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
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   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)).

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

   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(_))