class Brzozowski:
"""
This class transforms a pyfst DFA to regular expressions
using the Brzozowski Algebraic Method
"""
def __init__(self, input_fst_a, alphabet=None):
"""
Args:
input_fst_a (DFA): The DFA states
alphabet (list): the input alphabet
Returns:
None
"""
if alphabet is None:
alphabet = createalphabet()
self.alphabet = alphabet
self.mma = DFA(self.alphabet)
self.mma.init_from_acceptor(input_fst_a)
# a is a matrix that holds all transitions
# If there is a transition from state 0 to state 1 with the symbol x
# then a[0][1]=x
self.A = {}
# B[n] holds the regular expression that describes how a final state
# can be reached from state n
self.B = {}
self.epsilon = ''
self.empty = None
def _bfs_sort(self, start):
"""
maintain a map of states distance using BFS
Args:
start (fst state): The initial DFA state
Returns:
list: An ordered list of DFA states
using path distance
"""
pathstates = {}
# maintain a queue of nodes to be visited. Both current and previous
# node must be included.
queue = []
# push the first path into the queue
queue.append([0, start])
pathstates[start.stateid] = 0
while queue:
# get the first node from the queue
leaf = queue.pop(0)
node = leaf[1]
pathlen = leaf[0]
# enumerate all adjacent nodes, construct a new path and push it
# into the queue
for arc in node.arcs:
next_state = self.mma[arc.nextstate]
if next_state.stateid not in pathstates:
queue.append([pathlen + 1, next_state])
pathstates[next_state.stateid] = pathlen + 1
orderedstatesdict = OrderedDict(
sorted(pathstates.items(), key=lambda x: x[1], reverse=False))
for state in self.mma.states:
orderedstatesdict[state.stateid] = state
orderedstates = [x[1] for x in list(orderedstatesdict.items())]
return orderedstates
def star(self, input_string):
"""
Kleene star operation
Args:
input_string (str): The string that the kleene star will be made
Returns:
str: The applied Kleene star operation on the input string
"""
if input_string != self.epsilon and input_string != self.empty:
return "(" + input_string + ")*"
else:
return ""
def _brzozowski_algebraic_method_init(self):
"""Initialize Brzozowski Algebraic Method"""
# Initialize B
for state_a in self.mma.states:
if state_a.final:
self.B[state_a.stateid] = self.epsilon
else:
self.B[state_a.stateid] = self.empty
# Initialize A
for state_b in self.mma.states:
self.A[state_a.stateid, state_b.stateid] = self.empty
for arc in state_a.arcs:
if arc.nextstate == state_b.stateid:
self.A[state_a.stateid, state_b.stateid] = \
self.mma.isyms.find(arc.ilabel)
def _brzozowski_algebraic_method_solve(self):
"""Perform Brzozowski Algebraic Method"""
orderedstates = self._bfs_sort(
sorted(self.mma.states, key=attrgetter('initial'),
reverse=True)[0])
for n in range(len(orderedstates) - 1, 0, -1):
# print "n:" + repr(n)
if self.A[orderedstates[n].stateid,
orderedstates[n].stateid] != self.empty:
# B[n] := star(A[n,n]) . B[n]
if self.B[orderedstates[n].stateid] != self.empty:
self.B[orderedstates[n].stateid] = \
self.star(self.A[orderedstates[n].stateid, orderedstates[n].stateid]) \
+ self.B[orderedstates[n].stateid]
else:
self.B[orderedstates[n].stateid] = self.star(
self.A[orderedstates[n].stateid,
orderedstates[n].stateid])
for j in range(0, n):
# A[n,j] := star(A[n,n]) . A[n,j]
if self.A[orderedstates[n].stateid,
orderedstates[j].stateid] != self.empty:
self.A[
orderedstates[n].stateid,
orderedstates[j].stateid] = \
self.star(self.A[orderedstates[n].stateid, orderedstates[n].stateid]) \
+ self.A[orderedstates[n].stateid, orderedstates[j].stateid]
else:
self.A[orderedstates[n].stateid,
orderedstates[j].stateid] = self.star(
self.A[orderedstates[n].stateid,
orderedstates[n].stateid])
for i in range(0, n):
# B[i] += A[i,n] . B[n]
newnode = None
if self.A[orderedstates[i].stateid, orderedstates[n].stateid] != self.empty \
and self.B[orderedstates[n].stateid] != self.empty:
newnode = self.A[orderedstates[i].stateid,
orderedstates[n].stateid] + self.B[
orderedstates[n].stateid]
elif self.A[orderedstates[i].stateid,
orderedstates[n].stateid] != self.empty:
newnode = self.A[orderedstates[i].stateid,
orderedstates[n].stateid]
elif self.B[orderedstates[n].stateid] != self.empty:
newnode = self.B[orderedstates[n].stateid]
if self.B[orderedstates[i].stateid] != self.empty:
if newnode is not None:
self.B[orderedstates[i].stateid] += newnode
else:
self.B[orderedstates[i].stateid] = newnode
for j in range(0, n):
# A[i,j] += A[i,n] . A[n,j]
newnode = None
if self.A[
orderedstates[i].stateid,
orderedstates[n].stateid] != self.empty \
and self.A[orderedstates[n].stateid, orderedstates[j].stateid] \
!= self.empty:
newnode = self.A[orderedstates[i].stateid,
orderedstates[n].stateid] + self.A[
orderedstates[n].stateid,
orderedstates[j].stateid]
elif self.A[orderedstates[i].stateid,
orderedstates[n].stateid] != self.empty:
newnode = self.A[orderedstates[i].stateid,
orderedstates[n].stateid]
elif self.A[orderedstates[n].stateid,
orderedstates[j].stateid] != self.empty:
newnode = self.A[orderedstates[n].stateid,
orderedstates[j].stateid]
if self.A[orderedstates[i].stateid,
orderedstates[j].stateid] != self.empty:
if newnode is not None:
self.A[orderedstates[i].stateid,
orderedstates[j].stateid] += newnode
else:
self.A[orderedstates[i].stateid,
orderedstates[j].stateid] = newnode
def get_regex(self):
"""Generate regular expressions from DFA automaton"""
self._brzozowski_algebraic_method_init()
self._brzozowski_algebraic_method_solve()
return self.B
class Regex:
"""
This class transforms a pyfst DFA to regular expressions
using the Brzozowski Algebraic Method
"""
def __init__(self, input_fst_a, alphabet=None):
"""
Args:
input_fst_a (DFA): The DFA states
alphabet (list): the input alphabet
Returns:
None
"""
if alphabet is None:
alphabet = createalphabet()
self.alphabet = alphabet
self.mma = DFA(self.alphabet)
self.mma.init_from_acceptor(input_fst_a)
# a is a matrix that holds all transitions
# If there is a transition from state 0 to state 1 with the symbol x
# then a[0][1]=x
self.A = {}
# B[n] holds the regular expression that describes how a final state
# can be reached from state n
self.B = {}
self.epsilon = ''
self.empty = None
def _bfs_sort(self, start):
"""
maintain a map of states distance using BFS
Args:
start (fst state): The initial DFA state
Returns:
list: An ordered list of DFA states
using path distance
"""
pathstates = {}
# maintain a queue of nodes to be visited. Both current and previous
# node must be included.
queue = []
# push the first path into the queue
queue.append([0, start])
pathstates[start.stateid] = 0
while queue:
# get the first node from the queue
leaf = queue.pop(0)
node = leaf[1]
pathlen = leaf[0]
# enumerate all adjacent nodes, construct a new path and push it
# into the queue
for arc in node.arcs:
next_state = self.mma[arc.nextstate]
if next_state.stateid not in pathstates:
queue.append([pathlen + 1, next_state])
pathstates[next_state.stateid] = pathlen + 1
orderedstatesdict = OrderedDict(
sorted(pathstates.items(), key=lambda x: x[1], reverse=False))
for state in self.mma.states:
orderedstatesdict[state.stateid] = state
orderedstates = [x[1] for x in list(orderedstatesdict.items())]
return orderedstates
def star(self, input_string):
"""
Kleene star operation
Args:
input_string (str): The string that the kleene star will be made
Returns:
str: The applied Kleene star operation on the input string
"""
if input_string != self.epsilon and input_string != self.empty:
return "(" + input_string + ")*"
else:
return ""
def _create_map(self):
"""Initialize Brzozowski Algebraic Method"""
# at state i is represented by the regex self.B[i]
for state_a in self.mma.states:
self.A[state_a.stateid] = {}
# Create a map state to state, with the transition symbols
for arc in state_a.arcs:
if arc.nextstate in self.A[state_a.stateid]:
self.A[state_a.stateid][arc.nextstate].append(
self.mma.isyms.find(arc.ilabel))
else:
self.A[state_a.stateid][arc.nextstate] = [
self.mma.isyms.find(arc.ilabel)
]
if state_a.final:
self.A[state_a.stateid]['string'] = ['']
# In both self.B and Self.A there are empty spots that we will fill in _brzozowski_algebraic_method_solve
def _fix_pattern(self):
for state_a in self.mma.states:
for target in self.A[state_a.stateid]:
if len(self.A[state_a.stateid][target]) == 0:
self.A[state_a.stateid][target] = ''
elif len(self.A[state_a.stateid][target]) == 1:
self.A[state_a.stateid][target] = self.A[
state_a.stateid][target][0]
elif len(self.A[state_a.stateid][target]) == len(
self.alphabet):
self.A[state_a.stateid][target] = '.'
elif len(
[a for a in self.A[state_a.stateid][target] if len(a) > 1
]) == 0 and len(self.A[state_a.stateid][target]) > len(
self.alphabet) / 2:
self.A[state_a.stateid][target] = '[^' + ''.join(
filter(
lambda x: x not in self.A[state_a.stateid][target],
self.alphabet)) + ']'
elif len(
[a for a in self.A[state_a.stateid][target] if len(a) > 1
]) == 0 and len(self.A[state_a.stateid][target]) < len(
self.alphabet) / 2:
self.A[state_a.stateid][target] = '[' + ''.join(
self.A[state_a.stateid][target]) + ']'
elif len(
[a for a in self.A[state_a.stateid][target] if len(a) > 1
]) > 0:
self.A[state_a.stateid][target] = '(' + '|'.join(
self.A[state_a.stateid][target]) + ')'
def partitionAlphabet(self, alphabetLen, parsedInput):
intoInput = []
notInInput = []
for c in self.alphabet:
if c in parsedInput:
intoInput.append(c)
else:
notInInput.append(c)
if len(intoInput) == alphabetLen:
return '.'
if (len(intoInput) < len(notInInput)):
final = '[' + ''.join(intoInput) + ']'
else:
final = '[^' + ''.join(notInInput) + ']'
return final
def replaceAlphabet(self, input):
if "|" not in input:
return input
alphabetLen = len(self.alphabet)
parsedInput = input.split("|")
if "|||" in input:
parsedInput.append("|")
for c in parsedInput:
if len(c) > 1:
return input
final = self.partitionAlphabet(alphabetLen, parsedInput)
return final
def cleaner(self, res):
res = self.replaceAlphabet(res)
import re
if '|' in re.sub('\(.*\)', '', res):
res = '(' + res + ')'
return res
def cleanerS(self, res):
res = self.replaceAlphabet(res)
import re
if '|' in re.sub(r'\([^)]*\)', '', res):
res = '(' + res + ')*'
return res
def findWhichSymbolsFromOtherStatesConnectToMe(self, state):
array = []
for n in self.A:
if n != state and state in self.A[n]:
if self.A[n][state] not in array:
array.append(self.A[n][state])
return array
def checkIfSameStateNotNeeded(self, state, same):
array = self.findWhichSymbolsFromOtherStatesConnectToMe(state)
parts = []
if len(array) == 0:
return same
try:
if len(self.A[state]['same']
) > 3 and self.A[state]['same'][0] == '(' and self.A[state][
'same'][len(self.A[state]['same']) -
1:len(self.A[state]['same']) + 1]:
parts.append(
self.A[state]['same'][1:len(self.A[state]['same']) - 2])
else:
parts = re.findall(r'\((.+?)\)\*', self.A[state]['same'])
for n in parts:
if n[len(n) - 1] != array[0]:
return same
return ''
except AttributeError:
return same
def checkIfBothAreNeeded(
self, inputA,
inputB): # based on the fact that ([^b]*|b([^i])*) is equal to .*
try:
input1 = re.search('\(\[\^(.+?)\]\)\*', inputA).group(1)
except AttributeError:
input1 = inputA
try:
input2FirstChar = re.search('\((.+?)\)\*', inputB).group(1)[0]
except AttributeError:
input2FirstChar = inputB[0]
if len(input1) == 1 and input1 == input2FirstChar:
return 1
else:
return -1
def replaceAlphabetMixed(self, input1, input2):
found1 = 0
found2 = 0
if "|" not in input1:
final1 = input1
if len(input1) > 1:
found1 = 1
else:
parsedInput = input1.split("|")
for c in parsedInput:
if len(c) > 1:
final1 = input1
found1 = 1
break
if "|" not in input2:
final2 = input2
if len(input2) > 1:
found2 = 1
else:
parsedInput = input2.split("|")
for c in parsedInput:
if len(c) > 1:
final2 = input2
found2 = 1
break
if found1 == 1 and found2 == 0:
if (self.checkIfBothAreNeeded(input1, input2) == 1):
return '(.)*'
final2 = self.replaceAlphabet(input2)
if found1 == 0 and found2 == 1:
if (self.checkIfBothAreNeeded(input1, input2) == 1):
return '(.)*'
final1 = self.replaceAlphabet(input1)
if found1 == 1 and found2 == 1:
if (self.checkIfBothAreNeeded(input1, input2) == 1):
return '(.)*'
if found1 == 0 and found2 == 0:
final1 = input1
final2 = input2
return final1 + "|" + final2
def getMaxInternalPath(self, inkeys):
maxkey = 0
keys = inkeys
if 'same' in keys:
keys.remove('same')
if 'rest' in keys:
keys.remove('rest')
if 'string' in keys:
keys.remove('string')
if len(keys) > 0:
maxkey = sorted(keys, reverse=True)[0]
return maxkey
def existsPath(self, initial, finalstate, visited):
for i in self.A:
if finalstate in self.A[i] and i not in visited:
if i == initial:
return 1, self.A[i][finalstate], finalstate
else:
visited.append(i)
res, key, transfer_state = self.existsPath(
initial, i, visited)
if res == 1:
return 1, key, finalstate
else:
continue
else:
continue
return 0, 0, 0
def fixBrzozowskiBackwardLoopRemoval(self):
# Remove targets that point to start
for i in self.A:
if i != 0:
for target in self.A[i].keys():
if target == 0:
self.A[i].pop(target)
for i in self.A:
poplist = []
for target in self.A[i]:
if target < i:
exists, transfer_value, transfer_state = self.existsPath(
target, i, [])
if exists and (
transfer_value == self.A[i][target] or
(target in self.A[target] and
(self.A[target][target] == self.A[i][target] or len(
set(self.A[i][target]) -
set(self.A[target][target])) == 0))):
poplist.append(target)
for k in poplist:
self.A[i].pop(k)
def _Lexical(self):
found = 0
start = 0
# First Try to Optimize the Strings by doing the possible replacements of special cases to string. e.c change a loop with character e to (e)*
for state_a in self.A.keys():
# Loopholes
if state_a in self.A[state_a]:
same = ''
if 'same' in self.A[state_a]:
same = '|' + self.A[state_a]['same']
self.A[state_a]['same'] = '(' + ''.join(
self.replaceAlphabet(
self.A[state_a][state_a])) + ')*' + same
del (self.A[state_a][state_a])
# Final State
if len(self.A[state_a].keys()
) == 1 and 'string' in self.A[state_a].keys():
for state_b in self.A:
if state_b != state_a and state_b in self.A:
if state_a in self.A[state_b]:
if 'rest' in self.A[state_b] and self.A[state_b][
'rest'] != '' and self.A[state_b][
'rest'] == self.cleaner(
self.A[state_a]['string']):
if 'string' not in self.A[state_b]:
self.A[state_b]['string'] = "(" + self.A[
state_b][state_a] + ")?" + self.A[
state_b]['rest']
else:
self.A[state_b]['string'] = "(" + self.A[
state_b]['string'] + "|(" + self.A[
state_b][state_a] + ")?" + self.A[
state_b]['rest'] + ")"
del (self.A[state_b][state_a])
del (self.A[state_b]['rest'])
found = 1
else:
newinput = ''.join(
self.A[state_b][state_a]) + self.cleaner(
self.A[state_a]['string'])
if 'rest' in self.A[state_b] and self.A[
state_b]['rest'] != '':
newinput = '(' + newinput + '|' + self.A[
state_b]['rest'] + ')'
self.A[state_b]['rest'] = newinput
del (self.A[state_b][state_a])
found = 1
if state_a != start:
del (self.A[state_a])
if state_a != start and state_a in self.A and len(
self.A[state_a].keys(
)) == 1 and 'same' in self.A[state_a].keys():
del (self.A[state_a])
for state_b in self.A:
if state_b in self.A and state_a in self.A[state_b]:
del (self.A[state_b][state_a])
found = 1
# Clean Loophole
if state_a in self.A and len(self.A[state_a].keys(
)) == 1 and 'same' in self.A[state_a].keys():
del (self.A[state_a])
found = 1
# Final State
if state_a in self.A and len(
self.A[state_a].keys()) == 1 and 'rest' in self.A[state_a]:
self.A[state_a]['string'] = self.A[state_a]['rest']
del (self.A[state_a]['rest'])
found = 1
# Final State with alternative path
if state_a in self.A and len(self.A[state_a].keys()) == 2 and 'string' in self.A[state_a] and 'rest' in \
self.A[state_a]:
if self.A[state_a]['rest'] != '':
self.A[state_a]['string'] = self.cleaner(
self.A[state_a]
['string']) + '(' + self.replaceAlphabet(
self.A[state_a]['rest']) + ')?'
del (self.A[state_a]['rest'])
found = 1
# State with alternative path and self loop
if state_a in self.A and len(self.A[state_a].keys()) == 2 and 'same' in self.A[state_a] and 'rest' in \
self.A[state_a]:
self.A[state_a]['rest'] = self.checkIfSameStateNotNeeded(
state_a, self.cleanerS(
self.A[state_a]['same'])) + self.cleaner(
self.A[state_a]['rest'])
del (self.A[state_a]['same'])
found = 1
# Final State with self loop
if state_a in self.A and len(self.A[state_a].keys()) == 2 and 'string' in self.A[state_a] and 'same' in \
self.A[state_a]:
self.A[state_a]['string'] = self.checkIfSameStateNotNeeded(
state_a, self.cleanerS(
self.A[state_a]['same'])) + self.cleaner(
self.A[state_a]['string'])
del (self.A[state_a]['same'])
found = 1
# Final State with alternative path and self loop
if state_a in self.A and len(self.A[state_a].keys()) == 3 and 'string' in self.A[state_a] and 'rest' in \
self.A[state_a] and 'same' in self.A[state_a]:
if self.A[state_a]['rest'] != '':
add = '(' + self.A[state_a]['rest'] + ')?'
self.A[state_a]['string'] = self.checkIfSameStateNotNeeded(
state_a, self.cleanerS(
self.A[state_a]['same'])) + self.cleaner(
self.A[state_a]['string']) + add
del (self.A[state_a]['rest'])
del (self.A[state_a]['same'])
found = 1
# No path State
if state_a != start and state_a in self.A and len(
self.A[state_a].keys()) == 0:
del (self.A[state_a])
for state_b in self.A:
if state_b in self.A and state_a in self.A[state_b]:
del (self.A[state_b][state_a])
return found
def fixBrzozowskiAdvanced(self, found):
start = 0
for state_a in self.A:
maxkey = self.getMaxInternalPath(self.A[state_a].keys())
if state_a != start and state_a in self.A and maxkey < state_a and (
(len(self.A[state_a].keys()) > 1) or
(len(self.A[state_a].keys()) == 1
and 'same' not in self.A[state_a])):
same = ''
if 'same' in self.A[state_a]:
same = self.checkIfSameStateNotNeeded(
state_a, self.cleanerS(self.A[state_a]['same']))
# del(self.A[i]['same'])
for state_b in [
x.stateid for x in self._bfs_sort(
sorted(self.mma.states,
key=attrgetter('initial'),
reverse=True)[0])
]:
if state_b != state_a and state_b in self.A:
if state_a in self.A[state_b]:
temp = self.cleaner(self.A[state_b][state_a])
del (self.A[state_b][state_a])
for newTarget in self.A[state_a]:
if newTarget != 'same':
transValue = same + self.cleaner(
self.A[state_a][newTarget])
found = 1
add = temp + transValue
if newTarget == state_b:
newTarget = 'same'
add = '(' + self.replaceAlphabet(
add) + ')*'
if ((newTarget not in self.A[state_b]) or
(self.A[state_b][newTarget] == '')):
self.A[state_b][newTarget] = add
else:
self.A[state_b][
newTarget] = self.replaceAlphabetMixed(
self.A[state_b][newTarget],
add)
found = 1
if found == 1:
break
return found
def _solve(self):
self._create_map()
self._fix_pattern()
self.fixBrzozowskiBackwardLoopRemoval(
) # Remove backward paths because of kleene star
while 1:
found = self._Lexical()
if found == 0:
found = self.fixBrzozowskiAdvanced(found)
if found == 0:
break
if 'string' in self.A[0]:
return ''.join(self.A[0]['string'].splitlines())
def get_regex(self):
"""Generate regular expressions from DFA automaton"""
return self._solve()
class StateRemoval:
"""Transforms a pyfst DFA to regular expressions"""
def __init__(self, input_fst_a, alphabet=None):
"""
Args:
input_fst_a (DFA): The DFA states
alphabet (list): the input alphabet
Returns:
None
"""
if alphabet is None:
alphabet = createalphabet()
self.mma = DFA(self.alphabet)
self.mma.init_from_acceptor(input_fst_a)
self.alphabet = alphabet
self.l_transitions = {}
self.epsilon = ''
self.empty = None
def star(self, input_string):
"""
Kleene star operation
Args:
input_string (str): The string that the kleene star will be made
Returns:
str: The applied Kleene star operation on the input string
"""
if input_string != self.epsilon and input_string != self.empty:
return "(" + input_string + ")*"
else:
return ""
def _state_removal_init(self):
"""State Removal Operation Initialization"""
# First, we remove all multi-edges:
for state_i in self.mma.states:
for state_j in self.mma.states:
if state_i.stateid == state_j.stateid:
self.l_transitions[
state_i.stateid, state_j.stateid] = self.epsilon
else:
self.l_transitions[
state_i.stateid, state_j.stateid] = self.empty
for arc in state_i.arcs:
if arc.nextstate == state_j.stateid:
if self.l_transitions[state_i.stateid, state_j.stateid] != self.empty:
self.l_transitions[state_i.stateid, state_j.stateid] \
+= self.mma.isyms.find(arc.ilabel)
else:
self.l_transitions[state_i.stateid, state_j.stateid] = \
self.mma.isyms.find(arc.ilabel)
def _state_removal_remove(self, k):
"""
State Removal Remove operation
l_transitions[i,i] += l_transitions[i,k] . star(l_transitions[k,k]) . l_transitions[k,i]
l_transitions[j,j] += l_transitions[j,k] . star(l_transitions[k,k]) . l_transitions[k,j]
l_transitions[i,j] += l_transitions[i,k] . star(l_transitions[k,k]) . l_transitions[k,j]
l_transitions[j,i] += l_transitions[j,k] . star(l_transitions[k,k]) . l_transitions[k,i]
Args:
k (int): The node that will be removed
Returns:
None
"""
for state_i in self.mma.states:
for state_j in self.mma.states:
if self.l_transitions[state_i.stateid, k] != self.empty:
l_ik = self.l_transitions[state_i.stateid, k]
else:
l_ik = ""
if self.l_transitions[state_j.stateid, k] != self.empty:
l_jk = self.l_transitions[state_j.stateid, k]
else:
l_jk = ""
if self.l_transitions[k, state_i.stateid] != self.empty:
l_ki = self.l_transitions[k, state_i.stateid]
else:
l_ki = ""
if self.l_transitions[k, state_j.stateid] != self.empty:
l_kj = self.l_transitions[k, state_j.stateid]
else:
l_kj = ""
if self.l_transitions[state_i.stateid, state_i.stateid] != self.empty:
self.l_transitions[state_i.stateid, state_i.stateid] += l_ik + \
self.star(self.l_transitions[k, k]) + l_ki
else:
self.l_transitions[state_i.stateid, state_i.stateid] = l_ik + \
self.star(self.l_transitions[k, k]) + l_ki
if self.l_transitions[state_j.stateid, state_j.stateid] != self.empty:
self.l_transitions[state_j.stateid, state_j.stateid] += l_jk + \
self.star(self.l_transitions[k, k]) + l_kj
else:
self.l_transitions[state_j.stateid, state_j.stateid] = l_jk + \
self.star(self.l_transitions[k, k]) + l_kj
if self.l_transitions[state_i.stateid, state_j.stateid] != self.empty:
self.l_transitions[state_i.stateid, state_j.stateid] += l_ik + \
self.star(self.l_transitions[k, k]) + l_kj
else:
self.l_transitions[state_i.stateid, state_j.stateid] = l_ik + \
self.star(self.l_transitions[k, k]) + l_kj
if self.l_transitions[state_j.stateid, state_i.stateid] != self.empty:
self.l_transitions[state_j.stateid, state_i.stateid] += l_jk + \
self.star(self.l_transitions[k, k]) + l_ki
else:
self.l_transitions[state_j.stateid, state_i.stateid] = l_jk + \
self.star(self.l_transitions[k, k]) + l_ki
def _state_removal_solve(self):
"""The State Removal Operation"""
initial = sorted(
self.mma.states,
key=attrgetter('initial'),
reverse=True)[0].stateid
for state_k in self.mma.states:
if state_k.final:
continue
if state_k.stateid == initial:
continue
self._state_removal_remove(state_k.stateid)
print self.l_transitions
return self.l_transitions
def get_regex(self):
"""Regular Expression Generation"""
self._state_removal_init()
self._state_removal_solve()
return self.l_transitions[0]
