385 lines
13 KiB
Python
385 lines
13 KiB
Python
|
# Copyright 2004-2005 Elemental Security, Inc. All Rights Reserved.
|
||
|
|
# Licensed to PSF under a Contributor Agreement.
|
||
|
|
|
||
|
|
# Pgen imports
|
||
|
|
from pgen2 import grammar, token, tokenize
|
||
|
|
|
||
|
|
class PgenGrammar(grammar.Grammar):
|
||
|
|
pass
|
||
|
|
|
||
|
|
class ParserGenerator(object):
|
||
|
|
|
||
|
|
def __init__(self, filename, stream=None):
|
||
|
|
close_stream = None
|
||
|
|
if stream is None:
|
||
|
|
stream = open(filename)
|
||
|
|
close_stream = stream.close
|
||
|
|
self.filename = filename
|
||
|
|
self.stream = stream
|
||
|
|
self.generator = tokenize.generate_tokens(stream.readline)
|
||
|
|
self.gettoken() # Initialize lookahead
|
||
|
|
self.dfas, self.startsymbol = self.parse()
|
||
|
|
if close_stream is not None:
|
||
|
|
close_stream()
|
||
|
|
self.first = {} # map from symbol name to set of tokens
|
||
|
|
self.addfirstsets()
|
||
|
|
|
||
|
|
def make_grammar(self):
|
||
|
|
c = PgenGrammar()
|
||
|
|
names = self.dfas.keys()
|
||
|
|
names.sort()
|
||
|
|
names.remove(self.startsymbol)
|
||
|
|
names.insert(0, self.startsymbol)
|
||
|
|
for name in names:
|
||
|
|
i = 256 + len(c.symbol2number)
|
||
|
|
c.symbol2number[name] = i
|
||
|
|
c.number2symbol[i] = name
|
||
|
|
for name in names:
|
||
|
|
dfa = self.dfas[name]
|
||
|
|
states = []
|
||
|
|
for state in dfa:
|
||
|
|
arcs = []
|
||
|
|
for label, next in state.arcs.iteritems():
|
||
|
|
arcs.append((self.make_label(c, label), dfa.index(next)))
|
||
|
|
if state.isfinal:
|
||
|
|
arcs.append((0, dfa.index(state)))
|
||
|
|
states.append(arcs)
|
||
|
|
c.states.append(states)
|
||
|
|
c.dfas[c.symbol2number[name]] = (states, self.make_first(c, name))
|
||
|
|
c.start = c.symbol2number[self.startsymbol]
|
||
|
|
return c
|
||
|
|
|
||
|
|
def make_first(self, c, name):
|
||
|
|
rawfirst = self.first[name]
|
||
|
|
first = {}
|
||
|
|
for label in rawfirst:
|
||
|
|
ilabel = self.make_label(c, label)
|
||
|
|
##assert ilabel not in first # XXX failed on <> ... !=
|
||
|
|
first[ilabel] = 1
|
||
|
|
return first
|
||
|
|
|
||
|
|
def make_label(self, c, label):
|
||
|
|
# XXX Maybe this should be a method on a subclass of converter?
|
||
|
|
ilabel = len(c.labels)
|
||
|
|
if label[0].isalpha():
|
||
|
|
# Either a symbol name or a named token
|
||
|
|
if label in c.symbol2number:
|
||
|
|
# A symbol name (a non-terminal)
|
||
|
|
if label in c.symbol2label:
|
||
|
|
return c.symbol2label[label]
|
||
|
|
else:
|
||
|
|
c.labels.append((c.symbol2number[label], None))
|
||
|
|
c.symbol2label[label] = ilabel
|
||
|
|
return ilabel
|
||
|
|
else:
|
||
|
|
# A named token (NAME, NUMBER, STRING)
|
||
|
|
itoken = getattr(token, label, None)
|
||
|
|
assert isinstance(itoken, int), label
|
||
|
|
assert itoken in token.tok_name, label
|
||
|
|
if itoken in c.tokens:
|
||
|
|
return c.tokens[itoken]
|
||
|
|
else:
|
||
|
|
c.labels.append((itoken, None))
|
||
|
|
c.tokens[itoken] = ilabel
|
||
|
|
return ilabel
|
||
|
|
else:
|
||
|
|
# Either a keyword or an operator
|
||
|
|
assert label[0] in ('"', "'"), label
|
||
|
|
value = eval(label)
|
||
|
|
if value[0].isalpha():
|
||
|
|
# A keyword
|
||
|
|
if value in c.keywords:
|
||
|
|
return c.keywords[value]
|
||
|
|
else:
|
||
|
|
c.labels.append((token.NAME, value))
|
||
|
|
c.keywords[value] = ilabel
|
||
|
|
return ilabel
|
||
|
|
else:
|
||
|
|
# An operator (any non-numeric token)
|
||
|
|
itoken = grammar.opmap[value] # Fails if unknown token
|
||
|
|
if itoken in c.tokens:
|
||
|
|
return c.tokens[itoken]
|
||
|
|
else:
|
||
|
|
c.labels.append((itoken, None))
|
||
|
|
c.tokens[itoken] = ilabel
|
||
|
|
return ilabel
|
||
|
|
|
||
|
|
def addfirstsets(self):
|
||
|
|
names = self.dfas.keys()
|
||
|
|
names.sort()
|
||
|
|
for name in names:
|
||
|
|
if name not in self.first:
|
||
|
|
self.calcfirst(name)
|
||
|
|
#print name, self.first[name].keys()
|
||
|
|
|
||
|
|
def calcfirst(self, name):
|
||
|
|
dfa = self.dfas[name]
|
||
|
|
self.first[name] = None # dummy to detect left recursion
|
||
|
|
state = dfa[0]
|
||
|
|
totalset = {}
|
||
|
|
overlapcheck = {}
|
||
|
|
for label, next in state.arcs.iteritems():
|
||
|
|
if label in self.dfas:
|
||
|
|
if label in self.first:
|
||
|
|
fset = self.first[label]
|
||
|
|
if fset is None:
|
||
|
|
raise ValueError("recursion for rule %r" % name)
|
||
|
|
else:
|
||
|
|
self.calcfirst(label)
|
||
|
|
fset = self.first[label]
|
||
|
|
totalset.update(fset)
|
||
|
|
overlapcheck[label] = fset
|
||
|
|
else:
|
||
|
|
totalset[label] = 1
|
||
|
|
overlapcheck[label] = {label: 1}
|
||
|
|
inverse = {}
|
||
|
|
for label, itsfirst in overlapcheck.iteritems():
|
||
|
|
for symbol in itsfirst:
|
||
|
|
if symbol in inverse:
|
||
|
|
raise ValueError("rule %s is ambiguous; %s is in the"
|
||
|
|
" first sets of %s as well as %s" %
|
||
|
|
(name, symbol, label, inverse[symbol]))
|
||
|
|
inverse[symbol] = label
|
||
|
|
self.first[name] = totalset
|
||
|
|
|
||
|
|
def parse(self):
|
||
|
|
dfas = {}
|
||
|
|
startsymbol = None
|
||
|
|
# MSTART: (NEWLINE | RULE)* ENDMARKER
|
||
|
|
while self.type != token.ENDMARKER:
|
||
|
|
while self.type == token.NEWLINE:
|
||
|
|
self.gettoken()
|
||
|
|
# RULE: NAME ':' RHS NEWLINE
|
||
|
|
name = self.expect(token.NAME)
|
||
|
|
self.expect(token.OP, ":")
|
||
|
|
a, z = self.parse_rhs()
|
||
|
|
self.expect(token.NEWLINE)
|
||
|
|
#self.dump_nfa(name, a, z)
|
||
|
|
dfa = self.make_dfa(a, z)
|
||
|
|
#self.dump_dfa(name, dfa)
|
||
|
|
oldlen = len(dfa)
|
||
|
|
self.simplify_dfa(dfa)
|
||
|
|
newlen = len(dfa)
|
||
|
|
dfas[name] = dfa
|
||
|
|
#print name, oldlen, newlen
|
||
|
|
if startsymbol is None:
|
||
|
|
startsymbol = name
|
||
|
|
return dfas, startsymbol
|
||
|
|
|
||
|
|
def make_dfa(self, start, finish):
|
||
|
|
# To turn an NFA into a DFA, we define the states of the DFA
|
||
|
|
# to correspond to *sets* of states of the NFA. Then do some
|
||
|
|
# state reduction. Let's represent sets as dicts with 1 for
|
||
|
|
# values.
|
||
|
|
assert isinstance(start, NFAState)
|
||
|
|
assert isinstance(finish, NFAState)
|
||
|
|
def closure(state):
|
||
|
|
base = {}
|
||
|
|
addclosure(state, base)
|
||
|
|
return base
|
||
|
|
def addclosure(state, base):
|
||
|
|
assert isinstance(state, NFAState)
|
||
|
|
if state in base:
|
||
|
|
return
|
||
|
|
base[state] = 1
|
||
|
|
for label, next in state.arcs:
|
||
|
|
if label is None:
|
||
|
|
addclosure(next, base)
|
||
|
|
states = [DFAState(closure(start), finish)]
|
||
|
|
for state in states: # NB states grows while we're iterating
|
||
|
|
arcs = {}
|
||
|
|
for nfastate in state.nfaset:
|
||
|
|
for label, next in nfastate.arcs:
|
||
|
|
if label is not None:
|
||
|
|
addclosure(next, arcs.setdefault(label, {}))
|
||
|
|
for label, nfaset in arcs.iteritems():
|
||
|
|
for st in states:
|
||
|
|
if st.nfaset == nfaset:
|
||
|
|
break
|
||
|
|
else:
|
||
|
|
st = DFAState(nfaset, finish)
|
||
|
|
states.append(st)
|
||
|
|
state.addarc(st, label)
|
||
|
|
return states # List of DFAState instances; first one is start
|
||
|
|
|
||
|
|
def dump_nfa(self, name, start, finish):
|
||
|
|
print "Dump of NFA for", name
|
||
|
|
todo = [start]
|
||
|
|
for i, state in enumerate(todo):
|
||
|
|
print " State", i, state is finish and "(final)" or ""
|
||
|
|
for label, next in state.arcs:
|
||
|
|
if next in todo:
|
||
|
|
j = todo.index(next)
|
||
|
|
else:
|
||
|
|
j = len(todo)
|
||
|
|
todo.append(next)
|
||
|
|
if label is None:
|
||
|
|
print " -> %d" % j
|
||
|
|
else:
|
||
|
|
print " %s -> %d" % (label, j)
|
||
|
|
|
||
|
|
def dump_dfa(self, name, dfa):
|
||
|
|
print "Dump of DFA for", name
|
||
|
|
for i, state in enumerate(dfa):
|
||
|
|
print " State", i, state.isfinal and "(final)" or ""
|
||
|
|
for label, next in state.arcs.iteritems():
|
||
|
|
print " %s -> %d" % (label, dfa.index(next))
|
||
|
|
|
||
|
|
def simplify_dfa(self, dfa):
|
||
|
|
# This is not theoretically optimal, but works well enough.
|
||
|
|
# Algorithm: repeatedly look for two states that have the same
|
||
|
|
# set of arcs (same labels pointing to the same nodes) and
|
||
|
|
# unify them, until things stop changing.
|
||
|
|
|
||
|
|
# dfa is a list of DFAState instances
|
||
|
|
changes = True
|
||
|
|
while changes:
|
||
|
|
changes = False
|
||
|
|
for i, state_i in enumerate(dfa):
|
||
|
|
for j in range(i+1, len(dfa)):
|
||
|
|
state_j = dfa[j]
|
||
|
|
if state_i == state_j:
|
||
|
|
#print " unify", i, j
|
||
|
|
del dfa[j]
|
||
|
|
for state in dfa:
|
||
|
|
state.unifystate(state_j, state_i)
|
||
|
|
changes = True
|
||
|
|
break
|
||
|
|
|
||
|
|
def parse_rhs(self):
|
||
|
|
# RHS: ALT ('|' ALT)*
|
||
|
|
a, z = self.parse_alt()
|
||
|
|
if self.value != "|":
|
||
|
|
return a, z
|
||
|
|
else:
|
||
|
|
aa = NFAState()
|
||
|
|
zz = NFAState()
|
||
|
|
aa.addarc(a)
|
||
|
|
z.addarc(zz)
|
||
|
|
while self.value == "|":
|
||
|
|
self.gettoken()
|
||
|
|
a, z = self.parse_alt()
|
||
|
|
aa.addarc(a)
|
||
|
|
z.addarc(zz)
|
||
|
|
return aa, zz
|
||
|
|
|
||
|
|
def parse_alt(self):
|
||
|
|
# ALT: ITEM+
|
||
|
|
a, b = self.parse_item()
|
||
|
|
while (self.value in ("(", "[") or
|
||
|
|
self.type in (token.NAME, token.STRING)):
|
||
|
|
c, d = self.parse_item()
|
||
|
|
b.addarc(c)
|
||
|
|
b = d
|
||
|
|
return a, b
|
||
|
|
|
||
|
|
def parse_item(self):
|
||
|
|
# ITEM: '[' RHS ']' | ATOM ['+' | '*']
|
||
|
|
if self.value == "[":
|
||
|
|
self.gettoken()
|
||
|
|
a, z = self.parse_rhs()
|
||
|
|
self.expect(token.OP, "]")
|
||
|
|
a.addarc(z)
|
||
|
|
return a, z
|
||
|
|
else:
|
||
|
|
a, z = self.parse_atom()
|
||
|
|
value = self.value
|
||
|
|
if value not in ("+", "*"):
|
||
|
|
return a, z
|
||
|
|
self.gettoken()
|
||
|
|
z.addarc(a)
|
||
|
|
if value == "+":
|
||
|
|
return a, z
|
||
|
|
else:
|
||
|
|
return a, a
|
||
|
|
|
||
|
|
def parse_atom(self):
|
||
|
|
# ATOM: '(' RHS ')' | NAME | STRING
|
||
|
|
if self.value == "(":
|
||
|
|
self.gettoken()
|
||
|
|
a, z = self.parse_rhs()
|
||
|
|
self.expect(token.OP, ")")
|
||
|
|
return a, z
|
||
|
|
elif self.type in (token.NAME, token.STRING):
|
||
|
|
a = NFAState()
|
||
|
|
z = NFAState()
|
||
|
|
a.addarc(z, self.value)
|
||
|
|
self.gettoken()
|
||
|
|
return a, z
|
||
|
|
else:
|
||
|
|
self.raise_error("expected (...) or NAME or STRING, got %s/%s",
|
||
|
|
self.type, self.value)
|
||
|
|
|
||
|
|
def expect(self, type, value=None):
|
||
|
|
if self.type != type or (value is not None and self.value != value):
|
||
|
|
self.raise_error("expected %s/%s, got %s/%s",
|
||
|
|
type, value, self.type, self.value)
|
||
|
|
value = self.value
|
||
|
|
self.gettoken()
|
||
|
|
return value
|
||
|
|
|
||
|
|
def gettoken(self):
|
||
|
|
tup = self.generator.next()
|
||
|
|
while tup[0] in (tokenize.COMMENT, tokenize.NL):
|
||
|
|
tup = self.generator.next()
|
||
|
|
self.type, self.value, self.begin, self.end, self.line = tup
|
||
|
|
#print token.tok_name[self.type], repr(self.value)
|
||
|
|
|
||
|
|
def raise_error(self, msg, *args):
|
||
|
|
if args:
|
||
|
|
try:
|
||
|
|
msg = msg % args
|
||
|
|
except:
|
||
|
|
msg = " ".join([msg] + map(str, args))
|
||
|
|
raise SyntaxError(msg, (self.filename, self.end[0],
|
||
|
|
self.end[1], self.line))
|
||
|
|
|
||
|
|
class NFAState(object):
|
||
|
|
|
||
|
|
def __init__(self):
|
||
|
|
self.arcs = [] # list of (label, NFAState) pairs
|
||
|
|
|
||
|
|
def addarc(self, next, label=None):
|
||
|
|
assert label is None or isinstance(label, str)
|
||
|
|
assert isinstance(next, NFAState)
|
||
|
|
self.arcs.append((label, next))
|
||
|
|
|
||
|
|
class DFAState(object):
|
||
|
|
|
||
|
|
def __init__(self, nfaset, final):
|
||
|
|
assert isinstance(nfaset, dict)
|
||
|
|
assert isinstance(iter(nfaset).next(), NFAState)
|
||
|
|
assert isinstance(final, NFAState)
|
||
|
|
self.nfaset = nfaset
|
||
|
|
self.isfinal = final in nfaset
|
||
|
|
self.arcs = {} # map from label to DFAState
|
||
|
|
|
||
|
|
def addarc(self, next, label):
|
||
|
|
assert isinstance(label, str)
|
||
|
|
assert label not in self.arcs
|
||
|
|
assert isinstance(next, DFAState)
|
||
|
|
self.arcs[label] = next
|
||
|
|
|
||
|
|
def unifystate(self, old, new):
|
||
|
|
for label, next in self.arcs.iteritems():
|
||
|
|
if next is old:
|
||
|
|
self.arcs[label] = new
|
||
|
|
|
||
|
|
def __eq__(self, other):
|
||
|
|
# Equality test -- ignore the nfaset instance variable
|
||
|
|
assert isinstance(other, DFAState)
|
||
|
|
if self.isfinal != other.isfinal:
|
||
|
|
return False
|
||
|
|
# Can't just return self.arcs == other.arcs, because that
|
||
|
|
# would invoke this method recursively, with cycles...
|
||
|
|
if len(self.arcs) != len(other.arcs):
|
||
|
|
return False
|
||
|
|
for label, next in self.arcs.iteritems():
|
||
|
|
if next is not other.arcs.get(label):
|
||
|
|
return False
|
||
|
|
return True
|
||
|
|
|
||
|
|
def generate_grammar(filename="Grammar.txt"):
|
||
|
|
p = ParserGenerator(filename)
|
||
|
|
return p.make_grammar()
|