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deb-python-autobahn
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deb-python-autobahn/autobahn/websocket/utf8validator.py

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Python
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###############################################################################
#
# The MIT License (MIT)
#
# Copyright (c) Tavendo GmbH
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
###############################################################################
# Note: This code is a Python implementation of the algorithm
# "Flexible and Economical UTF-8 Decoder" by Bjoern Hoehrmann
# bjoern@hoehrmann.de, http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
__all__ = ("Utf8Validator",)
# DFA transitions
UTF8VALIDATOR_DFA = (
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, # 00..1f
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, # 20..3f
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, # 40..5f
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, # 60..7f
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, # 80..9f
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, # a0..bf
8, 8, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, # c0..df
0xa, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x4, 0x3, 0x3, # e0..ef
0xb, 0x6, 0x6, 0x6, 0x5, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, # f0..ff
0x0, 0x1, 0x2, 0x3, 0x5, 0x8, 0x7, 0x1, 0x1, 0x1, 0x4, 0x6, 0x1, 0x1, 0x1, 0x1, # s0..s0
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, # s1..s2
1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, # s3..s4
1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, # s5..s6
1, 3, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, # s7..s8
)
UTF8_ACCEPT = 0
UTF8_REJECT = 1
# use Cython implementation of UTF8 validator if available
#
try:
from wsaccel.utf8validator import Utf8Validator
except ImportError:
#
# Fallback to pure Python implementation - also for PyPy.
#
# Do NOT touch this code unless you know what you are doing!
# https://github.com/oberstet/scratchbox/tree/master/python/utf8
#
import six
if six.PY3:
# Python 3 and above
# convert DFA table to bytes (performance)
UTF8VALIDATOR_DFA_S = bytes(UTF8VALIDATOR_DFA)
class Utf8Validator:
"""
Incremental UTF-8 validator with constant memory consumption (minimal state).
Implements the algorithm "Flexible and Economical UTF-8 Decoder" by
Bjoern Hoehrmann (http://bjoern.hoehrmann.de/utf-8/decoder/dfa/).
"""
def __init__(self):
self.reset()
def decode(self, b):
"""
Eat one UTF-8 octet, and validate on the fly.
Returns ``UTF8_ACCEPT`` when enough octets have been consumed, in which case
``self.codepoint`` contains the decoded Unicode code point.
Returns ``UTF8_REJECT`` when invalid UTF-8 was encountered.
Returns some other positive integer when more octets need to be eaten.
"""
tt = UTF8VALIDATOR_DFA_S[b]
if self.state != UTF8_ACCEPT:
self.codepoint = (b & 0x3f) | (self.codepoint << 6)
else:
self.codepoint = (0xff >> tt) & b
self.state = UTF8VALIDATOR_DFA_S[256 + self.state * 16 + tt]
return self.state
def reset(self):
"""
Reset validator to start new incremental UTF-8 decode/validation.
"""
self.state = UTF8_ACCEPT # the empty string is valid UTF8
self.codepoint = 0
self.i = 0
def validate(self, ba):
"""
Incrementally validate a chunk of bytes provided as string.
Will return a quad ``(valid?, endsOnCodePoint?, currentIndex, totalIndex)``.
As soon as an octet is encountered which renders the octet sequence
invalid, a quad with ``valid? == False`` is returned. ``currentIndex`` returns
the index within the currently consumed chunk, and ``totalIndex`` the
index within the total consumed sequence that was the point of bail out.
When ``valid? == True``, currentIndex will be ``len(ba)`` and ``totalIndex`` the
total amount of consumed bytes.
"""
#
# The code here is written for optimal JITting in PyPy, not for best
# readability by your grandma or particular elegance. Do NOT touch!
#
l = len(ba)
i = 0
state = self.state
while i < l:
# optimized version of decode(), since we are not interested in actual code points
state = UTF8VALIDATOR_DFA_S[256 + (state << 4) + UTF8VALIDATOR_DFA_S[ba[i]]]
if state == UTF8_REJECT:
self.state = state
self.i += i
return False, False, i, self.i
i += 1
self.state = state
self.i += l
return True, state == UTF8_ACCEPT, l, self.i
else:
# convert DFA table to string (performance)
UTF8VALIDATOR_DFA_S = ''.join([chr(c) for c in UTF8VALIDATOR_DFA])
class Utf8Validator:
"""
Incremental UTF-8 validator with constant memory consumption (minimal state).
Implements the algorithm "Flexible and Economical UTF-8 Decoder" by
Bjoern Hoehrmann (http://bjoern.hoehrmann.de/utf-8/decoder/dfa/).
"""
def __init__(self):
self.reset()
def decode(self, b):
"""
Eat one UTF-8 octet, and validate on the fly.
Returns ``UTF8_ACCEPT`` when enough octets have been consumed, in which case
``self.codepoint`` contains the decoded Unicode code point.
Returns ``UTF8_REJECT`` when invalid UTF-8 was encountered.
Returns some other positive integer when more octets need to be eaten.
"""
tt = ord(UTF8VALIDATOR_DFA_S[b])
if self.state != UTF8_ACCEPT:
self.codepoint = (b & 0x3f) | (self.codepoint << 6)
else:
self.codepoint = (0xff >> tt) & b
self.state = ord(UTF8VALIDATOR_DFA_S[256 + self.state * 16 + tt])
return self.state
def reset(self):
"""
Reset validator to start new incremental UTF-8 decode/validation.
"""
self.state = UTF8_ACCEPT # the empty string is valid UTF8
self.codepoint = 0
self.i = 0
def validate(self, ba):
"""
Incrementally validate a chunk of bytes provided as string.
Will return a quad ``(valid?, endsOnCodePoint?, currentIndex, totalIndex)``.
As soon as an octet is encountered which renders the octet sequence
invalid, a quad with ``valid? == False`` is returned. ``currentIndex`` returns
the index within the currently consumed chunk, and ``totalIndex`` the
index within the total consumed sequence that was the point of bail out.
When ``valid? == True``, currentIndex will be ``len(ba)`` and ``totalIndex`` the
total amount of consumed bytes.
"""
#
# The code here is written for optimal JITting in PyPy, not for best
# readability by your grandma or particular elegance. Do NOT touch!
#
l = len(ba)
i = 0
state = self.state
while i < l:
# optimized version of decode(), since we are not interested in actual code points
state = ord(UTF8VALIDATOR_DFA_S[256 + (state << 4) + ord(UTF8VALIDATOR_DFA_S[ord(ba[i])])])
if state == UTF8_REJECT:
self.state = state
self.i += i
return False, False, i, self.i
i += 1
self.state = state
self.i += l
return True, state == UTF8_ACCEPT, l, self.i
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