129 lines
4.2 KiB
Perl
129 lines
4.2 KiB
Perl
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/* $Id$
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Part of SWI-Prolog
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Author: Jan Wielemaker
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E-mail: J.Wielemaker@cs.vu.nl
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WWW: http://www.swi-prolog.org
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Copyright (C): 1985-2010, University of Amsterdam, VU University Amsterdam
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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As a special exception, if you link this library with other files,
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compiled with a Free Software compiler, to produce an executable, this
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library does not by itself cause the resulting executable to be covered
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by the GNU General Public License. This exception does not however
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invalidate any other reasons why the executable file might be covered by
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the GNU General Public License.
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*/
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:- module(http_sgml_plugin, []).
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:- use_module(http_client).
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:- use_module(library(memfile)).
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:- use_module(library(sgml)).
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:- use_module(library(lists)).
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:- use_module(library(debug)).
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:- multifile
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http_client:http_convert_data/4.
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:- multifile
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markup_type/2. % +MimeType, -ParseOptions
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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This module provides a plugin for the HTTP client to handle xml, html
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and sgml files using the SWI-Prolog sgml-parser from library(sgml).
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Using this library avoids unnecessary copying of data as the sgml-parser
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reads directly from the stream that established the HTTP connection.
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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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http_client:http_convert_data(In, Fields, Data, Options) :-
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memberchk(content_type(Type), Fields),
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debug(sgml_plugin, 'Content type: ~w', [Type]),
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( markup_type(Type, ParseOptions)
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-> true
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; type_major_props(Type, Major, Props),
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default_markup_type(Major, ParseOptions0),
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type_props(Props, ParseOptions0, ParseOptions)
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),
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merge_options([ max_errors(-1),
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syntax_errors(quiet)
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| ParseOptions
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], Options, Merged),
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markup_options(Fields, Merged, MarkupOptions),
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debug(sgml_plugin, 'Markup options: ~p', [MarkupOptions]),
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load_structure(stream(In), Data, MarkupOptions).
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type_major_props(Type0, Type, Props) :-
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sub_atom(Type0, B, _, A, ;), !,
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sub_atom(Type0, 0, B, _, Major),
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sub_atom(Type0, _, A, 0, Props),
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normalize_space(atom(Type), Major).
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type_major_props(Type, Type, '').
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type_props('', L, L).
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type_props(Props, L0, L) :-
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sub_atom(Props, _, _, A, 'charset='),
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sub_atom(Props, _, A, 0, CharSet0),
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downcase_atom(CharSet0, CharSet),
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known_charset(CharSet),
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L = [encoding(CharSet)|L0].
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type_props(_, L, L).
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known_charset('iso-8859-1').
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known_charset('us-ascii').
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known_charset('utf-8').
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%% default_markup_type(+MimeType, -ParseOptions)
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%
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% State that the HTTP contents should be parsed with
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% load_structure/3 using the returned options. This predicate may
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% be hooked using the multifile predicate markup_type/2.
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default_markup_type('text/xml',
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[ dialect(xmlns)
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]).
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default_markup_type('text/html',
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[ dtd(DTD),
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dialect(sgml),
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shorttag(false)
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]) :-
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dtd(html, DTD).
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default_markup_type('text/x-sgml',
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[ dialect(sgml)
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]).
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markup_options(Fields, Opt0, Options) :-
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( memberchk(content_length(Bytes), Fields)
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-> Options = [content_length(Bytes)|Opt0]
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; Options = Opt0
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).
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%% merge_options(+Defaults, +GivenOptions, -Options)
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%
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% If an option is not in GivenOptions, use the one from
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% Defaults.
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merge_options([], Options, Options).
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merge_options([H|T], Options0, Options) :-
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functor(H, Name, Arity),
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functor(H0, Name, Arity),
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memberchk(H0, Options0), !,
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merge_options(T, Options0, Options).
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merge_options([H|T], Options0, Options) :-
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merge_options(T, [H|Options0], Options).
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