269 lines
7.3 KiB
Python
269 lines
7.3 KiB
Python
########################################################################
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# File name: stringprep.py
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# This file is part of: aioxmpp
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#
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# LICENSE
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Lesser General Public License as
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# published by the Free Software Foundation, either version 3 of the
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# License, or (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this program. If not, see
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# <http://www.gnu.org/licenses/>.
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#
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########################################################################
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"""
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Stringprep support
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##################
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This module implements the Nodeprep (`RFC 6122`_) and Resourceprep
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(`RFC 6122`_) stringprep profiles.
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.. autofunction:: nodeprep
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.. autofunction:: resourceprep
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.. autofunction:: nameprep
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.. _RFC 3454: https://tools.ietf.org/html/rfc3454
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.. _RFC 6122: https://tools.ietf.org/html/rfc6122
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"""
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import stringprep
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from unicodedata import ucd_3_2_0 as unicodedata
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_nodeprep_prohibited = frozenset("\"&'/:<>@")
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def is_RandALCat(c):
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return unicodedata.bidirectional(c) in ("R", "AL")
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def is_LCat(c):
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return unicodedata.bidirectional(c) == "L"
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def check_against_tables(chars, tables):
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"""
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Perform a check against the table predicates in `tables`. `tables` must be
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a reusable iterable containing characteristic functions of character sets,
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that is, functions which return :data:`True` if the character is in the
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table.
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The function returns the first character occurring in any of the tables or
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:data:`None` if no character matches.
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"""
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for c in chars:
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if any(in_table(c) for in_table in tables):
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return c
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return None
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def do_normalization(chars):
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"""
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Perform the stringprep normalization. Operates in-place on a list of
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unicode characters provided in `chars`.
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"""
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chars[:] = list(unicodedata.normalize("NFKC", "".join(chars)))
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def check_bidi(chars):
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"""
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Check proper bidirectionality as per stringprep. Operates on a list of
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unicode characters provided in `chars`.
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"""
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# the empty string is valid, as it cannot violate the RandALCat constraints
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if not chars:
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return
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# first_is_RorAL = unicodedata.bidirectional(chars[0]) in {"R", "AL"}
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# if first_is_RorAL:
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has_RandALCat = any(is_RandALCat(c) for c in chars)
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if not has_RandALCat:
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return
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has_LCat = any(is_LCat(c) for c in chars)
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if has_LCat:
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raise ValueError("L and R/AL characters must not occur in the same"
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" string")
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if not is_RandALCat(chars[0]) or not is_RandALCat(chars[-1]):
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raise ValueError("R/AL string must start and end with R/AL character.")
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def check_prohibited_output(chars, bad_tables):
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"""
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Check against prohibited output, by checking whether any of the characters
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from `chars` are in any of the `bad_tables`.
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Operates in-place on a list of code points from `chars`.
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"""
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violator = check_against_tables(chars, bad_tables)
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if violator is not None:
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raise ValueError("Input contains invalid unicode codepoint: "
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"U+{:04x}".format(ord(violator)))
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def check_unassigned(chars, bad_tables):
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"""
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Check that `chars` does not contain any unassigned code points as per
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the given list of `bad_tables`.
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Operates on a list of unicode code points provided in `chars`.
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"""
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bad_tables = (
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stringprep.in_table_a1,)
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violator = check_against_tables(chars, bad_tables)
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if violator is not None:
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raise ValueError("Input contains unassigned code point: "
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"U+{:04x}".format(ord(violator)))
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def _nodeprep_do_mapping(chars):
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i = 0
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while i < len(chars):
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c = chars[i]
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if stringprep.in_table_b1(c):
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del chars[i]
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else:
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replacement = stringprep.map_table_b2(c)
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if replacement != c:
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chars[i:(i + 1)] = list(replacement)
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i += len(replacement)
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def nodeprep(string, allow_unassigned=False):
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"""
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Process the given `string` using the Nodeprep (`RFC 6122`_) profile. In the
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error cases defined in `RFC 3454`_ (stringprep), a :class:`ValueError` is
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raised.
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"""
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chars = list(string)
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_nodeprep_do_mapping(chars)
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do_normalization(chars)
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check_prohibited_output(
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chars,
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(
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stringprep.in_table_c11,
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stringprep.in_table_c12,
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stringprep.in_table_c21,
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stringprep.in_table_c22,
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stringprep.in_table_c3,
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stringprep.in_table_c4,
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stringprep.in_table_c5,
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stringprep.in_table_c6,
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stringprep.in_table_c7,
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stringprep.in_table_c8,
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stringprep.in_table_c9,
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lambda x: x in _nodeprep_prohibited
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))
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check_bidi(chars)
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if not allow_unassigned:
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check_unassigned(
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chars,
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(
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stringprep.in_table_a1,
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)
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)
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return "".join(chars)
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def _resourceprep_do_mapping(chars):
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i = 0
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while i < len(chars):
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c = chars[i]
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if stringprep.in_table_b1(c):
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del chars[i]
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continue
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i += 1
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def resourceprep(string, allow_unassigned=False):
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"""
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Process the given `string` using the Resourceprep (`RFC 6122`_) profile. In
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the error cases defined in `RFC 3454`_ (stringprep), a :class:`ValueError`
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is raised.
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"""
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chars = list(string)
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_resourceprep_do_mapping(chars)
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do_normalization(chars)
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check_prohibited_output(
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chars,
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(
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stringprep.in_table_c12,
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stringprep.in_table_c21,
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stringprep.in_table_c22,
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stringprep.in_table_c3,
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stringprep.in_table_c4,
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stringprep.in_table_c5,
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stringprep.in_table_c6,
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stringprep.in_table_c7,
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stringprep.in_table_c8,
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stringprep.in_table_c9,
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))
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check_bidi(chars)
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if not allow_unassigned:
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check_unassigned(
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chars,
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(
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stringprep.in_table_a1,
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)
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)
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return "".join(chars)
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def nameprep(string, allow_unassigned=False):
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"""
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Process the given `string` using the Nameprep (`RFC 3491`_) profile. In the
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error cases defined in `RFC 3454`_ (stringprep), a :class:`ValueError` is
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raised.
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"""
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chars = list(string)
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_nodeprep_do_mapping(chars)
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do_normalization(chars)
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check_prohibited_output(
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chars,
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(
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stringprep.in_table_c12,
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stringprep.in_table_c22,
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stringprep.in_table_c3,
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stringprep.in_table_c4,
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stringprep.in_table_c5,
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stringprep.in_table_c6,
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stringprep.in_table_c7,
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stringprep.in_table_c8,
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stringprep.in_table_c9,
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))
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check_bidi(chars)
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if not allow_unassigned:
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check_unassigned(
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chars,
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(
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stringprep.in_table_a1,
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)
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)
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return "".join(chars)
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