139 lines
4.1 KiB
Python
139 lines
4.1 KiB
Python
# -*- coding: utf-8 -*-
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# vi:tabstop=4:expandtab:sw=4
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"""Transliterate Unicode text into plain 7-bit ASCII.
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Example usage:
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>>> from unidecode import unidecode
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>>> unidecode("\u5317\u4EB0")
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"Bei Jing "
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The transliteration uses a straightforward map, and doesn't have alternatives
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for the same character based on language, position, or anything else.
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A standard string object will be returned. If you need bytes, use:
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>>> unidecode("Κνωσός").encode("ascii")
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b'Knosos'
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"""
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import warnings
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from typing import Dict, Optional, Sequence
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Cache = {} # type: Dict[int, Optional[Sequence[Optional[str]]]]
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class UnidecodeError(ValueError):
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def __init__(self, message: str, index: Optional[int] = None) -> None:
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"""Raised for Unidecode-related errors.
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The index attribute contains the index of the character that caused
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the error.
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"""
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super(UnidecodeError, self).__init__(message)
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self.index = index
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def unidecode_expect_ascii(string: str, errors: str = 'ignore', replace_str: str = '?') -> str:
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"""Transliterate an Unicode object into an ASCII string
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>>> unidecode("\u5317\u4EB0")
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"Bei Jing "
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This function first tries to convert the string using ASCII codec.
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If it fails (because of non-ASCII characters), it falls back to
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transliteration using the character tables.
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This is approx. five times faster if the string only contains ASCII
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characters, but slightly slower than unicode_expect_nonascii if
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non-ASCII characters are present.
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errors specifies what to do with characters that have not been
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found in replacement tables. The default is 'ignore' which ignores
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the character. 'strict' raises an UnidecodeError. 'replace'
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substitutes the character with replace_str (default is '?').
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'preserve' keeps the original character.
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Note that if 'preserve' is used the returned string might not be
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ASCII!
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"""
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try:
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bytestring = string.encode('ASCII')
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except UnicodeEncodeError:
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pass
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else:
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return string
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return _unidecode(string, errors, replace_str)
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def unidecode_expect_nonascii(string: str, errors: str = 'ignore', replace_str: str = '?') -> str:
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"""Transliterate an Unicode object into an ASCII string
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>>> unidecode("\u5317\u4EB0")
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"Bei Jing "
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See unidecode_expect_ascii.
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"""
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return _unidecode(string, errors, replace_str)
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unidecode = unidecode_expect_ascii
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def _get_repl_str(char: str) -> Optional[str]:
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codepoint = ord(char)
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if codepoint < 0x80:
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# Already ASCII
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return str(char)
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if codepoint > 0xeffff:
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# No data on characters in Private Use Area and above.
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return None
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if 0xd800 <= codepoint <= 0xdfff:
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warnings.warn( "Surrogate character %r will be ignored. "
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"You might be using a narrow Python build." % (char,),
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RuntimeWarning, 2)
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section = codepoint >> 8 # Chop off the last two hex digits
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position = codepoint % 256 # Last two hex digits
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try:
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table = Cache[section]
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except KeyError:
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try:
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mod = __import__('unidecode.x%03x'%(section), globals(), locals(), ['data'])
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except ImportError:
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# No data on this character
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Cache[section] = None
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return None
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Cache[section] = table = mod.data
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if table and len(table) > position:
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return table[position]
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else:
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return None
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def _unidecode(string: str, errors: str, replace_str:str) -> str:
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retval = []
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for index, char in enumerate(string):
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repl = _get_repl_str(char)
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if repl is None:
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if errors == 'ignore':
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repl = ''
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elif errors == 'strict':
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raise UnidecodeError('no replacement found for character %r '
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'in position %d' % (char, index), index)
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elif errors == 'replace':
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repl = replace_str
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elif errors == 'preserve':
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repl = char
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else:
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raise UnidecodeError('invalid value for errors parameter %r' % (errors,))
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retval.append(repl)
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return ''.join(retval)
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