/interpreter/tags/at2dist041108/src/edu/vub/at/objects/natives/grammar/AGDefExternalMethod.java

  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.ATMethod;
 35import edu.vub.at.objects.ATObject;
 36import edu.vub.at.objects.ATTable;
 37import edu.vub.at.objects.ATTypeTag;
 38import edu.vub.at.objects.coercion.NativeTypeTags;
 39import edu.vub.at.objects.grammar.ATBegin;
 40import edu.vub.at.objects.grammar.ATDefExternalMethod;
 41import edu.vub.at.objects.grammar.ATDefinition;
 42import edu.vub.at.objects.grammar.ATExpression;
 43import edu.vub.at.objects.grammar.ATSymbol;
 44import edu.vub.at.objects.natives.NATClosureMethod;
 45import edu.vub.at.objects.natives.NATMethod;
 46import edu.vub.at.objects.natives.NATTable;
 47import edu.vub.at.objects.natives.NATText;
 48
 49import java.util.HashSet;
 50import java.util.Set;
 51
 52/**
 53 * The native implementation of an external method definition abstract grammar element.
 54 * 
 55 * @author tvcutsem
 56 */
 57public final class AGDefExternalMethod extends AGDefinition implements ATDefExternalMethod {
 58
 59	private final ATSymbol		rcvNam_;
 60	private final ATSymbol		selectorExp_;
 61	private final ATTable		argumentExps_;
 62	private final ATBegin		bodyStmts_;
 63	private final ATExpression	annotationExps_;
 64
 65	private ATMethod preprocessedMethod_;
 66	
 67	public AGDefExternalMethod(ATSymbol rcv, ATSymbol sel, ATTable args, ATBegin bdy, ATExpression ann)
 68	       throws InterpreterException {
 69		rcvNam_ = rcv;
 70		selectorExp_ = sel;
 71		argumentExps_ = args;
 72		bodyStmts_ = bdy;
 73		annotationExps_ = ann;
 74	}
 75
 76	public ATSymbol base_receiver() {
 77		return rcvNam_;
 78	}
 79	
 80	public ATSymbol base_selector() {
 81		return selectorExp_;
 82	}
 83
 84	public ATTable base_arguments() {
 85		return argumentExps_;
 86	}
 87
 88	public ATBegin base_bodyExpression() {
 89		return bodyStmts_;
 90	}
 91	
 92	public ATExpression base_annotationExpression() {
 93		return annotationExps_;
 94	}
 95	
 96	/**
 97	 * Evaluates the receiver symbol to an object to which a new 'closure method' will be added.
 98	 * Such a closure captures the current lexical scope, but not the values for 'self' and 'super'.
 99	 * 
100	 * The return value of an external method definition is always the external method itself.
101	 * 
102	 * AGDEFEXTMTH(rcv,nam,par,bdy).eval(ctx) =
103	 *   rcv.eval(ctx).defineField(nam, NATCLOMTH(ctx.cur,nam,par,bdy))
104	 *   
105	 * @throws XIllegalOperation if the receiver is an instance of a native 
106	 * type (whose method dictionaries are sealed) or if the receiver is an isolate. 
107	 */
108	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
109		// the method is not yet created in the constructor because this gives problems
110		// with quoted parameters: a quoted parameter would result in an illegal parameter
111		// exception while actually the external method was defined in the context of a quotation,
112		// so at runtime the external definition would have never been evaluated (but quoted instead)
113		if (preprocessedMethod_ == null) {
114			ATObject oneOrMoreAnnotation = annotationExps_.meta_eval(ctx);
115			ATTable  annotationTable;
116			
117			if(oneOrMoreAnnotation.isTable()) {
118				annotationTable = oneOrMoreAnnotation.asTable();
119			} else {
120				annotationTable = NATTable.of(oneOrMoreAnnotation);
121			}
122			
123			preprocessedMethod_ = new NATMethod(selectorExp_, argumentExps_, bodyStmts_, annotationTable);
124
125			ATObject[] annotations = annotationTable.asNativeTable().elements_;
126			
127			for (int i = 0; i < annotations.length; i++) {
128				ATTypeTag theAnnotation = annotations[i].asTypeTag();
129				
130				preprocessedMethod_ = theAnnotation.base_annotateMethod(preprocessedMethod_);
131			}
132		}
133		
134		ATObject receiver = rcvNam_.meta_eval(ctx);
135		if (receiver.meta_isTaggedAs(NativeTypeTags._ISOLATE_).asNativeBoolean().javaValue) {
136			throw new XIllegalOperation("Cannot define external methods on isolates");
137			
138		} else {
139			NATClosureMethod extMethod = new NATClosureMethod(ctx.base_lexicalScope(),
140                    preprocessedMethod_);
141
142			receiver.meta_addMethod(extMethod);
143			return extMethod;
144		}
145	}
146
147	/**
148	 * Quoting an external method definition results in a new quoted external method definition.
149	 * 
150	 * AGDEFEXTMTH(rcv,nam,par,bdy).quote(ctx) = AGDEFEXTMTH(rcv.quote(ctx),nam.quote(ctx), par.quote(ctx), bdy.quote(ctx))
151	 */
152	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
153		return new AGDefExternalMethod(rcvNam_.meta_quote(ctx).asSymbol(),
154				               selectorExp_.meta_quote(ctx).asSymbol(),
155				               argumentExps_.meta_quote(ctx).asTable(),
156				               bodyStmts_.meta_quote(ctx).asBegin(),
157				               annotationExps_.meta_quote(ctx).asExpression());
158	}
159	
160	public NATText meta_print() throws InterpreterException {
161		return NATText.atValue("def " +
162				rcvNam_.meta_print().javaValue + "." +
163				selectorExp_.meta_print().javaValue +
164				Evaluator.printAsList(argumentExps_).javaValue +
165				" { " + bodyStmts_.meta_print().javaValue + " }");
166	}
167
168	/**
169	 * IV(def o.m(args) @ anns { body }) = { }
170	 */
171	public Set impl_introducedVariables() throws InterpreterException {
172		return new HashSet();
173	}
174
175	/**
176	 * FV(def o.m(args) @ anns { body }) =
177	 *   { o } U FV(anns) U FV(optionalArgExps) U (FV(body) \ { args }) 
178	 */
179	public Set impl_freeVariables() throws InterpreterException {
180		Set fvBody = bodyStmts_.impl_freeVariables();
181		Evaluator.processFreeVariables(fvBody, argumentExps_);
182		fvBody.add(rcvNam_);
183		fvBody.addAll(annotationExps_.impl_freeVariables());
184		return fvBody;
185	}
186	
187	public Set impl_quotedFreeVariables() throws InterpreterException {
188		Set qfv = argumentExps_.impl_quotedFreeVariables();
189		qfv.addAll(bodyStmts_.impl_quotedFreeVariables());
190		qfv.addAll(annotationExps_.impl_quotedFreeVariables());
191		qfv.addAll(rcvNam_.impl_quotedFreeVariables());
192		qfv.addAll(selectorExp_.impl_quotedFreeVariables());
193		return qfv;
194	}
195	
196}