/* $Id$
Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: wielemak@science.uva.nl
WWW: http://www.swi-prolog.org
Copyright (C): 1985-2005, University of Amsterdam
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
As a special exception, if you link this library with other files,
compiled with a Free Software compiler, to produce an executable, this
library does not by itself cause the resulting executable to be covered
by the GNU General Public License. This exception does not however
invalidate any other reasons why the executable file might be covered by
the GNU General Public License.
*/
:- module(sgml,
[ load_sgml_file/2, % +File, -ListOfContent
load_xml_file/2, % +File, -ListOfContent
load_html_file/2, % +File, -Document
load_structure/3, % +File, -Term, +Options
load_dtd/2, % +DTD, +File
load_dtd/3, % +DTD, +File, +Options
dtd/2, % +Type, -DTD
dtd_property/2, % +DTD, ?Property
new_dtd/2, % +Doctype, -DTD
free_dtd/1, % +DTD
open_dtd/3, % +DTD, +Options, -Stream
new_sgml_parser/2, % -Parser, +Options
free_sgml_parser/1, % +Parser
set_sgml_parser/2, % +Parser, +Options
get_sgml_parser/2, % +Parser, +Options
sgml_parse/2, % +Parser, +Options
sgml_register_catalog_file/2, % +File, +StartOrEnd
xml_quote_attribute/3, % +In, -Quoted, +Encoding
xml_quote_cdata/3, % +In, -Quoted, +Encoding
xml_quote_attribute/2, % +In, -Quoted
xml_quote_cdata/2, % +In, -Quoted
xml_name/1, % +In
xml_is_dom/1 % +Term
]).
:- expects_dialect(swi).
:- use_module(library(lists)).
:- use_module(library(option)).
:- multifile user:file_search_path/2.
:- dynamic user:file_search_path/2.
user:file_search_path(dtd, '.').
:- if(current_prolog_flag(version_data, swi(_,_,_,_))).
user:file_search_path(dtd, swi('library/DTD')).
:- else.
user:file_search_path(dtd, library('DTD')).
:- endif.
sgml_register_catalog_file(File, Location) :-
prolog_to_os_filename(File, OsFile),
'_sgml_register_catalog_file'(OsFile, Location).
load_foreign :-
current_predicate(_, _:sgml_parse(_,_)), !.
load_foreign :-
load_foreign_library(foreign(sgml2pl)).
register_catalog(Base) :-
absolute_file_name(dtd(Base),
[ extensions([soc]),
access(read),
file_errors(fail)
],
SocFile),
sgml_register_catalog_file(SocFile, end).
init :-
load_foreign,
ignore(register_catalog('HTML4')).
:- initialization
init.
/*******************************
* DTD HANDLING *
*******************************/
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Note that concurrent access to DTD objects is not allowed, and hence we
will allocate and destroy them in each thread. Possibibly it would be
nicer to find out why concurrent access to DTD's is flawed. It is
diagnosed to mess with the entity resolution by Fabien Todescato.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
:- thread_local
current_dtd/2.
:- volatile
current_dtd/2.
:- thread_local
registered_cleanup/0.
:- volatile
registered_cleanup/0.
:- multifile
dtd_alias/2.
dtd_alias(html, 'HTML4').
dtd(Type, DTD) :-
current_dtd(Type, DTD), !.
dtd(Type, DTD) :-
new_dtd(Type, DTD),
( dtd_alias(Type, Base)
-> true
; Base = Type
),
absolute_file_name(dtd(Base),
[ extensions([dtd]),
access(read)
], DtdFile),
load_dtd(DTD, DtdFile),
register_cleanup,
asserta(current_dtd(Type, DTD)).
%% load_dtd(+DTD, +DtdFile, +Options)
%
% Load file into a DTD. Defined options are:
%
% * dialect(+Dialect)
% Dialect to use (xml, xmlns, sgml)
%
% * encoding(+Encoding)
% Encoding of DTD file
load_dtd(DTD, DtdFile) :-
load_dtd(DTD, DtdFile, []).
load_dtd(DTD, DtdFile, Options) :-
split_dtd_options(Options, DTDOptions, FileOptions),
open_dtd(DTD, DTDOptions, DtdOut),
swi:swi_open(DtdFile, read, DtdIn, FileOptions),
swi:swi_copy_stream_data(DtdIn, DtdOut),
swi:swi_close(DtdIn),
swi:swi_close(DtdOut).
split_dtd_options([], [], []).
split_dtd_options([H|T], [H|TD], S) :-
dtd_option(H), !,
split_dtd_options(T, TD, S).
split_dtd_options([H|T], TD, [H|S]) :-
split_dtd_options(T, TD, S).
dtd_option(dialect(_)).
%% destroy_dtds
%
% Destroy DTDs cached by this thread as they will become
% unreachable anyway.
destroy_dtds :-
( current_dtd(_Type, DTD),
free_dtd(DTD),
fail
; true
).
%% register_cleanup
%
% Register cleanup of DTDs created for this thread.
register_cleanup :-
registered_cleanup, !.
register_cleanup :-
catch(thread_at_exit(destroy_dtds), _, true),
assert(registered_cleanup).
/*******************************
* EXAMINE DTD *
*******************************/
prop(doctype(_), _).
prop(elements(_), _).
prop(entities(_), _).
prop(notations(_), _).
prop(entity(E, _), DTD) :-
( nonvar(E)
-> true
; '$dtd_property'(DTD, entities(EL)),
member(E, EL)
).
prop(element(E, _, _), DTD) :-
( nonvar(E)
-> true
; '$dtd_property'(DTD, elements(EL)),
member(E, EL)
).
prop(attributes(E, _), DTD) :-
( nonvar(E)
-> true
; '$dtd_property'(DTD, elements(EL)),
member(E, EL)
).
prop(attribute(E, A, _, _), DTD) :-
( nonvar(E)
-> true
; '$dtd_property'(DTD, elements(EL)),
member(E, EL)
),
( nonvar(A)
-> true
; '$dtd_property'(DTD, attributes(E, AL)),
member(A, AL)
).
prop(notation(N, _), DTD) :-
( nonvar(N)
-> true
; '$dtd_property'(DTD, notations(NL)),
member(N, NL)
).
dtd_property(DTD, Prop) :-
prop(Prop, DTD),
'$dtd_property'(DTD, Prop).
/*******************************
* SGML *
*******************************/
parser_option(dialect(_)).
parser_option(shorttag(_)).
parser_option(file(_)).
parser_option(line(_)).
parser_option(space(_)).
parser_option(number(_)).
parser_option(defaults(_)).
parser_option(doctype(_)).
parser_option(qualify_attributes(_)).
parser_option(encoding(_)).
set_parser_options(Parser, Options, RestOptions) :-
parser_option(Option),
select_option(Option, Options, RestOptions0), !,
set_sgml_parser(Parser, Option),
set_parser_options(Parser, RestOptions0, RestOptions).
set_parser_options(_, Options, Options).
load_structure(stream(In), Term, Options) :- !,
( select_option(offset(Offset), Options, Options1)
-> seek(In, Offset, bof, _)
; Options1 = Options
),
( select_option(dtd(DTD), Options1, Options2)
-> ExplicitDTD = true
; ExplicitDTD = false,
Options2 = Options1
),
new_sgml_parser(Parser,
[ dtd(DTD)
]),
def_entities(Options2, DTD, Options3),
call_cleanup(parse(Parser, Options3, TermRead, In),
free_sgml_parser(Parser)),
( ExplicitDTD == true
-> ( DTD = dtd(_, DocType),
dtd_property(DTD, doctype(DocType))
-> true
; true
)
; free_dtd(DTD)
),
Term = TermRead.
load_structure(Stream, Term, Options) :-
swi:swi_is_stream(Stream), !,
load_structure(stream(Stream), Term, Options).
load_structure(File, Term, Options) :-
swi:swi_open(File, read, In, [type(binary)]),
load_structure(stream(In), Term, [file(File)|Options]),
swi:swi_close(In).
parse(Parser, Options, Document, In) :-
set_parser_options(Parser, Options, Options1),
sgml_parse(Parser,
[ document(Document),
source(In)
| Options1
]).
def_entities([], _, []).
def_entities([entity(Name, Value)|T], DTD, Opts) :- !,
def_entity(DTD, Name, Value),
def_entities(T, DTD, Opts).
def_entities([H|T0], DTD, [H|T]) :-
def_entities(T0, DTD, T).
def_entity(DTD, Name, Value) :-
open_dtd(DTD, [], Stream),
xml_quote_attribute(Value, QValue),
swi:swi_format(Stream, '<!ENTITY ~w "~w">~n', [Name, QValue]),
swi:close(Stream).
/*******************************
* UTILITIES *
*******************************/
load_sgml_file(File, Term) :-
load_structure(File, Term, [dialect(sgml)]).
load_xml_file(File, Term) :-
load_structure(File, Term, [dialect(xml)]).
load_html_file(File, Term) :-
dtd(html, DTD),
load_structure(File, Term,
[ dtd(DTD),
dialect(sgml),
shorttag(false)
]).
/*******************************
* ENCODING *
*******************************/
% xml_quote_attribute(+In, -Quoted)
% xml_quote_cdata(+In, -Quoted)
%
% Backward compatibility for versions that allow to specify
% encoding. All characters that cannot fit the encoding are mapped
% to XML character entities (&#dd;). Using ASCII is the safest
% value.
xml_quote_attribute(In, Quoted) :-
xml_quote_attribute(In, Quoted, ascii).
xml_quote_cdata(In, Quoted) :-
xml_quote_cdata(In, Quoted, ascii).
xml_name(In) :-
xml_name(In, ascii).
/*******************************
* TYPE CHECKING *
*******************************/
% xml_is_dome(@Term)
%
% True if term statisfies the structure as returned by
% load_structure/3 and friends.
xml_is_dom(0) :- !, fail. % catch variables
xml_is_dom([]) :- !.
xml_is_dom([H|T]) :- !,
xml_is_dom(H),
xml_is_dom(T).
xml_is_dom(element(Name, Attributes, Content)) :- !,
dom_name(Name),
dom_attributes(Attributes),
xml_is_dom(Content).
xml_is_dom(pi(Pi)) :- !,
atom(Pi).
xml_is_dom(CDATA) :-
atom(CDATA).
dom_name(NS:Local) :-
atom(NS),
atom(Local), !.
dom_name(Local) :-
atom(Local).
dom_attributes(0) :- !, fail.
dom_attributes([]).
dom_attributes([H|T]) :-
dom_attribute(H),
dom_attributes(T).
dom_attribute(Name=Value) :-
dom_name(Name),
atomic(Value).
/*******************************
* MESSAGES *
*******************************/
:- multifile
prolog:message/3.
% Catch messages. sgml/4 is generated by the SGML2PL binding.
prolog:message(sgml(Parser, File, Line, Message)) -->
{ get_sgml_parser(Parser, dialect(Dialect))
},
[ 'SGML2PL(~w): ~w:~w: ~w'-[Dialect, File, Line, Message] ].
/*******************************
* XREF SUPPORT *
*******************************/
:- multifile
prolog:called_by/2.
prolog:called_by(sgml_parse(_, Options), Called) :-
is_list(Options),
findall(G+3,
( member(call(_, G), Options),
callable(G)
),
Called).