/interpreter/tags/at2dist220411/src/edu/vub/at/objects/natives/grammar/AGMultiAssignment.java

  1/**
  2 * AmbientTalk/2 Project
  3 * AGMultiAssignment.java created on 18-aug-2006 at 9:31:38
  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.PartialBinder;
 31import edu.vub.at.exceptions.InterpreterException;
 32import edu.vub.at.objects.ATContext;
 33import edu.vub.at.objects.ATObject;
 34import edu.vub.at.objects.ATTable;
 35import edu.vub.at.objects.grammar.ATExpression;
 36import edu.vub.at.objects.grammar.ATMultiAssignment;
 37import edu.vub.at.objects.natives.NATText;
 38import edu.vub.util.TempFieldGenerator;
 39
 40import java.util.HashMap;
 41import java.util.HashSet;
 42import java.util.Set;
 43
 44/**
 45 * @author tvc
 46 *
 47 * The native implementation of a multiple assignment AG element.
 48 */
 49public final class AGMultiAssignment extends NATAbstractGrammar implements ATMultiAssignment {
 50
 51	private final ATTable parameters_;
 52	private final ATExpression valueExp_;
 53	
 54	private final PartialBinder binderPartialFunction_;
 55	
 56	public AGMultiAssignment(ATTable par, ATExpression val) throws InterpreterException {
 57		parameters_ = par;
 58		valueExp_ = val;
 59		binderPartialFunction_ = PartialBinder.calculateResidual("multi-assignment", par);
 60	}
 61
 62	public ATTable base_parameters() { return parameters_; }
 63	
 64	public ATExpression base_valueExpression() { return valueExp_; }
 65	
 66	/**
 67	 * To evaluate a multiple assignment, evaluate the right hand side to a table
 68	 * and assign the parameters on the left hand side to the 'arguments' of the right hand side,
 69	 * almost as if they were bound during a function call (the parameters are assigned instead of defined).
 70	 * 
 71	 * AGMULTIASS(par,val).eval(ctx) = assign(ctx.scope, par, val.eval(ctx))
 72	 * 
 73	 * @return the evaluated arguments table
 74	 */
 75	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
 76		ATTable args = valueExp_.meta_eval(ctx).asTable();
 77		PartialBinder.assignArgsToParams(binderPartialFunction_, ctx, args);
 78		return args;
 79	}
 80
 81	/**
 82	 * AGMULTIASS(par,val).quote(ctx) = AGMULTIASS(par.quote(ctx), val.quote(ctx))
 83	 */
 84	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
 85		return new AGMultiAssignment(parameters_.meta_quote(ctx).asTable(), valueExp_.meta_quote(ctx).asExpression());
 86	}
 87	
 88	public NATText meta_print() throws InterpreterException {
 89		return NATText.atValue(parameters_.meta_print().javaValue + " := " + valueExp_.meta_print().javaValue);
 90	}
 91	
 92	public NATText impl_asUnquotedCode(TempFieldGenerator objectMap) throws InterpreterException {
 93		return NATText.atValue(parameters_.impl_asUnquotedCode(objectMap).javaValue + " := " + valueExp_.impl_asUnquotedCode(objectMap).javaValue);
 94	}
 95	
 96	/**
 97	 * FV([var1, var2 := exp1, @ rest] := exp2) =
 98	 *   { var1, var2, rest } U FV(exp1) U FV(exp2)
 99	 */
100	public Set impl_freeVariables() throws InterpreterException {
101        Set fvValExp = valueExp_.impl_freeVariables();
102        
103		ATObject[] params = parameters_.asNativeTable().elements_;
104		for (int i = 0; i < params.length; i++) {
105			if (params[i].isSymbol()) {
106				// Mandatory arguments, e.g. x
107				fvValExp.add(params[i].asSymbol());				
108			} else if (params[i].isVariableAssignment()) {
109				// Optional args or rest args
110				// Note: for optional args, both assigned var and free vars
111				// of the initialization expression are considered free vars
112				fvValExp.addAll(params[i].asExpression().impl_freeVariables());
113			} else if (params[i].isSplice()) {
114				fvValExp.add(params[i].asSplice().base_expression().asSymbol());
115			}
116		}
117        return fvValExp;
118	}
119	
120	
121	public Set impl_quotedFreeVariables() throws InterpreterException {
122		Set qfv = parameters_.impl_quotedFreeVariables();
123		qfv.addAll(valueExp_.impl_quotedFreeVariables());
124		return qfv;
125	}
126
127}