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%% File         : MULTI_EVAL
%% Created by   : Joakim Eriksson & Niclas Finne
%% Created date : 01-12-4
%%
%% $Author: joakime $
%% $Date: 2001/12/18 20:20:15 $
%% $Revision: 1.13 $
%%
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%%
%% Description:
%%
%% Methods:
%%

:- module(multi_eval, [start/0,stop/0,alt/0]).
:- use_module('../../jeval/jeval_server', []).
:- use_module('../../jeval/jeval', []).
:- use_module('../../http/http_server', []).
:- use_module('../../html/html', []).

http_request(_HttpReq, HttpRes) :-
    html:page_start(HttpRes, "Multi Eval Jeval Example"),
    html:heading1(HttpRes, "Multi Eval Jeval Example"),
    jeval_server:generate_applet(HttpRes, eval, "width=300 height=100"),
    html:page_end(HttpRes).

client_connected(_Host, User) :-
    jeval:jeval(User, '\c
	       jevalApplet.setLayout(new GridLayout(0,1));\c
	       jevalApplet.add(new Label("Enter expression"));\c
	       expr = new TextField("5 * 7");\c
	       jevalApplet.add(expr);\c
	       result = new Label("Result:");\c
	       jevalApplet.add(result);\c
	       button = new Button("Evaluate!");\c
	       jevalApplet.add(button);\c
	       jeval.addActionListener("button");\c
	       jeval.addActionListener("expr");\c
	       jevalApplet.validate();\c
	       jevalApplet.repaint();').

client_disconnected(_User).

client_event(action_event(_, _, _), User) :-
    jeval:jeval(User, exp, 'expr.getText()').

client_result(exp, ExpAtom, User) :-
    eval(ExpAtom, Val),
    jeval:jeval(User, 'result.setText("Result: ' + Val + '")').

eval(ExpAtom, Val) :-
    get_term(ExpAtom, Expr),
    catch(Val is Expr, _, fail), !.
eval(_, Val) :-
    Val = 'Syntax error, please type in an arithmetic expression!'.

get_term(Result, Term) :-
    charsio:atom_to_chars(Result, R_S, "."),
    catch(charsio:read_from_chars(R_S, Term), _, fail).

start :-
    jeval_server:register_applet(eval, multi_eval), %% applet or application...
    http_server:register_page('index.html', multi_eval),
    http_server:set_default_port(30002),
    server:init,
    http_server:get_url(URL),
    format('Please browse to ~s~n', [URL]),
    server:run.