/interpreter/tags/at2dist220411/src/edu/vub/at/objects/symbiosis/JavaClosure.java

  1/**
  2 * AmbientTalk/2 Project
  3 * JavaClosure.java created on 9-dec-2006 at 21:16:12
  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.symbiosis;
 29
 30import edu.vub.at.exceptions.InterpreterException;
 31import edu.vub.at.exceptions.XSymbiosisFailure;
 32import edu.vub.at.objects.ATClosure;
 33import edu.vub.at.objects.ATContext;
 34import edu.vub.at.objects.ATObject;
 35import edu.vub.at.objects.natives.NATClosure;
 36import edu.vub.at.objects.natives.NATContext;
 37import edu.vub.at.objects.natives.NATNumber;
 38import edu.vub.at.objects.natives.NATTable;
 39import edu.vub.at.objects.natives.NATText;
 40
 41import java.lang.reflect.Array;
 42import java.lang.reflect.Method;
 43import java.util.Vector;
 44
 45/**
 46 * A JavaClosure pairs a JavaMethod (a bundle of native overloaded java.lang.reflect.Method objects)
 47 * together with a Java object receiver.
 48 * 
 49 * It also provides the possibility of casting the JavaMethod instances to fit a
 50 * narrower static type signature.
 51 * 
 52 * @author tvcutsem
 53 */
 54public final class JavaClosure extends NATClosure implements ATJavaClosure {
 55
 56	private final ATObject scope_;
 57	
 58	public JavaClosure(ATObject scope, JavaMethod meth) {
 59		super(meth, null);
 60		scope_ = scope;
 61	}
 62
 63	/**
 64	 * Overridden to allow for lazy instantiation of the context.
 65	 * 
 66	 * A 'default' context is lazily constructed and returned.
 67	 */
 68	public ATContext base_context() throws InterpreterException {
 69		if (context_ == null)
 70			context_ = new NATContext(scope_, scope_);
 71		return context_;
 72	}
 73	
 74	public NATText meta_print() throws InterpreterException {
 75		return NATText.atValue("<java closure:"+base_method().base_name().base_text().asNativeText().javaValue+">");
 76	}
 77
 78	/**
 79	 * For each Method in the wrapped JavaMethod's choices_, check whether it is compatible with
 80	 * the given types. If so, add it to the choices_ array of the new JavaMethod.
 81	 */
 82	public ATClosure base_cast(ATObject[] types) throws InterpreterException {
 83		Method[] choices = ((JavaMethod) method_).choices_;
 84		
 85		// unwrap the JavaClass wrappers
 86		Class[] actualTypes = new Class[types.length];
 87		for (int i = 0; i < actualTypes.length; i++) {
 88			// Array types may be represented as one-arg tables of a type: [Type]
 89			// TODO: properly refactor the instanceof test
 90			// problem: cannot do base_isTable because JavaObject/JavaClass objects will say yes!
 91			if (types[i] instanceof NATTable) {
 92				// Array.newInstance([Type][1],0).getClass()
 93				actualTypes[i] = Array.newInstance(types[i].asTable().
 94				    base_at(NATNumber.ONE).asJavaClassUnderSymbiosis().getWrappedClass(), 0).getClass();
 95			} else {
 96				actualTypes[i] = types[i].asJavaClassUnderSymbiosis().getWrappedClass();
 97			}
 98		}
 99		Vector matchingMethods = new Vector();
100		
101		for (int i = 0; i < choices.length; i++) {
102			if(matches(choices[i].getParameterTypes(), actualTypes)) {
103				matchingMethods.add(choices[i]);
104			}
105		}
106		
107		Method[] matches = (Method[]) matchingMethods.toArray(new Method[matchingMethods.size()]);
108		if (matches.length > 0) {
109			return new JavaClosure(scope_, new JavaMethod(matches));
110		} else {
111			throw new XSymbiosisFailure(scope_, choices[0], types);
112		}
113	}
114	
115	/**
116	 * Compares two Class arrays and returns true iff both arrays have equal size and all members are the same.
117	 */
118	private static final boolean matches(Class[] formals, Class[] actuals) {
119		if (formals.length != actuals.length)
120			return false;
121		
122		for (int i = 0; i < formals.length; i++) {
123			if (!(formals[i] == actuals[i])) {
124				return false;
125			}
126		}
127		
128		return true;
129	}
130
131}