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wireshark/tools/yacc.py
Balint Reczey d04be0149d Ply parser updated to 3.8 from http://www.dabeaz.com/ply/ 
The Ubuntu packaged Ply 3.7 with Ubuntu 16.04's Python makes
ASN.1 based dissector generation fail.

Ply's API changed after 3.5 and the small change to asn2wrs.py
adapts to that.
The commit breaking the API in Ply's repository is the following:

 commit af651673ba6117a0a5405055a92170fffd028106
 Author: David Beazley <dave@dabeaz.com>
 Date:   Tue Apr 21 16:31:32 2015 -0500

    Added optional support for defaulted states

Change-Id: I1db33fdcccf7c39ecdb0e435a5ea9183362471ad
Bug: 12621
Reviewed-on: https://code.wireshark.org/review/16864
Reviewed-by: Balint Reczey <balint@balintreczey.hu>
Petri-Dish: Balint Reczey <balint@balintreczey.hu>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: João Valverde <j@v6e.pt>
Tested-by: João Valverde <j@v6e.pt>
2016-08-04 08:20:24 +00:00

3472 lines
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# -----------------------------------------------------------------------------
# ply: yacc.py
#
# Copyright (C) 2001-2015,
# David M. Beazley (Dabeaz LLC)
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
# * Neither the name of the David Beazley or Dabeaz LLC may be used to
# endorse or promote products derived from this software without
# specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
# -----------------------------------------------------------------------------
#
# This implements an LR parser that is constructed from grammar rules defined
# as Python functions. The grammer is specified by supplying the BNF inside
# Python documentation strings. The inspiration for this technique was borrowed
# from John Aycock's Spark parsing system. PLY might be viewed as cross between
# Spark and the GNU bison utility.
#
# The current implementation is only somewhat object-oriented. The
# LR parser itself is defined in terms of an object (which allows multiple
# parsers to co-exist). However, most of the variables used during table
# construction are defined in terms of global variables. Users shouldn't
# notice unless they are trying to define multiple parsers at the same
# time using threads (in which case they should have their head examined).
#
# This implementation supports both SLR and LALR(1) parsing. LALR(1)
# support was originally implemented by Elias Ioup (ezioup@alumni.uchicago.edu),
# using the algorithm found in Aho, Sethi, and Ullman "Compilers: Principles,
# Techniques, and Tools" (The Dragon Book). LALR(1) has since been replaced
# by the more efficient DeRemer and Pennello algorithm.
#
# :::::::: WARNING :::::::
#
# Construction of LR parsing tables is fairly complicated and expensive.
# To make this module run fast, a *LOT* of work has been put into
# optimization---often at the expensive of readability and what might
# consider to be good Python "coding style." Modify the code at your
# own risk!
# ----------------------------------------------------------------------------
import re
import types
import sys
import os.path
import inspect
import base64
import warnings
__version__ = '3.8'
__tabversion__ = '3.8'
#-----------------------------------------------------------------------------
# === User configurable parameters ===
#
# Change these to modify the default behavior of yacc (if you wish)
#-----------------------------------------------------------------------------
yaccdebug = True # Debugging mode. If set, yacc generates a
# a 'parser.out' file in the current directory
debug_file = 'parser.out' # Default name of the debugging file
tab_module = 'parsetab' # Default name of the table module
default_lr = 'LALR' # Default LR table generation method
error_count = 3 # Number of symbols that must be shifted to leave recovery mode
yaccdevel = False # Set to True if developing yacc. This turns off optimized
# implementations of certain functions.
resultlimit = 40 # Size limit of results when running in debug mode.
pickle_protocol = 0 # Protocol to use when writing pickle files
# String type-checking compatibility
if sys.version_info[0] < 3:
string_types = basestring
else:
string_types = str
MAXINT = sys.maxsize
# This object is a stand-in for a logging object created by the
# logging module. PLY will use this by default to create things
# such as the parser.out file. If a user wants more detailed
# information, they can create their own logging object and pass
# it into PLY.
class PlyLogger(object):
def __init__(self, f):
self.f = f
def debug(self, msg, *args, **kwargs):
self.f.write((msg % args) + '\n')
info = debug
def warning(self, msg, *args, **kwargs):
self.f.write('WARNING: ' + (msg % args) + '\n')
def error(self, msg, *args, **kwargs):
self.f.write('ERROR: ' + (msg % args) + '\n')
critical = debug
# Null logger is used when no output is generated. Does nothing.
class NullLogger(object):
def __getattribute__(self, name):
return self
def __call__(self, *args, **kwargs):
return self
# Exception raised for yacc-related errors
class YaccError(Exception):
pass
# Format the result message that the parser produces when running in debug mode.
def format_result(r):
repr_str = repr(r)
if '\n' in repr_str:
repr_str = repr(repr_str)
if len(repr_str) > resultlimit:
repr_str = repr_str[:resultlimit] + ' ...'
result = '<%s @ 0x%x> (%s)' % (type(r).__name__, id(r), repr_str)
return result
# Format stack entries when the parser is running in debug mode
def format_stack_entry(r):
repr_str = repr(r)
if '\n' in repr_str:
repr_str = repr(repr_str)
if len(repr_str) < 16:
return repr_str
else:
return '<%s @ 0x%x>' % (type(r).__name__, id(r))
# Panic mode error recovery support. This feature is being reworked--much of the
# code here is to offer a deprecation/backwards compatible transition
_errok = None
_token = None
_restart = None
_warnmsg = '''PLY: Don't use global functions errok(), token(), and restart() in p_error().
Instead, invoke the methods on the associated parser instance:
def p_error(p):
...
# Use parser.errok(), parser.token(), parser.restart()
...
parser = yacc.yacc()
'''
def errok():
warnings.warn(_warnmsg)
return _errok()
def restart():
warnings.warn(_warnmsg)
return _restart()
def token():
warnings.warn(_warnmsg)
return _token()
# Utility function to call the p_error() function with some deprecation hacks
def call_errorfunc(errorfunc, token, parser):
global _errok, _token, _restart
_errok = parser.errok
_token = parser.token
_restart = parser.restart
r = errorfunc(token)
try:
del _errok, _token, _restart
except NameError:
pass
return r
#-----------------------------------------------------------------------------
# === LR Parsing Engine ===
#
# The following classes are used for the LR parser itself. These are not
# used during table construction and are independent of the actual LR
# table generation algorithm
#-----------------------------------------------------------------------------
# This class is used to hold non-terminal grammar symbols during parsing.
# It normally has the following attributes set:
# .type = Grammar symbol type
# .value = Symbol value
# .lineno = Starting line number
# .endlineno = Ending line number (optional, set automatically)
# .lexpos = Starting lex position
# .endlexpos = Ending lex position (optional, set automatically)
class YaccSymbol:
def __str__(self):
return self.type
def __repr__(self):
return str(self)
# This class is a wrapper around the objects actually passed to each
# grammar rule. Index lookup and assignment actually assign the
# .value attribute of the underlying YaccSymbol object.
# The lineno() method returns the line number of a given
# item (or 0 if not defined). The linespan() method returns
# a tuple of (startline,endline) representing the range of lines
# for a symbol. The lexspan() method returns a tuple (lexpos,endlexpos)
# representing the range of positional information for a symbol.
class YaccProduction:
def __init__(self, s, stack=None):
self.slice = s
self.stack = stack
self.lexer = None
self.parser = None
def __getitem__(self, n):
if isinstance(n, slice):
return [s.value for s in self.slice[n]]
elif n >= 0:
return self.slice[n].value
else:
return self.stack[n].value
def __setitem__(self, n, v):
self.slice[n].value = v
def __getslice__(self, i, j):
return [s.value for s in self.slice[i:j]]
def __len__(self):
return len(self.slice)
def lineno(self, n):
return getattr(self.slice[n], 'lineno', 0)
def set_lineno(self, n, lineno):
self.slice[n].lineno = lineno
def linespan(self, n):
startline = getattr(self.slice[n], 'lineno', 0)
endline = getattr(self.slice[n], 'endlineno', startline)
return startline, endline
def lexpos(self, n):
return getattr(self.slice[n], 'lexpos', 0)
def lexspan(self, n):
startpos = getattr(self.slice[n], 'lexpos', 0)
endpos = getattr(self.slice[n], 'endlexpos', startpos)
return startpos, endpos
def error(self):
raise SyntaxError
# -----------------------------------------------------------------------------
# == LRParser ==
#
# The LR Parsing engine.
# -----------------------------------------------------------------------------
class LRParser:
def __init__(self, lrtab, errorf):
self.productions = lrtab.lr_productions
self.action = lrtab.lr_action
self.goto = lrtab.lr_goto
self.errorfunc = errorf
self.set_defaulted_states()
self.errorok = True
def errok(self):
self.errorok = True
def restart(self):
del self.statestack[:]
del self.symstack[:]
sym = YaccSymbol()
sym.type = '$end'
self.symstack.append(sym)
self.statestack.append(0)
# Defaulted state support.
# This method identifies parser states where there is only one possible reduction action.
# For such states, the parser can make a choose to make a rule reduction without consuming
# the next look-ahead token. This delayed invocation of the tokenizer can be useful in
# certain kinds of advanced parsing situations where the lexer and parser interact with
# each other or change states (i.e., manipulation of scope, lexer states, etc.).
#
# See: http://www.gnu.org/software/bison/manual/html_node/Default-Reductions.html#Default-Reductions
def set_defaulted_states(self):
self.defaulted_states = {}
for state, actions in self.action.items():
rules = list(actions.values())
if len(rules) == 1 and rules[0] < 0:
self.defaulted_states[state] = rules[0]
def disable_defaulted_states(self):
self.defaulted_states = {}
def parse(self, input=None, lexer=None, debug=False, tracking=False, tokenfunc=None):
if debug or yaccdevel:
if isinstance(debug, int):
debug = PlyLogger(sys.stderr)
return self.parsedebug(input, lexer, debug, tracking, tokenfunc)
elif tracking:
return self.parseopt(input, lexer, debug, tracking, tokenfunc)
else:
return self.parseopt_notrack(input, lexer, debug, tracking, tokenfunc)
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
# parsedebug().
#
# This is the debugging enabled version of parse(). All changes made to the
# parsing engine should be made here. Optimized versions of this function
# are automatically created by the ply/ygen.py script. This script cuts out
# sections enclosed in markers such as this:
#
# #--! DEBUG
# statements
# #--! DEBUG
#
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
def parsedebug(self, input=None, lexer=None, debug=False, tracking=False, tokenfunc=None):
#--! parsedebug-start
lookahead = None # Current lookahead symbol
lookaheadstack = [] # Stack of lookahead symbols
actions = self.action # Local reference to action table (to avoid lookup on self.)
goto = self.goto # Local reference to goto table (to avoid lookup on self.)
prod = self.productions # Local reference to production list (to avoid lookup on self.)
defaulted_states = self.defaulted_states # Local reference to defaulted states
pslice = YaccProduction(None) # Production object passed to grammar rules
errorcount = 0 # Used during error recovery
#--! DEBUG
debug.info('PLY: PARSE DEBUG START')
#--! DEBUG
# If no lexer was given, we will try to use the lex module
if not lexer:
from . import lex
lexer = lex.lexer
# Set up the lexer and parser objects on pslice
pslice.lexer = lexer
pslice.parser = self
# If input was supplied, pass to lexer
if input is not None:
lexer.input(input)
if tokenfunc is None:
# Tokenize function
get_token = lexer.token
else:
get_token = tokenfunc
# Set the parser() token method (sometimes used in error recovery)
self.token = get_token
# Set up the state and symbol stacks
statestack = [] # Stack of parsing states
self.statestack = statestack
symstack = [] # Stack of grammar symbols
self.symstack = symstack
pslice.stack = symstack # Put in the production
errtoken = None # Err token
# The start state is assumed to be (0,$end)
statestack.append(0)
sym = YaccSymbol()
sym.type = '$end'
symstack.append(sym)
state = 0
while True:
# Get the next symbol on the input. If a lookahead symbol
# is already set, we just use that. Otherwise, we'll pull
# the next token off of the lookaheadstack or from the lexer
#--! DEBUG
debug.debug('')
debug.debug('State : %s', state)
#--! DEBUG
if state not in defaulted_states:
if not lookahead:
if not lookaheadstack:
lookahead = get_token() # Get the next token
else:
lookahead = lookaheadstack.pop()
if not lookahead:
lookahead = YaccSymbol()
lookahead.type = '$end'
# Check the action table
ltype = lookahead.type
t = actions[state].get(ltype)
else:
t = defaulted_states[state]
#--! DEBUG
debug.debug('Defaulted state %s: Reduce using %d', state, -t)
#--! DEBUG
#--! DEBUG
debug.debug('Stack : %s',
('%s . %s' % (' '.join([xx.type for xx in symstack][1:]), str(lookahead))).lstrip())
#--! DEBUG
if t is not None:
if t > 0:
# shift a symbol on the stack
statestack.append(t)
state = t
#--! DEBUG
debug.debug('Action : Shift and goto state %s', t)
#--! DEBUG
symstack.append(lookahead)
lookahead = None
# Decrease error count on successful shift
if errorcount:
errorcount -= 1
continue
if t < 0:
# reduce a symbol on the stack, emit a production
p = prod[-t]
pname = p.name
plen = p.len
# Get production function
sym = YaccSymbol()
sym.type = pname # Production name
sym.value = None
#--! DEBUG
if plen:
debug.info('Action : Reduce rule [%s] with %s and goto state %d', p.str,
'['+','.join([format_stack_entry(_v.value) for _v in symstack[-plen:]])+']',
goto[statestack[-1-plen]][pname])
else:
debug.info('Action : Reduce rule [%s] with %s and goto state %d', p.str, [],
goto[statestack[-1]][pname])
#--! DEBUG
if plen:
targ = symstack[-plen-1:]
targ[0] = sym
#--! TRACKING
if tracking:
t1 = targ[1]
sym.lineno = t1.lineno
sym.lexpos = t1.lexpos
t1 = targ[-1]
sym.endlineno = getattr(t1, 'endlineno', t1.lineno)
sym.endlexpos = getattr(t1, 'endlexpos', t1.lexpos)
#--! TRACKING
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
# The code enclosed in this section is duplicated
# below as a performance optimization. Make sure
# changes get made in both locations.
pslice.slice = targ
try:
# Call the grammar rule with our special slice object
del symstack[-plen:]
del statestack[-plen:]
p.callable(pslice)
#--! DEBUG
debug.info('Result : %s', format_result(pslice[0]))
#--! DEBUG
symstack.append(sym)
state = goto[statestack[-1]][pname]
statestack.append(state)
except SyntaxError:
# If an error was set. Enter error recovery state
lookaheadstack.append(lookahead)
symstack.pop()
statestack.pop()
state = statestack[-1]
sym.type = 'error'
lookahead = sym
errorcount = error_count
self.errorok = False
continue
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
else:
#--! TRACKING
if tracking:
sym.lineno = lexer.lineno
sym.lexpos = lexer.lexpos
#--! TRACKING
targ = [sym]
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
# The code enclosed in this section is duplicated
# above as a performance optimization. Make sure
# changes get made in both locations.
pslice.slice = targ
try:
# Call the grammar rule with our special slice object
p.callable(pslice)
#--! DEBUG
debug.info('Result : %s', format_result(pslice[0]))
#--! DEBUG
symstack.append(sym)
state = goto[statestack[-1]][pname]
statestack.append(state)
except SyntaxError:
# If an error was set. Enter error recovery state
lookaheadstack.append(lookahead)
symstack.pop()
statestack.pop()
state = statestack[-1]
sym.type = 'error'
lookahead = sym
errorcount = error_count
self.errorok = False
continue
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
if t == 0:
n = symstack[-1]
result = getattr(n, 'value', None)
#--! DEBUG
debug.info('Done : Returning %s', format_result(result))
debug.info('PLY: PARSE DEBUG END')
#--! DEBUG
return result
if t is None:
#--! DEBUG
debug.error('Error : %s',
('%s . %s' % (' '.join([xx.type for xx in symstack][1:]), str(lookahead))).lstrip())
#--! DEBUG
# We have some kind of parsing error here. To handle
# this, we are going to push the current token onto
# the tokenstack and replace it with an 'error' token.
# If there are any synchronization rules, they may
# catch it.
#
# In addition to pushing the error token, we call call
# the user defined p_error() function if this is the
# first syntax error. This function is only called if
# errorcount == 0.
if errorcount == 0 or self.errorok:
errorcount = error_count
self.errorok = False
errtoken = lookahead
if errtoken.type == '$end':
errtoken = None # End of file!
if self.errorfunc:
if errtoken and not hasattr(errtoken, 'lexer'):
errtoken.lexer = lexer
tok = call_errorfunc(self.errorfunc, errtoken, self)
if self.errorok:
# User must have done some kind of panic
# mode recovery on their own. The
# returned token is the next lookahead
lookahead = tok
errtoken = None
continue
else:
if errtoken:
if hasattr(errtoken, 'lineno'):
lineno = lookahead.lineno
else:
lineno = 0
if lineno:
sys.stderr.write('yacc: Syntax error at line %d, token=%s\n' % (lineno, errtoken.type))
else:
sys.stderr.write('yacc: Syntax error, token=%s' % errtoken.type)
else:
sys.stderr.write('yacc: Parse error in input. EOF\n')
return
else:
errorcount = error_count
# case 1: the statestack only has 1 entry on it. If we're in this state, the
# entire parse has been rolled back and we're completely hosed. The token is
# discarded and we just keep going.
if len(statestack) <= 1 and lookahead.type != '$end':
lookahead = None
errtoken = None
state = 0
# Nuke the pushback stack
del lookaheadstack[:]
continue
# case 2: the statestack has a couple of entries on it, but we're
# at the end of the file. nuke the top entry and generate an error token
# Start nuking entries on the stack
if lookahead.type == '$end':
# Whoa. We're really hosed here. Bail out
return
if lookahead.type != 'error':
sym = symstack[-1]
if sym.type == 'error':
# Hmmm. Error is on top of stack, we'll just nuke input
# symbol and continue
#--! TRACKING
if tracking:
sym.endlineno = getattr(lookahead, 'lineno', sym.lineno)
sym.endlexpos = getattr(lookahead, 'lexpos', sym.lexpos)
#--! TRACKING
lookahead = None
continue
# Create the error symbol for the first time and make it the new lookahead symbol
t = YaccSymbol()
t.type = 'error'
if hasattr(lookahead, 'lineno'):
t.lineno = t.endlineno = lookahead.lineno
if hasattr(lookahead, 'lexpos'):
t.lexpos = t.endlexpos = lookahead.lexpos
t.value = lookahead
lookaheadstack.append(lookahead)
lookahead = t
else:
sym = symstack.pop()
#--! TRACKING
if tracking:
lookahead.lineno = sym.lineno
lookahead.lexpos = sym.lexpos
#--! TRACKING
statestack.pop()
state = statestack[-1]
continue
# Call an error function here
raise RuntimeError('yacc: internal parser error!!!\n')
#--! parsedebug-end
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
# parseopt().
#
# Optimized version of parse() method. DO NOT EDIT THIS CODE DIRECTLY!
# This code is automatically generated by the ply/ygen.py script. Make
# changes to the parsedebug() method instead.
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
def parseopt(self, input=None, lexer=None, debug=False, tracking=False, tokenfunc=None):
#--! parseopt-start
lookahead = None # Current lookahead symbol
lookaheadstack = [] # Stack of lookahead symbols
actions = self.action # Local reference to action table (to avoid lookup on self.)
goto = self.goto # Local reference to goto table (to avoid lookup on self.)
prod = self.productions # Local reference to production list (to avoid lookup on self.)
defaulted_states = self.defaulted_states # Local reference to defaulted states
pslice = YaccProduction(None) # Production object passed to grammar rules
errorcount = 0 # Used during error recovery
# If no lexer was given, we will try to use the lex module
if not lexer:
from . import lex
lexer = lex.lexer
# Set up the lexer and parser objects on pslice
pslice.lexer = lexer
pslice.parser = self
# If input was supplied, pass to lexer
if input is not None:
lexer.input(input)
if tokenfunc is None:
# Tokenize function
get_token = lexer.token
else:
get_token = tokenfunc
# Set the parser() token method (sometimes used in error recovery)
self.token = get_token
# Set up the state and symbol stacks
statestack = [] # Stack of parsing states
self.statestack = statestack
symstack = [] # Stack of grammar symbols
self.symstack = symstack
pslice.stack = symstack # Put in the production
errtoken = None # Err token
# The start state is assumed to be (0,$end)
statestack.append(0)
sym = YaccSymbol()
sym.type = '$end'
symstack.append(sym)
state = 0
while True:
# Get the next symbol on the input. If a lookahead symbol
# is already set, we just use that. Otherwise, we'll pull
# the next token off of the lookaheadstack or from the lexer
if state not in defaulted_states:
if not lookahead:
if not lookaheadstack:
lookahead = get_token() # Get the next token
else:
lookahead = lookaheadstack.pop()
if not lookahead:
lookahead = YaccSymbol()
lookahead.type = '$end'
# Check the action table
ltype = lookahead.type
t = actions[state].get(ltype)
else:
t = defaulted_states[state]
if t is not None:
if t > 0:
# shift a symbol on the stack
statestack.append(t)
state = t
symstack.append(lookahead)
lookahead = None
# Decrease error count on successful shift
if errorcount:
errorcount -= 1
continue
if t < 0:
# reduce a symbol on the stack, emit a production
p = prod[-t]
pname = p.name
plen = p.len
# Get production function
sym = YaccSymbol()
sym.type = pname # Production name
sym.value = None
if plen:
targ = symstack[-plen-1:]
targ[0] = sym
#--! TRACKING
if tracking:
t1 = targ[1]
sym.lineno = t1.lineno
sym.lexpos = t1.lexpos
t1 = targ[-1]
sym.endlineno = getattr(t1, 'endlineno', t1.lineno)
sym.endlexpos = getattr(t1, 'endlexpos', t1.lexpos)
#--! TRACKING
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
# The code enclosed in this section is duplicated
# below as a performance optimization. Make sure
# changes get made in both locations.
pslice.slice = targ
try:
# Call the grammar rule with our special slice object
del symstack[-plen:]
del statestack[-plen:]
p.callable(pslice)
symstack.append(sym)
state = goto[statestack[-1]][pname]
statestack.append(state)
except SyntaxError:
# If an error was set. Enter error recovery state
lookaheadstack.append(lookahead)
symstack.pop()
statestack.pop()
state = statestack[-1]
sym.type = 'error'
lookahead = sym
errorcount = error_count
self.errorok = False
continue
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
else:
#--! TRACKING
if tracking:
sym.lineno = lexer.lineno
sym.lexpos = lexer.lexpos
#--! TRACKING
targ = [sym]
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
# The code enclosed in this section is duplicated
# above as a performance optimization. Make sure
# changes get made in both locations.
pslice.slice = targ
try:
# Call the grammar rule with our special slice object
p.callable(pslice)
symstack.append(sym)
state = goto[statestack[-1]][pname]
statestack.append(state)
except SyntaxError:
# If an error was set. Enter error recovery state
lookaheadstack.append(lookahead)
symstack.pop()
statestack.pop()
state = statestack[-1]
sym.type = 'error'
lookahead = sym
errorcount = error_count
self.errorok = False
continue
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
if t == 0:
n = symstack[-1]
result = getattr(n, 'value', None)
return result
if t is None:
# We have some kind of parsing error here. To handle
# this, we are going to push the current token onto
# the tokenstack and replace it with an 'error' token.
# If there are any synchronization rules, they may
# catch it.
#
# In addition to pushing the error token, we call call
# the user defined p_error() function if this is the
# first syntax error. This function is only called if
# errorcount == 0.
if errorcount == 0 or self.errorok:
errorcount = error_count
self.errorok = False
errtoken = lookahead
if errtoken.type == '$end':
errtoken = None # End of file!
if self.errorfunc:
if errtoken and not hasattr(errtoken, 'lexer'):
errtoken.lexer = lexer
tok = call_errorfunc(self.errorfunc, errtoken, self)
if self.errorok:
# User must have done some kind of panic
# mode recovery on their own. The
# returned token is the next lookahead
lookahead = tok
errtoken = None
continue
else:
if errtoken:
if hasattr(errtoken, 'lineno'):
lineno = lookahead.lineno
else:
lineno = 0
if lineno:
sys.stderr.write('yacc: Syntax error at line %d, token=%s\n' % (lineno, errtoken.type))
else:
sys.stderr.write('yacc: Syntax error, token=%s' % errtoken.type)
else:
sys.stderr.write('yacc: Parse error in input. EOF\n')
return
else:
errorcount = error_count
# case 1: the statestack only has 1 entry on it. If we're in this state, the
# entire parse has been rolled back and we're completely hosed. The token is
# discarded and we just keep going.
if len(statestack) <= 1 and lookahead.type != '$end':
lookahead = None
errtoken = None
state = 0
# Nuke the pushback stack
del lookaheadstack[:]
continue
# case 2: the statestack has a couple of entries on it, but we're
# at the end of the file. nuke the top entry and generate an error token
# Start nuking entries on the stack
if lookahead.type == '$end':
# Whoa. We're really hosed here. Bail out
return
if lookahead.type != 'error':
sym = symstack[-1]
if sym.type == 'error':
# Hmmm. Error is on top of stack, we'll just nuke input
# symbol and continue
#--! TRACKING
if tracking:
sym.endlineno = getattr(lookahead, 'lineno', sym.lineno)
sym.endlexpos = getattr(lookahead, 'lexpos', sym.lexpos)
#--! TRACKING
lookahead = None
continue
# Create the error symbol for the first time and make it the new lookahead symbol
t = YaccSymbol()
t.type = 'error'
if hasattr(lookahead, 'lineno'):
t.lineno = t.endlineno = lookahead.lineno
if hasattr(lookahead, 'lexpos'):
t.lexpos = t.endlexpos = lookahead.lexpos
t.value = lookahead
lookaheadstack.append(lookahead)
lookahead = t
else:
sym = symstack.pop()
#--! TRACKING
if tracking:
lookahead.lineno = sym.lineno
lookahead.lexpos = sym.lexpos
#--! TRACKING
statestack.pop()
state = statestack[-1]
continue
# Call an error function here
raise RuntimeError('yacc: internal parser error!!!\n')
#--! parseopt-end
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
# parseopt_notrack().
#
# Optimized version of parseopt() with line number tracking removed.
# DO NOT EDIT THIS CODE DIRECTLY. This code is automatically generated
# by the ply/ygen.py script. Make changes to the parsedebug() method instead.
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
def parseopt_notrack(self, input=None, lexer=None, debug=False, tracking=False, tokenfunc=None):
#--! parseopt-notrack-start
lookahead = None # Current lookahead symbol
lookaheadstack = [] # Stack of lookahead symbols
actions = self.action # Local reference to action table (to avoid lookup on self.)
goto = self.goto # Local reference to goto table (to avoid lookup on self.)
prod = self.productions # Local reference to production list (to avoid lookup on self.)
defaulted_states = self.defaulted_states # Local reference to defaulted states
pslice = YaccProduction(None) # Production object passed to grammar rules
errorcount = 0 # Used during error recovery
# If no lexer was given, we will try to use the lex module
if not lexer:
from . import lex
lexer = lex.lexer
# Set up the lexer and parser objects on pslice
pslice.lexer = lexer
pslice.parser = self
# If input was supplied, pass to lexer
if input is not None:
lexer.input(input)
if tokenfunc is None:
# Tokenize function
get_token = lexer.token
else:
get_token = tokenfunc
# Set the parser() token method (sometimes used in error recovery)
self.token = get_token
# Set up the state and symbol stacks
statestack = [] # Stack of parsing states
self.statestack = statestack
symstack = [] # Stack of grammar symbols
self.symstack = symstack
pslice.stack = symstack # Put in the production
errtoken = None # Err token
# The start state is assumed to be (0,$end)
statestack.append(0)
sym = YaccSymbol()
sym.type = '$end'
symstack.append(sym)
state = 0
while True:
# Get the next symbol on the input. If a lookahead symbol
# is already set, we just use that. Otherwise, we'll pull
# the next token off of the lookaheadstack or from the lexer
if state not in defaulted_states:
if not lookahead:
if not lookaheadstack:
lookahead = get_token() # Get the next token
else:
lookahead = lookaheadstack.pop()
if not lookahead:
lookahead = YaccSymbol()
lookahead.type = '$end'
# Check the action table
ltype = lookahead.type
t = actions[state].get(ltype)
else:
t = defaulted_states[state]
if t is not None:
if t > 0:
# shift a symbol on the stack
statestack.append(t)
state = t
symstack.append(lookahead)
lookahead = None
# Decrease error count on successful shift
if errorcount:
errorcount -= 1
continue
if t < 0:
# reduce a symbol on the stack, emit a production
p = prod[-t]
pname = p.name
plen = p.len
# Get production function
sym = YaccSymbol()
sym.type = pname # Production name
sym.value = None
if plen:
targ = symstack[-plen-1:]
targ[0] = sym
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
# The code enclosed in this section is duplicated
# below as a performance optimization. Make sure
# changes get made in both locations.
pslice.slice = targ
try:
# Call the grammar rule with our special slice object
del symstack[-plen:]
del statestack[-plen:]
p.callable(pslice)
symstack.append(sym)
state = goto[statestack[-1]][pname]
statestack.append(state)
except SyntaxError:
# If an error was set. Enter error recovery state
lookaheadstack.append(lookahead)
symstack.pop()
statestack.pop()
state = statestack[-1]
sym.type = 'error'
lookahead = sym
errorcount = error_count
self.errorok = False
continue
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
else:
targ = [sym]
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
# The code enclosed in this section is duplicated
# above as a performance optimization. Make sure
# changes get made in both locations.
pslice.slice = targ
try:
# Call the grammar rule with our special slice object
p.callable(pslice)
symstack.append(sym)
state = goto[statestack[-1]][pname]
statestack.append(state)
except SyntaxError:
# If an error was set. Enter error recovery state
lookaheadstack.append(lookahead)
symstack.pop()
statestack.pop()
state = statestack[-1]
sym.type = 'error'
lookahead = sym
errorcount = error_count
self.errorok = False
continue
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
if t == 0:
n = symstack[-1]
result = getattr(n, 'value', None)
return result
if t is None:
# We have some kind of parsing error here. To handle
# this, we are going to push the current token onto
# the tokenstack and replace it with an 'error' token.
# If there are any synchronization rules, they may
# catch it.
#
# In addition to pushing the error token, we call call
# the user defined p_error() function if this is the
# first syntax error. This function is only called if
# errorcount == 0.
if errorcount == 0 or self.errorok:
errorcount = error_count
self.errorok = False
errtoken = lookahead
if errtoken.type == '$end':
errtoken = None # End of file!
if self.errorfunc:
if errtoken and not hasattr(errtoken, 'lexer'):
errtoken.lexer = lexer
tok = call_errorfunc(self.errorfunc, errtoken, self)
if self.errorok:
# User must have done some kind of panic
# mode recovery on their own. The
# returned token is the next lookahead
lookahead = tok
errtoken = None
continue
else:
if errtoken:
if hasattr(errtoken, 'lineno'):
lineno = lookahead.lineno
else:
lineno = 0
if lineno:
sys.stderr.write('yacc: Syntax error at line %d, token=%s\n' % (lineno, errtoken.type))
else:
sys.stderr.write('yacc: Syntax error, token=%s' % errtoken.type)
else:
sys.stderr.write('yacc: Parse error in input. EOF\n')
return
else:
errorcount = error_count
# case 1: the statestack only has 1 entry on it. If we're in this state, the
# entire parse has been rolled back and we're completely hosed. The token is
# discarded and we just keep going.
if len(statestack) <= 1 and lookahead.type != '$end':
lookahead = None
errtoken = None
state = 0
# Nuke the pushback stack
del lookaheadstack[:]
continue
# case 2: the statestack has a couple of entries on it, but we're
# at the end of the file. nuke the top entry and generate an error token
# Start nuking entries on the stack
if lookahead.type == '$end':
# Whoa. We're really hosed here. Bail out
return
if lookahead.type != 'error':
sym = symstack[-1]
if sym.type == 'error':
# Hmmm. Error is on top of stack, we'll just nuke input
# symbol and continue
lookahead = None
continue
# Create the error symbol for the first time and make it the new lookahead symbol
t = YaccSymbol()
t.type = 'error'
if hasattr(lookahead, 'lineno'):
t.lineno = t.endlineno = lookahead.lineno
if hasattr(lookahead, 'lexpos'):
t.lexpos = t.endlexpos = lookahead.lexpos
t.value = lookahead
lookaheadstack.append(lookahead)
lookahead = t
else:
sym = symstack.pop()
statestack.pop()
state = statestack[-1]
continue
# Call an error function here
raise RuntimeError('yacc: internal parser error!!!\n')
#--! parseopt-notrack-end
# -----------------------------------------------------------------------------
# === Grammar Representation ===
#
# The following functions, classes, and variables are used to represent and
# manipulate the rules that make up a grammar.
# -----------------------------------------------------------------------------
# regex matching identifiers
_is_identifier = re.compile(r'^[a-zA-Z0-9_-]+$')
# -----------------------------------------------------------------------------
# class Production:
#
# This class stores the raw information about a single production or grammar rule.
# A grammar rule refers to a specification such as this:
#
# expr : expr PLUS term
#
# Here are the basic attributes defined on all productions
#
# name - Name of the production. For example 'expr'
# prod - A list of symbols on the right side ['expr','PLUS','term']
# prec - Production precedence level
# number - Production number.
# func - Function that executes on reduce
# file - File where production function is defined
# lineno - Line number where production function is defined
#
# The following attributes are defined or optional.
#
# len - Length of the production (number of symbols on right hand side)
# usyms - Set of unique symbols found in the production
# -----------------------------------------------------------------------------
class Production(object):
reduced = 0
def __init__(self, number, name, prod, precedence=('right', 0), func=None, file='', line=0):
self.name = name
self.prod = tuple(prod)
self.number = number
self.func = func
self.callable = None
self.file = file
self.line = line
self.prec = precedence
# Internal settings used during table construction
self.len = len(self.prod) # Length of the production
# Create a list of unique production symbols used in the production
self.usyms = []
for s in self.prod:
if s not in self.usyms:
self.usyms.append(s)
# List of all LR items for the production
self.lr_items = []
self.lr_next = None
# Create a string representation
if self.prod:
self.str = '%s -> %s' % (self.name, ' '.join(self.prod))
else:
self.str = '%s -> <empty>' % self.name
def __str__(self):
return self.str
def __repr__(self):
return 'Production(' + str(self) + ')'
def __len__(self):
return len(self.prod)
def __nonzero__(self):
return 1
def __getitem__(self, index):
return self.prod[index]
# Return the nth lr_item from the production (or None if at the end)
def lr_item(self, n):
if n > len(self.prod):
return None
p = LRItem(self, n)
# Precompute the list of productions immediately following.
try:
p.lr_after = Prodnames[p.prod[n+1]]
except (IndexError, KeyError):
p.lr_after = []
try:
p.lr_before = p.prod[n-1]
except IndexError:
p.lr_before = None
return p
# Bind the production function name to a callable
def bind(self, pdict):
if self.func:
self.callable = pdict[self.func]
# This class serves as a minimal standin for Production objects when
# reading table data from files. It only contains information
# actually used by the LR parsing engine, plus some additional
# debugging information.
class MiniProduction(object):
def __init__(self, str, name, len, func, file, line):
self.name = name
self.len = len
self.func = func
self.callable = None
self.file = file
self.line = line
self.str = str
def __str__(self):
return self.str
def __repr__(self):
return 'MiniProduction(%s)' % self.str
# Bind the production function name to a callable
def bind(self, pdict):
if self.func:
self.callable = pdict[self.func]
# -----------------------------------------------------------------------------
# class LRItem
#
# This class represents a specific stage of parsing a production rule. For
# example:
#
# expr : expr . PLUS term
#
# In the above, the "." represents the current location of the parse. Here
# basic attributes:
#
# name - Name of the production. For example 'expr'
# prod - A list of symbols on the right side ['expr','.', 'PLUS','term']
# number - Production number.
#
# lr_next Next LR item. Example, if we are ' expr -> expr . PLUS term'
# then lr_next refers to 'expr -> expr PLUS . term'
# lr_index - LR item index (location of the ".") in the prod list.
# lookaheads - LALR lookahead symbols for this item
# len - Length of the production (number of symbols on right hand side)
# lr_after - List of all productions that immediately follow
# lr_before - Grammar symbol immediately before
# -----------------------------------------------------------------------------
class LRItem(object):
def __init__(self, p, n):
self.name = p.name
self.prod = list(p.prod)
self.number = p.number
self.lr_index = n
self.lookaheads = {}
self.prod.insert(n, '.')
self.prod = tuple(self.prod)
self.len = len(self.prod)
self.usyms = p.usyms
def __str__(self):
if self.prod:
s = '%s -> %s' % (self.name, ' '.join(self.prod))
else:
s = '%s -> <empty>' % self.name
return s
def __repr__(self):
return 'LRItem(' + str(self) + ')'
# -----------------------------------------------------------------------------
# rightmost_terminal()
#
# Return the rightmost terminal from a list of symbols. Used in add_production()
# -----------------------------------------------------------------------------
def rightmost_terminal(symbols, terminals):
i = len(symbols) - 1
while i >= 0:
if symbols[i] in terminals:
return symbols[i]
i -= 1
return None
# -----------------------------------------------------------------------------
# === GRAMMAR CLASS ===
#
# The following class represents the contents of the specified grammar along
# with various computed properties such as first sets, follow sets, LR items, etc.
# This data is used for critical parts of the table generation process later.
# -----------------------------------------------------------------------------
class GrammarError(YaccError):
pass
class Grammar(object):
def __init__(self, terminals):
self.Productions = [None] # A list of all of the productions. The first
# entry is always reserved for the purpose of
# building an augmented grammar
self.Prodnames = {} # A dictionary mapping the names of nonterminals to a list of all
# productions of that nonterminal.
self.Prodmap = {} # A dictionary that is only used to detect duplicate
# productions.
self.Terminals = {} # A dictionary mapping the names of terminal symbols to a
# list of the rules where they are used.
for term in terminals:
self.Terminals[term] = []
self.Terminals['error'] = []
self.Nonterminals = {} # A dictionary mapping names of nonterminals to a list
# of rule numbers where they are used.
self.First = {} # A dictionary of precomputed FIRST(x) symbols
self.Follow = {} # A dictionary of precomputed FOLLOW(x) symbols
self.Precedence = {} # Precedence rules for each terminal. Contains tuples of the
# form ('right',level) or ('nonassoc', level) or ('left',level)
self.UsedPrecedence = set() # Precedence rules that were actually used by the grammer.
# This is only used to provide error checking and to generate
# a warning about unused precedence rules.
self.Start = None # Starting symbol for the grammar
def __len__(self):
return len(self.Productions)
def __getitem__(self, index):
return self.Productions[index]
# -----------------------------------------------------------------------------
# set_precedence()
#
# Sets the precedence for a given terminal. assoc is the associativity such as
# 'left','right', or 'nonassoc'. level is a numeric level.
#
# -----------------------------------------------------------------------------
def set_precedence(self, term, assoc, level):
assert self.Productions == [None], 'Must call set_precedence() before add_production()'
if term in self.Precedence:
raise GrammarError('Precedence already specified for terminal %r' % term)
if assoc not in ['left', 'right', 'nonassoc']:
raise GrammarError("Associativity must be one of 'left','right', or 'nonassoc'")
self.Precedence[term] = (assoc, level)
# -----------------------------------------------------------------------------
# add_production()
#
# Given an action function, this function assembles a production rule and
# computes its precedence level.
#
# The production rule is supplied as a list of symbols. For example,
# a rule such as 'expr : expr PLUS term' has a production name of 'expr' and
# symbols ['expr','PLUS','term'].
#
# Precedence is determined by the precedence of the right-most non-terminal
# or the precedence of a terminal specified by %prec.
#
# A variety of error checks are performed to make sure production symbols
# are valid and that %prec is used correctly.
# -----------------------------------------------------------------------------
def add_production(self, prodname, syms, func=None, file='', line=0):
if prodname in self.Terminals:
raise GrammarError('%s:%d: Illegal rule name %r. Already defined as a token' % (file, line, prodname))
if prodname == 'error':
raise GrammarError('%s:%d: Illegal rule name %r. error is a reserved word' % (file, line, prodname))
if not _is_identifier.match(prodname):
raise GrammarError('%s:%d: Illegal rule name %r' % (file, line, prodname))
# Look for literal tokens
for n, s in enumerate(syms):
if s[0] in "'\"":
try:
c = eval(s)
if (len(c) > 1):
raise GrammarError('%s:%d: Literal token %s in rule %r may only be a single character' %
(file, line, s, prodname))
if c not in self.Terminals:
self.Terminals[c] = []
syms[n] = c
continue
except SyntaxError:
pass
if not _is_identifier.match(s) and s != '%prec':
raise GrammarError('%s:%d: Illegal name %r in rule %r' % (file, line, s, prodname))
# Determine the precedence level
if '%prec' in syms:
if syms[-1] == '%prec':
raise GrammarError('%s:%d: Syntax error. Nothing follows %%prec' % (file, line))
if syms[-2] != '%prec':
raise GrammarError('%s:%d: Syntax error. %%prec can only appear at the end of a grammar rule' %
(file, line))
precname = syms[-1]
prodprec = self.Precedence.get(precname)
if not prodprec:
raise GrammarError('%s:%d: Nothing known about the precedence of %r' % (file, line, precname))
else:
self.UsedPrecedence.add(precname)
del syms[-2:] # Drop %prec from the rule
else:
# If no %prec, precedence is determined by the rightmost terminal symbol
precname = rightmost_terminal(syms, self.Terminals)
prodprec = self.Precedence.get(precname, ('right', 0))
# See if the rule is already in the rulemap
map = '%s -> %s' % (prodname, syms)
if map in self.Prodmap:
m = self.Prodmap[map]
raise GrammarError('%s:%d: Duplicate rule %s. ' % (file, line, m) +
'Previous definition at %s:%d' % (m.file, m.line))
# From this point on, everything is valid. Create a new Production instance
pnumber = len(self.Productions)
if prodname not in self.Nonterminals:
self.Nonterminals[prodname] = []
# Add the production number to Terminals and Nonterminals
for t in syms:
if t in self.Terminals:
self.Terminals[t].append(pnumber)
else:
if t not in self.Nonterminals:
self.Nonterminals[t] = []
self.Nonterminals[t].append(pnumber)
# Create a production and add it to the list of productions
p = Production(pnumber, prodname, syms, prodprec, func, file, line)
self.Productions.append(p)
self.Prodmap[map] = p
# Add to the global productions list
try:
self.Prodnames[prodname].append(p)
except KeyError:
self.Prodnames[prodname] = [p]
# -----------------------------------------------------------------------------
# set_start()
#
# Sets the starting symbol and creates the augmented grammar. Production
# rule 0 is S' -> start where start is the start symbol.
# -----------------------------------------------------------------------------
def set_start(self, start=None):
if not start:
start = self.Productions[1].name
if start not in self.Nonterminals:
raise GrammarError('start symbol %s undefined' % start)
self.Productions[0] = Production(0, "S'", [start])
self.Nonterminals[start].append(0)
self.Start = start
# -----------------------------------------------------------------------------
# find_unreachable()
#
# Find all of the nonterminal symbols that can't be reached from the starting
# symbol. Returns a list of nonterminals that can't be reached.
# -----------------------------------------------------------------------------
def find_unreachable(self):
# Mark all symbols that are reachable from a symbol s
def mark_reachable_from(s):
if s in reachable:
return
reachable.add(s)
for p in self.Prodnames.get(s, []):
for r in p.prod:
mark_reachable_from(r)
reachable = set()
mark_reachable_from(self.Productions[0].prod[0])
return [s for s in self.Nonterminals if s not in reachable]
# -----------------------------------------------------------------------------
# infinite_cycles()
#
# This function looks at the various parsing rules and tries to detect
# infinite recursion cycles (grammar rules where there is no possible way
# to derive a string of only terminals).
# -----------------------------------------------------------------------------
def infinite_cycles(self):
terminates = {}
# Terminals:
for t in self.Terminals:
terminates[t] = True
terminates['$end'] = True
# Nonterminals:
# Initialize to false:
for n in self.Nonterminals:
terminates[n] = False
# Then propagate termination until no change:
while True:
some_change = False
for (n, pl) in self.Prodnames.items():
# Nonterminal n terminates iff any of its productions terminates.
for p in pl:
# Production p terminates iff all of its rhs symbols terminate.
for s in p.prod:
if not terminates[s]:
# The symbol s does not terminate,
# so production p does not terminate.
p_terminates = False
break
else:
# didn't break from the loop,
# so every symbol s terminates
# so production p terminates.
p_terminates = True
if p_terminates:
# symbol n terminates!
if not terminates[n]:
terminates[n] = True
some_change = True
# Don't need to consider any more productions for this n.
break
if not some_change:
break
infinite = []
for (s, term) in terminates.items():
if not term:
if s not in self.Prodnames and s not in self.Terminals and s != 'error':
# s is used-but-not-defined, and we've already warned of that,
# so it would be overkill to say that it's also non-terminating.
pass
else:
infinite.append(s)
return infinite
# -----------------------------------------------------------------------------
# undefined_symbols()
#
# Find all symbols that were used the grammar, but not defined as tokens or
# grammar rules. Returns a list of tuples (sym, prod) where sym in the symbol
# and prod is the production where the symbol was used.
# -----------------------------------------------------------------------------
def undefined_symbols(self):
result = []
for p in self.Productions:
if not p:
continue
for s in p.prod:
if s not in self.Prodnames and s not in self.Terminals and s != 'error':
result.append((s, p))
return result
# -----------------------------------------------------------------------------
# unused_terminals()
#
# Find all terminals that were defined, but not used by the grammar. Returns
# a list of all symbols.
# -----------------------------------------------------------------------------
def unused_terminals(self):
unused_tok = []
for s, v in self.Terminals.items():
if s != 'error' and not v:
unused_tok.append(s)
return unused_tok
# ------------------------------------------------------------------------------
# unused_rules()
#
# Find all grammar rules that were defined, but not used (maybe not reachable)
# Returns a list of productions.
# ------------------------------------------------------------------------------
def unused_rules(self):
unused_prod = []
for s, v in self.Nonterminals.items():
if not v:
p = self.Prodnames[s][0]
unused_prod.append(p)
return unused_prod
# -----------------------------------------------------------------------------
# unused_precedence()
#
# Returns a list of tuples (term,precedence) corresponding to precedence
# rules that were never used by the grammar. term is the name of the terminal
# on which precedence was applied and precedence is a string such as 'left' or
# 'right' corresponding to the type of precedence.
# -----------------------------------------------------------------------------
def unused_precedence(self):
unused = []
for termname in self.Precedence:
if not (termname in self.Terminals or termname in self.UsedPrecedence):
unused.append((termname, self.Precedence[termname][0]))
return unused
# -------------------------------------------------------------------------
# _first()
#
# Compute the value of FIRST1(beta) where beta is a tuple of symbols.
#
# During execution of compute_first1, the result may be incomplete.
# Afterward (e.g., when called from compute_follow()), it will be complete.
# -------------------------------------------------------------------------
def _first(self, beta):
# We are computing First(x1,x2,x3,...,xn)
result = []
for x in beta:
x_produces_empty = False
# Add all the non-<empty> symbols of First[x] to the result.
for f in self.First[x]:
if f == '<empty>':
x_produces_empty = True
else:
if f not in result:
result.append(f)
if x_produces_empty:
# We have to consider the next x in beta,
# i.e. stay in the loop.
pass
else:
# We don't have to consider any further symbols in beta.
break
else:
# There was no 'break' from the loop,
# so x_produces_empty was true for all x in beta,
# so beta produces empty as well.
result.append('<empty>')
return result
# -------------------------------------------------------------------------
# compute_first()
#
# Compute the value of FIRST1(X) for all symbols
# -------------------------------------------------------------------------
def compute_first(self):
if self.First:
return self.First
# Terminals:
for t in self.Terminals:
self.First[t] = [t]
self.First['$end'] = ['$end']
# Nonterminals:
# Initialize to the empty set:
for n in self.Nonterminals:
self.First[n] = []
# Then propagate symbols until no change:
while True:
some_change = False
for n in self.Nonterminals:
for p in self.Prodnames[n]:
for f in self._first(p.prod):
if f not in self.First[n]:
self.First[n].append(f)
some_change = True
if not some_change:
break
return self.First
# ---------------------------------------------------------------------
# compute_follow()
#
# Computes all of the follow sets for every non-terminal symbol. The
# follow set is the set of all symbols that might follow a given
# non-terminal. See the Dragon book, 2nd Ed. p. 189.
# ---------------------------------------------------------------------
def compute_follow(self, start=None):
# If already computed, return the result
if self.Follow:
return self.Follow
# If first sets not computed yet, do that first.
if not self.First:
self.compute_first()
# Add '$end' to the follow list of the start symbol
for k in self.Nonterminals:
self.Follow[k] = []
if not start:
start = self.Productions[1].name
self.Follow[start] = ['$end']
while True:
didadd = False
for p in self.Productions[1:]:
# Here is the production set
for i, B in enumerate(p.prod):
if B in self.Nonterminals:
# Okay. We got a non-terminal in a production
fst = self._first(p.prod[i+1:])
hasempty = False
for f in fst:
if f != '<empty>' and f not in self.Follow[B]:
self.Follow[B].append(f)
didadd = True
if f == '<empty>':
hasempty = True
if hasempty or i == (len(p.prod)-1):
# Add elements of follow(a) to follow(b)
for f in self.Follow[p.name]:
if f not in self.Follow[B]:
self.Follow[B].append(f)
didadd = True
if not didadd:
break
return self.Follow
# -----------------------------------------------------------------------------
# build_lritems()
#
# This function walks the list of productions and builds a complete set of the
# LR items. The LR items are stored in two ways: First, they are uniquely
# numbered and placed in the list _lritems. Second, a linked list of LR items
# is built for each production. For example:
#
# E -> E PLUS E
#
# Creates the list
#
# [E -> . E PLUS E, E -> E . PLUS E, E -> E PLUS . E, E -> E PLUS E . ]
# -----------------------------------------------------------------------------
def build_lritems(self):
for p in self.Productions:
lastlri = p
i = 0
lr_items = []
while True:
if i > len(p):
lri = None
else:
lri = LRItem(p, i)
# Precompute the list of productions immediately following
try:
lri.lr_after = self.Prodnames[lri.prod[i+1]]
except (IndexError, KeyError):
lri.lr_after = []
try:
lri.lr_before = lri.prod[i-1]
except IndexError:
lri.lr_before = None
lastlri.lr_next = lri
if not lri:
break
lr_items.append(lri)
lastlri = lri
i += 1
p.lr_items = lr_items
# -----------------------------------------------------------------------------
# == Class LRTable ==
#
# This basic class represents a basic table of LR parsing information.
# Methods for generating the tables are not defined here. They are defined
# in the derived class LRGeneratedTable.
# -----------------------------------------------------------------------------
class VersionError(YaccError):
pass
class LRTable(object):
def __init__(self):
self.lr_action = None
self.lr_goto = None
self.lr_productions = None
self.lr_method = None
def read_table(self, module):
if isinstance(module, types.ModuleType):
parsetab = module
else:
exec('import %s' % module)
parsetab = sys.modules[module]
if parsetab._tabversion != __tabversion__:
raise VersionError('yacc table file version is out of date')
self.lr_action = parsetab._lr_action
self.lr_goto = parsetab._lr_goto
self.lr_productions = []
for p in parsetab._lr_productions:
self.lr_productions.append(MiniProduction(*p))
self.lr_method = parsetab._lr_method
return parsetab._lr_signature
def read_pickle(self, filename):
try:
import cPickle as pickle
except ImportError:
import pickle
if not os.path.exists(filename):
raise ImportError
in_f = open(filename, 'rb')
tabversion = pickle.load(in_f)
if tabversion != __tabversion__:
raise VersionError('yacc table file version is out of date')
self.lr_method = pickle.load(in_f)
signature = pickle.load(in_f)
self.lr_action = pickle.load(in_f)
self.lr_goto = pickle.load(in_f)
productions = pickle.load(in_f)
self.lr_productions = []
for p in productions:
self.lr_productions.append(MiniProduction(*p))
in_f.close()
return signature
# Bind all production function names to callable objects in pdict
def bind_callables(self, pdict):
for p in self.lr_productions:
p.bind(pdict)
# -----------------------------------------------------------------------------
# === LR Generator ===
#
# The following classes and functions are used to generate LR parsing tables on
# a grammar.
# -----------------------------------------------------------------------------
# -----------------------------------------------------------------------------
# digraph()
# traverse()
#
# The following two functions are used to compute set valued functions
# of the form:
#
# F(x) = F'(x) U U{F(y) | x R y}
#
# This is used to compute the values of Read() sets as well as FOLLOW sets
# in LALR(1) generation.
#
# Inputs: X - An input set
# R - A relation
# FP - Set-valued function
# ------------------------------------------------------------------------------
def digraph(X, R, FP):
N = {}
for x in X:
N[x] = 0
stack = []
F = {}
for x in X:
if N[x] == 0:
traverse(x, N, stack, F, X, R, FP)
return F
def traverse(x, N, stack, F, X, R, FP):
stack.append(x)
d = len(stack)
N[x] = d
F[x] = FP(x) # F(X) <- F'(x)
rel = R(x) # Get y's related to x
for y in rel:
if N[y] == 0:
traverse(y, N, stack, F, X, R, FP)
N[x] = min(N[x], N[y])
for a in F.get(y, []):
if a not in F[x]:
F[x].append(a)
if N[x] == d:
N[stack[-1]] = MAXINT
F[stack[-1]] = F[x]
element = stack.pop()
while element != x:
N[stack[-1]] = MAXINT
F[stack[-1]] = F[x]
element = stack.pop()
class LALRError(YaccError):
pass
# -----------------------------------------------------------------------------
# == LRGeneratedTable ==
#
# This class implements the LR table generation algorithm. There are no
# public methods except for write()
# -----------------------------------------------------------------------------
class LRGeneratedTable(LRTable):
def __init__(self, grammar, method='LALR', log=None):
if method not in ['SLR', 'LALR']:
raise LALRError('Unsupported method %s' % method)
self.grammar = grammar
self.lr_method = method
# Set up the logger
if not log:
log = NullLogger()
self.log = log
# Internal attributes
self.lr_action = {} # Action table
self.lr_goto = {} # Goto table
self.lr_productions = grammar.Productions # Copy of grammar Production array
self.lr_goto_cache = {} # Cache of computed gotos
self.lr0_cidhash = {} # Cache of closures
self._add_count = 0 # Internal counter used to detect cycles
# Diagonistic information filled in by the table generator
self.sr_conflict = 0
self.rr_conflict = 0
self.conflicts = [] # List of conflicts
self.sr_conflicts = []
self.rr_conflicts = []
# Build the tables
self.grammar.build_lritems()
self.grammar.compute_first()
self.grammar.compute_follow()
self.lr_parse_table()
# Compute the LR(0) closure operation on I, where I is a set of LR(0) items.
def lr0_closure(self, I):
self._add_count += 1
# Add everything in I to J
J = I[:]
didadd = True
while didadd:
didadd = False
for j in J:
for x in j.lr_after:
if getattr(x, 'lr0_added', 0) == self._add_count:
continue
# Add B --> .G to J
J.append(x.lr_next)
x.lr0_added = self._add_count
didadd = True
return J
# Compute the LR(0) goto function goto(I,X) where I is a set
# of LR(0) items and X is a grammar symbol. This function is written
# in a way that guarantees uniqueness of the generated goto sets
# (i.e. the same goto set will never be returned as two different Python
# objects). With uniqueness, we can later do fast set comparisons using
# id(obj) instead of element-wise comparison.
def lr0_goto(self, I, x):
# First we look for a previously cached entry
g = self.lr_goto_cache.get((id(I), x))
if g:
return g
# Now we generate the goto set in a way that guarantees uniqueness
# of the result
s = self.lr_goto_cache.get(x)
if not s:
s = {}
self.lr_goto_cache[x] = s
gs = []
for p in I:
n = p.lr_next
if n and n.lr_before == x:
s1 = s.get(id(n))
if not s1:
s1 = {}
s[id(n)] = s1
gs.append(n)
s = s1
g = s.get('$end')
if not g:
if gs:
g = self.lr0_closure(gs)
s['$end'] = g
else:
s['$end'] = gs
self.lr_goto_cache[(id(I), x)] = g
return g
# Compute the LR(0) sets of item function
def lr0_items(self):
C = [self.lr0_closure([self.grammar.Productions[0].lr_next])]
i = 0
for I in C:
self.lr0_cidhash[id(I)] = i
i += 1
# Loop over the items in C and each grammar symbols
i = 0
while i < len(C):
I = C[i]
i += 1
# Collect all of the symbols that could possibly be in the goto(I,X) sets
asyms = {}
for ii in I:
for s in ii.usyms:
asyms[s] = None
for x in asyms:
g = self.lr0_goto(I, x)
if not g or id(g) in self.lr0_cidhash:
continue
self.lr0_cidhash[id(g)] = len(C)
C.append(g)
return C
# -----------------------------------------------------------------------------
# ==== LALR(1) Parsing ====
#
# LALR(1) parsing is almost exactly the same as SLR except that instead of
# relying upon Follow() sets when performing reductions, a more selective
# lookahead set that incorporates the state of the LR(0) machine is utilized.
# Thus, we mainly just have to focus on calculating the lookahead sets.
#
# The method used here is due to DeRemer and Pennelo (1982).
#
# DeRemer, F. L., and T. J. Pennelo: "Efficient Computation of LALR(1)
# Lookahead Sets", ACM Transactions on Programming Languages and Systems,
# Vol. 4, No. 4, Oct. 1982, pp. 615-649
#
# Further details can also be found in:
#
# J. Tremblay and P. Sorenson, "The Theory and Practice of Compiler Writing",
# McGraw-Hill Book Company, (1985).
#
# -----------------------------------------------------------------------------
# -----------------------------------------------------------------------------
# compute_nullable_nonterminals()
#
# Creates a dictionary containing all of the non-terminals that might produce
# an empty production.
# -----------------------------------------------------------------------------
def compute_nullable_nonterminals(self):
nullable = set()
num_nullable = 0
while True:
for p in self.grammar.Productions[1:]:
if p.len == 0:
nullable.add(p.name)
continue
for t in p.prod:
if t not in nullable:
break
else:
nullable.add(p.name)
if len(nullable) == num_nullable:
break
num_nullable = len(nullable)
return nullable
# -----------------------------------------------------------------------------
# find_nonterminal_trans(C)
#
# Given a set of LR(0) items, this functions finds all of the non-terminal
# transitions. These are transitions in which a dot appears immediately before
# a non-terminal. Returns a list of tuples of the form (state,N) where state
# is the state number and N is the nonterminal symbol.
#
# The input C is the set of LR(0) items.
# -----------------------------------------------------------------------------
def find_nonterminal_transitions(self, C):
trans = []
for stateno, state in enumerate(C):
for p in state:
if p.lr_index < p.len - 1:
t = (stateno, p.prod[p.lr_index+1])
if t[1] in self.grammar.Nonterminals:
if t not in trans:
trans.append(t)
return trans
# -----------------------------------------------------------------------------
# dr_relation()
#
# Computes the DR(p,A) relationships for non-terminal transitions. The input
# is a tuple (state,N) where state is a number and N is a nonterminal symbol.
#
# Returns a list of terminals.
# -----------------------------------------------------------------------------
def dr_relation(self, C, trans, nullable):
dr_set = {}
state, N = trans
terms = []
g = self.lr0_goto(C[state], N)
for p in g:
if p.lr_index < p.len - 1:
a = p.prod[p.lr_index+1]
if a in self.grammar.Terminals:
if a not in terms:
terms.append(a)
# This extra bit is to handle the start state
if state == 0 and N == self.grammar.Productions[0].prod[0]:
terms.append('$end')
return terms
# -----------------------------------------------------------------------------
# reads_relation()
#
# Computes the READS() relation (p,A) READS (t,C).
# -----------------------------------------------------------------------------
def reads_relation(self, C, trans, empty):
# Look for empty transitions
rel = []
state, N = trans
g = self.lr0_goto(C[state], N)
j = self.lr0_cidhash.get(id(g), -1)
for p in g:
if p.lr_index < p.len - 1:
a = p.prod[p.lr_index + 1]
if a in empty:
rel.append((j, a))
return rel
# -----------------------------------------------------------------------------
# compute_lookback_includes()
#
# Determines the lookback and includes relations
#
# LOOKBACK:
#
# This relation is determined by running the LR(0) state machine forward.
# For example, starting with a production "N : . A B C", we run it forward
# to obtain "N : A B C ." We then build a relationship between this final
# state and the starting state. These relationships are stored in a dictionary
# lookdict.
#
# INCLUDES:
#
# Computes the INCLUDE() relation (p,A) INCLUDES (p',B).
#
# This relation is used to determine non-terminal transitions that occur
# inside of other non-terminal transition states. (p,A) INCLUDES (p', B)
# if the following holds:
#
# B -> LAT, where T -> epsilon and p' -L-> p
#
# L is essentially a prefix (which may be empty), T is a suffix that must be
# able to derive an empty string. State p' must lead to state p with the string L.
#
# -----------------------------------------------------------------------------
def compute_lookback_includes(self, C, trans, nullable):
lookdict = {} # Dictionary of lookback relations
includedict = {} # Dictionary of include relations
# Make a dictionary of non-terminal transitions
dtrans = {}
for t in trans:
dtrans[t] = 1
# Loop over all transitions and compute lookbacks and includes
for state, N in trans:
lookb = []
includes = []
for p in C[state]:
if p.name != N:
continue
# Okay, we have a name match. We now follow the production all the way
# through the state machine until we get the . on the right hand side
lr_index = p.lr_index
j = state
while lr_index < p.len - 1:
lr_index = lr_index + 1
t = p.prod[lr_index]
# Check to see if this symbol and state are a non-terminal transition
if (j, t) in dtrans:
# Yes. Okay, there is some chance that this is an includes relation
# the only way to know for certain is whether the rest of the
# production derives empty
li = lr_index + 1
while li < p.len:
if p.prod[li] in self.grammar.Terminals:
break # No forget it
if p.prod[li] not in nullable:
break
li = li + 1
else:
# Appears to be a relation between (j,t) and (state,N)
includes.append((j, t))
g = self.lr0_goto(C[j], t) # Go to next set
j = self.lr0_cidhash.get(id(g), -1) # Go to next state
# When we get here, j is the final state, now we have to locate the production
for r in C[j]:
if r.name != p.name:
continue
if r.len != p.len:
continue
i = 0
# This look is comparing a production ". A B C" with "A B C ."
while i < r.lr_index:
if r.prod[i] != p.prod[i+1]:
break
i = i + 1
else:
lookb.append((j, r))
for i in includes:
if i not in includedict:
includedict[i] = []
includedict[i].append((state, N))
lookdict[(state, N)] = lookb
return lookdict, includedict
# -----------------------------------------------------------------------------
# compute_read_sets()
#
# Given a set of LR(0) items, this function computes the read sets.
#
# Inputs: C = Set of LR(0) items
# ntrans = Set of nonterminal transitions
# nullable = Set of empty transitions
#
# Returns a set containing the read sets
# -----------------------------------------------------------------------------
def compute_read_sets(self, C, ntrans, nullable):
FP = lambda x: self.dr_relation(C, x, nullable)
R = lambda x: self.reads_relation(C, x, nullable)
F = digraph(ntrans, R, FP)
return F
# -----------------------------------------------------------------------------
# compute_follow_sets()
#
# Given a set of LR(0) items, a set of non-terminal transitions, a readset,
# and an include set, this function computes the follow sets
#
# Follow(p,A) = Read(p,A) U U {Follow(p',B) | (p,A) INCLUDES (p',B)}
#
# Inputs:
# ntrans = Set of nonterminal transitions
# readsets = Readset (previously computed)
# inclsets = Include sets (previously computed)
#
# Returns a set containing the follow sets
# -----------------------------------------------------------------------------
def compute_follow_sets(self, ntrans, readsets, inclsets):
FP = lambda x: readsets[x]
R = lambda x: inclsets.get(x, [])
F = digraph(ntrans, R, FP)
return F
# -----------------------------------------------------------------------------
# add_lookaheads()
#
# Attaches the lookahead symbols to grammar rules.
#
# Inputs: lookbacks - Set of lookback relations
# followset - Computed follow set
#
# This function directly attaches the lookaheads to productions contained
# in the lookbacks set
# -----------------------------------------------------------------------------
def add_lookaheads(self, lookbacks, followset):
for trans, lb in lookbacks.items():
# Loop over productions in lookback
for state, p in lb:
if state not in p.lookaheads:
p.lookaheads[state] = []
f = followset.get(trans, [])
for a in f:
if a not in p.lookaheads[state]:
p.lookaheads[state].append(a)
# -----------------------------------------------------------------------------
# add_lalr_lookaheads()
#
# This function does all of the work of adding lookahead information for use
# with LALR parsing
# -----------------------------------------------------------------------------
def add_lalr_lookaheads(self, C):
# Determine all of the nullable nonterminals
nullable = self.compute_nullable_nonterminals()
# Find all non-terminal transitions
trans = self.find_nonterminal_transitions(C)
# Compute read sets
readsets = self.compute_read_sets(C, trans, nullable)
# Compute lookback/includes relations
lookd, included = self.compute_lookback_includes(C, trans, nullable)
# Compute LALR FOLLOW sets
followsets = self.compute_follow_sets(trans, readsets, included)
# Add all of the lookaheads
self.add_lookaheads(lookd, followsets)
# -----------------------------------------------------------------------------
# lr_parse_table()
#
# This function constructs the parse tables for SLR or LALR
# -----------------------------------------------------------------------------
def lr_parse_table(self):
Productions = self.grammar.Productions
Precedence = self.grammar.Precedence
goto = self.lr_goto # Goto array
action = self.lr_action # Action array
log = self.log # Logger for output
actionp = {} # Action production array (temporary)
log.info('Parsing method: %s', self.lr_method)
# Step 1: Construct C = { I0, I1, ... IN}, collection of LR(0) items
# This determines the number of states
C = self.lr0_items()
if self.lr_method == 'LALR':
self.add_lalr_lookaheads(C)
# Build the parser table, state by state
st = 0
for I in C:
# Loop over each production in I
actlist = [] # List of actions
st_action = {}
st_actionp = {}
st_goto = {}
log.info('')
log.info('state %d', st)
log.info('')
for p in I:
log.info(' (%d) %s', p.number, p)
log.info('')
for p in I:
if p.len == p.lr_index + 1:
if p.name == "S'":
# Start symbol. Accept!
st_action['$end'] = 0
st_actionp['$end'] = p
else:
# We are at the end of a production. Reduce!
if self.lr_method == 'LALR':
laheads = p.lookaheads[st]
else:
laheads = self.grammar.Follow[p.name]
for a in laheads:
actlist.append((a, p, 'reduce using rule %d (%s)' % (p.number, p)))
r = st_action.get(a)
if r is not None:
# Whoa. Have a shift/reduce or reduce/reduce conflict
if r > 0:
# Need to decide on shift or reduce here
# By default we favor shifting. Need to add
# some precedence rules here.
sprec, slevel = Productions[st_actionp[a].number].prec
rprec, rlevel = Precedence.get(a, ('right', 0))
if (slevel < rlevel) or ((slevel == rlevel) and (rprec == 'left')):
# We really need to reduce here.
st_action[a] = -p.number
st_actionp[a] = p
if not slevel and not rlevel:
log.info(' ! shift/reduce conflict for %s resolved as reduce', a)
self.sr_conflicts.append((st, a, 'reduce'))
Productions[p.number].reduced += 1
elif (slevel == rlevel) and (rprec == 'nonassoc'):
st_action[a] = None
else:
# Hmmm. Guess we'll keep the shift
if not rlevel:
log.info(' ! shift/reduce conflict for %s resolved as shift', a)
self.sr_conflicts.append((st, a, 'shift'))
elif r < 0:
# Reduce/reduce conflict. In this case, we favor the rule
# that was defined first in the grammar file
oldp = Productions[-r]
pp = Productions[p.number]
if oldp.line > pp.line:
st_action[a] = -p.number
st_actionp[a] = p
chosenp, rejectp = pp, oldp
Productions[p.number].reduced += 1
Productions[oldp.number].reduced -= 1
else:
chosenp, rejectp = oldp, pp
self.rr_conflicts.append((st, chosenp, rejectp))
log.info(' ! reduce/reduce conflict for %s resolved using rule %d (%s)',
a, st_actionp[a].number, st_actionp[a])
else:
raise LALRError('Unknown conflict in state %d' % st)
else:
st_action[a] = -p.number
st_actionp[a] = p
Productions[p.number].reduced += 1
else:
i = p.lr_index
a = p.prod[i+1] # Get symbol right after the "."
if a in self.grammar.Terminals:
g = self.lr0_goto(I, a)
j = self.lr0_cidhash.get(id(g), -1)
if j >= 0:
# We are in a shift state
actlist.append((a, p, 'shift and go to state %d' % j))
r = st_action.get(a)
if r is not None:
# Whoa have a shift/reduce or shift/shift conflict
if r > 0:
if r != j:
raise LALRError('Shift/shift conflict in state %d' % st)
elif r < 0:
# Do a precedence check.
# - if precedence of reduce rule is higher, we reduce.
# - if precedence of reduce is same and left assoc, we reduce.
# - otherwise we shift
rprec, rlevel = Productions[st_actionp[a].number].prec
sprec, slevel = Precedence.get(a, ('right', 0))
if (slevel > rlevel) or ((slevel == rlevel) and (rprec == 'right')):
# We decide to shift here... highest precedence to shift
Productions[st_actionp[a].number].reduced -= 1
st_action[a] = j
st_actionp[a] = p
if not rlevel:
log.info(' ! shift/reduce conflict for %s resolved as shift', a)
self.sr_conflicts.append((st, a, 'shift'))
elif (slevel == rlevel) and (rprec == 'nonassoc'):
st_action[a] = None
else:
# Hmmm. Guess we'll keep the reduce
if not slevel and not rlevel:
log.info(' ! shift/reduce conflict for %s resolved as reduce', a)
self.sr_conflicts.append((st, a, 'reduce'))
else:
raise LALRError('Unknown conflict in state %d' % st)
else:
st_action[a] = j
st_actionp[a] = p
# Print the actions associated with each terminal
_actprint = {}
for a, p, m in actlist:
if a in st_action:
if p is st_actionp[a]:
log.info(' %-15s %s', a, m)
_actprint[(a, m)] = 1
log.info('')
# Print the actions that were not used. (debugging)
not_used = 0
for a, p, m in actlist:
if a in st_action:
if p is not st_actionp[a]:
if not (a, m) in _actprint:
log.debug(' ! %-15s [ %s ]', a, m)
not_used = 1
_actprint[(a, m)] = 1
if not_used:
log.debug('')
# Construct the goto table for this state
nkeys = {}
for ii in I:
for s in ii.usyms:
if s in self.grammar.Nonterminals:
nkeys[s] = None
for n in nkeys:
g = self.lr0_goto(I, n)
j = self.lr0_cidhash.get(id(g), -1)
if j >= 0:
st_goto[n] = j
log.info(' %-30s shift and go to state %d', n, j)
action[st] = st_action
actionp[st] = st_actionp
goto[st] = st_goto
st += 1
# -----------------------------------------------------------------------------
# write()
#
# This function writes the LR parsing tables to a file
# -----------------------------------------------------------------------------
def write_table(self, tabmodule, outputdir='', signature=''):
if isinstance(tabmodule, types.ModuleType):
raise IOError("Won't overwrite existing tabmodule")
basemodulename = tabmodule.split('.')[-1]
filename = os.path.join(outputdir, basemodulename) + '.py'
try:
f = open(filename, 'w')
f.write('''
# %s
# This file is automatically generated. Do not edit.
_tabversion = %r
_lr_method = %r
_lr_signature = %r
''' % (os.path.basename(filename), __tabversion__, self.lr_method, signature))
# Change smaller to 0 to go back to original tables
smaller = 1
# Factor out names to try and make smaller
if smaller:
items = {}
for s, nd in self.lr_action.items():
for name, v in nd.items():
i = items.get(name)
if not i:
i = ([], [])
items[name] = i
i[0].append(s)
i[1].append(v)
f.write('\n_lr_action_items = {')
for k, v in items.items():
f.write('%r:([' % k)
for i in v[0]:
f.write('%r,' % i)
f.write('],[')
for i in v[1]:
f.write('%r,' % i)
f.write(']),')
f.write('}\n')
f.write('''
_lr_action = {}
for _k, _v in _lr_action_items.items():
for _x,_y in zip(_v[0],_v[1]):
if not _x in _lr_action: _lr_action[_x] = {}
_lr_action[_x][_k] = _y
del _lr_action_items
''')
else:
f.write('\n_lr_action = { ')
for k, v in self.lr_action.items():
f.write('(%r,%r):%r,' % (k[0], k[1], v))
f.write('}\n')
if smaller:
# Factor out names to try and make smaller
items = {}
for s, nd in self.lr_goto.items():
for name, v in nd.items():
i = items.get(name)
if not i:
i = ([], [])
items[name] = i
i[0].append(s)
i[1].append(v)
f.write('\n_lr_goto_items = {')
for k, v in items.items():
f.write('%r:([' % k)
for i in v[0]:
f.write('%r,' % i)
f.write('],[')
for i in v[1]:
f.write('%r,' % i)
f.write(']),')
f.write('}\n')
f.write('''
_lr_goto = {}
for _k, _v in _lr_goto_items.items():
for _x, _y in zip(_v[0], _v[1]):
if not _x in _lr_goto: _lr_goto[_x] = {}
_lr_goto[_x][_k] = _y
del _lr_goto_items
''')
else:
f.write('\n_lr_goto = { ')
for k, v in self.lr_goto.items():
f.write('(%r,%r):%r,' % (k[0], k[1], v))
f.write('}\n')
# Write production table
f.write('_lr_productions = [\n')
for p in self.lr_productions:
if p.func:
f.write(' (%r,%r,%d,%r,%r,%d),\n' % (p.str, p.name, p.len,
p.func, os.path.basename(p.file), p.line))
else:
f.write(' (%r,%r,%d,None,None,None),\n' % (str(p), p.name, p.len))
f.write(']\n')
f.close()
except IOError as e:
raise
# -----------------------------------------------------------------------------
# pickle_table()
#
# This function pickles the LR parsing tables to a supplied file object
# -----------------------------------------------------------------------------
def pickle_table(self, filename, signature=''):
try:
import cPickle as pickle
except ImportError:
import pickle
with open(filename, 'wb') as outf:
pickle.dump(__tabversion__, outf, pickle_protocol)
pickle.dump(self.lr_method, outf, pickle_protocol)
pickle.dump(signature, outf, pickle_protocol)
pickle.dump(self.lr_action, outf, pickle_protocol)
pickle.dump(self.lr_goto, outf, pickle_protocol)
outp = []
for p in self.lr_productions:
if p.func:
outp.append((p.str, p.name, p.len, p.func, os.path.basename(p.file), p.line))
else:
outp.append((str(p), p.name, p.len, None, None, None))
pickle.dump(outp, outf, pickle_protocol)
# -----------------------------------------------------------------------------
# === INTROSPECTION ===
#
# The following functions and classes are used to implement the PLY
# introspection features followed by the yacc() function itself.
# -----------------------------------------------------------------------------
# -----------------------------------------------------------------------------
# get_caller_module_dict()
#
# This function returns a dictionary containing all of the symbols defined within
# a caller further down the call stack. This is used to get the environment
# associated with the yacc() call if none was provided.
# -----------------------------------------------------------------------------
def get_caller_module_dict(levels):
f = sys._getframe(levels)
ldict = f.f_globals.copy()
if f.f_globals != f.f_locals:
ldict.update(f.f_locals)
return ldict
# -----------------------------------------------------------------------------
# parse_grammar()
#
# This takes a raw grammar rule string and parses it into production data
# -----------------------------------------------------------------------------
def parse_grammar(doc, file, line):
grammar = []
# Split the doc string into lines
pstrings = doc.splitlines()
lastp = None
dline = line
for ps in pstrings:
dline += 1
p = ps.split()
if not p:
continue
try:
if p[0] == '|':
# This is a continuation of a previous rule
if not lastp:
raise SyntaxError("%s:%d: Misplaced '|'" % (file, dline))
prodname = lastp
syms = p[1:]
else:
prodname = p[0]
lastp = prodname
syms = p[2:]
assign = p[1]
if assign != ':' and assign != '::=':
raise SyntaxError("%s:%d: Syntax error. Expected ':'" % (file, dline))
grammar.append((file, dline, prodname, syms))
except SyntaxError:
raise
except Exception:
raise SyntaxError('%s:%d: Syntax error in rule %r' % (file, dline, ps.strip()))
return grammar
# -----------------------------------------------------------------------------
# ParserReflect()
#
# This class represents information extracted for building a parser including
# start symbol, error function, tokens, precedence list, action functions,
# etc.
# -----------------------------------------------------------------------------
class ParserReflect(object):
def __init__(self, pdict, log=None):
self.pdict = pdict
self.start = None
self.error_func = None
self.tokens = None
self.modules = set()
self.grammar = []
self.error = False
if log is None:
self.log = PlyLogger(sys.stderr)
else:
self.log = log
# Get all of the basic information
def get_all(self):
self.get_start()
self.get_error_func()
self.get_tokens()
self.get_precedence()
self.get_pfunctions()
# Validate all of the information
def validate_all(self):
self.validate_start()
self.validate_error_func()
self.validate_tokens()
self.validate_precedence()
self.validate_pfunctions()
self.validate_modules()
return self.error
# Compute a signature over the grammar
def signature(self):
try:
from hashlib import md5
except ImportError:
from md5 import md5
try:
sig = md5()
if self.start:
sig.update(self.start.encode('latin-1'))
if self.prec:
sig.update(''.join([''.join(p) for p in self.prec]).encode('latin-1'))
if self.tokens:
sig.update(' '.join(self.tokens).encode('latin-1'))
for f in self.pfuncs:
if f[3]:
sig.update(f[3].encode('latin-1'))
except (TypeError, ValueError):
pass
digest = base64.b16encode(sig.digest())
if sys.version_info[0] >= 3:
digest = digest.decode('latin-1')
return digest
# -----------------------------------------------------------------------------
# validate_modules()
#
# This method checks to see if there are duplicated p_rulename() functions
# in the parser module file. Without this function, it is really easy for
# users to make mistakes by cutting and pasting code fragments (and it's a real
# bugger to try and figure out why the resulting parser doesn't work). Therefore,
# we just do a little regular expression pattern matching of def statements
# to try and detect duplicates.
# -----------------------------------------------------------------------------
def validate_modules(self):
# Match def p_funcname(
fre = re.compile(r'\s*def\s+(p_[a-zA-Z_0-9]*)\(')
for module in self.modules:
lines, linen = inspect.getsourcelines(module)
counthash = {}
for linen, line in enumerate(lines):
linen += 1
m = fre.match(line)
if m:
name = m.group(1)
prev = counthash.get(name)
if not prev:
counthash[name] = linen
else:
filename = inspect.getsourcefile(module)
self.log.warning('%s:%d: Function %s redefined. Previously defined on line %d',
filename, linen, name, prev)
# Get the start symbol
def get_start(self):
self.start = self.pdict.get('start')
# Validate the start symbol
def validate_start(self):
if self.start is not None:
if not isinstance(self.start, string_types):
self.log.error("'start' must be a string")
# Look for error handler
def get_error_func(self):
self.error_func = self.pdict.get('p_error')
# Validate the error function
def validate_error_func(self):
if self.error_func:
if isinstance(self.error_func, types.FunctionType):
ismethod = 0
elif isinstance(self.error_func, types.MethodType):
ismethod = 1
else:
self.log.error("'p_error' defined, but is not a function or method")
self.error = True
return
eline = self.error_func.__code__.co_firstlineno
efile = self.error_func.__code__.co_filename
module = inspect.getmodule(self.error_func)
self.modules.add(module)
argcount = self.error_func.__code__.co_argcount - ismethod
if argcount != 1:
self.log.error('%s:%d: p_error() requires 1 argument', efile, eline)
self.error = True
# Get the tokens map
def get_tokens(self):
tokens = self.pdict.get('tokens')
if not tokens:
self.log.error('No token list is defined')
self.error = True
return
if not isinstance(tokens, (list, tuple)):
self.log.error('tokens must be a list or tuple')
self.error = True
return
if not tokens:
self.log.error('tokens is empty')
self.error = True
return
self.tokens = tokens
# Validate the tokens
def validate_tokens(self):
# Validate the tokens.
if 'error' in self.tokens:
self.log.error("Illegal token name 'error'. Is a reserved word")
self.error = True
return
terminals = set()
for n in self.tokens:
if n in terminals:
self.log.warning('Token %r multiply defined', n)
terminals.add(n)
# Get the precedence map (if any)
def get_precedence(self):
self.prec = self.pdict.get('precedence')
# Validate and parse the precedence map
def validate_precedence(self):
preclist = []
if self.prec:
if not isinstance(self.prec, (list, tuple)):
self.log.error('precedence must be a list or tuple')
self.error = True
return
for level, p in enumerate(self.prec):
if not isinstance(p, (list, tuple)):
self.log.error('Bad precedence table')
self.error = True
return
if len(p) < 2:
self.log.error('Malformed precedence entry %s. Must be (assoc, term, ..., term)', p)
self.error = True
return
assoc = p[0]
if not isinstance(assoc, string_types):
self.log.error('precedence associativity must be a string')
self.error = True
return
for term in p[1:]:
if not isinstance(term, string_types):
self.log.error('precedence items must be strings')
self.error = True
return
preclist.append((term, assoc, level+1))
self.preclist = preclist
# Get all p_functions from the grammar
def get_pfunctions(self):
p_functions = []
for name, item in self.pdict.items():
if not name.startswith('p_') or name == 'p_error':
continue
if isinstance(item, (types.FunctionType, types.MethodType)):
line = item.__code__.co_firstlineno
module = inspect.getmodule(item)
p_functions.append((line, module, name, item.__doc__))
# Sort all of the actions by line number; make sure to stringify
# modules to make them sortable, since `line` may not uniquely sort all
# p functions
p_functions.sort(key=lambda p_function: (
p_function[0],
str(p_function[1]),
p_function[2],
p_function[3]))
self.pfuncs = p_functions
# Validate all of the p_functions
def validate_pfunctions(self):
grammar = []
# Check for non-empty symbols
if len(self.pfuncs) == 0:
self.log.error('no rules of the form p_rulename are defined')
self.error = True
return
for line, module, name, doc in self.pfuncs:
file = inspect.getsourcefile(module)
func = self.pdict[name]
if isinstance(func, types.MethodType):
reqargs = 2
else:
reqargs = 1
if func.__code__.co_argcount > reqargs:
self.log.error('%s:%d: Rule %r has too many arguments', file, line, func.__name__)
self.error = True
elif func.__code__.co_argcount < reqargs:
self.log.error('%s:%d: Rule %r requires an argument', file, line, func.__name__)
self.error = True
elif not func.__doc__:
self.log.warning('%s:%d: No documentation string specified in function %r (ignored)',
file, line, func.__name__)
else:
try:
parsed_g = parse_grammar(doc, file, line)
for g in parsed_g:
grammar.append((name, g))
except SyntaxError as e:
self.log.error(str(e))
self.error = True
# Looks like a valid grammar rule
# Mark the file in which defined.
self.modules.add(module)
# Secondary validation step that looks for p_ definitions that are not functions
# or functions that look like they might be grammar rules.
for n, v in self.pdict.items():
if n.startswith('p_') and isinstance(v, (types.FunctionType, types.MethodType)):
continue
if n.startswith('t_'):
continue
if n.startswith('p_') and n != 'p_error':
self.log.warning('%r not defined as a function', n)
if ((isinstance(v, types.FunctionType) and v.__code__.co_argcount == 1) or
(isinstance(v, types.MethodType) and v.__func__.__code__.co_argcount == 2)):
if v.__doc__:
try:
doc = v.__doc__.split(' ')
if doc[1] == ':':
self.log.warning('%s:%d: Possible grammar rule %r defined without p_ prefix',
v.__code__.co_filename, v.__code__.co_firstlineno, n)
except IndexError:
pass
self.grammar = grammar
# -----------------------------------------------------------------------------
# yacc(module)
#
# Build a parser
# -----------------------------------------------------------------------------
def yacc(method='LALR', debug=yaccdebug, module=None, tabmodule=tab_module, start=None,
check_recursion=True, optimize=False, write_tables=True, debugfile=debug_file,
outputdir=None, debuglog=None, errorlog=None, picklefile=None):
if tabmodule is None:
tabmodule = tab_module
# Reference to the parsing method of the last built parser
global parse
# If pickling is enabled, table files are not created
if picklefile:
write_tables = 0
if errorlog is None:
errorlog = PlyLogger(sys.stderr)
# Get the module dictionary used for the parser
if module:
_items = [(k, getattr(module, k)) for k in dir(module)]
pdict = dict(_items)
# If no __file__ attribute is available, try to obtain it from the __module__ instead
if '__file__' not in pdict:
pdict['__file__'] = sys.modules[pdict['__module__']].__file__
else:
pdict = get_caller_module_dict(2)
if outputdir is None:
# If no output directory is set, the location of the output files
# is determined according to the following rules:
# - If tabmodule specifies a package, files go into that package directory
# - Otherwise, files go in the same directory as the specifying module
if isinstance(tabmodule, types.ModuleType):
srcfile = tabmodule.__file__
else:
if '.' not in tabmodule:
srcfile = pdict['__file__']
else:
parts = tabmodule.split('.')
pkgname = '.'.join(parts[:-1])
exec('import %s' % pkgname)
srcfile = getattr(sys.modules[pkgname], '__file__', '')
outputdir = os.path.dirname(srcfile)
# Determine if the module is package of a package or not.
# If so, fix the tabmodule setting so that tables load correctly
pkg = pdict.get('__package__')
if pkg and isinstance(tabmodule, str):
if '.' not in tabmodule:
tabmodule = pkg + '.' + tabmodule
# Set start symbol if it's specified directly using an argument
if start is not None:
pdict['start'] = start
# Collect parser information from the dictionary
pinfo = ParserReflect(pdict, log=errorlog)
pinfo.get_all()
if pinfo.error:
raise YaccError('Unable to build parser')
# Check signature against table files (if any)
signature = pinfo.signature()
# Read the tables
try:
lr = LRTable()
if picklefile:
read_signature = lr.read_pickle(picklefile)
else:
read_signature = lr.read_table(tabmodule)
if optimize or (read_signature == signature):
try:
lr.bind_callables(pinfo.pdict)
parser = LRParser(lr, pinfo.error_func)
parse = parser.parse
return parser
except Exception as e:
errorlog.warning('There was a problem loading the table file: %r', e)
except VersionError as e:
errorlog.warning(str(e))
except ImportError:
pass
if debuglog is None:
if debug:
try:
debuglog = PlyLogger(open(os.path.join(outputdir, debugfile), 'w'))
except IOError as e:
errorlog.warning("Couldn't open %r. %s" % (debugfile, e))
debuglog = NullLogger()
else:
debuglog = NullLogger()
debuglog.info('Created by PLY version %s (http://www.dabeaz.com/ply)', __version__)
errors = False
# Validate the parser information
if pinfo.validate_all():
raise YaccError('Unable to build parser')
if not pinfo.error_func:
errorlog.warning('no p_error() function is defined')
# Create a grammar object
grammar = Grammar(pinfo.tokens)
# Set precedence level for terminals
for term, assoc, level in pinfo.preclist:
try:
grammar.set_precedence(term, assoc, level)
except GrammarError as e:
errorlog.warning('%s', e)
# Add productions to the grammar
for funcname, gram in pinfo.grammar:
file, line, prodname, syms = gram
try:
grammar.add_production(prodname, syms, funcname, file, line)
except GrammarError as e:
errorlog.error('%s', e)
errors = True
# Set the grammar start symbols
try:
if start is None:
grammar.set_start(pinfo.start)
else:
grammar.set_start(start)
except GrammarError as e:
errorlog.error(str(e))
errors = True
if errors:
raise YaccError('Unable to build parser')
# Verify the grammar structure
undefined_symbols = grammar.undefined_symbols()
for sym, prod in undefined_symbols:
errorlog.error('%s:%d: Symbol %r used, but not defined as a token or a rule', prod.file, prod.line, sym)
errors = True
unused_terminals = grammar.unused_terminals()
if unused_terminals:
debuglog.info('')
debuglog.info('Unused terminals:')
debuglog.info('')
for term in unused_terminals:
errorlog.warning('Token %r defined, but not used', term)
debuglog.info(' %s', term)
# Print out all productions to the debug log
if debug:
debuglog.info('')
debuglog.info('Grammar')
debuglog.info('')
for n, p in enumerate(grammar.Productions):
debuglog.info('Rule %-5d %s', n, p)
# Find unused non-terminals
unused_rules = grammar.unused_rules()
for prod in unused_rules:
errorlog.warning('%s:%d: Rule %r defined, but not used', prod.file, prod.line, prod.name)
if len(unused_terminals) == 1:
errorlog.warning('There is 1 unused token')
if len(unused_terminals) > 1:
errorlog.warning('There are %d unused tokens', len(unused_terminals))
if len(unused_rules) == 1:
errorlog.warning('There is 1 unused rule')
if len(unused_rules) > 1:
errorlog.warning('There are %d unused rules', len(unused_rules))
if debug:
debuglog.info('')
debuglog.info('Terminals, with rules where they appear')
debuglog.info('')
terms = list(grammar.Terminals)
terms.sort()
for term in terms:
debuglog.info('%-20s : %s', term, ' '.join([str(s) for s in grammar.Terminals[term]]))
debuglog.info('')
debuglog.info('Nonterminals, with rules where they appear')
debuglog.info('')
nonterms = list(grammar.Nonterminals)
nonterms.sort()
for nonterm in nonterms:
debuglog.info('%-20s : %s', nonterm, ' '.join([str(s) for s in grammar.Nonterminals[nonterm]]))
debuglog.info('')
if check_recursion:
unreachable = grammar.find_unreachable()
for u in unreachable:
errorlog.warning('Symbol %r is unreachable', u)
infinite = grammar.infinite_cycles()
for inf in infinite:
errorlog.error('Infinite recursion detected for symbol %r', inf)
errors = True
unused_prec = grammar.unused_precedence()
for term, assoc in unused_prec:
errorlog.error('Precedence rule %r defined for unknown symbol %r', assoc, term)
errors = True
if errors:
raise YaccError('Unable to build parser')
# Run the LRGeneratedTable on the grammar
if debug:
errorlog.debug('Generating %s tables', method)
lr = LRGeneratedTable(grammar, method, debuglog)
if debug:
num_sr = len(lr.sr_conflicts)
# Report shift/reduce and reduce/reduce conflicts
if num_sr == 1:
errorlog.warning('1 shift/reduce conflict')
elif num_sr > 1:
errorlog.warning('%d shift/reduce conflicts', num_sr)
num_rr = len(lr.rr_conflicts)
if num_rr == 1:
errorlog.warning('1 reduce/reduce conflict')
elif num_rr > 1:
errorlog.warning('%d reduce/reduce conflicts', num_rr)
# Write out conflicts to the output file
if debug and (lr.sr_conflicts or lr.rr_conflicts):
debuglog.warning('')
debuglog.warning('Conflicts:')
debuglog.warning('')
for state, tok, resolution in lr.sr_conflicts:
debuglog.warning('shift/reduce conflict for %s in state %d resolved as %s', tok, state, resolution)
already_reported = set()
for state, rule, rejected in lr.rr_conflicts:
if (state, id(rule), id(rejected)) in already_reported:
continue
debuglog.warning('reduce/reduce conflict in state %d resolved using rule (%s)', state, rule)
debuglog.warning('rejected rule (%s) in state %d', rejected, state)
errorlog.warning('reduce/reduce conflict in state %d resolved using rule (%s)', state, rule)
errorlog.warning('rejected rule (%s) in state %d', rejected, state)
already_reported.add((state, id(rule), id(rejected)))
warned_never = []
for state, rule, rejected in lr.rr_conflicts:
if not rejected.reduced and (rejected not in warned_never):
debuglog.warning('Rule (%s) is never reduced', rejected)
errorlog.warning('Rule (%s) is never reduced', rejected)
warned_never.append(rejected)
# Write the table file if requested
if write_tables:
try:
lr.write_table(tabmodule, outputdir, signature)
except IOError as e:
errorlog.warning("Couldn't create %r. %s" % (tabmodule, e))
# Write a pickled version of the tables
if picklefile:
try:
lr.pickle_table(picklefile, signature)
except IOError as e:
errorlog.warning("Couldn't create %r. %s" % (picklefile, e))
# Build the parser
lr.bind_callables(pinfo.pdict)
parser = LRParser(lr, pinfo.error_func)
parse = parser.parse
return parser
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