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

  1/**
  2 * AmbientTalk/2 Project
  3 * NATDelegation.java created on 29-jan-2007 at 16:24:59
  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;
 29
 30import edu.vub.at.eval.Evaluator;
 31import edu.vub.at.exceptions.InterpreterException;
 32import edu.vub.at.objects.ATMessage;
 33import edu.vub.at.objects.ATMethodInvocation;
 34import edu.vub.at.objects.ATObject;
 35import edu.vub.at.objects.ATTypeTag;
 36import edu.vub.at.objects.ATTable;
 37import edu.vub.at.objects.coercion.NativeTypeTags;
 38import edu.vub.at.objects.grammar.ATSymbol;
 39import edu.vub.at.objects.natives.grammar.AGSymbol;
 40
 41import java.util.LinkedList;
 42import java.util.Vector;
 43
 44/**
 45 * Instances of the class NATMethodInvocation represent first-class method invocations.
 46 * They encapsulate a selector and arguments and may be turned into an actual invocation by invoking meta_sendTo.
 47 * This method provides the invocation with a receiver to apply itself to.
 48 * 
 49 * @author tvcutsem
 50 */
 51public final class NATDelegation extends NATMessage implements ATMethodInvocation {
 52
 53	private final static AGSymbol _DELEGATOR_ = AGSymbol.jAlloc("delegator");
 54	
 55	public NATDelegation(ATObject delegator, ATSymbol sel, ATTable arg, ATTable annotations) throws InterpreterException {
 56		super(sel, arg, annotations, NativeTypeTags._DELEGATION_);
 57		super.meta_defineField(_DELEGATOR_, delegator);
 58	}
 59	
 60    /**
 61     * Copy constructor.
 62     */
 63    private NATDelegation(FieldMap map,
 64            Vector state,
 65            LinkedList originalCustomFields,
 66            MethodDictionary methodDict,
 67            ATObject dynamicParent,
 68            ATObject lexicalParent,
 69            byte flags,
 70            ATTypeTag[] types) throws InterpreterException {
 71    	super(map, state, originalCustomFields, methodDict, dynamicParent, lexicalParent, flags, types);
 72    }
 73
 74    public ATMethodInvocation asMethodInvocation() { return this; }
 75    
 76	/**
 77	 * To evaluate a delegating message send, invoke the method corresponding to the encapsulated
 78	 * selector with the encapsulated arguments. During execution of the method, 'self' should be
 79	 * bound to the object that initiated the delegating method invocation.
 80	 * 
 81	 * @return the return value of the invoked method.
 82	 */
 83	public ATObject prim_sendTo(ATMessage self, ATObject receiver, ATObject sender) throws InterpreterException {
 84		return receiver.meta_invoke(super.meta_invokeField(self, _DELEGATOR_), self.asMethodInvocation());
 85	}
 86	
 87	public NATText meta_print() throws InterpreterException {
 88		return NATText.atValue("<delegation:"+base_selector()+Evaluator.printAsList(base_arguments()).javaValue+">");
 89	}
 90	
 91	protected NATObject createClone(FieldMap map,
 92			Vector state,
 93			LinkedList originalCustomFields,
 94			MethodDictionary methodDict,
 95			ATObject dynamicParent,
 96			ATObject lexicalParent,
 97			byte flags,
 98			ATTypeTag[] types) throws InterpreterException {
 99		return new NATDelegation(map,
100				state,
101				originalCustomFields,
102				methodDict,
103				dynamicParent,
104				lexicalParent,
105				flags,
106				types);
107	}
108	
109}