/interpreter/tags/at2-build060407/src/edu/vub/at/objects/natives/grammar/AGSelection.java

 1/**
 2 * AmbientTalk/2 Project
 3 * AGSelection.java created on 26-jul-2006 at 16:16:07
 4 * (c) Programming Technology Lab, 2006 - 2007
 5 * Authors: Tom Van Cutsem & Stijn Mostinckx
 6 * 
 7 * Permission is hereby granted, free of charge, to any person
 8 * obtaining a copy of this software and associated documentation
 9 * files (the "Software"), to deal in the Software without
10 * restriction, including without limitation the rights to use,
11 * copy, modify, merge, publish, distribute, sublicense, and/or
12 * sell copies of the Software, and to permit persons to whom the
13 * Software is furnished to do so, subject to the following
14 * conditions:
15 *
16 * The above copyright notice and this permission notice shall be
17 * included in all copies or substantial portions of the Software.
18 *
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
20 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
21 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
22 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
23 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
24 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
25 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
26 * OTHER DEALINGS IN THE SOFTWARE.
27 */
28package edu.vub.at.objects.natives.grammar;
29
30import edu.vub.at.exceptions.InterpreterException;
31import edu.vub.at.objects.ATContext;
32import edu.vub.at.objects.ATObject;
33import edu.vub.at.objects.grammar.ATExpression;
34import edu.vub.at.objects.grammar.ATSelection;
35import edu.vub.at.objects.grammar.ATSymbol;
36import edu.vub.at.objects.natives.NATText;
37
38/**
39 * @author tvc
40 *
41 * The native implementation of a selection AG element.
42 */
43public final class AGSelection extends AGExpression implements ATSelection {
44
45	private final ATExpression rcvExp_;
46	private final ATSymbol selector_;
47	
48	public AGSelection(ATExpression rcv, ATSymbol sel) {
49		rcvExp_ = rcv;
50		selector_ = sel;
51	}
52	
53	public ATExpression base_getReceiverExpression() { return rcvExp_; }
54
55	public ATSymbol base_getSelector() { return selector_; }
56
57	/**
58	 * To evaluate a selection, evaluate the receiver expression to an object and select
59	 * the slot with the given name from that object.
60	 * 
61	 * AGSEL(rcv,sel).eval(ctx) = rcv.eval(ctx).meta_select(sel)
62	 * 
63	 * @return the value of the selected slot.
64	 */
65	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
66		ATObject receiver = rcvExp_.meta_eval(ctx);
67		return receiver.meta_select(receiver, selector_);
68	}
69
70	/**
71	 * Quoting a selection results in a new quoted selection.
72	 * 
73	 * AGSEL(rcv,sel).quote(ctx) = AGSEL(rcv.quote(ctx), sel.quote(ctx))
74	 */
75	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
76		return new AGSelection(rcvExp_.meta_eval(ctx).asExpression(),
77				              selector_.meta_eval(ctx).asSymbol());
78	}
79	
80	public NATText meta_print() throws InterpreterException {
81		return NATText.atValue(rcvExp_.meta_print().javaValue + "." + selector_.meta_print().javaValue);
82	}
83
84}