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# ----------------------------------------------------------------------------- 

# ply: yacc.py 

# 

# Copyright (C) 2001-2018 

# 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 grammar 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 warnings 

 

__version__ = '3.11' 

__tabversion__ = '3.10' 

 

#----------------------------------------------------------------------------- 

# === 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 

95 ↛ 96line 95 didn't jump to line 96, because the condition on line 95 was never trueif 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 set_lexpos(self, n, lexpos): 

self.slice[n].lexpos = lexpos 

 

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:] 

self.state = state 

p.callable(pslice) 

del statestack[-plen:] 

#--! 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) # Save the current lookahead token 

symstack.extend(targ[1:-1]) # Put the production slice back on the stack 

statestack.pop() # Pop back one state (before the reduce) 

state = statestack[-1] 

sym.type = 'error' 

sym.value = '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 

self.state = state 

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) # Save the current lookahead token 

statestack.pop() # Pop back one state (before the reduce) 

state = statestack[-1] 

sym.type = 'error' 

sym.value = '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 

self.state = state 

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:] 

self.state = state 

p.callable(pslice) 

del statestack[-plen:] 

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) # Save the current lookahead token 

symstack.extend(targ[1:-1]) # Put the production slice back on the stack 

statestack.pop() # Pop back one state (before the reduce) 

state = statestack[-1] 

sym.type = 'error' 

sym.value = '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 

self.state = state 

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) # Save the current lookahead token 

statestack.pop() # Pop back one state (before the reduce) 

state = statestack[-1] 

sym.type = 'error' 

sym.value = '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 

self.state = state 

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:] 

self.state = state 

p.callable(pslice) 

del statestack[-plen:] 

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) # Save the current lookahead token 

symstack.extend(targ[1:-1]) # Put the production slice back on the stack 

statestack.pop() # Pop back one state (before the reduce) 

state = statestack[-1] 

sym.type = 'error' 

sym.value = '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 

self.state = state 

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) # Save the current lookahead token 

statestack.pop() # Pop back one state (before the reduce) 

state = statestack[-1] 

sym.type = 'error' 

sym.value = '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 

self.state = state 

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 = self.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): 

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. 

 

# Shift precedence comes from the token 

sprec, slevel = Precedence.get(a, ('right', 0)) 

 

# Reduce precedence comes from rule being reduced (p) 

rprec, rlevel = Productions[p.number].prec 

 

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 

 

# Shift precedence comes from the token 

sprec, slevel = Precedence.get(a, ('right', 0)) 

 

# Reduce precedence comes from the rule that could have been reduced 

rprec, rlevel = Productions[st_actionp[a].number].prec 

 

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. 

# pylint: disable=W,C,R 

_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): 

parts = [] 

try: 

if self.start: 

parts.append(self.start) 

if self.prec: 

parts.append(''.join([''.join(p) for p in self.prec])) 

if self.tokens: 

parts.append(' '.join(self.tokens)) 

for f in self.pfuncs: 

if f[3]: 

parts.append(f[3]) 

except (TypeError, ValueError): 

pass 

return ''.join(parts) 

 

# ----------------------------------------------------------------------------- 

# 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: 

try: 

lines, linen = inspect.getsourcelines(module) 

except IOError: 

continue 

 

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 = sorted(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 = getattr(item, 'co_firstlineno', 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__ or __package__ attributes are available, try to obtain them 

# from the __module__ instead 

if '__file__' not in pdict: 

pdict['__file__'] = sys.modules[pdict['__module__']].__file__ 

if '__package__' not in pdict and '__module__' in pdict: 

if hasattr(sys.modules[pdict['__module__']], '__package__'): 

pdict['__package__'] = sys.modules[pdict['__module__']].__package__ 

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) 

if tabmodule in sys.modules: 

del sys.modules[tabmodule] 

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