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

http://ambienttalk.googlecode.com/
Java | 100 lines | 42 code | 11 blank | 47 comment | 0 complexity | d89b22b7fe88e95dc5b04d0d1eb41959 MD5 | raw file
  1/**
  2 * AmbientTalk/2 Project
  3 * AGAssignField.java created on 17-aug-2006 at 13:45:32
  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.ATObject;
 34import edu.vub.at.objects.grammar.ATAssignField;
 35import edu.vub.at.objects.grammar.ATExpression;
 36import edu.vub.at.objects.grammar.ATSymbol;
 37import edu.vub.at.objects.natives.NATTable;
 38import edu.vub.at.objects.natives.NATText;
 39
 40/**
 41 * The native implementation of a field assignment AG element.
 42 *  
 43 *  @author tvc
 44 */
 45public final class AGAssignField extends NATAbstractGrammar implements ATAssignField {
 46
 47	private final ATExpression rcvExp_;
 48	private final ATSymbol fieldName_;
 49	private final ATExpression valueExp_;
 50	
 51	public AGAssignField(ATExpression rcv, ATSymbol nam, ATExpression val) {
 52		rcvExp_ = rcv;
 53		fieldName_ = nam;
 54		valueExp_ = val;
 55	}
 56	
 57	public ATExpression base_receiverExpression() { return rcvExp_; }
 58	
 59	public ATSymbol base_fieldName() { return fieldName_; }
 60
 61	public ATExpression base_valueExpression() { return valueExp_; }
 62	
 63	/**
 64	 * To evaluate a field assignment, evaluate the receiver expression, evaluate the right hand side and ask
 65	 * the receiver object to assign the RHS value to the field corresponding to the given field name.
 66	 * 
 67	 * In AmbientTalk using the uniform access principle, assignments are represented as message sends.
 68	 * For example <tt>o.x := 5</tt> is represented as <tt>o.x:=(5)</tt> where <tt>`x:=</tt> is a special
 69	 * selector identifying a field assignment.
 70	 * 
 71	 * AGASSFIELD(rcv,nam,val).eval(ctx) = rcv.eval(ctx).invoke(rcv,nam:=, [ val.eval(ctx) ])
 72	 * 
 73	 * @return the new value of the field
 74	 */
 75	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
 76		ATObject receiver = rcvExp_.meta_eval(ctx);
 77		NATTable arg = NATTable.of(valueExp_.meta_eval(ctx));
 78		ATObject result = null;
 79		InvocationStack stack = InvocationStack.getInvocationStack();
 80		try {
 81			stack.methodInvoked(this, receiver, arg);
 82			result = receiver.impl_invokeMutator(receiver, fieldName_.asAssignmentSymbol(), arg);
 83		} finally {
 84			stack.methodReturned(result);
 85		}
 86		return result;
 87	}
 88
 89	/**
 90	 * AGASSFIELD(rcv,nam,val).quote(ctx) = AGASSFIELD(rcv.quote(ctx), nam.quote(ctx), val.quote(ctx))
 91	 */
 92	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
 93		return new AGAssignField(rcvExp_.meta_quote(ctx).asExpression(), fieldName_.meta_quote(ctx).asSymbol(), valueExp_.meta_quote(ctx).asExpression());
 94	}
 95	
 96	public NATText meta_print() throws InterpreterException {
 97		return NATText.atValue(rcvExp_.meta_print().javaValue + "." + fieldName_.meta_print().javaValue + " := " + valueExp_.meta_print().javaValue);
 98	}
 99
100}