93 lines
2.2 KiB
Perl
93 lines
2.2 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: wielemak@science.uva.nl
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WWW: http://www.swi-prolog.org
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Copyright (C): Public domain
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*/
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:- use_module(library('http/thread_httpd')).
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:- use_module(library('http/html_write')).
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:- use_module(library('http/http_session')).
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:- use_module(library('http/http_error')).
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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This demo shows session state management in a very simple calculator
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package. It also demonstrates the use of the html_write library. To use
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it, start Prolog, load this file and run
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?- server.
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Now direct your browser to http://localhost:3000/
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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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server :-
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server(3000, []).
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server(Port, Options) :-
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http_server(reply,
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[ port(Port),
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timeout(20)
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| Options
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]).
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reply(Request) :-
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memberchk(path(Path), Request),
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reply(Path, Request).
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reply(/, _Request) :-
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http_session_retractall(formula(_)),
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Formula = 0,
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http_session_assert(formula(Formula)),
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page(Formula).
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reply('/calc', Request) :-
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memberchk(search(Search), Request),
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memberchk(operation=Op, Search),
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memberchk(value=AtomVal, Search),
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atom_number(AtomVal, Val),
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http_session_retract(formula(Formula0)),
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debug(calc, 'Formula0 = ~w', [Formula0]),
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Formula =.. [Op, Formula0, Val],
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http_session_assert(formula(Formula)),
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page(Formula).
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page(Formula) :-
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reply_page('HTTP Session DEMO',
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[ h2('Simple session demo'),
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form([ action('/calc'),
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method('GET')
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],
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table([align(center), border(1)],
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[ tr(td(\formula(Formula))),
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tr(td([ \ops,
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input([ name(value) ]),
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input([ type(submit),
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value('Calc!')
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])
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]))
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]))
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]).
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formula(Formula) -->
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{ sformat(S, '~w', [Formula]),
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Value is Formula
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},
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html([ S, ' = ', Value ]).
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ops -->
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html(select(name(operation),
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[ option([selected], +),
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option([], -),
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option([], /),
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option([], *)
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])).
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reply_page(Title, Content) :-
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phrase(page(title(Title), Content), HTML),
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format('Content-type: text/html~n~n'),
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print_html(HTML).
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