/interpreter/tags/at2dist110511/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;
 40import edu.vub.util.TempFieldGenerator;
 41
 42import java.util.HashMap;
 43import java.util.Set;
 44
 45/**
 46 * The native implementation of a variable assignment AG element.
 47 *  
 48 *  @author tvc
 49 */
 50public final class AGAssignVariable extends NATAbstractGrammar implements ATAssignVariable {
 51
 52	private final ATSymbol variableName_;
 53	private final ATExpression valueExp_;
 54	
 55	public AGAssignVariable(ATSymbol nam, ATExpression val) {
 56		variableName_ = nam;
 57		valueExp_ = val;
 58	}
 59	
 60	public ATSymbol base_name() { return variableName_; }
 61
 62	public ATExpression base_valueExpression() { return valueExp_; }
 63	
 64	/**
 65	 * To evaluate a variable assignment, evaluate the right hand side and ask
 66	 * the current object to assign that value to the field corresponding to the left hand side.
 67	 * 
 68	 * AGASSVAR(nam,val).eval(ctx) = ctx.scope.assignVariable(nam, val.eval(ctx))
 69	 * 
 70	 * @return the value assigned to the variable
 71	 */
 72	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
 73		NATTable arg = NATTable.of(valueExp_.meta_eval(ctx));
 74		ATObject result = null;
 75		InvocationStack stack = InvocationStack.getInvocationStack();
 76		try {
 77			stack.functionCalled(this, null, arg);
 78			result = ctx.base_lexicalScope().impl_callMutator(variableName_.asAssignmentSymbol(), arg);
 79		} finally {
 80			stack.funcallReturned(result);
 81		}
 82		return result;
 83	}
 84
 85	/**
 86	 * AGASSVAR(nam,val).quote(ctx) = AGASSVAR(nam.quote(ctx), val.quote(ctx))
 87	 */
 88	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
 89		return new AGAssignVariable(variableName_.meta_quote(ctx).asSymbol(), valueExp_.meta_quote(ctx).asExpression());
 90	}
 91	
 92	public NATText meta_print() throws InterpreterException {
 93		return NATText.atValue(variableName_.meta_print().javaValue + " := " + valueExp_.meta_print().javaValue);
 94	}
 95	
 96	public NATText impl_asUnquotedCode(TempFieldGenerator objectMap) throws InterpreterException {
 97		return NATText.atValue(variableName_.impl_asUnquotedCode(objectMap).javaValue + " := " + valueExp_.impl_asUnquotedCode(objectMap).javaValue);
 98	}
 99    
100    public boolean isVariableAssignment() {
101        return true;
102    }
103    
104    public ATAssignVariable asVariableAssignment() throws XTypeMismatch {
105        return this;
106    }
107    
108	/**
109	 * FV(var := valExp) = { var } U FV(valExp)
110	 */
111	public Set impl_freeVariables() throws InterpreterException {
112		Set fvValExp = valueExp_.impl_freeVariables();
113		fvValExp.add(variableName_);
114		return fvValExp;
115	}
116	
117	
118	public Set impl_quotedFreeVariables() throws InterpreterException {
119		Set qfv = valueExp_.impl_quotedFreeVariables();
120		qfv.addAll(variableName_.impl_quotedFreeVariables());
121		return qfv;
122	}
123}