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/interpreter/tags/at2dist030708/src/edu/vub/at/objects/natives/grammar/AGMultiAssignment.java

http://ambienttalk.googlecode.com/
Java | 87 lines | 32 code | 11 blank | 44 comment | 0 complexity | 6072373979d31032e004e059f020b5e8 MD5 | raw file
 1/**
 2 * AmbientTalk/2 Project
 3 * AGMultiAssignment.java created on 18-aug-2006 at 9:31:38
 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.eval.PartialBinder;
31import edu.vub.at.exceptions.InterpreterException;
32import edu.vub.at.objects.ATContext;
33import edu.vub.at.objects.ATObject;
34import edu.vub.at.objects.ATTable;
35import edu.vub.at.objects.grammar.ATExpression;
36import edu.vub.at.objects.grammar.ATMultiAssignment;
37import edu.vub.at.objects.natives.NATText;
38
39/**
40 * @author tvc
41 *
42 * The native implementation of a multiple assignment AG element.
43 */
44public final class AGMultiAssignment extends NATAbstractGrammar implements ATMultiAssignment {
45
46	private final ATTable parameters_;
47	private final ATExpression valueExp_;
48	
49	private final PartialBinder binderPartialFunction_;
50	
51	public AGMultiAssignment(ATTable par, ATExpression val) throws InterpreterException {
52		parameters_ = par;
53		valueExp_ = val;
54		binderPartialFunction_ = PartialBinder.calculateResidual("multi-assignment", par);
55	}
56
57	public ATTable base_parameters() { return parameters_; }
58	
59	public ATExpression base_valueExpression() { return valueExp_; }
60	
61	/**
62	 * To evaluate a multiple assignment, evaluate the right hand side to a table
63	 * and assign the parameters on the left hand side to the 'arguments' of the right hand side,
64	 * almost as if they were bound during a function call (the parameters are assigned instead of defined).
65	 * 
66	 * AGMULTIASS(par,val).eval(ctx) = assign(ctx.scope, par, val.eval(ctx))
67	 * 
68	 * @return the evaluated arguments table
69	 */
70	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
71		ATTable args = valueExp_.meta_eval(ctx).asTable();
72		PartialBinder.assignArgsToParams(binderPartialFunction_, ctx, args);
73		return args;
74	}
75
76	/**
77	 * AGMULTIASS(par,val).quote(ctx) = AGMULTIASS(par.quote(ctx), val.quote(ctx))
78	 */
79	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
80		return new AGMultiAssignment(parameters_.meta_quote(ctx).asTable(), valueExp_.meta_quote(ctx).asExpression());
81	}
82	
83	public NATText meta_print() throws InterpreterException {
84		return NATText.atValue(parameters_.meta_print().javaValue + " := " + valueExp_.meta_print().javaValue);
85	}
86
87}