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/interpreter/tags/at2-build270707/src/edu/vub/at/objects/natives/grammar/AGDefExternalMethod.java

http://ambienttalk.googlecode.com/
Java | 136 lines | 67 code | 16 blank | 53 comment | 4 complexity | 86c61a4d2d9245f6535c02d3c856cec5 MD5 | raw file
  1/**
  2 * AmbientTalk/2 Project
  3 * AGDefExternalMethod.java created on 15-nov-2006 at 19:33:18
  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.Evaluator;
 31import edu.vub.at.exceptions.InterpreterException;
 32import edu.vub.at.exceptions.XIllegalOperation;
 33import edu.vub.at.objects.ATContext;
 34import edu.vub.at.objects.ATObject;
 35import edu.vub.at.objects.ATTable;
 36import edu.vub.at.objects.coercion.NativeTypeTags;
 37import edu.vub.at.objects.grammar.ATBegin;
 38import edu.vub.at.objects.grammar.ATDefExternalMethod;
 39import edu.vub.at.objects.grammar.ATSymbol;
 40import edu.vub.at.objects.natives.NATClosureMethod;
 41import edu.vub.at.objects.natives.NATMethod;
 42import edu.vub.at.objects.natives.NATText;
 43
 44/**
 45 * The native implementation of an external method definition abstract grammar element.
 46 * 
 47 * @author tvcutsem
 48 */
 49public final class AGDefExternalMethod extends NATAbstractGrammar implements ATDefExternalMethod {
 50
 51	private final ATSymbol rcvNam_;
 52	private final ATSymbol selectorExp_;
 53	private final ATTable argumentExps_;
 54	private final ATBegin bodyStmts_;
 55	
 56	private NATMethod preprocessedMethod_;
 57	
 58	public AGDefExternalMethod(ATSymbol rcv, ATSymbol sel, ATTable args, ATBegin bdy)
 59	       throws InterpreterException {
 60		rcvNam_ = rcv;
 61		selectorExp_ = sel;
 62		argumentExps_ = args;
 63		bodyStmts_ = bdy;
 64	}
 65
 66	public ATSymbol base_receiver() {
 67		return rcvNam_;
 68	}
 69	
 70	public ATSymbol base_selector() {
 71		return selectorExp_;
 72	}
 73
 74	public ATTable base_arguments() {
 75		return argumentExps_;
 76	}
 77
 78	public ATBegin base_bodyExpression() {
 79		return bodyStmts_;
 80	}
 81	
 82	/**
 83	 * Evaluates the receiver symbol to an object to which a new 'closure method' will be added.
 84	 * Such a closure captures the current lexical scope, but not the values for 'self' and 'super'.
 85	 * 
 86	 * The return value of an external method definition is always the external method itself.
 87	 * 
 88	 * AGDEFEXTMTH(rcv,nam,par,bdy).eval(ctx) =
 89	 *   rcv.eval(ctx).defineField(nam, NATCLOMTH(ctx.cur,nam,par,bdy))
 90	 *   
 91	 * @throws XIllegalOperation if the receiver is an instance of a native 
 92	 * type (whose method dictionaries are sealed) or if the receiver is an isolate. 
 93	 */
 94	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
 95		// the method is not yet created in the constructor because this gives problems
 96		// with quoted parameters: a quoted parameter would result in an illegal parameter
 97		// exception while actually the external method was defined in the context of a quotation,
 98		// so at runtime the external definition would have never been evaluated (but quoted instead)
 99		if (preprocessedMethod_ == null) {
100			preprocessedMethod_ = new NATMethod(selectorExp_, argumentExps_, bodyStmts_);
101		}
102		
103		ATObject receiver = rcvNam_.meta_eval(ctx);
104		if (receiver.meta_isTaggedAs(NativeTypeTags._ISOLATE_).asNativeBoolean().javaValue) {
105			throw new XIllegalOperation("Cannot define external methods on isolates");
106			
107		} else {
108			NATClosureMethod extMethod = new NATClosureMethod(ctx.base_lexicalScope(),
109                    preprocessedMethod_);
110
111			receiver.meta_addMethod(extMethod);
112			return extMethod;
113		}
114	}
115
116	/**
117	 * Quoting an external method definition results in a new quoted external method definition.
118	 * 
119	 * AGDEFEXTMTH(rcv,nam,par,bdy).quote(ctx) = AGDEFEXTMTH(rcv.quote(ctx),nam.quote(ctx), par.quote(ctx), bdy.quote(ctx))
120	 */
121	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
122		return new AGDefExternalMethod(rcvNam_.meta_quote(ctx).asSymbol(),
123				               selectorExp_.meta_quote(ctx).asSymbol(),
124				               argumentExps_.meta_quote(ctx).asTable(),
125				               bodyStmts_.meta_quote(ctx).asBegin());
126	}
127	
128	public NATText meta_print() throws InterpreterException {
129		return NATText.atValue("def " +
130				rcvNam_.meta_print().javaValue + "." +
131				selectorExp_.meta_print().javaValue +
132				Evaluator.printAsList(argumentExps_).javaValue +
133				" { " + bodyStmts_.meta_print().javaValue + " }");
134	}
135
136}