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

  1/**
  2 * AmbientTalk/2 Project
  3 * AGDefExternalField.java created on 16-nov-2006 at 8:31:45
  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.exceptions.InterpreterException;
 32import edu.vub.at.exceptions.XIllegalOperation;
 33import edu.vub.at.objects.ATContext;
 34import edu.vub.at.objects.ATObject;
 35import edu.vub.at.objects.grammar.ATDefExternalField;
 36import edu.vub.at.objects.grammar.ATDefinition;
 37import edu.vub.at.objects.grammar.ATExpression;
 38import edu.vub.at.objects.grammar.ATSymbol;
 39import edu.vub.at.objects.natives.NATText;
 40
 41import java.util.HashSet;
 42import java.util.Set;
 43
 44/**
 45 * Represents the abstract grammar for defining external fields.
 46 *   
 47 *  @author tvcutsem
 48 */
 49public class AGDefExternalField extends AGDefinition implements ATDefExternalField {
 50
 51	private final ATSymbol rcvNam_;
 52	private final ATSymbol name_;
 53	private final ATExpression valueExp_;
 54	
 55	public AGDefExternalField(ATSymbol rcv, ATSymbol name, ATExpression value) {
 56		rcvNam_ = rcv;
 57		name_ = name;
 58		valueExp_ = value;
 59	}
 60	
 61	public ATSymbol base_receiver() { return rcvNam_; }
 62	public ATSymbol base_name() { return name_; }
 63	public ATExpression base_valueExpression() { return valueExp_; }
 64	
 65	/**
 66	 * Defines a new field in the object denoted by the receiver symbol.
 67	 * The return value is the value of the field.
 68	 * 
 69	 * AGDEFEXTFLD(rcv,nam,val).eval(ctx) =
 70	 *   rcv.eval(ctx).addField(nam, val.eval(ctx))
 71	 *   
 72	 * @throws XIllegalOperation if the receiver is an instance of a native type (whose field maps are sealed).
 73	 */
 74	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
 75		ATObject receiver = rcvNam_.meta_eval(ctx);
 76		ATObject val = valueExp_.meta_eval(ctx);
 77		receiver.meta_defineField(name_, val);
 78		return val;
 79	}
 80
 81	/**
 82	 * Quoting an external field definition results in a new quoted external field definition.
 83	 * 
 84	 * AGDEFEXTFLD(rcv,nam,val).quote(ctx) = AGDEFEXTFLD(rcv.quote(ctx), nam.quote(ctx), val.quote(ctx))
 85	 */
 86	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
 87		return new AGDefExternalField(rcvNam_.meta_quote(ctx).asSymbol(),
 88									name_.meta_quote(ctx).asSymbol(),
 89									valueExp_.meta_quote(ctx).asExpression());
 90	}
 91	
 92	public NATText meta_print() throws InterpreterException {
 93		return NATText.atValue("def " + rcvNam_.meta_print().javaValue
 94				+ "." + name_.meta_print().javaValue
 95				+ " := " + valueExp_.meta_print().javaValue);
 96	}
 97	
 98	/**
 99	 * IV(def o.x := val) = { }
100	 */
101	public Set impl_introducedVariables() throws InterpreterException {
102		return new HashSet();
103	}
104
105	/**
106	 * FV(def o.x := val) = FV(val) U { o }
107	 */
108	public Set impl_freeVariables() throws InterpreterException {
109		Set fvValueExp = valueExp_.impl_freeVariables();
110		fvValueExp.add(rcvNam_);
111		return fvValueExp;
112	}
113	
114	
115	public Set impl_quotedFreeVariables() throws InterpreterException {
116		Set qfv = valueExp_.impl_quotedFreeVariables();
117		qfv.addAll(rcvNam_.impl_quotedFreeVariables());
118		qfv.addAll(name_.impl_quotedFreeVariables());
119		return qfv;
120	}
121	
122}