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