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%% File         : JEVAL_DEMO
%% Created by   : Joakim Eriksson & Niclas Finne
%% Created date : 01-11-15
%%
%% $Author: nfi $
%% $Date: 2001/12/11 13:03:28 $
%% $Revision: 1.6 $
%%
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%%
%% Description: Demo of jeval - single user mode.
%%
%% Comments:
%%     Workaround to get window positioned and sized under Unix / X.
%%     window.show();window.pack();window.setLocation(100,100);
%%     ( should normally be setBounds() )

:- use_module('../../jeval/jeval', []).

start :-
    start(client).

start(Mode) :-
    jeval:jeval_init(Mode, []),
    jeval:jeval('window=new JFrame("Jeval Demo");\c
		pane = window.getContentPane();\c
		pane.setLayout(new GridLayout(0,1));\c
		pane.add(new JLabel("Enter expression"));\c
		expr = new JTextField("5 * 7");\c
		pane.add(expr);\c
		result = new JLabel("Result:");\c
		pane.add(result);\c
		button = new JButton("Evaluate!");\c
		pane.add(button);\c
	        window.show();\c
	        window.pack();\c
	        window.setLocation(100, 100);\c
		jeval.addActionListener("button");\c
		jeval.addActionListener("expr");'),
    event_loop.

stop:-
    jeval:jeval('jeval.removeActionListener("button");\c
	         jeval.removeActionListener("expr");\c
	         window.setVisible(false)'),
    jeval:jeval_deinit.

event_loop :-
    jeval:jeval_result('jeval.getNextEvent(1000)', Result),
    get_term(Result, Event),
    handle_event(Event),
    event_loop.

handle_event(nil).
handle_event(action_event(_, _, _)) :-
    jeval:jeval_result('expr.getText()', ExpAtom),
    eval(ExpAtom, Val),
    jeval:jeval('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).