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/interpreter/tags/at2-build270707/src/edu/vub/at/objects/natives/grammar/AGAssignVariable.java

http://ambienttalk.googlecode.com/
Java | 100 lines | 46 code | 11 blank | 43 comment | 0 complexity | d5a63c342db15b525b2cf4cd1ab8ea75 MD5 | raw file
  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.Evaluator;
 31import edu.vub.at.eval.InvocationStack;
 32import edu.vub.at.exceptions.InterpreterException;
 33import edu.vub.at.exceptions.XTypeMismatch;
 34import edu.vub.at.objects.ATContext;
 35import edu.vub.at.objects.ATObject;
 36import edu.vub.at.objects.grammar.ATAssignVariable;
 37import edu.vub.at.objects.grammar.ATExpression;
 38import edu.vub.at.objects.grammar.ATSymbol;
 39import edu.vub.at.objects.natives.NATTable;
 40import edu.vub.at.objects.natives.NATText;
 41
 42/**
 43 * The native implementation of a variable assignment AG element.
 44 *  
 45 *  @author tvc
 46 */
 47public final class AGAssignVariable extends NATAbstractGrammar implements ATAssignVariable {
 48
 49	private final ATSymbol variableName_;
 50	private final ATExpression valueExp_;
 51	
 52	public AGAssignVariable(ATSymbol nam, ATExpression val) {
 53		variableName_ = nam;
 54		valueExp_ = val;
 55	}
 56	
 57	public ATSymbol base_name() { return variableName_; }
 58
 59	public ATExpression base_valueExpression() { return valueExp_; }
 60	
 61	/**
 62	 * To evaluate a variable assignment, evaluate the right hand side and ask
 63	 * the current object to assign that value to the field corresponding to the left hand side.
 64	 * 
 65	 * AGASSVAR(nam,val).eval(ctx) = ctx.scope.assignVariable(nam, val.eval(ctx))
 66	 * 
 67	 * @return the value assigned to the variable
 68	 */
 69	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
 70		NATTable arg = NATTable.of(valueExp_.meta_eval(ctx));
 71		ATObject result = null;
 72		InvocationStack stack = InvocationStack.getInvocationStack();
 73		try {
 74			stack.functionCalled(this, null, arg);
 75			result = ctx.base_lexicalScope().impl_callMutator(variableName_.asAssignmentSymbol(), arg);
 76		} finally {
 77			stack.funcallReturned(result);
 78		}
 79		return result;
 80	}
 81
 82	/**
 83	 * AGASSVAR(nam,val).quote(ctx) = AGASSVAR(nam.quote(ctx), val.quote(ctx))
 84	 */
 85	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
 86		return new AGAssignVariable(variableName_.meta_quote(ctx).asSymbol(), valueExp_.meta_quote(ctx).asExpression());
 87	}
 88	
 89	public NATText meta_print() throws InterpreterException {
 90		return NATText.atValue(variableName_.meta_print().javaValue + " := " + valueExp_.meta_print().javaValue);
 91	}
 92    
 93    public boolean isVariableAssignment() {
 94        return true;
 95    }
 96    
 97    public ATAssignVariable asVariableAssignment() throws XTypeMismatch {
 98        return this;
 99    }
100}