/interpreter/tags/at2dist090708/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.Evaluator;
 31import edu.vub.at.eval.InvocationStack;
 32import edu.vub.at.exceptions.InterpreterException;
 33import edu.vub.at.objects.ATContext;
 34import edu.vub.at.objects.ATMessage;
 35import edu.vub.at.objects.ATNil;
 36import edu.vub.at.objects.ATObject;
 37import edu.vub.at.objects.ATTable;
 38import edu.vub.at.objects.grammar.ATExpression;
 39import edu.vub.at.objects.grammar.ATMessageSend;
 40import edu.vub.at.objects.natives.NATText;
 41
 42/**
 43 * @author tvc
 44 *
 45 * The native implementation of a synchronous message send AG element.
 46 */
 47public final class AGMessageSend extends AGExpression implements ATMessageSend {
 48
 49	private ATExpression rcvExp_;
 50	private final ATExpression message_;
 51	
 52	public AGMessageSend(ATExpression rcv, ATExpression msg) {
 53		rcvExp_ = rcv;
 54		message_ = msg;
 55	}
 56	
 57	public ATExpression base_receiverExpression() { return rcvExp_; }
 58	
 59	public ATNil base_receiverExpression__opeql_(ATExpression rcv) { 
 60		rcvExp_ = rcv;
 61		return Evaluator.getNil();
 62	}
 63
 64	public ATExpression base_messageExpression() { return message_; }
 65
 66	/**
 67	 * To evaluate a message send, evaluate the receiver expression into an object.
 68	 * Next, evaluate the message expression into a first-class message (asynchronous message or method invocation).
 69	 * The evaluation of the message send is delegated to the first-class message itself.
 70	 * 
 71	 * AGMSGSEND(rcv,msg).eval(ctx) = msg.eval(ctx).meta_sendTo(rcv.eval(ctx), ctx.self)
 72	 * 
 73	 * @return the value of the invoked method or NIL in the case of an asynchronous message send.
 74	 */
 75	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
 76		ATMessage msg = message_.meta_eval(ctx).asMessage();
 77		ATObject rcvr = rcvExp_.meta_eval(ctx);
 78		ATObject result = null;
 79		InvocationStack stack = InvocationStack.getInvocationStack();
 80		ATTable args = msg.base_arguments();
 81		try {
 82			stack.methodInvoked(this, rcvr, args);
 83			result = msg.base_sendTo(rcvr, ctx.base_receiver());
 84		} finally {
 85			stack.methodReturned(result);
 86		}
 87		return result;
 88	}
 89
 90	/**
 91	 * Quoting a message send returns a new quoted message send.
 92	 * 
 93	 * AGMSGSEND(rcv,msg).quote(ctx) = AGMSGSEND(rcv.quote(ctx), msg.quote(ctx))
 94	 */
 95	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
 96		return new AGMessageSend(rcvExp_.meta_quote(ctx).asExpression(),
 97				                message_.meta_quote(ctx).asExpression());
 98	}
 99	
100	public NATText meta_print() throws InterpreterException {
101		return NATText.atValue(rcvExp_.meta_print().javaValue +
102				               ((message_.isMessageCreation()) ? "" : "<+") + message_.meta_print().javaValue);
103	}
104
105}