146 lines
5 KiB
Python
146 lines
5 KiB
Python
|
######################## BEGIN LICENSE BLOCK ########################
|
||
|
|
# The Original Code is Mozilla Universal charset detector code.
|
||
|
|
#
|
||
|
|
# The Initial Developer of the Original Code is
|
||
|
|
# Netscape Communications Corporation.
|
||
|
|
# Portions created by the Initial Developer are Copyright (C) 2001
|
||
|
|
# the Initial Developer. All Rights Reserved.
|
||
|
|
#
|
||
|
|
# Contributor(s):
|
||
|
|
# Mark Pilgrim - port to Python
|
||
|
|
# Shy Shalom - original C code
|
||
|
|
#
|
||
|
|
# This library is free software; you can redistribute it and/or
|
||
|
|
# modify it under the terms of the GNU Lesser General Public
|
||
|
|
# License as published by the Free Software Foundation; either
|
||
|
|
# version 2.1 of the License, or (at your option) any later version.
|
||
|
|
#
|
||
|
|
# This library is distributed in the hope that it will be useful,
|
||
|
|
# but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||
|
|
# Lesser General Public License for more details.
|
||
|
|
#
|
||
|
|
# You should have received a copy of the GNU Lesser General Public
|
||
|
|
# License along with this library; if not, write to the Free Software
|
||
|
|
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
|
||
|
|
# 02110-1301 USA
|
||
|
|
######################### END LICENSE BLOCK #########################
|
||
|
|
|
||
|
|
import logging
|
||
|
|
import re
|
||
|
|
|
||
|
|
from .enums import ProbingState
|
||
|
|
|
||
|
|
|
||
|
|
class CharSetProber(object):
|
||
|
|
|
||
|
|
SHORTCUT_THRESHOLD = 0.95
|
||
|
|
|
||
|
|
def __init__(self, lang_filter=None):
|
||
|
|
self._state = None
|
||
|
|
self.lang_filter = lang_filter
|
||
|
|
self.logger = logging.getLogger(__name__)
|
||
|
|
|
||
|
|
def reset(self):
|
||
|
|
self._state = ProbingState.DETECTING
|
||
|
|
|
||
|
|
@property
|
||
|
|
def charset_name(self):
|
||
|
|
return None
|
||
|
|
|
||
|
|
def feed(self, buf):
|
||
|
|
pass
|
||
|
|
|
||
|
|
@property
|
||
|
|
def state(self):
|
||
|
|
return self._state
|
||
|
|
|
||
|
|
def get_confidence(self):
|
||
|
|
return 0.0
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def filter_high_byte_only(buf):
|
||
|
|
buf = re.sub(b'([\x00-\x7F])+', b' ', buf)
|
||
|
|
return buf
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def filter_international_words(buf):
|
||
|
|
"""
|
||
|
|
We define three types of bytes:
|
||
|
|
alphabet: english alphabets [a-zA-Z]
|
||
|
|
international: international characters [\x80-\xFF]
|
||
|
|
marker: everything else [^a-zA-Z\x80-\xFF]
|
||
|
|
|
||
|
|
The input buffer can be thought to contain a series of words delimited
|
||
|
|
by markers. This function works to filter all words that contain at
|
||
|
|
least one international character. All contiguous sequences of markers
|
||
|
|
are replaced by a single space ascii character.
|
||
|
|
|
||
|
|
This filter applies to all scripts which do not use English characters.
|
||
|
|
"""
|
||
|
|
filtered = bytearray()
|
||
|
|
|
||
|
|
# This regex expression filters out only words that have at-least one
|
||
|
|
# international character. The word may include one marker character at
|
||
|
|
# the end.
|
||
|
|
words = re.findall(b'[a-zA-Z]*[\x80-\xFF]+[a-zA-Z]*[^a-zA-Z\x80-\xFF]?',
|
||
|
|
buf)
|
||
|
|
|
||
|
|
for word in words:
|
||
|
|
filtered.extend(word[:-1])
|
||
|
|
|
||
|
|
# If the last character in the word is a marker, replace it with a
|
||
|
|
# space as markers shouldn't affect our analysis (they are used
|
||
|
|
# similarly across all languages and may thus have similar
|
||
|
|
# frequencies).
|
||
|
|
last_char = word[-1:]
|
||
|
|
if not last_char.isalpha() and last_char < b'\x80':
|
||
|
|
last_char = b' '
|
||
|
|
filtered.extend(last_char)
|
||
|
|
|
||
|
|
return filtered
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def filter_with_english_letters(buf):
|
||
|
|
"""
|
||
|
|
Returns a copy of ``buf`` that retains only the sequences of English
|
||
|
|
alphabet and high byte characters that are not between <> characters.
|
||
|
|
Also retains English alphabet and high byte characters immediately
|
||
|
|
before occurrences of >.
|
||
|
|
|
||
|
|
This filter can be applied to all scripts which contain both English
|
||
|
|
characters and extended ASCII characters, but is currently only used by
|
||
|
|
``Latin1Prober``.
|
||
|
|
"""
|
||
|
|
filtered = bytearray()
|
||
|
|
in_tag = False
|
||
|
|
prev = 0
|
||
|
|
|
||
|
|
for curr in range(len(buf)):
|
||
|
|
# Slice here to get bytes instead of an int with Python 3
|
||
|
|
buf_char = buf[curr:curr + 1]
|
||
|
|
# Check if we're coming out of or entering an HTML tag
|
||
|
|
if buf_char == b'>':
|
||
|
|
in_tag = False
|
||
|
|
elif buf_char == b'<':
|
||
|
|
in_tag = True
|
||
|
|
|
||
|
|
# If current character is not extended-ASCII and not alphabetic...
|
||
|
|
if buf_char < b'\x80' and not buf_char.isalpha():
|
||
|
|
# ...and we're not in a tag
|
||
|
|
if curr > prev and not in_tag:
|
||
|
|
# Keep everything after last non-extended-ASCII,
|
||
|
|
# non-alphabetic character
|
||
|
|
filtered.extend(buf[prev:curr])
|
||
|
|
# Output a space to delimit stretch we kept
|
||
|
|
filtered.extend(b' ')
|
||
|
|
prev = curr + 1
|
||
|
|
|
||
|
|
# If we're not in a tag...
|
||
|
|
if not in_tag:
|
||
|
|
# Keep everything after last non-extended-ASCII, non-alphabetic
|
||
|
|
# character
|
||
|
|
filtered.extend(buf[prev:])
|
||
|
|
|
||
|
|
return filtered
|