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Allowing a feature for preprocessors by appending "lookahead" and "lookaheadstack " under "self." #33

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Allowing a feature for preprocessors by appending "lookahead" and "lookaheadstack " under "self." #33

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56 changes: 28 additions & 28 deletions sly/yacc.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1834,8 +1834,8 @@ def parse(self, tokens):
'''
Parse the given input tokens.
'''
lookahead = None # Current lookahead symbol
lookaheadstack = [] # Stack of lookahead symbols
self.lookahead = None # Current lookahead symbol
self.lookaheadstack = [] # Stack of lookahead symbols
actions = self._lrtable.lr_action # Local reference to action table (to avoid lookup on self.)
goto = self._lrtable.lr_goto # Local reference to goto table (to avoid lookup on self.)
prod = self._grammar.Productions # Local reference to production list (to avoid lookup on self.)
Expand All @@ -1856,17 +1856,17 @@ def parse(self, tokens):
# is already set, we just use that. Otherwise, we'll pull
# the next token off of the lookaheadstack or from the lexer
if self.state not in defaulted_states:
if not lookahead:
if not lookaheadstack:
lookahead = next(tokens, None) # Get the next token
if not self.lookahead:
if not self.lookaheadstack:
self.lookahead = next(tokens, None) # Get the next token
else:
lookahead = lookaheadstack.pop()
if not lookahead:
lookahead = YaccSymbol()
lookahead.type = '$end'
self.lookahead = self.lookaheadstack.pop()
if not self.lookahead:
self.lookahead = YaccSymbol()
self.lookahead.type = '$end'

# Check the action table
ltype = lookahead.type
ltype = self.lookahead.type
t = actions[self.state].get(ltype)
else:
t = defaulted_states[self.state]
Expand All @@ -1877,8 +1877,8 @@ def parse(self, tokens):
statestack.append(t)
self.state = t

symstack.append(lookahead)
lookahead = None
symstack.append(self.lookahead)
self.lookahead = None

# Decrease error count on successful shift
if errorcount:
Expand Down Expand Up @@ -1929,17 +1929,17 @@ def parse(self, tokens):
if errorcount == 0 or self.errorok:
errorcount = ERROR_COUNT
self.errorok = False
if lookahead.type == '$end':
if self.lookahead.type == '$end':
errtoken = None # End of file!
else:
errtoken = lookahead
errtoken = self.lookahead

tok = self.error(errtoken)
if tok:
# User must have done some kind of panic
# mode recovery on their own. The
# returned token is the next lookahead
lookahead = tok
self.lookahead = tok
self.errorok = True
continue
else:
Expand All @@ -1954,40 +1954,40 @@ def parse(self, tokens):
# 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 != '$end':
lookahead = None
if len(statestack) <= 1 and self.lookahead.type != '$end':
self.lookahead = None
self.state = 0
# Nuke the lookahead stack
del lookaheadstack[:]
del self.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 == '$end':
if self.lookahead.type == '$end':
# Whoa. We're really hosed here. Bail out
return

if lookahead.type != 'error':
if self.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
self.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 = lookahead.lineno
if hasattr(lookahead, 'index'):
t.index = lookahead.index
t.value = lookahead
lookaheadstack.append(lookahead)
lookahead = t
if hasattr(self.lookahead, 'lineno'):
t.lineno = self.lookahead.lineno
if hasattr(self.lookahead, 'index'):
t.index = self.lookahead.index
t.value = self.lookahead
self.lookaheadstack.append(self.lookahead)
self.lookahead = t
else:
sym = symstack.pop()
statestack.pop()
Expand Down