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)  2013-2025, VU University Amsterdam
    7                              SWI-Prolog Solutions b.v.
    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(html_quasi_quotations, [ html/4 ]).   37:- use_module(library(sgml)).   38:- use_module(library(apply)).   39:- use_module(library(error)).   40:- use_module(library(lists)).   41:- use_module(library(quasi_quotations)).   42
   43/** <module> HTML quasi quotations
   44
   45This  module  implements  quasi  quotations   for  HTML.  Together  with
   46library(http/html_write),  this  allows  for  inclusion   of  long  HTML
   47fragments in the Prolog  source  code   while  replacing  attributes and
   48content with variable that come from the surrounding Prolog clause.
   49
   50This module is included and re-exported from library(http/html_write).
   51
   52@see    library(http/js_write) provides quasi quotation for JavaScript.
   53*/
   54
   55%!  html(+Content, +Vars, +VarDict, -DOM) is det.
   56%
   57%   The predicate html/4 implements  HTML   quasi  quotations. These
   58%   quotations produce a DOM term that   is suitable for html//1 and
   59%   other predicates that are declared to   consume this format. The
   60%   quasi quoter only  accepts  valid,   but  possibly  partial HTML
   61%   documents. The document *must* begin  with   a  tag.  The quoter
   62%   replaces attributes or content whose value  is a Prolog variable
   63%   that appears in the argument list   of  the =html= indicator. If
   64%   the variable defines content, it must  be the only content. Here
   65%   is  an  example,  replacing  both  a   content  element  and  an
   66%   attribute. Note that the document is valid HTML.
   67%
   68%     ==
   69%       html({|html(Name, URL)||
   70%              <p>Dear <span class="name">Name</span>,
   71%
   72%              <p>You can <a href="URL">download</a> the requested
   73%              article now.
   74%              |}
   75%     ==
   76
   77:- quasi_quotation_syntax(html).   78
   79html(Content, Vars, Dict, DOM) :-
   80    must_be(list, Dict),
   81    include(qq_var(Vars), Dict, QQDict),
   82    with_quasi_quotation_input(
   83        Content, In,
   84        load_html(In, DOM0,
   85                  [ max_errors(0),
   86                    syntax_errors(print),
   87                    case_preserving_attributes(true)
   88                  ])),
   89    xml_content(QQDict, DOM0, DOM).
   90
   91qq_var(Vars, _=Var) :- member(V, Vars), V == Var, !.
   92
   93xml_content(Dict, [Name], [Var]) :-
   94    atom(Name),
   95    memberchk(Name=Var, Dict),
   96    !.
   97xml_content(Dict, Content0, Content) :-
   98    maplist(xml_content_element(Dict), Content0, Content).
   99
  100xml_content_element(Dict,
  101                    element(Tag, Attrs0, Content0),
  102                    element(Tag, Attrs, Content)) :-
  103    !,
  104    maplist(xml_attribute(Dict), Attrs0, Attrs),
  105    xml_content(Dict, Content0, Content).
  106xml_content_element(_, Element, Element).
  107
  108xml_attribute(Dict, Attr=Name, Attr=Var) :-
  109    memberchk(Name=Var, Dict),
  110    !.
  111xml_attribute(_, Attr, Attr).
  112
  113
  114                /*******************************
  115                *           SANDBOX            *
  116                *******************************/
  117
  118:- multifile sandbox:safe_primitive/1.  119
  120sandbox:safe_primitive(html_quasi_quotations:html(_,_,_,_))