates iff all of its rhs symbols terminate. for s in p.prod: if not terminates[s]: # The symbol s does not terminate, # so production p does not terminate. p_terminates = False break else: # didn't break from the loop, # so every symbol s terminates # so production p terminates. p_terminates = True if p_terminates: # symbol n terminates! if not terminates[n]: terminates[n] = True some_change = True # Don't need to consider any more productions for this n. break if not some_change: break infinite = [] for (s, term) in terminates.items(): if not term: if s not in self.Prodnames and s not in self.Terminals and s != 'error': # s is used-but-not-defined, and we've already warned of that, # so it would be overkill to say that it's also non-terminating. pass else: infinite.append(s) return infinite # ----------------------------------------------------------------------------- # undefined_symbols() # # Find all symbols that were used the grammar, but not defined as tokens or # grammar rules. Returns a list of tuples (sym, prod) where sym in the symbol # and prod is the production where the symbol was used. # ----------------------------------------------------------------------------- def undefined_symbols(self): result = [] for p in self.Productions: if not p: continue for s in p.prod: if s not in self.Prodnames and s not in self.Terminals and s != 'error': result.append((s, p)) return result # ----------------------------------------------------------------------------- # unused_terminals() # # Find all terminals that were defined, but not used by the grammar. Returns # a list of all symbols. # ----------------------------------------------------------------------------- def unused_terminals(self): unused_tok = [] for s, v in self.Terminals.items(): if s != 'error' and not v: unused_tok.append(s) return unused_tok # ------------------------------------------------------------------------------ # unused_rules() # # Find all grammar rules that were defined, but not used (maybe not reachable) # Returns a list of productions. # ------------------------------------------------------------------------------ def unused_rules(self): unused_prod = [] for s, v in self.Nonterminals.items(): if not v: p = self.Prodnames[s][0] unused_prod.append(p) return unused_prod # ----------------------------------------------------------------------------- # unused_precedence() # # Returns a list of tuples (term,precedence) corresponding to precedence # rules that were never used by the grammar. term is the name of the terminal # on which precedence was applied and precedence is a string such as 'left' or # 'right' corresponding to the type of precedence. # ----------------------------------------------------------------------------- def unused_precedence(self): unused = [] for termname in self.Precedence: if not (termname in self.Terminals or termname in self.UsedPrecedence): unused.append((termname, self.Precedence[termname][0])) return unused # ------------------------------------------------------------------------- # _first() # # Compute the value of FIRST1(beta) where beta is a tuple of symbols. # # During execution of compute_first1, the result may be incomplete. # Afterward (e.g., when called from compute_follow()), it will be complete. # ------------------------------------------------------------------------- def _first(self, beta): # We are computing First(x1,x2,x3,...,xn) result = [] for x in beta: x_produces_empty = False # Add all the non-<empty> symbols of First[x] to the result. for f in self.First[x]: if f == '<empty>': x_produces_empty = True else: if f not in result: result.append(f) if x_produces_empty: # We have to consider the next x in beta, # i.e. stay in the loop. pass else: # We don't have to consider any further symbols in beta. break else: # There was no 'break' from the loop, # so x_produces_empty was true for all x in beta, # so beta produces empty as well. result.append('<empty>') return result # ------------------------------------------------------------------------- # compute_first() # # Compute the value of FIRST1(X) for all symbols # ------------------------------------------------------------------------- def compute_first(self): if self.First: return self.First # Terminals: for t in self.Terminals: self.First[t] = [t] self.First['$end'] = ['$end'] # Nonterminals: # Initialize to the empty set: for n in self.Nonterminals: self.First[n] = [] # Then propagate symbols until no change: while True: some_change = False for n in self.Nonterminals: for p in self.Prodnames[n]: for f in self._first(p.prod): if f not in self.First[n]: self.First[n].append(f) some_change = True if not some_change: break return self.First # --------------------------------------------------------------------- # compute_follow() # # Computes all of the follow sets for every non-terminal symbol. The # follow set is the set of all symbols that might follow a given # non-terminal. See the Dragon book, 2nd Ed. p. 189. # --------------------------------------------------------------------- def compute_follow(self, start=None): # If already computed, return the result if self.Follow: return self.Follow # If first sets not computed yet, do that first. if not self.First: self.compute_first() # Add '$end' to the follow list of the start symbol for k in self.Nonterminals: self.Follow[k] = [] if not start: start = self.Productions[1].name self.Follow[start] = ['$end'] while True: didadd = False for p in self.Productions[1:]: # Here is the production set for i, B in enumerate(p.prod): if B in self.Nonterminals: # Okay. We got a non-terminal in a production fst = self._first(p.prod[i+1:]) hasempty = False for f in fst: if f != '<empty>' and f not in self.Follow[B]: self.Follow[B].append(f) didadd = True if f == '<empty>': hasempty = True if hasempty or i == (len(p.prod)-1): # Add elements of follow(a) to follow(b) for f in self.Follow[p.name]: if f not in self.Follow[B]: self.Follow[B].append(f) didadd = True if not didadd: break return self.Follow # ----------------------------------------------------------------------------- # build_lritems() # # This function walks the list of productions and builds a complete set of the # LR items. The LR items are stored in two ways: First, they are uniquely # numbered and placed in the list _lritems. Second, a linked list of LR items # is built for each production. For example: # # E -> E PLUS E # # Creates the list # # [E -> . E PLUS E, E -> E . PLUS E, E -> E PLUS . E, E -> E PLUS E . ] # ----------------------------------------------------------------------------- def build_lritems(self): for p in self.Productions: lastlri = p i = 0 lr_items = [] while True: if i > len(p): lri = None else: lri = LRItem(p, i) # Precompute the list of productions immediately following try: lri.lr_after = self.Prodnames[lri.prod[i+1]] except (IndexError, KeyError): lri.lr_after = [] try: lri.lr_before = lri.prod[i-1] except IndexError: lri.lr_before = None lastlri.lr_next = lri if not lri: break lr_items.append(lri) lastlri = lri i += 1 p.lr_items = lr_items # ----------------------------------------------------------------------------- # == Class LRTable == # # This basic class represents a basic table of LR parsing information. # Methods for generating the tables are not defined here. They are defined # in the derived class LRGeneratedTable. # ----------------------------------------------------------------------------- class VersionError(YaccError): pass class LRTable(object): def __init__(self): self.lr_action = None self.lr_goto = None self.lr_productions = None self.lr_method = None def read_table(self, module): if isinstance(module, types.ModuleType): parsetab = module else: exec('import %s' % module) parsetab = sys.modules[module] if parsetab._tabversion != __tabversion__: raise VersionError('yacc table file version is out of date') self.lr_action = parsetab._lr_action self.lr_goto = parsetab._lr_goto self.lr_productions = [] for p in parsetab._lr_productions: self.lr_productions.append(MiniProduction(*p)) self.lr_method = parsetab._lr_method return parsetab._lr_signature def read_pickle(self, filename): try: import cPickle as pickle except ImportError: import pickle if not os.path.exists(filename): raise ImportError in_f = open(filename, 'rb') tabversion = pickle.load(in_f) if tabversion != __tabversion__: raise VersionError('yacc table file version is out of date') self.lr_method = pickle.load(in_f) signature = pickle.load(in_f) self.lr_action = pickle.load(in_f) self.lr_goto = pickle.load(in_f) productions = pickle.load(in_f) self.lr_productions = [] for p in productions: self.lr_productions.append(MiniProduction(*p)) in_f.close() return signature # Bind all production function names to callable objects in pdict def bind_callables(self, pdict): for p in self.lr_productions: p.bind(pdict) # ----------------------------------------------------------------------------- # === LR Generator === # # The following classes and functions are used to generate LR parsing tables on # a grammar. # ----------------------------------------------------------------------------- # ----------------------------------------------------------------------------- # digraph() # traverse() # # The following two functions are used to compute set valued functions # of the form: # # F(x) = F'(x) U U{F(y) | x R y} # # This is used to compute the values of Read() sets as well as FOLLOW sets # in LALR(1) generation. # # Inputs: X - An input set # R - A relation # FP - Set-valued function # ------------------------------------------------------------------------------ def digraph(X, R, FP): N = {} for x in X: N[x] = 0 stack = [] F = {} for x in X: if N[x] == 0: traverse(x, N, stack, F, X, R, FP) return F def traverse(x, N, stack, F, X, R, FP): stack.append(x) d = len(stack) N[x] = d F[x] = FP(x) # F(X) <- F'(x) rel = R(x) # Get y's related to x for y in rel: if N[y] == 0: traverse(y, N, stack, F, X, R, FP) N[x] = min(N[x], N[y]) for a in F.get(y, []): if a not in F[x]: F[x].append(a) if N[x] == d: N[stack[-1]] = MAXINT F[stack[-1]] = F[x] element = stack.pop() while element != x: N[stack[-1]] = MAXINT F[stack[-1]] = F[x] element = stack.pop() class LALRError(YaccError): pass # ----------------------------------------------------------------------------- # == LRGeneratedTable == # # This class implements the LR table generation algorithm. There are no # public methods except for write() # ----------------------------------------------------------------------------- class LRGeneratedTable(LRTable): def __init__(self, grammar, method='LALR', log=None): if method not in ['SLR', 'LALR']: raise LALRError('Unsupported method %s' % method) self.grammar = grammar self.lr_method = method # Set up the logger if not log: log = NullLogger() self.log = log # Internal attributes self.lr_action = {} # Action table self.lr_goto = {} # Goto table self.lr_productions = grammar.Productions # Copy of grammar Production array self.lr_goto_cache = {} # Cache of computed gotos self.lr0_cidhash = {} # Cache of closures self._add_count = 0 # Internal counter used to detect cycles # Diagonistic information filled in by the table generator self.sr_conflict = 0 self.rr_conflict = 0 self.conflicts = [] # List of conflicts self.sr_conflicts = [] self.rr_conflicts = [] # Build the tables self.grammar.build_lritems() self.grammar.compute_first() self.grammar.compute_follow() self.lr_parse_table() # Compute the LR(0) closure operation on I, where I is a set of LR(0) items. def lr0_closure(self, I): self._add_count += 1 # Add everything in I to J J = I[:] didadd = True while didadd: didadd = False for j in J: for x in j.lr_after: if getattr(x, 'lr0_added', 0) == self._add_count: continue # Add B --> .G to J J.append(x.lr_next) x.lr0_added = self._add_count didadd = True return J # Compute the LR(0) goto function goto(I,X) where I is a set # of LR(0) items and X is a grammar symbol. This function is written # in a way that guarantees uniqueness of the generated goto sets # (i.e. the same goto set will never be returned as two different Python # objects). With uniqueness, we can later do fast set comparisons using # id(obj) instead of element-wise comparison. def lr0_goto(self, I, x): # First we look for a previously cached entry g = self.lr_goto_cache.get((id(I), x)) if g: return g # Now we generate the goto set in a way that guarantees uniqueness # of the result s = self.lr_goto_cache.get(x) if not s: s = {} self.lr_goto_cache[x] = s gs = [] for p in I: n = p.lr_next if n and n.lr_before == x: s1 = s.get(id(n)) if not s1: s1 = {} s[id(n)] = s1 gs.append(n) s = s1 g = s.get('$end') if not g: if gs: g = self.lr0_closure(gs) s['$end'] = g else: s['$end'] = gs self.lr_goto_cache[(id(I), x)] = g return g # Compute the LR(0) sets of item function def lr0_items(self): C = [self.lr0_closure([self.grammar.Productions[0].lr_next])] i = 0 for I in C: self.lr0_cidhash[id(I)] = i i += 1 # Loop over the items in C and each grammar symbols i = 0 while i < len(C): I = C[i] i += 1 # Collect all of the symbols that could possibly be in the goto(I,X) sets asyms = {} for ii in I: for s in ii.usyms: asyms[s] = None for x in asyms: g = self.lr0_goto(I, x) if not g or id(g) in self.lr0_cidhash: continue self.lr0_cidhash[id(g)] = len(C) C.append(g) return C # ----------------------------------------------------------------------------- # ==== LALR(1) Parsing ==== # # LALR(1) parsing is almost exactly the same as SLR except that instead of # relying upon Follow() sets when performing reductions, a more selective # lookahead set that incorporates the state of the LR(0) machine is utilized. # Thus, we mainly just have to focus on calculating the lookahead sets. # # The method used here is due to DeRemer and Pennelo (1982). # # DeRemer, F. L., and T. J. Pennelo: "Efficient Computation of LALR(1) # Lookahead Sets", ACM Transactions on Programming Languages and Systems, # Vol. 4, No. 4, Oct. 1982, pp. 615-649 # # Further details can also be found in: # # J. Tremblay and P. Sorenson, "The Theory and Practice of Compiler Writing", # McGraw-Hill Book Company, (1985). # # ----------------------------------------------------------------------------- # ----------------------------------------------------------------------------- # compute_nullable_nonterminals() # # Creates a dictionary containing all of the non-terminals that might produce # an empty production. # ----------------------------------------------------------------------------- def compute_nullable_nonterminals(self): nullable = set() num_nullable = 0 while True: for p in self.grammar.Productions[1:]: if p.len == 0: nullable.add(p.name) continue for t in p.prod: if t not in nullable: break else: nullable.add(p.name) if len(nullable) == num_nullable: break num_nullable = len(nullable) return nullable # ----------------------------------------------------------------------------- # find_nonterminal_trans(C) # # Given a set of LR(0) items, this functions finds all of the non-terminal # transitions. These are transitions in which a dot appears immediately before # a non-terminal. Returns a list of tuples of the form (state,N) where state # is the state number and N is the nonterminal symbol. # # The input C is the set of LR(0) items. # ----------------------------------------------------------------------------- def find_nonterminal_transitions(self, C): trans = [] for stateno, state in enumerate(C): for p in state: if p.lr_index < p.len - 1: t = (stateno, p.prod[p.lr_index+1]) if t[1] in self.grammar.Nonterminals: if t not in trans: trans.append(t) return trans # ----------------------------------------------------------------------------- # dr_relation() # # Computes the DR(p,A) relationships for non-terminal transitions. The input # is a tuple (state,N) where state is a number and N is a nonterminal symbol. # # Returns a list of terminals. # ----------------------------------------------------------------------------- def dr_relation(self, C, trans, nullable): dr_set = {} state, N = trans terms = [] g = self.lr0_goto(C[state], N) for p in g: if p.lr_index < p.len - 1: a = p.prod[p.lr_index+1] if a in self.grammar.Terminals: if a not in terms: terms.append(a) # This extra bit is to handle the start state if state == 0 and N == self.grammar.Productions[0].prod[0]: terms.append('$end') return terms # ----------------------------------------------------------------------------- # reads_relation() # # Computes the READS() relation (p,A) READS (t,C). # ----------------------------------------------------------------------------- def reads_relation(self, C, trans, empty): # Look for empty transitions rel = [] state, N = trans g = self.lr0_goto(C[state], N) j = self.lr0_cidhash.get(id(g), -1) for p in g: if p.lr_index < p.len - 1: a = p.prod[p.lr_index + 1] if a in empty: rel.append((j, a)) return rel # ----------------------------------------------------------------------------- # compute_lookback_includes() # # Determines the lookback and includes relations # # LOOKBACK: # # This relation is determined by running the LR(0) state machine forward. # For example, starting with a production "N : . A B C", we run it forward # to obtain "N : A B C ." We then build a relationship between this final # state and the starting state. These relationships are stored in a dictionary # lookdict. # # INCLUDES: # # Computes the INCLUDE() relation (p,A) INCLUDES (p',B). # # This relation is used to determine non-terminal transitions that occur # inside of other non-terminal transition states. (p,A) INCLUDES (p', B) # if the following holds: # # B -> LAT, where T -> epsilon and p' -L-> p # # L is essentially a prefix (which may be empty), T is a suffix that must be # able to derive an empty string. State p' must lead to state p with the string L. # # ----------------------------------------------------------------------------- def compute_lookback_includes(self, C, trans, nullable): lookdict = {} # Dictionary of lookback relations includedict = {} # Dictionary of include relations # Make a dictionary of non-terminal transitions dtrans = {} for t in trans: dtrans[t] = 1 # Loop over all transitions and compute lookbacks and includes for state, N in trans: lookb = [] includes = [] for p in C[state]: if p.name != N: continue # Okay, we have a name match. We now follow the production all the way # through the state machine until we get the . on the right hand side lr_index = p.lr_index j = state while lr_index < p.len - 1: lr_index = lr_index + 1 t = p.prod[lr_index] # Check to see if this symbol and state are a non-terminal transition if (j, t) in dtrans: # Yes. Okay, there is some chance that this is an includes relation # the only way to know for certain is whether the rest of the # production derives empty li = lr_index + 1 while li < p.len: if p.prod[li] in self.grammar.Terminals: break # No forget it if p.prod[li] not in nullable: break li = li + 1 else: # Appears to be a relation between (j,t) and (state,N) includes.append((j, t)) g = self.lr0_goto(C[j], t) # Go to next set j = self.lr0_cidhash.get(id(g), -1) # Go to next state # When we get here, j is the final state, now we have to locate the production for r in C[j]: if r.name != p.name: continue if r.len != p.len: continue i = 0 # This look is comparing a production ". A B C" with "A B C ." while i < r.lr_index: if r.prod[i] != p.prod[i+1]: break i = i + 1 else: lookb.append((j, r)) for i in includes: if i not in includedict: includedict[i] = [] includedict[i].append((state, N)) lookdict[(state, N)] = lookb return lookdict, includedict # ----------------------------------------------------------------------------- # compute_read_sets() # # Given a set of LR(0) items, this function computes the read sets. # # Inputs: C = Set of LR(0) items # ntrans = Set of nonterminal transitions # nullable = Set of empty transitions # # Returns a set containing the read sets # ----------------------------------------------------------------------------- def compute_read_sets(self, C, ntrans, nullable): FP = lambda x: self.dr_relation(C, x, nullable) R = lambda x: self.reads_relation(C, x, nullable) F = digraph(ntrans, R, FP) return F # ----------------------------------------------------------------------------- # compute_follow_sets() # # Given a set of LR(0) items, a set of non-terminal transitions, a readset, # and an include set, this function computes the follow sets # # Follow(p,A) = Read(p,A) U U {Follow(p',B) | (p,A) INCLUDES (p',B)} # # Inputs: # ntrans = Set of nonterminal transitions # readsets = Readset (previously computed) # inclsets = Include sets (previously computed) # # Returns a set containing the follow sets # ----------------------------------------------------------------------------- def compute_follow_sets(self, ntrans, readsets, inclsets): FP = lambda x: readsets[x] R = lambda x: inclsets.get(x, []) F = digraph(ntrans, R, FP) return F # ----------------------------------------------------------------------------- # add_lookaheads() # # Attaches the lookahead symbols to grammar rules. # # Inputs: lookbacks - Set of lookback relations # followset - Computed follow set # # This function directly attaches the lookaheads to productions contained # in the lookbacks set # ----------------------------------------------------------------------------- def add_lookaheads(self, lookbacks, followset): for trans, lb in lookbacks.items(): # Loop over productions in lookback for state, p in lb: if state not in p.lookaheads: p.lookaheads[state] = [] f = followset.get(trans, []) for a in f: if a not in p.lookaheads[state]: p.lookaheads[state].append(a) # ----------------------------------------------------------------------------- # add_lalr_lookaheads() # # This function does all of the work of adding lookahead information for use # with LALR parsing # ----------------------------------------------------------------------------- def add_lalr_lookaheads(self, C): # Determine all of the nullable nonterminals nullable = self.compute_nullable_nonterminals() # Find all non-terminal transitions trans = self.find_nonterminal_transitions(C) # Compute read sets readsets = self.compute_read_sets(C, trans, nullable) # Compute lookback/includes relations lookd, included = self.compute_lookback_includes(C, trans, nullable) # Compute LALR FOLLOW sets followsets = self.compute_follow_sets(trans, readsets, included) # Add all of the lookaheads self.add_lookaheads(lookd, followsets) # ----------------------------------------------------------------------------- # lr_parse_table() # # This function constructs the parse tables for SLR or LALR # ----------------------------------------------------------------------------- def lr_parse_table(self): Productions = self.grammar.Productions Precedence = self.grammar.Precedence goto = self.lr_goto # Goto array action = self.lr_action # Action array log = self.log # Logger for output actionp = {} # Action production array (temporary) log.info('Parsing method: %s', self.lr_method) # Step 1: Construct C = { I0, I1, ... IN}, collection of LR(0) items # This determines the number of states C = self.lr0_items() if self.lr_method == 'LALR': self.add_lalr_lookaheads(C) # Build the parser table, state by state st = 0 for I in C: # Loop over each production in I actlist = [] # List of actions st_action = {} st_actionp = {} st_goto = {} log.info('') log.info('state %d', st) log.info('') for p in I: log.info(' (%d) %s', p.number, p) log.info('') for p in I: if p.len == p.lr_index + 1: if p.name == "S'": # Start symbol. Accept! st_action['$end'] = 0 st_actionp['$end'] = p else: # We are at the end of a production. Reduce! if self.lr_method == 'LALR': laheads = p.lookaheads[st] else: laheads = self.grammar.Follow[p.name] for a in laheads: actlist.append((a, p, 'reduce using rule %d (%s)' % (p.number, p))) r = st_action.get(a) if r is not None: # Whoa. Have a shift/reduce or reduce/reduce conflict if r > 0: # Need to decide on shift or reduce here # By default we favor shifting. Need to add # some precedence rules here. sprec, slevel = Productions[st_actionp[a].number].prec rprec, rlevel = Precedence.get(a, ('right', 0)) if (slevel < rlevel) or ((slevel == rlevel) and (rprec == 'left')): # We really need to reduce here. st_action[a] = -p.number st_actionp[a] = p if not slevel and not rlevel: log.info(' ! shift/reduce conflict for %s resolved as reduce', a) self.sr_conflicts.append((st, a, 'reduce')) Productions[p.number].reduced += 1 elif (slevel == rlevel) and (rprec == 'nonassoc'): st_action[a] = None else: # Hmmm. Guess we'll keep the shift if not rlevel: log.info(' ! shift/reduce conflict for %s resolved as shift', a) self.sr_conflicts.append((st, a, 'shift')) elif r < 0: # Reduce/reduce conflict. In this case, we favor the rule # that was defined first in the grammar file oldp = Productions[-r] pp = Productions[p.number] if oldp.line > pp.line: st_action[a] = -p.number st_actionp[a] = p chosenp, rejectp = pp, oldp Productions[p.number].reduced += 1 Productions[oldp.number].reduced -= 1 else: chosenp, rejectp = oldp, pp self.rr_conflicts.append((st, chosenp, rejectp)) log.info(' ! reduce/reduce conflict for %s resolved using rule %d (%s)', a, st_actionp[a].number, st_actionp[a]) else: raise LALRError('Unknown conflict in state %d' % st) else: st_action[a] = -p.number st_actionp[a] = p Productions[p.number].reduced += 1 else: i = p.lr_index a = p.prod[i+1] # Get symbol right after the "." if a in self.grammar.Terminals: g = self.lr0_goto(I, a) j = self.lr0_cidhash.get(id(g), -1) if j >= 0: # We are in a shift state actlist.append((a, p, 'shift and go to state %d' % j)) r = st_action.get(a) if r is not None: # Whoa have a shift/reduce or shift/shift conflict if r > 0: if r != j: raise LALRError('Shift/shift conflict in state %d' % st) elif r < 0: # Do a precedence check. # - if precedence of reduce rule is higher, we reduce. # - if precedence of reduce is same and left assoc, we reduce. # - otherwise we shift rprec, rlevel = Productions[st_actionp[a].number].prec sprec, slevel = Precedence.get(a, ('right', 0)) if (slevel > rlevel) or ((slevel == rlevel) and (rprec == 'right')): # We decide to shift here... highest precedence to shift Productions[st_actionp[a].number].reduced -= 1 st_action[a] = j st_actionp[a] = p if not rlevel: log.info(' ! shift/reduce conflict for %s resolved as shift', a) self.sr_conflicts.append((st, a, 'shift')) elif (slevel == rlevel) and (rprec == 'nonassoc'): st_action[a] = None else: # Hmmm. Guess we'll keep the reduce if not slevel and not rlevel: log.info(' ! shift/reduce conflict for %s resolved as reduce', a) self.sr_conflicts.append((st, a, 'reduce')) else: raise LALRError('Unknown conflict in state %d' % st) else: st_action[a] = j st_actionp[a] = p # Print the actions associated with each terminal _actprint = {} for a, p, m in actlist: if a in st_action: if p is st_actionp[a]: log.info(' %-15s %s', a, m) _actprint[(a, m)] = 1 log.info('') # Print the actions that were not used. (debugging) not_used = 0 for a, p, m in actlist: if a in st_action: if p is not st_actionp[a]: if not (a, m) in _actprint: log.debug(' ! %-15s [ %s ]', a, m) not_used = 1 _actprint[(a, m)] = 1 if not_used: log.debug('') # Construct the goto table for this state nkeys = {} for ii in I: for s in ii.usyms: if s in self.grammar.Nonterminals: nkeys[s] = None for n in nkeys: g = self.lr0_goto(I, n) j = self.lr0_cidhash.get(id(g), -1) if j >= 0: st_goto[n] = j log.info(' %-30s shift and go to state %d', n, j) action[st] = st_action actionp[st] = st_actionp goto[st] = st_goto st += 1 # ----------------------------------------------------------------------------- # write() # # This function writes the LR parsing tables to a file # ----------------------------------------------------------------------------- def write_table(self, tabmodule, outputdir='', signature=''): if isinstance(tabmodule, types.ModuleType): raise IOError("Won't overwrite existing tabmodule") basemodulename = tabmodule.split('.')[-1] filename = os.path.join(outputdir, basemodulename) + '.py' try: f = open(filename, 'w') f.write(''' # %s # This file is automatically generated. Do not edit. _tabversion = %r _lr_method = %r _lr_signature = %r ''' % (os.path.basename(filename), __tabversion__, self.lr_method, signature)) # Change smaller to 0 to go back to original tables smaller = 1 # Factor out names to try and make smaller if smaller: items = {} for s, nd in self.lr_action.items(): for name, v in nd.items(): i = items.get(name) if not i: i = ([], []) items[name] = i i[0].append(s) i[1].append(v) f.write('\n_lr_action_items = {') for k, v in items.items(): f.write('%r:([' % k) for i in v[0]: f.write('%r,' % i) f.write('],[') for i in v[1]: f.write('%r,' % i) f.write(']),') f.write('}\n') f.write(''' _lr_action = {} for _k, _v in _lr_action_items.items(): for _x,_y in zip(_v[0],_v[1]): if not _x in _lr_action: _lr_action[_x] = {} _lr_action[_x][_k] = _y del _lr_action_items ''') else: f.write('\n_lr_action = { ') for k, v in self.lr_action.items(): f.write('(%r,%r):%r,' % (k[0], k[1], v)) f.write('}\n') if smaller: # Factor out names to try and make smaller items = {} for s, nd in self.lr_goto.items(): for name, v in nd.items(): i = items.get(name) if not i: i = ([], []) items[name] = i i[0].append(s) i[1].append(v) f.write('\n_lr_goto_items = {') for k, v in items.items(): f.write('%r:([' % k) for i in v[0]: f.write('%r,' % i) f.write('],[') for i in v[1]: f.write('%r,' % i) f.write(']),') f.write('}\n') f.write(''' _lr_goto = {} for _k, _v in _lr_goto_items.items(): for _x, _y in zip(_v[0], _v[1]): if not _x in _lr_goto: _lr_goto[_x] = {} _lr_goto[_x][_k] = _y del _lr_goto_items ''') else: f.write('\n_lr_goto = { ') for k, v in self.lr_goto.items(): f.write('(%r,%r):%r,' % (k[0], k[1], v)) f.write('}\n') # Write production table f.write('_lr_productions = [\n') for p in self.lr_productions: if p.func: f.write(' (%r,%r,%d,%r,%r,%d),\n' % (p.str, p.name, p.len, p.func, os.path.basename(p.file), p.line)) else: f.write(' (%r,%r,%d,None,None,None),\n' % (str(p), p.name, p.len)) f.write(']\n') f.close() except IOError as e: raise # ----------------------------------------------------------------------------- # pickle_table() # # This function pickles the LR parsing tables to a supplied file object # ----------------------------------------------------------------------------- def pickle_table(self, filename, signature=''): try: import cPickle as pickle except ImportError: import pickle with open(filename, 'wb') as outf: pickle.dump(__tabversion__, outf, pickle_protocol) pickle.dump(self.lr_method, outf, pickle_protocol) pickle.dump(signature, outf, pickle_protocol) pickle.dump(self.lr_action, outf, pickle_protocol) pickle.dump(self.lr_goto, outf, pickle_protocol) outp = [] for p in self.lr_productions: if p.func: outp.append((p.str, p.name, p.len, p.func, os.path.basename(p.file), p.line)) else: outp.append((str(p), p.name, p.len, None, None, None)) pickle.dump(outp, outf, pickle_protocol) # ----------------------------------------------------------------------------- # === INTROSPECTION === # # The following functions and classes are used to implement the PLY # introspection features followed by the yacc() function itself. # ----------------------------------------------------------------------------- # ----------------------------------------------------------------------------- # get_caller_module_dict() # # This function returns a dictionary containing all of the symbols defined within # a caller further down the call stack. This is used to get the environment # associated with the yacc() call if none was provided. # ----------------------------------------------------------------------------- def get_caller_module_dict(levels): f = sys._getframe(levels) ldict = f.f_globals.copy() if f.f_globals != f.f_locals: ldict.update(f.f_locals) return ldict # ----------------------------------------------------------------------------- # parse_grammar() # # This takes a raw grammar rule string and parses it into production data # ----------------------------------------------------------------------------- def parse_grammar(doc, file, line): grammar = [] # Split the doc string into lines pstrings = doc.splitlines() lastp = None dline = line for ps in pstrings: dline += 1 p = ps.split() if not p: continue try: if p[0] == '|': # This is a continuation of a previous rule if not lastp: raise SyntaxError("%s:%d: Misplaced '|'" % (file, dline)) prodname = lastp syms = p[1:] else: prodname = p[0] lastp = prodname syms = p[2:] assign = p[1] if assign != ':' and assign != '::=': raise SyntaxError("%s:%d: Syntax error. Expected ':'" % (file, dline)) grammar.append((file, dline, prodname, syms)) except SyntaxError: raise except Exception: raise SyntaxError('%s:%d: Syntax error in rule %r' % (file, dline, ps.strip())) return grammar # ----------------------------------------------------------------------------- # ParserReflect() # # This class represents information extracted for building a parser including # start symbol, error function, tokens, precedence list, action functions, # etc. # ----------------------------------------------------------------------------- class ParserReflect(object): def __init__(self, pdict, log=None): self.pdict = pdict self.start = None self.error_func = None self.tokens = None self.modules = set() self.grammar = [] self.error = False if log is None: self.log = PlyLogger(sys.stderr) else: self.log = log # Get all of the basic information def get_all(self): self.get_start() self.get_error_func() self.get_tokens() self.get_precedence() self.get_pfunctions() # Validate all of the information def validate_all(self): self.validate_start() self.validate_error_func() self.validate_tokens() self.validate_precedence() self.validate_pfunctions() self.validate_modules() return self.error # Compute a signature over the grammar def signature(self): try: from hashlib import md5 except ImportError: from md5 import md5 try: sig = md5() if self.start: sig.update(self.start.encode('latin-1')) if self.prec: sig.update(''.join([''.join(p) for p in self.prec]).encode('latin-1')) if self.tokens: sig.update(' '.join(self.tokens).encode('latin-1')) for f in self.pfuncs: if f[3]: sig.update(f[3].encode('latin-1')) except (TypeError, ValueError): pass digest = base64.b16encode(sig.digest()) if sys.version_info[0] >= 3: digest = digest.decode('latin-1') return digest # ----------------------------------------------------------------------------- # validate_modules() # # This method checks to see if there are duplicated p_rulename() functions # in the parser module file. Without this function, it is really easy for # users to make mistakes by cutting and pasting code fragments (and it's a real # bugger to try and figure out why the resulting parser doesn't work). Therefore, # we just do a little regular expression pattern matching of def statements # to try and detect duplicates. # ----------------------------------------------------------------------------- def validate_modules(self): # Match def p_funcname( fre = re.compile(r'\s*def\s+(p_[a-zA-Z_0-9]*)\(') for module in self.modules: lines, linen = inspect.getsourcelines(module) counthash = {} for linen, line in enumerate(lines): linen += 1 m = fre.match(line) if m: name = m.group(1) prev = counthash.get(name) if not prev: counthash[name] = linen else: filename = inspect.getsourcefile(module) self.log.warning('%s:%d: Function %s redefined. Previously defined on line %d', filename, linen, name, prev) # Get the start symbol def get_start(self): self.start = self.pdict.get('start') # Validate the start symbol def validate_start(self): if self.start is not None: if not isinstance(self.start, string_types): self.log.error("'start' must be a string") # Look for error handler def get_error_func(self): self.error_func = self.pdict.get('p_error') # Validate the error function def validate_error_func(self): if self.error_func: if isinstance(self.error_func, types.FunctionType): ismethod = 0 elif isinstance(self.error_func, types.MethodType): ismethod = 1 else: self.log.error("'p_error' defined, but is not a function or method") self.error = True return eline = self.error_func.__code__.co_firstlineno efile = self.error_func.__code__.co_filename module = inspect.getmodule(self.error_func) self.modules.add(module) argcount = self.error_func.__code__.co_argcount - ismethod if argcount != 1: self.log.error('%s:%d: p_error() requires 1 argument', efile, eline) self.error = True # Get the tokens map def get_tokens(self): tokens = self.pdict.get('tokens') if not tokens: self.log.error('No token list is defined') self.error = True return if not isinstance(tokens, (list, tuple)): self.log.error('tokens must be a list or tuple') self.error = True return if not tokens: self.log.error('tokens is empty') self.error = True return self.tokens = tokens # Validate the tokens def validate_tokens(self): # Validate the tokens. if 'error' in self.tokens: self.log.error("Illegal token name 'error'. Is a reserved word") self.error = True return terminals = set() for n in self.tokens: if n in terminals: self.log.warning('Token %r multiply defined', n) terminals.add(n) # Get the precedence map (if any) def get_precedence(self): self.prec = self.pdict.get('precedence') # Validate and parse the precedence map def validate_precedence(self): preclist = [] if self.prec: if not isinstance(self.prec, (list, tuple)): self.log.error('precedence must be a list or tuple') self.error = True return for level, p in enumerate(self.prec): if not isinstance(p, (list, tuple)): self.log.error('Bad precedence table') self.error = True return if len(p) < 2: self.log.error('Malformed precedence entry %s. Must be (assoc, term, ..., term)', p) self.error = True return assoc = p[0] if not isinstance(assoc, string_types): self.log.error('precedence associativity must be a string') self.error = True return for term in p[1:]: if not isinstance(term, string_types): self.log.error('precedence items must be strings') self.error = True return preclist.append((term, assoc, level+1)) self.preclist = preclist # Get all p_functions from the grammar def get_pfunctions(self): p_functions = [] for name, item in self.pdict.items(): if not name.startswith('p_') or name == 'p_error': continue if isinstance(item, (types.FunctionType, types.MethodType)): line = item.__code__.co_firstlineno module = inspect.getmodule(item) p_functions.append((line, module, name, item.__doc__)) # Sort all of the actions by line number; make sure to stringify # modules to make them sortable, since `line` may not uniquely sort all # p functions p_functions.sort(key=lambda p_function: ( p_function[0], str(p_function[1]), p_function[2], p_function[3])) self.pfuncs = p_functions # Validate all of the p_functions def validate_pfunctions(self): grammar = [] # Check for non-empty symbols if len(self.pfuncs) == 0: self.log.error('no rules of the form p_rulename are defined') self.error = True return for line, module, name, doc in self.pfuncs: file = inspect.getsourcefile(module) func = self.pdict[name] if isinstance(func, types.MethodType): reqargs = 2 else: reqargs = 1 if func.__code__.co_argcount > reqargs: self.log.error('%s:%d: Rule %r has too many arguments', file, line, func.__name__) self.error = True elif func.__code__.co_argcount < reqargs: self.log.error('%s:%d: Rule %r requires an argument', file, line, func.__name__) self.error = True elif not func.__doc__: self.log.warning('%s:%d: No documentation string specified in function %r (ignored)', file, line, func.__name__) else: try: parsed_g = parse_grammar(doc, file, line) for g in parsed_g: grammar.append((name, g)) except SyntaxError as e: self.log.error(str(e)) self.error = True # Looks like a valid grammar rule # Mark the file in which defined. self.modules.add(module) # Secondary validation step that looks for p_ definitions that are not functions # or functions that look like they might be grammar rules. for n, v in self.pdict.items(): if n.startswith('p_') and isinstance(v, (types.FunctionType, types.MethodType)): continue if n.startswith('t_'): continue if n.startswith('p_') and n != 'p_error': self.log.warning('%r not defined as a function', n) if ((isinstance(v, types.FunctionType) and v.__code__.co_argcount == 1) or (isinstance(v, types.MethodType) and v.__func__.__code__.co_argcount == 2)): if v.__doc__: try: doc = v.__doc__.split(' ') if doc[1] == ':': self.log.warning('%s:%d: Possible grammar rule %r defined without p_ prefix', v.__code__.co_filename, v.__code__.co_firstlineno, n) except IndexError: pass self.grammar = grammar # ----------------------------------------------------------------------------- # yacc(module) # # Build a parser # ----------------------------------------------------------------------------- def yacc(method='LALR', debug=yaccdebug, module=None, tabmodule=tab_module, start=None, check_recursion=True, optimize=False, write_tables=True, debugfile=debug_file, outputdir=None, debuglog=None, errorlog=None, picklefile=None): if tabmodule is None: tabmodule = tab_module # Reference to the parsing method of the last built parser global parse # If pickling is enabled, table files are not created if picklefile: write_tables = 0 if errorlog is None: errorlog = PlyLogger(sys.stderr) # Get the module dictionary used for the parser if module: _items = [(k, getattr(module, k)) for k in dir(module)] pdict = dict(_items) # If no __file__ attribute is available, try to obtain it from the __module__ instead if '__file__' not in pdict: pdict['__file__'] = sys.modules[pdict['__module__']].__file__ else: pdict = get_caller_module_dict(2) if outputdir is None: # If no output directory is set, the location of the output files # is determined according to the following rules: # - If tabmodule specifies a package, files go into that package directory # - Otherwise, files go in the same directory as the specifying module if isinstance(tabmodule, types.ModuleType): srcfile = tabmodule.__file__ else: if '.' not in tabmodule: srcfile = pdict['__file__'] else: parts = tabmodule.split('.') pkgname = '.'.join(parts[:-1]) exec('import %s' % pkgname) srcfile = getattr(sys.modules[pkgname], '__file__', '') outputdir = os.path.dirname(srcfile) # Determine if the module is package of a package or not. # If so, fix the tabmodule setting so that tables load correctly pkg = pdict.get('__package__') if pkg and isinstance(tabmodule, str): if '.' not in tabmodule: tabmodule = pkg + '.' + tabmodule # Set start symbol if it's specified directly using an argument if start is not None: pdict['start'] = start # Collect parser information from the dictionary pinfo = ParserReflect(pdict, log=errorlog) pinfo.get_all() if pinfo.error: raise YaccError('Unable to build parser') # Check signature against table files (if any) signature = pinfo.signature() # Read the tables try: lr = LRTable() if picklefile: read_signature = lr.read_pickle(picklefile) else: read_signature = lr.read_table(tabmodule) if optimize or (read_signature == signature): try: lr.bind_callables(pinfo.pdict) parser = LRParser(lr, pinfo.error_func) parse = parser.parse return parser except Exception as e: errorlog.warning('There was a problem loading the table file: %r', e) except VersionError as e: errorlog.warning(str(e)) except ImportError: pass if debuglog is None: if debug: try: debuglog = PlyLogger(open(os.path.join(outputdir, debugfile), 'w')) except IOError as e: errorlog.warning("Couldn't open %r. %s" % (debugfile, e)) debuglog = NullLogger() else: debuglog = NullLogger() debuglog.info('Created by PLY version %s (http://www.dabeaz.com/ply)', __version__) errors = False # Validate the parser information if pinfo.validate_all(): raise YaccError('Unable to build parser') if not pinfo.error_func: errorlog.warning('no p_error() function is defined') # Create a grammar object grammar = Grammar(pinfo.tokens) # Set precedence level for terminals for term, assoc, level in pinfo.preclist: try: grammar.set_precedence(term, assoc, level) except GrammarError as e: errorlog.warning('%s', e) # Add productions to the grammar for funcname, gram in pinfo.grammar: file, line, prodname, syms = gram try: grammar.add_production(prodname, syms, funcname, file, line) except GrammarError as e: errorlog.error('%s', e) errors = True # Set the grammar start symbols try: if start is None: grammar.set_start(pinfo.start) else: grammar.set_start(start) except GrammarError as e: errorlog.error(str(e)) errors = True if errors: raise YaccError('Unable to build parser') # Verify the grammar structure undefined_symbols = grammar.undefined_symbols() for sym, prod in undefined_symbols: errorlog.error('%s:%d: Symbol %r used, but not defined as a token or a rule', prod.file, prod.line, sym) errors = True unused_terminals = grammar.unused_terminals() if unused_terminals: debuglog.info('') debuglog.info('Unused terminals:') debuglog.info('') for term in unused_terminals: errorlog.warning('Token %r defined, but not used', term) debuglog.info(' %s', term) # Print out all productions to the debug log if debug: debuglog.info('') debuglog.info('Grammar') debuglog.info('') for n, p in enumerate(grammar.Productions): debuglog.info('Rule %-5d %s', n, p) # Find unused non-terminals unused_rules = grammar.unused_rules() for prod in unused_rules: errorlog.warning('%s:%d: Rule %r defined, but not used', prod.file, prod.line, prod.name) if len(unused_terminals) == 1: errorlog.warning('There is 1 unused token') if len(unused_terminals) > 1: errorlog.warning('There are %d unused tokens', len(unused_terminals)) if len(unused_rules) == 1: errorlog.warning('There is 1 unused rule') if len(unused_rules) > 1: errorlog.warning('There are %d unused rules', len(unused_rules)) if debug: debuglog.info('') debuglog.info('Terminals, with rules where they appear') debuglog.info('') terms = list(grammar.Terminals) terms.sort() for term in terms: debuglog.info('%-20s : %s', term, ' '.join([str(s) for s in grammar.Terminals[term]])) debuglog.info('') debuglog.info('Nonterminals, with rules where they appear') debuglog.info('') nonterms = list(grammar.Nonterminals) nonterms.sort() for nonterm in nonterms: debuglog.info('%-20s : %s', nonterm, ' '.join([str(s) for s in grammar.Nonterminals[nonterm]])) debuglog.info('') if check_recursion: unreachable = grammar.find_unreachable() for u in unreachable: errorlog.warning('Symbol %r is unreachable', u) infinite = grammar.infinite_cycles() for inf in infinite: errorlog.error('Infinite recursion detected for symbol %r', inf) errors = True unused_prec = grammar.unused_precedence() for term, assoc in unused_prec: errorlog.error('Precedence rule %r defined for unknown symbol %r', assoc, term) errors = True if errors: raise YaccError('Unable to build parser') # Run the LRGeneratedTable on the grammar if debug: errorlog.debug('Generating %s tables', method) lr = LRGeneratedTable(grammar, method, debuglog) if debug: num_sr = len(lr.sr_conflicts) # Report shift/reduce and reduce/reduce conflicts if num_sr == 1: errorlog.warning('1 shift/reduce conflict') elif num_sr > 1: errorlog.warning('%d shift/reduce conflicts', num_sr) num_rr = len(lr.rr_conflicts) if num_rr == 1: errorlog.warning('1 reduce/reduce conflict') elif num_rr > 1: errorlog.warning('%d reduce/reduce conflicts', num_rr) # Write out conflicts to the output file if debug and (lr.sr_conflicts or lr.rr_conflicts): debuglog.warning('') debuglog.warning('Conflicts:') debuglog.warning('') for state, tok, resolution in lr.sr_conflicts: debuglog.warning('shift/reduce conflict for %s in state %d resolved as %s', tok, state, resolution) already_reported = set() for state, rule, rejected in lr.rr_conflicts: if (state, id(rule), id(rejected)) in already_reported: continue debuglog.warning('reduce/reduce conflict in state %d resolved using rule (%s)', state, rule) debuglog.warning('rejected rule (%s) in state %d', rejected, state) errorlog.warning('reduce/reduce conflict in state %d resolved using rule (%s)', state, rule) errorlog.warning('rejected rule (%s) in state %d', rejected, state) already_reported.add((state, id(rule), id(rejected))) warned_never = [] for state, rule, rejected in lr.rr_conflicts: if not rejected.reduced and (rejected not in warned_never): debuglog.warning('Rule (%s) is never reduced', rejected) errorlog.warning('Rule (%s) is never reduced', rejected) warned_never.append(rejected) # Write the table file if requested if write_tables: try: lr.write_table(tabmodule, outputdir, signature) except IOError as e: errorlog.warning("Couldn't create %r. %s" % (tabmodule, e)) # Write a pickled version of the tables if picklefile: try: lr.pickle_table(picklefile, signature) except IOError as e: errorlog.warning("Couldn't create %r. %s" % (picklefile, e)) # Build the parser lr.bind_callables(pinfo.pdict) parser = LRParser(lr, pinfo.error_func) parse = parser.parse return parser