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

  1/**
  2 * AmbientTalk/2 Project
  3 * AGSelection.java created on 26-jul-2006 at 16:16:07
  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.exceptions.InterpreterException;
 31import edu.vub.at.objects.ATContext;
 32import edu.vub.at.objects.ATObject;
 33import edu.vub.at.objects.grammar.ATExpression;
 34import edu.vub.at.objects.grammar.ATSelection;
 35import edu.vub.at.objects.grammar.ATSymbol;
 36import edu.vub.at.objects.natives.NATText;
 37
 38import java.util.HashSet;
 39import java.util.Set;
 40
 41/**
 42 * The native implementation of a selection AG element <tt>o.&m</tt>.
 43 * @author tvcutsem
 44 */
 45public final class AGSelection extends AGExpression implements ATSelection {
 46
 47	private final ATExpression rcvExp_;
 48	private final ATSymbol selector_;
 49	
 50	public AGSelection(ATExpression rcv, ATSymbol sel) {
 51		rcvExp_ = rcv;
 52		selector_ = sel;
 53	}
 54	
 55	public ATExpression base_receiverExpression() { return rcvExp_; }
 56
 57	public ATSymbol base_selector() { return selector_; }
 58
 59	/**
 60	 * To evaluate a selection, evaluate the receiver expression to an object and select
 61	 * the slot with the given name from that object.
 62	 * 
 63	 * AGSEL(rcv,sel).eval(ctx) = rcv.eval(ctx).meta_select(sel)
 64	 * 
 65	 * @return the value of the selected slot.
 66	 */
 67	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
 68		ATObject receiver = rcvExp_.meta_eval(ctx);
 69		return receiver.meta_select(receiver, selector_);
 70	}
 71
 72	/**
 73	 * Quoting a selection results in a new quoted selection.
 74	 * 
 75	 * AGSEL(rcv,sel).quote(ctx) = AGSEL(rcv.quote(ctx), sel.quote(ctx))
 76	 */
 77	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
 78		return new AGSelection(rcvExp_.meta_quote(ctx).asExpression(),
 79				              selector_.meta_quote(ctx).asSymbol());
 80	}
 81	
 82	public NATText meta_print() throws InterpreterException {
 83		return NATText.atValue(rcvExp_.meta_print().javaValue + ".&" + selector_.meta_print().javaValue);
 84	}
 85	
 86	/**
 87	 * FV(rcvExp.&selector) = FV(rcvExp)
 88	 */
 89	public Set impl_freeVariables() throws InterpreterException {
 90		return rcvExp_.impl_freeVariables();
 91	}
 92	
 93	
 94	public Set impl_quotedFreeVariables() throws InterpreterException {
 95		Set qfv = rcvExp_.impl_quotedFreeVariables();
 96		qfv.addAll(selector_.impl_quotedFreeVariables());
 97		return qfv;
 98	}
 99
100}