1
#=======================================================================
3
# Python Lexical Analyser
5
# Classes for building NFAs and DFAs
7
#=======================================================================
11
from sys import maxint
12
from types import TupleType
14
from Transitions import TransitionMap
16
LOWEST_PRIORITY = -sys.maxint
19
"""A collection of Nodes representing an NFA or DFA."""
20
states = None # [Node]
22
initial_states = None # {(name, bol): Node}
26
self.initial_states = {}
29
#print "Destroying", self ###
30
for state in self.states:
34
"""Add a new state to the machine and return it."""
36
n = self.next_state_number
37
self.next_state_number = n + 1
42
def new_initial_state(self, name):
43
state = self.new_state()
44
self.make_initial_state(name, state)
47
def make_initial_state(self, name, state):
48
self.initial_states[name] = state
50
def get_initial_state(self, name):
51
return self.initial_states[name]
54
file.write("Plex.Machine:\n")
55
if self.initial_states is not None:
56
file.write(" Initial states:\n")
57
for (name, state) in self.initial_states.items():
58
file.write(" '%s': %d\n" % (name, state.number))
63
"""A state of an NFA or DFA."""
64
transitions = None # TransitionMap
65
action = None # Action
66
action_priority = None # integer
67
number = 0 # for debug output
68
epsilon_closure = None # used by nfa_to_dfa()
71
# Preinitialise the list of empty transitions, because
72
# the nfa-to-dfa algorithm needs it
73
#self.transitions = {'':[]}
74
self.transitions = TransitionMap()
75
self.action_priority = LOWEST_PRIORITY
78
#print "Destroying", self ###
79
self.transitions = None
81
self.epsilon_closure = None
83
def add_transition(self, event, new_state):
84
self.transitions.add(event, new_state)
86
def link_to(self, state):
87
"""Add an epsilon-move from this state to another state."""
88
self.add_transition('', state)
90
def set_action(self, action, priority):
91
"""Make this an accepting state with the given action. If
92
there is already an action, choose the action with highest
94
if priority > self.action_priority:
96
self.action_priority = priority
101
def get_action_priority(self):
102
return self.action_priority
104
# def merge_actions(self, other_state):
105
# """Merge actions of other state into this state according
106
# to their priorities."""
107
# action = other_state.get_action()
108
# priority = other_state.get_action_priority()
109
# self.set_action(action, priority)
111
def is_accepting(self):
112
return self.action is not None
115
return "State %d" % self.number
117
def dump(self, file):
120
file.write(" State %d:\n" % self.number)
122
# self.dump_transitions(file)
123
self.transitions.dump(file)
126
priority = self.action_priority
127
if action is not None:
128
file.write(" %s [priority %d]\n" % (action, priority))
133
FastMachine is a deterministic machine represented in a way that
134
allows fast scanning.
136
initial_states = None # {state_name:state}
137
states = None # [state]
138
# where state = {event:state, 'else':state, 'action':Action}
139
next_number = 1 # for debugging
141
new_state_template = {
142
'':None, 'bol':None, 'eol':None, 'eof':None, 'else':None
145
def __init__(self, old_machine = None):
146
self.initial_states = initial_states = {}
149
self.old_to_new = old_to_new = {}
150
for old_state in old_machine.states:
151
new_state = self.new_state()
152
old_to_new[old_state] = new_state
153
for name, old_state in old_machine.initial_states.items():
154
initial_states[name] = old_to_new[old_state]
155
for old_state in old_machine.states:
156
new_state = old_to_new[old_state]
157
for event, old_state_set in old_state.transitions.items():
159
new_state[event] = old_to_new[old_state_set.keys()[0]]
161
new_state[event] = None
162
new_state['action'] = old_state.action
165
for state in self.states:
168
def new_state(self, action = None):
169
number = self.next_number
170
self.next_number = number + 1
171
result = self.new_state_template.copy()
172
result['number'] = number
173
result['action'] = action
174
self.states.append(result)
177
def make_initial_state(self, name, state):
178
self.initial_states[name] = state
180
def add_transitions(self, state, event, new_state):
181
if type(event) == TupleType:
184
state['else'] = new_state
185
elif code1 <> maxint:
187
state[chr(code0)] = new_state
190
state[event] = new_state
192
def get_initial_state(self, name):
193
return self.initial_states[name]
195
def dump(self, file):
196
file.write("Plex.FastMachine:\n")
197
file.write(" Initial states:\n")
198
for name, state in self.initial_states.items():
199
file.write(" %s: %s\n" % (repr(name), state['number']))
200
for state in self.states:
201
self.dump_state(state, file)
203
def dump_state(self, state, file):
206
file.write(" State %d:\n" % state['number'])
208
self.dump_transitions(state, file)
210
action = state['action']
211
if action is not None:
212
file.write(" %s\n" % action)
214
def dump_transitions(self, state, file):
215
chars_leading_to_state = {}
216
special_to_state = {}
217
for (c, s) in state.items():
219
chars = chars_leading_to_state.get(id(s), None)
222
chars_leading_to_state[id(s)] = chars
225
special_to_state[c] = s
227
for state in self.states:
228
char_list = chars_leading_to_state.get(id(state), None)
230
ranges = self.chars_to_ranges(char_list)
231
ranges_to_state[ranges] = state
232
ranges_list = ranges_to_state.keys()
234
for ranges in ranges_list:
235
key = self.ranges_to_string(ranges)
236
state = ranges_to_state[ranges]
237
file.write(" %s --> State %d\n" % (key, state['number']))
238
for key in ('bol', 'eol', 'eof', 'else'):
239
state = special_to_state.get(key, None)
241
file.write(" %s --> State %d\n" % (key, state['number']))
243
def chars_to_ranges(self, char_list):
249
c1 = ord(char_list[i])
252
while i < n and ord(char_list[i]) == c2 + 1:
255
result.append((chr(c1), chr(c2)))
258
def ranges_to_string(self, range_list):
259
return string.join(map(self.range_to_string, range_list), ",")
261
def range_to_string(self, (c1, c2)):
265
return "%s..%s" % (repr(c1), repr(c2))
267
## (Superseded by Machines.FastMachine)
269
## class StateTableMachine:
271
## StateTableMachine is an alternative representation of a Machine
272
## that can be run more efficiently.
274
## initial_states = None # {state_name:state_index}
275
## states = None # [([state] indexed by char code, Action)]
277
## special_map = {'bol':256, 'eol':257, 'eof':258}
279
## def __init__(self, m):
281
## Initialise StateTableMachine from Machine |m|.
283
## initial_states = self.initial_states = {}
284
## states = self.states = [None]
287
## for old_state in m.states:
288
## new_state = ([0] * 259, old_state.get_action())
289
## states.append(new_state)
290
## old_to_new[old_state] = i # new_state
292
## for name, old_state in m.initial_states.items():
293
## initial_states[name] = old_to_new[old_state]
294
## for old_state in m.states:
295
## new_state_index = old_to_new[old_state]
296
## new_table = states[new_state_index][0]
297
## transitions = old_state.transitions
298
## for c, old_targets in transitions.items():
300
## old_target = old_targets[0]
301
## new_target_index = old_to_new[old_target]
305
## a = self.special_map[c]
306
## new_table[a] = states[new_target_index]
308
## def dump(self, f):
309
## f.write("Plex.StateTableMachine:\n")
310
## f.write(" Initial states:\n")
311
## for name, index in self.initial_states.items():
312
## f.write(" %s: State %d\n" % (
313
## repr(name), id(self.states[index])))
314
## for i in xrange(1, len(self.states)):
315
## table, action = self.states[i]
316
## f.write(" State %d:" % i)
318
## f.write("%s" % action)
320
## f.write(" %s\n" % map(id,table))