1/*  Part of ClioPatria SPARQL server
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  2015-2018, VU University Amsterdam
    7    All rights reserved.
    8
    9    Redistribution and use in source and binary forms, with or without
   10    modification, are permitted provided that the following conditions
   11    are met:
   12
   13    1. Redistributions of source code must retain the above copyright
   14       notice, this list of conditions and the following disclaimer.
   15
   16    2. Redistributions in binary form must reproduce the above copyright
   17       notice, this list of conditions and the following disclaimer in
   18       the documentation and/or other materials provided with the
   19       distribution.
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   21    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   22    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   23    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   24    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   25    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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   34
   35:- module(text_properties, []).   36:- use_module(library(dcg/basics)).   37:- use_module(library(semweb/rdf_db)).   38:- use_module(library(semweb/rdf_litindex)).   39
   40:- multifile
   41    sparql:functional_property/2,
   42    sparql:current_functional_property/3.   43
   44:- rdf_register_prefix(tpf, 'http://cliopatria.swi-prolog.org/pf/text#').   45
   46term_expansion((sparql:functional_property(S, NS:Term0) :- Body),
   47               [ (sparql:functional_property(S, Term) :- Body),
   48                 sparql:current_functional_property(P, P, Argc)
   49               ]) :-
   50    Term0 =.. [Name|Args],
   51    length(Args, Argc),
   52    rdf_global_id(NS:Name, P),
   53    Term =.. [P|Args].
   54
   55
   56                 /*******************************
   57                 *       PROPERTY FUNCTIONS     *
   58                 *******************************/

 sparql:functional_property(+Subject, +Term) is nondet

These functional properties deal with text matching. As we cannot refer to literals, the function both accepts a predicate and match.

   66sparql:functional_property(S, tpf:match(P, Pattern)) :-
   67    compile_pattern(Pattern, Spec, LV),
   68    search(S, P, Spec, LV).
   69sparql:functional_property(S, tpf:match(P, Pattern, literal(Found))) :-
   70    compile_pattern(Pattern, Spec, Found),
   71    search(S, P, Spec, Found).
   72
   73search(S, P, prefix0(Prefix), Literal) :-
   74    !,
   75    rdf_has(S, P, literal(prefix(Prefix), Literal)).
   76search(S, P, Pattern, Literal) :-
   77    rdf_find_literal(Pattern, Plain),
   78    rdf_has(S, P, literal(exact(Plain), Literal)).
   79
   80compile_pattern(Literal, Spec, LitValue) :-
   81    text_of(Literal, Pattern, Lang, LitValue),
   82    atom_codes(Pattern, PatternCodes),
   83    phrase(compile_pattern(Spec, Lang), PatternCodes).
   84
   85text_of(literal(lang(Lang, Pattern)), Pattern, Lang, lang(Lang,_)) :- !.
   86text_of(literal(Pattern), Pattern, _, _).
   87
   88compile_pattern(Spec, _) -->
   89    "^", !, rest(Prefix),
   90    { Spec = prefix0(Prefix) }.
   91compile_pattern(Spec, Lang) -->
   92    blanks, "(", compile_pattern(Spec, Lang), ")",
   93    !.
   94compile_pattern(Spec, Lang) -->
   95    blanks,
   96    simple_pattern(Left, Lang),
   97    (   and
   98    ->  compile_pattern(Right, Lang),
   99        { Spec = and(Left,Right) }
  100    ;   or
  101    ->  compile_pattern(Right, Lang),
  102        { Spec = or(Left,Right) }
  103    ;   compile_pattern(Right, Lang)
  104    ->  { Spec = and(Left,Right) }
  105    ;   blanks
  106    ->  { Spec = Left }
  107    ).
  108
  109and --> blanks, "AND", blank, !, blanks.
  110or  --> blanks, "OR",  blank, !, blanks.
  111
  112simple_pattern(not(Spec), Lang) -->
  113    "-",
  114    !,
  115    token_pattern(Spec, Lang).
  116simple_pattern(Spec, Lang) -->
  117    token_pattern(Spec, Lang).
  118
  119token_pattern(Spec, Lang) -->
  120    word(Word),
  121    !,
  122    modifiers(Word, Lang, Spec).
  123token_pattern(Spec, _) -->
  124    number(N1),
  125    (   "..",
  126        number(N2)
  127    ->  { Spec = between(N1, N2) }
  128    ;   { Spec = N1 }
  129    ).
  130token_pattern(ge(N), _) -->
  131    ">=", number(N),
  132    !.
  133token_pattern(le(N), _) -->
  134    "<=", number(N),
  135    !.
  136token_pattern(le(N), _) -->
  137    "=<", number(N),
  138    !.
  139
  140modifiers(Word, _, case(Word))   --> "/i", !.
  141modifiers(Word, _, prefix(Word)) --> "*", !.
  142modifiers(Word, L, stem(Word,L)) --> "/s", {nonvar(L)}, !.
  143modifiers(Word, _, stem(Word))   --> "/s", !.
  144modifiers(Word, _, sounds(Word)) --> "/S", !.
  145modifiers(Word, _, Word)         --> "".

 word(-Word)// is semidet

Get a sequence of alpha chars as an atom

  152word(Word) -->
  153    alpha(First),
  154    alphas(Alphas),
  155    { atom_codes(Word, [First|Alphas])
  156    }.
  157
  158alphas([H|T]) -->
  159    alpha(H),
  160    !,
  161    alphas(T).
  162alphas([]) --> [].
  163
  164alpha(H) -->
  165    [H],
  166    { code_type(H, alpha) }.
  167
  168rest(Atom, Codes, []) :-
  169    atom_codes(Atom, Codes)