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

  1/**
  2 * AmbientTalk/2 Project
  3 * AGMessageSend.java created on 26-jul-2006 at 16:03:06
  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.InvocationStack;
 31import edu.vub.at.exceptions.InterpreterException;
 32import edu.vub.at.objects.ATContext;
 33import edu.vub.at.objects.ATMessage;
 34import edu.vub.at.objects.ATNil;
 35import edu.vub.at.objects.ATObject;
 36import edu.vub.at.objects.grammar.ATExpression;
 37import edu.vub.at.objects.grammar.ATMessageSend;
 38import edu.vub.at.objects.natives.OBJNil;
 39import edu.vub.at.objects.natives.NATText;
 40
 41/**
 42 * @author tvc
 43 *
 44 * The native implementation of a synchronous message send AG element.
 45 */
 46public final class AGMessageSend extends AGExpression implements ATMessageSend {
 47
 48	private ATExpression rcvExp_;
 49	private final ATExpression message_;
 50	
 51	public AGMessageSend(ATExpression rcv, ATExpression msg) {
 52		rcvExp_ = rcv;
 53		message_ = msg;
 54	}
 55	
 56	public ATExpression base_receiverExpression() { return rcvExp_; }
 57	
 58	public ATNil base_receiverExpression__opeql_(ATExpression rcv) { 
 59		rcvExp_ = rcv;
 60		return OBJNil._INSTANCE_;
 61	}
 62
 63	public ATExpression base_messageExpression() { return message_; }
 64
 65	/**
 66	 * To evaluate a message send, evaluate the receiver expression into an object.
 67	 * Next, evaluate the message expression into a first-class message (asynchronous message or method invocation).
 68	 * The evaluation of the message send is delegated to the first-class message itself.
 69	 * 
 70	 * AGMSGSEND(rcv,msg).eval(ctx) = msg.eval(ctx).meta_sendTo(rcv.eval(ctx), ctx.self)
 71	 * 
 72	 * @return the value of the invoked method or NIL in the case of an asynchronous message send.
 73	 */
 74	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
 75		ATMessage msg = message_.meta_eval(ctx).asMessage();
 76		ATObject rcvr = rcvExp_.meta_eval(ctx);
 77		ATObject result = null;
 78		InvocationStack stack = InvocationStack.getInvocationStack();
 79		try {
 80			stack.methodInvoked(this, rcvr, msg.base_arguments());
 81			result = msg.base_sendTo(rcvr, ctx.base_self());
 82		} finally {
 83			stack.methodReturned(result);
 84		}
 85		return result;
 86	}
 87
 88	/**
 89	 * Quoting a message send returns a new quoted message send.
 90	 * 
 91	 * AGMSGSEND(rcv,msg).quote(ctx) = AGMSGSEND(rcv.quote(ctx), msg.quote(ctx))
 92	 */
 93	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
 94		return new AGMessageSend(rcvExp_.meta_quote(ctx).asExpression(),
 95				                message_.meta_quote(ctx).asMessageCreation());
 96	}
 97	
 98	public NATText meta_print() throws InterpreterException {
 99		return NATText.atValue(rcvExp_.meta_print().javaValue +
100				               ((message_.isMessageCreation()) ? "" : "<+") + message_.meta_print().javaValue);
101	}
102
103}