/interpreter/tags/at2dist041108/src/edu/vub/at/objects/natives/grammar/AGAssignVariable.java

  1/**
  2 * AmbientTalk/2 Project
  3 * AGAssignVariable.java created on 26-jul-2006 at 15:54:48
  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.exceptions.XTypeMismatch;
 33import edu.vub.at.objects.ATContext;
 34import edu.vub.at.objects.ATObject;
 35import edu.vub.at.objects.grammar.ATAssignVariable;
 36import edu.vub.at.objects.grammar.ATExpression;
 37import edu.vub.at.objects.grammar.ATSymbol;
 38import edu.vub.at.objects.natives.NATTable;
 39import edu.vub.at.objects.natives.NATText;
 40
 41import java.util.Set;
 42
 43/**
 44 * The native implementation of a variable assignment AG element.
 45 *  
 46 *  @author tvc
 47 */
 48public final class AGAssignVariable extends NATAbstractGrammar implements ATAssignVariable {
 49
 50	private final ATSymbol variableName_;
 51	private final ATExpression valueExp_;
 52	
 53	public AGAssignVariable(ATSymbol nam, ATExpression val) {
 54		variableName_ = nam;
 55		valueExp_ = val;
 56	}
 57	
 58	public ATSymbol base_name() { return variableName_; }
 59
 60	public ATExpression base_valueExpression() { return valueExp_; }
 61	
 62	/**
 63	 * To evaluate a variable assignment, evaluate the right hand side and ask
 64	 * the current object to assign that value to the field corresponding to the left hand side.
 65	 * 
 66	 * AGASSVAR(nam,val).eval(ctx) = ctx.scope.assignVariable(nam, val.eval(ctx))
 67	 * 
 68	 * @return the value assigned to the variable
 69	 */
 70	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
 71		NATTable arg = NATTable.of(valueExp_.meta_eval(ctx));
 72		ATObject result = null;
 73		InvocationStack stack = InvocationStack.getInvocationStack();
 74		try {
 75			stack.functionCalled(this, null, arg);
 76			result = ctx.base_lexicalScope().impl_callMutator(variableName_.asAssignmentSymbol(), arg);
 77		} finally {
 78			stack.funcallReturned(result);
 79		}
 80		return result;
 81	}
 82
 83	/**
 84	 * AGASSVAR(nam,val).quote(ctx) = AGASSVAR(nam.quote(ctx), val.quote(ctx))
 85	 */
 86	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
 87		return new AGAssignVariable(variableName_.meta_quote(ctx).asSymbol(), valueExp_.meta_quote(ctx).asExpression());
 88	}
 89	
 90	public NATText meta_print() throws InterpreterException {
 91		return NATText.atValue(variableName_.meta_print().javaValue + " := " + valueExp_.meta_print().javaValue);
 92	}
 93    
 94    public boolean isVariableAssignment() {
 95        return true;
 96    }
 97    
 98    public ATAssignVariable asVariableAssignment() throws XTypeMismatch {
 99        return this;
100    }
101    
102	/**
103	 * FV(var := valExp) = { var } U FV(valExp)
104	 */
105	public Set impl_freeVariables() throws InterpreterException {
106		Set fvValExp = valueExp_.impl_freeVariables();
107		fvValExp.add(variableName_);
108		return fvValExp;
109	}
110	
111	
112	public Set impl_quotedFreeVariables() throws InterpreterException {
113		Set qfv = valueExp_.impl_quotedFreeVariables();
114		qfv.addAll(variableName_.impl_quotedFreeVariables());
115		return qfv;
116	}
117}