1/*  Part of SWI-Prolog
    2
    3    Author:        Jan Wielemaker and Matt Lilley
    4    E-mail:        J.Wielemaker@vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  2016, CWI 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.
   20
   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,
   26    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   27    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   28    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   29    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   31    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   32    POSSIBILITY OF SUCH DAMAGE.
   33*/
   34
   35:- module(c14n2,
   36          [ xml_write_canonical/3       % +Stream, +Term, +Options
   37          ]).   38:- autoload(library(apply),[partition/4,maplist/3]).   39:- autoload(library(dicts),[dict_keys/2]).   40:- autoload(library(error),[instantiation_error/1,must_be/2]).   41:- autoload(library(lists),[member/2,append/2,select/3]).   42:- autoload(library(option),[option/3]).   43:- autoload(library(ordsets),[ord_subtract/3]).   44:- autoload(library(sgml_write),[xml_write/3]).   45
   46/** <module> C14n2 canonical XML documents
   47
   48C14n2 specifies a _canonical_ XML document.   This library writes such a
   49document from an XML DOM as returned by   the  XML (or SGML) parser. The
   50process takes two steps:
   51
   52  - Normalise the DOM
   53  - Call xml_write/3 with appropriate flags
   54*/
   55
   56%!  xml_write_canonical(+Stream, +DOM, +Options) is det.
   57%
   58%   Write an XML DOM using the   canonical conventions as defined by
   59%   C14n2. Namespace declarations in the   canonical document depend
   60%   on the original namespace  declarations.   For  this  reason the
   61%   input document must be parsed   (see load_structure/3) using the
   62%   dialect `xmlns` and the option keep_prefix(true).
   63
   64xml_write_canonical(Stream, DOM, Options) :-
   65    option(method(Method), Options, 'http://www.w3.org/TR/2001/REC-xml-c14n-20010315'),
   66    xml_canonical_dom(DOM, CDOM, xml{in_ns:ns{}, out_ns:ns{}, is_root:true, method:Method}),
   67    xml_write(Stream, CDOM,
   68              [ header(false),
   69                layout(false),
   70                net(false)
   71              ]).
   72
   73xml_canonical_dom(Var, _, _) :-
   74    var(Var),
   75    !,
   76    instantiation_error(Var).
   77xml_canonical_dom(DOM, CDOM, Options) :-
   78    is_list(DOM),
   79    !,
   80    xml_canonical_list(DOM, CDOM, Options).
   81xml_canonical_dom(element( Name,  Attrs,  Content),
   82                  element(CName, CAttrs, CContent),
   83                  Options) :-
   84    !,
   85    InNS0  = Options.in_ns,
   86    OutNS0 = Options.out_ns,
   87    Method = Options.method,
   88    % We must include namespaces which appear in attributes in this element, too, if using xml-exc-c14n
   89    % This means we need to know what they are
   90    findall(NS, (member(Attr, Attrs), Attr = (NS:_=_), NS \== xmlns), NamespacesInAttrs),
   91    take_ns(Attrs, Method, NamespacesInAttrs, Name, Attrs1, InNS0, InNS),
   92    partition(has_ns, Attrs1, AttrsWithNS0, AttrsSans0),
   93    sort(1, @<, AttrsWithNS0, AttrsWithNS1),
   94    sort(1, @<, AttrsSans0, AttrsSans),
   95    put_elemns(Name, CName, InNS, OutNS0, OutNS1, KillDefault),
   96    put_ns_attrs(AttrsWithNS1, AttrsWithNS, InNS, OutNS1, OutNS),
   97    ns_attrs(OutNS0, OutNS, NSAttrs),
   98    (  Options.is_root == true ->
   99           (  select(xmlns=DefaultNamespace, NSAttrs, NSAttrs0)
  100              % If there is a default namespace, it must come first, and I dont think sort/4 can sort on two keys at once
  101           -> findall(xmlns:NS=URI, member(xmlns:NS=URI, Attrs), RootNSAttrs, NSAttrs0),
  102              sort(2, @=<, RootNSAttrs, RootNSAttrs0),
  103              RootNSAttrs1 = [xmlns=DefaultNamespace|RootNSAttrs0]
  104           ;  Method == 'http://www.w3.org/2001/10/xml-exc-c14n#'
  105           -> RootNSAttrs1 = NSAttrs
  106           ;  findall(xmlns:NS=URI, member(xmlns:NS=URI, Attrs), RootNSAttrs, NSAttrs),
  107              sort(1, @<, RootNSAttrs, RootNSAttrs1)
  108           ),
  109           append([KillDefault, RootNSAttrs1, AttrsSans, AttrsWithNS], CAttrs)
  110    ;  append([KillDefault, NSAttrs, AttrsSans, AttrsWithNS], CAttrs)
  111    ),
  112    must_be(list, Content),
  113    xml_canonical_list(Content, CContent,
  114                       Options.put(_{in_ns:InNS, out_ns:OutNS, is_root:false})).
  115xml_canonical_dom(CDATA, CDATA, _) :-
  116    atomic(CDATA).
  117
  118has_ns(_NS:_Name=_Value).
  119
  120xml_canonical_list([], [], _).
  121xml_canonical_list([H0|T0], [H|T], Options) :-
  122    xml_canonical_dom(H0, H, Options),
  123    xml_canonical_list(T0, T, Options).
  124
  125take_ns([], _, _, _, [], NSList, NSList).
  126take_ns([H|T0], Method, NamespacesInAttrs, Name, T, NSList0, NSList) :-
  127    xml_ns(H, NS, URL),
  128    !,
  129    (  include_ns(Name, Method, NamespacesInAttrs, NS, URL)
  130    -> take_ns(T0, Method, NamespacesInAttrs, Name, T, NSList0.put(NS, URL), NSList)
  131    ;  take_ns(T0, Method, NamespacesInAttrs, Name, T, NSList0, NSList)
  132    ).
  133take_ns([H|T0], Method, NamespacesInAttrs, Name, [H|T], NSList0, NSList) :-
  134    take_ns(T0, Method, NamespacesInAttrs, Name, T, NSList0, NSList).
  135
  136include_ns(ns(Prefix, URI):_, 'http://www.w3.org/2001/10/xml-exc-c14n#', _, Prefix, URI):- !.
  137include_ns(_, 'http://www.w3.org/2001/10/xml-exc-c14n#', NamespacesInAttrs, _Prefix, URI):-
  138        memberchk(URI, NamespacesInAttrs).
  139include_ns(_, 'http://www.w3.org/TR/2001/REC-xml-c14n-20010315', _, _, _):- !.
  140
  141
  142put_ns_attrs([], [], _, OutNS, OutNS).
  143put_ns_attrs([Name=Value|T0], [CName=Value|T], InNS, OutNS0, OutNS) :-
  144    put_ns(Name, CName, InNS, OutNS0, OutNS1),
  145    put_ns_attrs(T0, T, InNS, OutNS1, OutNS).
  146
  147put_elemns(Name, Name, _InNS, OutNS0, OutNS1, [xmlns='']) :-
  148    atom(Name),
  149    dict_pairs(OutNS0, _, Pairs),
  150    memberchk(URL-'', Pairs),
  151    !,
  152    del_dict(URL, OutNS0, '', OutNS1).
  153put_elemns(Name, CName, InNS, OutNS0, OutNS, []) :-
  154    put_ns(Name, CName, InNS, OutNS0, OutNS).
  155
  156put_ns(ns('', xml):Name, xml:Name, _InNS, OutNS, OutNS) :-
  157    !.
  158put_ns(ns(NS, URL):Name, CName, _InNS, OutNS, OutNS) :-
  159    get_dict(URL, OutNS, NS),
  160    !,
  161    make_cname(NS:Name, CName).
  162put_ns(ns(NS, URL):Name, CName, _InNS, OutNS0, OutNS) :-
  163    !,
  164    make_cname(NS:Name, CName),
  165    OutNS = OutNS0.put(URL, NS).
  166put_ns(URL:Name, CName, _InNS, OutNS, OutNS) :-
  167    get_dict(URL, OutNS, NS),
  168    !,
  169    make_cname(NS:Name, CName).
  170put_ns(URL:Name, CName, InNS, OutNS0, OutNS) :-
  171    dict_pairs(InNS, _, Pairs),
  172    memberchk(NS-URL, Pairs),
  173    !,
  174    make_cname(NS:Name, CName),
  175    OutNS = OutNS0.put(URL, NS).
  176put_ns(Name, Name, _, OutNS, OutNS).
  177
  178ns_attrs(OutNS, OutNS, []) :- !.
  179ns_attrs(OutNS0, OutNS, NSAttrs) :-
  180    !,
  181    dict_pairs(OutNS, _, Pairs),
  182    dict_pairs(OutNS0, _, Pairs0),
  183    ord_subtract(Pairs, Pairs0, NewPairs),
  184    maplist(ns_attr(OutNS), NewPairs, NSAttrs0),
  185    sort(NSAttrs0, NSAttrs).
  186
  187ns_attr(Dict, URL-_, NSAttr) :-
  188    ns_simplify(xmlns:Dict.URL=URL, NSAttr).
  189
  190ns_simplify(xmlns:''=URL, xmlns=URL) :- !.
  191ns_simplify(xmlns:NS=URL, XMLNS=URL) :-
  192    make_cname(xmlns:NS, XMLNS).
  193
  194xml_ns(ns('', xmlns):NS=URL, NS, URL) :- !.
  195xml_ns(xmlns=URL, '', URL) :- !.
  196xml_ns(xmlns:NS=URL, NS, URL) :- !.
  197xml_ns(Name=URL, NS, URL) :-
  198    atom(Name),
  199    atom_concat('xmlns:', NS, Name).
  200
  201make_cname('':Name, Name) :- !.
  202make_cname(NS:Name, CName) :-
  203    atomic_list_concat([NS,Name], :, CName)