/interpreter/tags/at2dist091109/src/edu/vub/at/objects/natives/grammar/AGAssignField.java

  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
 40import java.util.Set;
 41
 42/**
 43 * The native implementation of a field assignment AG element.
 44 *  
 45 *  @author tvc
 46 */
 47public final class AGAssignField extends NATAbstractGrammar implements ATAssignField {
 48
 49	private final ATExpression rcvExp_;
 50	private final ATSymbol fieldName_;
 51	private final ATExpression valueExp_;
 52	
 53	public AGAssignField(ATExpression rcv, ATSymbol nam, ATExpression val) {
 54		rcvExp_ = rcv;
 55		fieldName_ = nam;
 56		valueExp_ = val;
 57	}
 58	
 59	public ATExpression base_receiverExpression() { return rcvExp_; }
 60	
 61	public ATSymbol base_fieldName() { return fieldName_; }
 62
 63	public ATExpression base_valueExpression() { return valueExp_; }
 64	
 65	/**
 66	 * To evaluate a field assignment, evaluate the receiver expression, evaluate the right hand side and ask
 67	 * the receiver object to assign the RHS value to the field corresponding to the given field name.
 68	 * 
 69	 * In AmbientTalk using the uniform access principle, assignments are represented as message sends.
 70	 * For example <tt>o.x := 5</tt> is represented as <tt>o.x:=(5)</tt> where <tt>`x:=</tt> is a special
 71	 * selector identifying a field assignment.
 72	 * 
 73	 * AGASSFIELD(rcv,nam,val).eval(ctx) = rcv.eval(ctx).invoke(rcv,nam:=, [ val.eval(ctx) ])
 74	 * 
 75	 * @return the new value of the field
 76	 */
 77	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
 78		ATObject receiver = rcvExp_.meta_eval(ctx);
 79		NATTable arg = NATTable.of(valueExp_.meta_eval(ctx));
 80		ATObject result = null;
 81		InvocationStack stack = InvocationStack.getInvocationStack();
 82		try {
 83			stack.methodInvoked(this, receiver, arg);
 84			result = receiver.impl_invokeMutator(receiver, fieldName_.asAssignmentSymbol(), arg);
 85		} finally {
 86			stack.methodReturned(result);
 87		}
 88		return result;
 89	}
 90
 91	/**
 92	 * AGASSFIELD(rcv,nam,val).quote(ctx) = AGASSFIELD(rcv.quote(ctx), nam.quote(ctx), val.quote(ctx))
 93	 */
 94	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
 95		return new AGAssignField(rcvExp_.meta_quote(ctx).asExpression(), fieldName_.meta_quote(ctx).asSymbol(), valueExp_.meta_quote(ctx).asExpression());
 96	}
 97	
 98	public NATText meta_print() throws InterpreterException {
 99		return NATText.atValue(rcvExp_.meta_print().javaValue + "." + fieldName_.meta_print().javaValue + " := " + valueExp_.meta_print().javaValue);
100	}
101
102	/**
103	 * FV(rcvexp.x := exp) = FV(rcvexp) U FV(exp)
104	 */
105	public Set impl_freeVariables() throws InterpreterException {
106		Set fvRcvExp = rcvExp_.impl_freeVariables();
107		fvRcvExp.addAll(valueExp_.impl_freeVariables());
108		return fvRcvExp;
109	}
110	
111	public Set impl_quotedFreeVariables() throws InterpreterException {
112		Set fvRcvExp = rcvExp_.impl_quotedFreeVariables();
113		fvRcvExp.addAll(fieldName_.impl_quotedFreeVariables());
114		fvRcvExp.addAll(valueExp_.impl_quotedFreeVariables());
115		return fvRcvExp;
116	}
117	
118}