def buildMinDFA(dfa, partition):
## showPartition(partition)
## print [s.name for s in dfa.listStates()]
## First make a new DFA and ensure that its start state is the same
## as that of the original DFA. For all the other states in the
## new DFA, just select a state from each of the state sets in the
## partition (expect for any dead-state state sets, which are
## ignored).
newDFA = DFA()
newDFA.startState = dfa.startState
newDFA.alphabet = dfa.alphabet
selectedStates = []
for stateSet in partition:
if newDFA.startState in stateSet:
selectedStates.append((newDFA.startState,stateSet))
elif stateSet != deadSS:
selectedStates.append((list(stateSet)[0],stateSet))
## Now construct new links in the new DFA. Note that we are
## modifiying states *shared* with the original DFA, so this
## action *corrupts* the original DFA.
newDFA.finalStates = []
newDFA.regExprs = []
for state,stateSet in selectedStates:
for i,successor in enumerate(state.successors):
for targetState,targetStateSet in selectedStates:
if successor[1] in targetStateSet:
state.successors[i] = (successor[0],targetState)
break
if state in dfa.finalStates:
newDFA.finalStates.append(state)
newDFA.regExprs.append(dfa.regExprs[dfa.finalStates.index(state)])
newDFA.stateCount = len(selectedStates)
return newDFA
def buildMinDFA(dfa, partition):
## showPartition(partition)
## print [s.name for s in dfa.listStates()]
## First make a new DFA and ensure that its start state is the same
## as that of the original DFA. For all the other states in the
## new DFA, just select a state from each of the state sets in the
## partition (expect for any dead-state state sets, which are
## ignored).
newDFA = DFA()
newDFA.startState = dfa.startState
newDFA.alphabet = dfa.alphabet
selectedStates = []
for stateSet in partition:
if newDFA.startState in stateSet:
selectedStates.append((newDFA.startState, stateSet))
elif stateSet != deadSS:
selectedStates.append((list(stateSet)[0], stateSet))
## Now construct new links in the new DFA. Note that we are
## modifiying states *shared* with the original DFA, so this
## action *corrupts* the original DFA.
newDFA.finalStates = []
newDFA.regExprs = []
for state, stateSet in selectedStates:
for i, successor in enumerate(state.successors):
for targetState, targetStateSet in selectedStates:
if successor[1] in targetStateSet:
state.successors[i] = (successor[0], targetState)
break
if state in dfa.finalStates:
newDFA.finalStates.append(state)
newDFA.regExprs.append(dfa.regExprs[dfa.finalStates.index(state)])
newDFA.stateCount = len(selectedStates)
return newDFA
def from_range(cls, alphabet: list, n_states: int, n_start_states: int,
n_final_states: int):
# Create a new empty list to hold generated states
states = []
# Generate n states and label them sequantially, addimg them to the states list
for i in range(0, n_states):
states.append(State.from_range("S" + str(i), alphabet, n_states))
# Create a new empty DFA
new_dfa = DFA()
# Assign the alphabet to the DFA
new_dfa.alphabet = alphabet
# Create a new dictionary where the state name is the key and the state object is the
# value, assign it to the DFA
new_dfa.states = {
k: v
for k, v in [(state.name, state) for state in states]
}
# Assign n random start states, record their names in a set member variable
new_dfa.assign_n_random_start_state_names(n_start_states)
# Run bfs to determine which states are reachable and which are unreachable,
# return the result
bfs_output = new_dfa.bfs()
# Assign which states are reachable and unreachable based on the output of bfs,
# record their names in set member variables
new_dfa.assign_reachable_unreachable_state_names(bfs_output)
# After BFS, remove states that are unreachable from the states dictionary data structure
new_dfa.remove_unreachable_states()
# Assign n random final states, record their names in a set member variable
new_dfa.assign_n_random_final_state_names(n_final_states)
# Create transition table with only reachable states
new_dfa.table_df = new_dfa.create_transition_table()
# Check if the resultant dfa is valid (i.e. at least one final state is reachable from
# any of the start states)
invalid = new_dfa.check_invalid()
# If for whatever reason it is invalid (shouldn't be possible), regenerate a new random
# DFA
if invalid:
return DFAFactory.from_range(alphabet, n_states, n_start_states,
n_final_states)
else:
return new_dfa
def from_parameters(cls, alphabet: list, states: list):
# Create a new empty DFA
new_dfa = DFA()
# Assign the alphabet to the DFA
new_dfa.alphabet = alphabet
# Create a new dictionary where the state name is the key and the state object is the
# value, assign it to the DFA
new_dfa.states = {
k: v
for k, v in [(state.name, state) for state in states]
}
# Iterate over the states assigned to the dfa, find all states which are start states
# and add them to the start_state_names set member variable
new_dfa.start_state_names = new_dfa.find_start_state_names()
# Run bfs to determine which states are reachable and which are unreachable,
# return the result
bfs_output = new_dfa.bfs()
# Assign which states are reachable and unreachable based on the output of bfs,
# record their names in set member variables
new_dfa.assign_reachable_unreachable_state_names(bfs_output)
# After BFS, remove states that are unreachable from the states dictionary data structure
new_dfa.remove_unreachable_states()
# Iterate over the remaining states assigned to the dfa, find all states which are final
# states and add them to the final_state_names set member variable
new_dfa.final_state_names = new_dfa.find_final_state_names()
# Create transition table with only reachable states
new_dfa.table_df = new_dfa.create_transition_table()
# Check if the resultant dfa is valid (i.e. at least one final state is reachable from
# any of the start states)
invalid = new_dfa.check_invalid()
# If the DFA is invalid, throw an error
if invalid:
raise ValueError("Proposed DFA is not valid")
else:
return new_dfa
