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import py
import string
from rpython.rlib.parsing.deterministic import NFA
set = py.builtin.set
class RegularExpression(object):
def __init__(self):
raise NotImplementedError("abstract base class")
def make_automaton(self):
raise NotImplementedError("abstract base class")
def __add__(self, other):
return AddExpression(self, other)
def __or__(self, other):
return OrExpression(self, other)
def __pos__(self):
return AddExpression(self, self.kleene())
def __mul__(self, i):
result = StringExpression("")
for x in range(i):
result += self
return result
def __invert__(self):
return NotExpression(self)
def kleene(self):
return KleeneClosure(self)
class StringExpression(RegularExpression):
def __init__(self, s):
self.string = s
def __add__(self, other):
if not isinstance(other, StringExpression):
return super(StringExpression, self).__add__(other)
return StringExpression(self.string + other.string)
def make_automaton(self):
nfa = NFA()
firstfinal = not self.string
state = nfa.add_state(start=True, final=firstfinal)
for i, char in enumerate(self.string):
final = i == len(self.string) - 1
next_state = nfa.add_state(final=final)
nfa.add_transition(state, next_state, char)
state = next_state
return nfa
def __repr__(self):
return "StringExpression(%r)" % (self.string, )
class RangeExpression(RegularExpression):
def __init__(self, fromchar, tochar):
self.fromchar = fromchar
self.tochar = tochar
def make_automaton(self):
nfa = NFA()
startstate = nfa.add_state(start=True)
finalstate = nfa.add_state(final=True)
for i in range(ord(self.fromchar), ord(self.tochar) + 1):
char = chr(i)
nfa.add_transition(startstate, finalstate, char)
return nfa
def __repr__(self):
return "RangeExpression(%r, %r)" % (self.fromchar, self.tochar)
class AddExpression(RegularExpression):
def __init__(self, rega, regb):
self.rega = rega
self.regb = regb
def make_automaton(self):
nfa1 = self.rega.make_automaton()
nfa2 = self.regb.make_automaton()
finalstates1 = nfa1.final_states
nfa1.final_states = set()
real_final = nfa1.add_state("final*", final=True)
orig_to_copy = nfa1.update(nfa2)
for final_state in finalstates1:
for start_state in nfa2.start_states:
start_state = orig_to_copy[start_state]
nfa1.add_transition(final_state, start_state)
for final_state in nfa2.final_states:
final_state = orig_to_copy[final_state]
nfa1.add_transition(final_state, real_final)
return nfa1
def __repr__(self):
return "AddExpression(%r, %r)" % (self.rega, self.regb)
class ExpressionTag(RegularExpression):
def __init__(self, reg, tag):
self.reg = reg
self.tag = tag
def make_automaton(self):
nfa = self.reg.make_automaton()
finalstates = nfa.final_states
nfa.final_states = set()
real_final = nfa.add_state(self.tag, final=True, unmergeable=True)
for final_state in finalstates:
nfa.add_transition(final_state, real_final)
return nfa
def __repr__(self):
return "ExpressionTag(%r, %r)" % (self.reg, self.tag)
class KleeneClosure(RegularExpression):
def __init__(self, regex):
self.regex = regex
def make_automaton(self):
nfa = self.regex.make_automaton()
oldfinal = nfa.final_states
nfa.final_states = set()
oldstart = nfa.start_states
nfa.start_states = set()
real_final = nfa.add_state("final*", final=True)
real_start = nfa.add_state("start*", start=True)
for start in oldstart:
nfa.add_transition(real_start, start)
for final in oldfinal:
nfa.add_transition(final, real_final)
nfa.add_transition(real_start, real_final)
nfa.add_transition(real_final, real_start)
return nfa
def __repr__(self):
return "KleeneClosure(%r)" % (self.regex, )
class OrExpression(RegularExpression):
def __init__(self, rega, regb):
self.rega = rega
self.regb = regb
def make_automaton(self):
nfa1 = self.rega.make_automaton()
nfa2 = self.regb.make_automaton()
oldfinal1 = nfa1.final_states
nfa1.final_states = set()
oldstart1 = nfa1.start_states
nfa1.start_states = set()
real_final = nfa1.add_state("final|", final=True)
real_start = nfa1.add_state("start|", start=True)
orig_to_copy = nfa1.update(nfa2)
for start in oldstart1:
nfa1.add_transition(real_start, start)
for final in oldfinal1:
nfa1.add_transition(final, real_final)
for start in nfa2.start_states:
start = orig_to_copy[start]
nfa1.add_transition(real_start, start)
for final in nfa2.final_states:
final = orig_to_copy[final]
nfa1.add_transition(final, real_final)
return nfa1
def __repr__(self):
return "OrExpression(%r, %r)" % (self.rega, self.regb)
class NotExpression(RegularExpression):
def __init__(self, reg):
self.reg = reg
def make_automaton(self):
nfa = self.reg.make_automaton()
# add error state
error = nfa.add_state("error")
for state in range(nfa.num_states):
occurring = set(nfa.transitions.get(state, {}).keys())
toerror = set([chr(i) for i in range(256)]) - occurring
for input in toerror:
nfa.add_transition(state, error, input)
nfa.final_states = set(range(nfa.num_states)) - nfa.final_states
return nfa
def __invert__(self):
return self.reg
class LexingOrExpression(RegularExpression):
def __init__(self, regs, names):
self.regs = regs
self.names = names
def make_automaton(self):
dfas = [reg.make_automaton().make_deterministic() for reg in self.regs]
[dfa.optimize() for dfa in dfas]
nfas = [dfa.make_nondeterministic() for dfa in dfas]
result_nfa = NFA()
start_state = result_nfa.add_state(start=True)
for i, nfa in enumerate(nfas):
final_state = result_nfa.add_state(self.names[i], final=True,
unmergeable=True)
state_map = {}
for j, name in enumerate(nfa.names):
start = j in nfa.start_states
final = j in nfa.final_states
newstate = result_nfa.add_state(name)
state_map[j] = newstate
if start:
result_nfa.add_transition(start_state, newstate)
if final:
result_nfa.add_transition(newstate, final_state)
for state, subtransitions in nfa.transitions.iteritems():
for input, states in subtransitions.iteritems():
newstate = state_map[state]
newstates = [state_map[s] for s in states]
for newtargetstate in newstates:
result_nfa.add_transition(
newstate, newtargetstate, input)
return result_nfa
def __repr__(self):
return "LexingOrExpression(%r, %r)" % (self.regs, self.names)
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