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Rules.py
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Rules.py
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#!/usr/bin/python
# -*- coding: utf-8 -*-
# Copyright (c) 2012 Denis Zalevskiy
# Licensed under MIT License
import cor
from cor import Err
from Common import *
class Parser(object):
def __init__(self, fn, name):
self.parse = fn
self.__name__ = name
self.__children = tuple()
@property
def children(self):
return self.__children
@children.setter
def children(self, v):
self.__children = v
@property
def name(self):
return self.__name__
def cache_clear(self):
pass
class CachingParser(Parser):
_cache_hits = 0
def __init__(self, fn, name):
super(CachingParser, self).__init__(fn, name)
self.__fn = self.parse
self.parse = self.__parse
self.__cache = dict()
def __parse(self, src):
apos = src.absolute_pos
if apos in self.__cache:
CachingParser._cache_hits += 1
return self.__cache[apos]
res = self.__fn(src)
self.__cache[apos] = res
return res
def cache_clear(self):
self.__cache = dict()
if len(self.children):
[x.cache_clear() for x in self.children]
class Tracer(object):
debug_indent_level = 0
debug_indent_sym = ' ' * 2
def __indent_plus(self):
Tracer.debug_indent_level += 1
def __indent_minus(self, *args):
Tracer.debug_indent_level -= 1
def debug_print(self, msg, *args, **kwargs):
indent = Tracer.debug_indent_sym * Tracer.debug_indent_level
cor.log("{}{}", indent, msg.format(*args, **kwargs))
def __init__(self, parser):
self.__indent = cor.Scope(self.__indent_plus,
self.__indent_minus)
self.__parser = parser
self.__name__ = parser.__name__
def parse(self, src):
pr = src if len(src) < 20 else ''.join([str(src[:20]), '...'])
pr = cor.escape_str(pr)
self.debug_print("{}({}) {{", self.__name__, cor.wrap('"', pr))
with self.__indent:
res = self.__parser.parse(src)
self.debug_print("}} => {}", cor.printable_args(res))
return res
@property
def children(self):
return self.__parser.children
@children.setter
def children(self, v):
self.__parser.children = v
@property
def name(self):
return self.__name__
def cache_clear(self):
return self.__parser.cache_clear()
def parser(name, options):
def mk_name(name):
return ''.join([name, '?'])
def decorate(match_fn):
cls = CachingParser if options.is_remember else Parser
fn = cls(match_fn, mk_name(name))
if options.is_trace:
return Tracer(fn)
else:
return fn
return decorate
class InfiniteInput(object):
'''imitates virtually infinite random access vector, returns empty
after the end of source input
'''
len_limit = 1024 * 64
def __init__(self, src, begin = 0, end = None):
self.__s = src
self.__begin = begin
self.absolute_pos = src.absolute_pos + begin \
if hasattr(src, 'absolute_pos') \
else begin
self.__is_endless = end is None
if end is None:
self._end = lambda: len(src)
else:
self._end = lambda: end
def __get_slice(self, k):
start, stop = k.start, k.stop
if not (k.step is None or k.step == 1):
raise cor.Err("Can't handle step != 1")
if start is None:
start = self.__begin
else:
start = min(self.__begin + start, len(self.__s))
if not stop is None:
stop = min(self.__begin + stop, len(self.__s))
return InfiniteInput(self.__s, start, stop)
def __getitem__(self, i):
if isinstance(i, slice):
return self.__get_slice(i)
end = self._end()
i = self.__begin + i
if i < end:
return self.__s[i]
elif i > self.len_limit:
raise Err("Length limit is reached")
else:
return empty
def __len__(self):
return self._end() - self.__begin
def __iter__(self):
def gen():
pos = 0
while pos < len(self):
yield self[pos]
pos += 1
return gen()
def __str__(self):
if isinstance(self.__s, str):
if self.__begin == 0 and self.__is_endless:
return self.__s
elif self.__is_endless:
return self.__s[self.__begin:]
else:
return self.__s[self.__begin:self._end()]
else:
res = [str(x) for x in self]
return ''.join(res)
def __repr__(self):
return cor.wrap("'", self)
#standard return if rule is not matched
_nomatch_res = (0, nomatch)
def match_first_predicate(pred):
def wrapper(name, dummy, action, options):
@parser(name, options)
def fn(src):
v = src[0]
if pred(v):
v = action(v)
return (1, v) if v != nomatch else _nomatch_res
else:
return _nomatch_res
return fn
return wrapper
def match_first(name, s, action, options):
if isinstance(s, str) or isinstance(s, unicode):
if len(s) != 1:
raise Err("{} len != 1", s)
if options.use_unicode:
if isinstance(s, str):
s = s.decode()
else:
if isinstance(s, unicode):
s = s.encode()
elif s != empty:
raise Err("{} is not a string", s)
custom_options = options.copy()
custom_options.is_remember = False
@parser(name, custom_options)
def fn(src):
v = src[0]
if v != s:
return _nomatch_res
v = action(v)
return (1, v) if v != nomatch else _nomatch_res
return fn
def match_string(name, s, action, options):
if not (isinstance(s, str) or isinstance(s, unicode)):
raise Err("{} is not a string", s)
if options.use_unicode:
if isinstance(s, str):
s = s.decode()
else:
if isinstance(s, unicode):
s = s.encode()
slen = len(s)
@parser(name, options)
def fn(src):
if len(src) < slen:
return _nomatch_res
v = str(src[0:slen])
return (slen, action(v)) if v == s else _nomatch_res
return fn
def match_iterable(name, pat, conv, options):
if not cor.is_iterable(pat):
raise Err("Don't know what to do with {}", seq)
seq = [x for x in pat] if isinstance(pat, str) else pat
@parser(name, options)
def fn(src):
v = src[0]
if v in seq:
v = conv(v)
return (1, v) if v != nomatch else _nomatch_res
else:
return _nomatch_res
return fn
def match_any(name, tests, conv, options):
@parser(name, options)
def fn(src):
for test in tests:
pos, value = test.parse(src)
if value != nomatch:
value = conv(value)
if (value != nomatch):
return (pos, value)
return _nomatch_res
fn.children = tests
return fn
def match_seq(name, tests, conv, options):
@parser(name, options)
def fn(src):
total = []
pos = 0
for test in tests:
dpos, value = test.parse(src[pos:])
if value == nomatch:
return _nomatch_res
if value != empty:
total.append(value)
pos += dpos
res = conv(total)
return (pos, res) if res != nomatch else _nomatch_res
fn.children = tests
return fn
def one_more(name, test, conv, options):
@parser(name, options)
def fn(src):
total = []
pos = 0
dpos, value = test.parse(src)
if value == nomatch:
return _nomatch_res
while value != nomatch:
if value != empty:
total.append(value)
pos += dpos
dpos, value = test.parse(src[pos:])
res = conv(total)
return (pos, res) if res != nomatch else _nomatch_res
fn.children = list((test,))
return fn
def mk_closed_range(begin, end):
def closed_range(name, test, conv, options):
@parser(name, options)
def fn(src):
count = 0
total = []
pos = 0
dpos, value = test.parse(src)
if value == nomatch:
return _nomatch_res
while value != nomatch:
count += 1
if count > end:
return _nomatch_res
if value != empty:
total.append(value)
pos += dpos
dpos, value = test.parse(src[pos:])
if count >= begin:
res = conv(total)
return (pos, res) if res != nomatch else _nomatch_res
else:
return _nomatch_res
fn.children = list((test,))
return fn
return closed_range
def zero_more(name, test, conv, options):
@parser(name, options)
def fn(src):
total = []
pos = 0
dpos, value = test.parse(src)
while value != nomatch:
if value != empty:
total.append(value)
pos += dpos
dpos, value = test.parse(src[pos:])
res = conv(total)
return (pos, res) if res != nomatch else _nomatch_res
fn.children = list((test,))
return fn
def range_0_1(name, test, conv, options):
@parser(name, options)
def fn(src):
pos, value = test.parse(src)
if value == nomatch:
pos, value = (0, empty)
value = conv(value)
return (pos, value) if value != nomatch else _nomatch_res
fn.children = list((test,))
return fn
def not_equal(name, test, conv, options):
@parser(name, options)
def fn(src):
if src[0] == empty:
return _nomatch_res
pos, value = test.parse(src)
if value == nomatch:
value = conv(src[0])
return (1, value) if value != nomatch else _nomatch_res
else:
return _nomatch_res
fn.children = list((test,))
return fn
def lookahead(name, test, conv, options):
@parser(name, options)
def fn(src):
pos, value = test.parse(src)
if value != nomatch:
value = conv(value)
return (0, value) if value != nomatch else _nomatch_res
else:
return _nomatch_res
fn.children = list((test,))
return fn