252 lines
7.0 KiB
Python
252 lines
7.0 KiB
Python
|
#
|
||
|
|
# Plex - Transition Maps
|
||
|
|
#
|
||
|
|
# This version represents state sets directly as dicts for speed.
|
||
|
|
#
|
||
|
|
|
||
|
|
from __future__ import absolute_import
|
||
|
|
|
||
|
|
try:
|
||
|
|
from sys import maxsize as maxint
|
||
|
|
except ImportError:
|
||
|
|
from sys import maxint
|
||
|
|
|
||
|
|
|
||
|
|
class TransitionMap(object):
|
||
|
|
"""
|
||
|
|
A TransitionMap maps an input event to a set of states.
|
||
|
|
An input event is one of: a range of character codes,
|
||
|
|
the empty string (representing an epsilon move), or one
|
||
|
|
of the special symbols BOL, EOL, EOF.
|
||
|
|
|
||
|
|
For characters, this implementation compactly represents
|
||
|
|
the map by means of a list:
|
||
|
|
|
||
|
|
[code_0, states_0, code_1, states_1, code_2, states_2,
|
||
|
|
..., code_n-1, states_n-1, code_n]
|
||
|
|
|
||
|
|
where |code_i| is a character code, and |states_i| is a
|
||
|
|
set of states corresponding to characters with codes |c|
|
||
|
|
in the range |code_i| <= |c| <= |code_i+1|.
|
||
|
|
|
||
|
|
The following invariants hold:
|
||
|
|
n >= 1
|
||
|
|
code_0 == -maxint
|
||
|
|
code_n == maxint
|
||
|
|
code_i < code_i+1 for i in 0..n-1
|
||
|
|
states_0 == states_n-1
|
||
|
|
|
||
|
|
Mappings for the special events '', BOL, EOL, EOF are
|
||
|
|
kept separately in a dictionary.
|
||
|
|
"""
|
||
|
|
|
||
|
|
map = None # The list of codes and states
|
||
|
|
special = None # Mapping for special events
|
||
|
|
|
||
|
|
def __init__(self, map=None, special=None):
|
||
|
|
if not map:
|
||
|
|
map = [-maxint, {}, maxint]
|
||
|
|
if not special:
|
||
|
|
special = {}
|
||
|
|
self.map = map
|
||
|
|
self.special = special
|
||
|
|
#self.check() ###
|
||
|
|
|
||
|
|
def add(self, event, new_state,
|
||
|
|
TupleType=tuple):
|
||
|
|
"""
|
||
|
|
Add transition to |new_state| on |event|.
|
||
|
|
"""
|
||
|
|
if type(event) is TupleType:
|
||
|
|
code0, code1 = event
|
||
|
|
i = self.split(code0)
|
||
|
|
j = self.split(code1)
|
||
|
|
map = self.map
|
||
|
|
while i < j:
|
||
|
|
map[i + 1][new_state] = 1
|
||
|
|
i += 2
|
||
|
|
else:
|
||
|
|
self.get_special(event)[new_state] = 1
|
||
|
|
|
||
|
|
def add_set(self, event, new_set,
|
||
|
|
TupleType=tuple):
|
||
|
|
"""
|
||
|
|
Add transitions to the states in |new_set| on |event|.
|
||
|
|
"""
|
||
|
|
if type(event) is TupleType:
|
||
|
|
code0, code1 = event
|
||
|
|
i = self.split(code0)
|
||
|
|
j = self.split(code1)
|
||
|
|
map = self.map
|
||
|
|
while i < j:
|
||
|
|
map[i + 1].update(new_set)
|
||
|
|
i += 2
|
||
|
|
else:
|
||
|
|
self.get_special(event).update(new_set)
|
||
|
|
|
||
|
|
def get_epsilon(self,
|
||
|
|
none=None):
|
||
|
|
"""
|
||
|
|
Return the mapping for epsilon, or None.
|
||
|
|
"""
|
||
|
|
return self.special.get('', none)
|
||
|
|
|
||
|
|
def iteritems(self,
|
||
|
|
len=len):
|
||
|
|
"""
|
||
|
|
Return the mapping as an iterable of ((code1, code2), state_set) and
|
||
|
|
(special_event, state_set) pairs.
|
||
|
|
"""
|
||
|
|
result = []
|
||
|
|
map = self.map
|
||
|
|
else_set = map[1]
|
||
|
|
i = 0
|
||
|
|
n = len(map) - 1
|
||
|
|
code0 = map[0]
|
||
|
|
while i < n:
|
||
|
|
set = map[i + 1]
|
||
|
|
code1 = map[i + 2]
|
||
|
|
if set or else_set:
|
||
|
|
result.append(((code0, code1), set))
|
||
|
|
code0 = code1
|
||
|
|
i += 2
|
||
|
|
for event, set in self.special.items():
|
||
|
|
if set:
|
||
|
|
result.append((event, set))
|
||
|
|
return iter(result)
|
||
|
|
|
||
|
|
items = iteritems
|
||
|
|
|
||
|
|
# ------------------- Private methods --------------------
|
||
|
|
|
||
|
|
def split(self, code,
|
||
|
|
len=len, maxint=maxint):
|
||
|
|
"""
|
||
|
|
Search the list for the position of the split point for |code|,
|
||
|
|
inserting a new split point if necessary. Returns index |i| such
|
||
|
|
that |code| == |map[i]|.
|
||
|
|
"""
|
||
|
|
# We use a funky variation on binary search.
|
||
|
|
map = self.map
|
||
|
|
hi = len(map) - 1
|
||
|
|
# Special case: code == map[-1]
|
||
|
|
if code == maxint:
|
||
|
|
return hi
|
||
|
|
# General case
|
||
|
|
lo = 0
|
||
|
|
# loop invariant: map[lo] <= code < map[hi] and hi - lo >= 2
|
||
|
|
while hi - lo >= 4:
|
||
|
|
# Find midpoint truncated to even index
|
||
|
|
mid = ((lo + hi) // 2) & ~1
|
||
|
|
if code < map[mid]:
|
||
|
|
hi = mid
|
||
|
|
else:
|
||
|
|
lo = mid
|
||
|
|
# map[lo] <= code < map[hi] and hi - lo == 2
|
||
|
|
if map[lo] == code:
|
||
|
|
return lo
|
||
|
|
else:
|
||
|
|
map[hi:hi] = [code, map[hi - 1].copy()]
|
||
|
|
#self.check() ###
|
||
|
|
return hi
|
||
|
|
|
||
|
|
def get_special(self, event):
|
||
|
|
"""
|
||
|
|
Get state set for special event, adding a new entry if necessary.
|
||
|
|
"""
|
||
|
|
special = self.special
|
||
|
|
set = special.get(event, None)
|
||
|
|
if not set:
|
||
|
|
set = {}
|
||
|
|
special[event] = set
|
||
|
|
return set
|
||
|
|
|
||
|
|
# --------------------- Conversion methods -----------------------
|
||
|
|
|
||
|
|
def __str__(self):
|
||
|
|
map_strs = []
|
||
|
|
map = self.map
|
||
|
|
n = len(map)
|
||
|
|
i = 0
|
||
|
|
while i < n:
|
||
|
|
code = map[i]
|
||
|
|
if code == -maxint:
|
||
|
|
code_str = "-inf"
|
||
|
|
elif code == maxint:
|
||
|
|
code_str = "inf"
|
||
|
|
else:
|
||
|
|
code_str = str(code)
|
||
|
|
map_strs.append(code_str)
|
||
|
|
i += 1
|
||
|
|
if i < n:
|
||
|
|
map_strs.append(state_set_str(map[i]))
|
||
|
|
i += 1
|
||
|
|
special_strs = {}
|
||
|
|
for event, set in self.special.items():
|
||
|
|
special_strs[event] = state_set_str(set)
|
||
|
|
return "[%s]+%s" % (
|
||
|
|
','.join(map_strs),
|
||
|
|
special_strs
|
||
|
|
)
|
||
|
|
|
||
|
|
# --------------------- Debugging methods -----------------------
|
||
|
|
|
||
|
|
def check(self):
|
||
|
|
"""Check data structure integrity."""
|
||
|
|
if not self.map[-3] < self.map[-1]:
|
||
|
|
print(self)
|
||
|
|
assert 0
|
||
|
|
|
||
|
|
def dump(self, file):
|
||
|
|
map = self.map
|
||
|
|
i = 0
|
||
|
|
n = len(map) - 1
|
||
|
|
while i < n:
|
||
|
|
self.dump_range(map[i], map[i + 2], map[i + 1], file)
|
||
|
|
i += 2
|
||
|
|
for event, set in self.special.items():
|
||
|
|
if set:
|
||
|
|
if not event:
|
||
|
|
event = 'empty'
|
||
|
|
self.dump_trans(event, set, file)
|
||
|
|
|
||
|
|
def dump_range(self, code0, code1, set, file):
|
||
|
|
if set:
|
||
|
|
if code0 == -maxint:
|
||
|
|
if code1 == maxint:
|
||
|
|
k = "any"
|
||
|
|
else:
|
||
|
|
k = "< %s" % self.dump_char(code1)
|
||
|
|
elif code1 == maxint:
|
||
|
|
k = "> %s" % self.dump_char(code0 - 1)
|
||
|
|
elif code0 == code1 - 1:
|
||
|
|
k = self.dump_char(code0)
|
||
|
|
else:
|
||
|
|
k = "%s..%s" % (self.dump_char(code0),
|
||
|
|
self.dump_char(code1 - 1))
|
||
|
|
self.dump_trans(k, set, file)
|
||
|
|
|
||
|
|
def dump_char(self, code):
|
||
|
|
if 0 <= code <= 255:
|
||
|
|
return repr(chr(code))
|
||
|
|
else:
|
||
|
|
return "chr(%d)" % code
|
||
|
|
|
||
|
|
def dump_trans(self, key, set, file):
|
||
|
|
file.write(" %s --> %s\n" % (key, self.dump_set(set)))
|
||
|
|
|
||
|
|
def dump_set(self, set):
|
||
|
|
return state_set_str(set)
|
||
|
|
|
||
|
|
|
||
|
|
#
|
||
|
|
# State set manipulation functions
|
||
|
|
#
|
||
|
|
|
||
|
|
#def merge_state_sets(set1, set2):
|
||
|
|
# for state in set2.keys():
|
||
|
|
# set1[state] = 1
|
||
|
|
|
||
|
|
def state_set_str(set):
|
||
|
|
return "[%s]" % ','.join(["S%d" % state.number for state in set])
|