View source with raw comments or as raw
    1/*  Part of SWI-Prolog
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  2010-2020, University of Amsterdam
    7                              CWI, Amsterdam
    8    All rights reserved.
    9
   10    Redistribution and use in source and binary forms, with or without
   11    modification, are permitted provided that the following conditions
   12    are met:
   13
   14    1. Redistributions of source code must retain the above copyright
   15       notice, this list of conditions and the following disclaimer.
   16
   17    2. Redistributions in binary form must reproduce the above copyright
   18       notice, this list of conditions and the following disclaimer in
   19       the documentation and/or other materials provided with the
   20       distribution.
   21
   22    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   23    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   24    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   25    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   26    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   27    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   28    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   29    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   30    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   32    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   33    POSSIBILITY OF SUCH DAMAGE.
   34*/
   35
   36:- module(unicode,
   37          [ unicode_property/2,         % ?Code, ?Property
   38            unicode_map/3,              % +In, -Out, +Options
   39            unicode_nfd/2,              % +In, -Out
   40            unicode_nfc/2,              % +In, -Out
   41            unicode_nfkd/2,             % +In, -Out
   42            unicode_nfkc/2              % +In, -Out
   43          ]).   44:- use_foreign_library(foreign(unicode4pl)).

Unicode string handling

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
See also
- http://www.public-software-group.org/utf8proc */
   90system:goal_expansion(unicode_map(In, Out, Options),
   91                      unicode_map(In, Out, Mask)) :-
   92    is_list(Options),
   93    unicode_option_mask(Options, Mask).
 unicode_map(+In, -Out, +Options) is det
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.
 unicode_nfd(+In, -Out) is det
Characters are decomposed by canonical equivalence.
  150unicode_nfd(In, Out) :-
  151    unicode_map(In, Out, [stable,decompose]).
 unicode_nfc(+In, -Out) is det
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
  161unicode_nfc(In, Out) :-
  162    unicode_map(In, Out, [stable,compose]).
 unicode_nfkd(+In, -Out) is det
Characters are decomposed by compatibility equivalence.
  168unicode_nfkd(In, Out) :-
  169    unicode_map(In, Out, [stable,decompose,compat]).
 unicode_nfkc(+In, -Out) is det
Characters are decomposed by compatibility equivalence, then recomposed by canonical equivalence.
  176unicode_nfkc(In, Out) :-
  177    unicode_map(In, Out, [stable,compose,compat]).
 unicode_property(?Char, ?Property) is nondet
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
  214unicode_property(Code, Property) :-
  215    nonvar(Code), nonvar(Property),
  216    !,
  217    '$unicode_property'(Code, Property).
  218unicode_property(Code, Property) :-
  219    nonvar(Code),
  220    !,
  221    property(Property),
  222    '$unicode_property'(Code, Property).
  223unicode_property(Code, Property) :-
  224    var(Code),
  225    !,
  226    between(0, 0x10ffff, Code),
  227    property(Property),
  228    '$unicode_property'(Code, Property).
  229
  230property(category(_)).
  231property(combining_class(_)).
  232property(bidi_class(_)).
  233property(decomp_type(_)).
  234property(decomp_mapping(_)).
  235property(bidi_mirrored(_)).
  236property(uppercase_mapping(_)).
  237property(lowercase_mapping(_)).
  238property(titlecase_mapping(_)).
  239property(comb1st_index(_)).
  240property(comb2nd_index(_)).
  241property(comp_exclusion(_)).
  242property(ignorable(_)).
  243property(control_boundary(_)).
  244property(extend(_)).
  245property(casefold_mapping(_))