SWI-Prolog Unicode library
Jan Wielemaker
VU University, Amsterdam
The Netherlands
E-mail: J.Wielemaker@cs.vu.nl
Abstract
This package wraps utf8proc unicode routines. This library provides the four unicode normalization forms (NFC, NFD, NFKC, NFKD) as well as access to the Unicode character properties.

# Table of Contents

## 1 library(unicode): Unicode string handling

See also
  http://www.public-software-group.org/utf8proc

This library is a wrapper around the utf8proc library, providing information about Unicode code-points and performing operations (mappings) on Unicode atoms. The central predicate is unicode_map/3, mapping a Unicode atom to another Unicode atom using a sequence of operations. The predicates unicode_nfd/2, unicode_nfc/2, unicode_nfkd/2 and unicode_nfkc/2 implement the four standard Unicode normalization forms.

Lump handling:

    U+0020      <-- all space characters (general category Zs)
    U+0027  '   <-- left/right single quotation mark U+2018..2019,
                    modifier letter apostrophe U+02BC,
                    modifier letter vertical line U+02C8
    U+002D  -   <-- all dash characters (general category Pd),
                    minus U+2212
    U+002F  /   <-- fraction slash U+2044,
                    division slash U+2215
    U+003A  :   <-- ratio U+2236
    U+003C  <   <-- single left-pointing angle quotation mark U+2039,
                    left-pointing angle bracket U+2329,
                    left angle bracket U+3008
    U+003E  >   <-- single right-pointing angle quotation mark U+203A,
                    right-pointing angle bracket U+232A,
                    right angle bracket U+3009
    U+005C  \   <-- set minus U+2216
    U+005E  ^   <-- modifier letter up arrowhead U+02C4,
                    modifier letter circumflex accent U+02C6,
                    caret U+2038,
                    up arrowhead U+2303
    U+005F  _   <-- all connector characters (general category Pc),
                    modifier letter low macron U+02CD
    U+0060  `   <-- modifier letter grave accent U+02CB
    U+007C  |   <-- divides U+2223
    U+007E  ~   <-- tilde operator U+223C

[det]unicode_map(+In, -Out, +Options)
  Perform unicode normalization operations. Options is a list of operations. Defined operations are:
  stable
    Unicode Versioning Stability has to be respected.
  compat
    Compatiblity decomposition (i.e. formatting information is lost)
  compose
    Return a result with composed characters.
  decompose
    Return a result with decomposed characters.
  ignore
    Strip "default ignorable characters"
  rejectna
    Return an error, if the input contains unassigned code points.
  nlf2ls
    Indicating that NLF-sequences (LF, CRLF, CR, NEL) are representing a line break, and should be converted to the unicode character for line separation (LS).
  nlf2ps
    Indicating that NLF-sequences are representing a paragraph break, and should be converted to the unicode character for paragraph separation (PS).
  nlf2lf
    Indicating that the meaning of NLF-sequences is unknown.
  stripcc
    Strips and/or convers control characters. NLF-sequences are transformed into space, except if one of the NLF2LS/PS/LF options is given. HorizontalTab (HT) and FormFeed (FF) are treated as a NLF-sequence in this case. All other control characters are simply removed.
  casefold
    Performs unicode case folding, to be able to do a case-insensitive string comparison.
  charbound
    Inserts 0xFF bytes at the beginning of each sequence which is representing a single grapheme cluster (see UAX#29).
  lump
    (e.g. HYPHEN U+2010 and MINUS U+2212 to ASCII "-"). (See module header for details.) If NLF2LF is set, this includes a transformation of paragraph and line separators to ASCII line-feed (LF).
  stripmark
    Strips all character markings (non-spacing, spacing and enclosing) (i.e. accents) NOTE: this option works only with `compose` or `decompose`.
[det]unicode_nfd(+In, -Out)
  Characters are decomposed by canonical equivalence.
[det]unicode_nfc(+In, -Out)
  Characters are decomposed and then recomposed by canonical equivalence. It is possible for the result to be a different sequence of characters than the original.
  See also
    http://en.wikipedia.org/wiki/Unicode_equivalence\#Normal_forms
[det]unicode_nfkd(+In, -Out)
  Characters are decomposed by compatibility equivalence.
[det]unicode_nfkc(+In, -Out)
  Characters are decomposed by compatibility equivalence, then recomposed by canonical equivalence.
[nondet]unicode_property(?Char, ?Property)
  True if Property is defined for Char. Property is a term Name(Value). Defined property-names are:
  category(atom)
    Unicode code category of Char. This is one of Cc, Cf, Cn, Co, Cs, Ll, Lm, Lo, Lt, Lu, Mc, Me, Mn, Nd, Nl, No, Pc, Pd, Pe, Pf, Pi, Po, Ps, Sc, Sk, Sm, So, Zl, Zp, Zs. When testing, a single letter stands for all its subcategories. E.g. to test form a letter, you can use

        unicode_property(C, category('L'))

  combining_class(integer)
  bidi_class(atom)
  decomp_type(atom)
  decomp_mapping(list(code))
  bidi_mirrored(bool)
  uppercase_mapping(code)
  lowercase_mapping(code)
  titlecase_mapping(code)
  comb1st_index(code)
  comb2nd_index(code)
  comp_exclusion(bool)
  ignorable(bool)
  control_boundary(bool)
  extend(bool)
  casefold_mapping(list(code))
  To be done
    Complete documentation

## 2 License

Copyright (c) 2009 Public Software Group e. V., Berlin, Germany

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.

This software distribution contains derived data from a modified version of the Unicode data files. The following license applies to that data:

COPYRIGHT AND PERMISSION NOTICE

Copyright (c) 1991-2007 Unicode, Inc. All rights reserved. Distributed under the Terms of Use in http://www.unicode.org/copyright.html.

Permission is hereby granted, free of charge, to any person obtaining a copy of the Unicode data files and any associated documentation (the "Data Files") or Unicode software and any associated documentation (the "Software") to deal in the Data Files or Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, and/or sell copies of the Data Files or Software, and to permit persons to whom the Data Files or Software are furnished to do so, provided that (a) the above copyright notice(s) and this permission notice appear with all copies of the Data Files or Software, (b) both the above copyright notice(s) and this permission notice appear in associated documentation, and (c) there is clear notice in each modified Data File or in the Software as well as in the documentation associated with the Data File(s) or Software that the data or software has been modified.

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# Index

?
unicode_map/3
unicode_nfc/2
unicode_nfd/2
unicode_nfkc/2
unicode_nfkd/2
unicode_property/2