/interpreter/tags/at2dist030708/src/edu/vub/at/objects/natives/grammar/AGClosureLiteral.java

  1/**
  2 * AmbientTalk/2 Project
  3 * AGClosureLiteral.java created on 26-jul-2006 at 16:59:04
  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.objects.ATContext;
 33import edu.vub.at.objects.ATObject;
 34import edu.vub.at.objects.ATTable;
 35import edu.vub.at.objects.grammar.ATBegin;
 36import edu.vub.at.objects.grammar.ATClosureLiteral;
 37import edu.vub.at.objects.mirrors.NativeClosure;
 38import edu.vub.at.objects.natives.NATClosure;
 39import edu.vub.at.objects.natives.NATMethod;
 40import edu.vub.at.objects.natives.NATTable;
 41import edu.vub.at.objects.natives.NATText;
 42
 43/**
 44 * The native implementation of a literal closure AG element.
 45 * 
 46 * @author tvc
 47 */
 48public final class AGClosureLiteral extends AGExpression implements ATClosureLiteral {
 49
 50	protected final ATTable arguments_;
 51	protected final ATBegin body_;
 52	
 53	private NATMethod preprocessedMethod_;
 54	
 55	public AGClosureLiteral(ATTable args, ATBegin body) throws InterpreterException {
 56		arguments_ = args;
 57		body_ = body;
 58	}
 59	
 60	public ATTable base_arguments() { return arguments_; }
 61
 62	public ATBegin base_bodyExpression() { return body_; }
 63	
 64	/**
 65	 * To evaluate a closure literal, construct a closure pairing the literal's arguments and body with the
 66	 * current evaluation context.
 67	 * 
 68	 * AGCLOLIT(arg,bdy).eval(ctx) = AGCLO(AGMTH("lambda",arg,bdy), ctx)
 69	 * 
 70	 * @return a native closure closing over the current evaluation context.
 71	 */
 72	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
 73		// the method is not yet created in the constructor because this gives problems
 74		// with quoted parameters: a quoted parameter would result in an illegal parameter
 75		// exception while actually the block was defined in the context of a quotation,
 76		// so at runtime the block would have never been evaluated (but quoted instead)
 77		if (preprocessedMethod_ == null) {
 78			preprocessedMethod_ = new NATMethod(Evaluator._LAMBDA_, arguments_, body_, NATTable.EMPTY);
 79		}
 80		return new NATClosure(preprocessedMethod_, ctx);
 81	}
 82
 83	/**
 84	 * Quoting a closure literal results in a new quoted closure literal.
 85	 * 
 86	 * AGCLOLIT(arg,bdy).quote(ctx) = AGCLOLIT(arg.quote(ctx), bdy.quote(ctx))
 87	 */
 88	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
 89		return new AGClosureLiteral(arguments_.meta_quote(ctx).asTable(),
 90				                   body_.meta_quote(ctx).asBegin());
 91	}
 92	
 93	public NATText meta_print() throws InterpreterException {
 94		return arguments_.base_isEmpty().base_ifTrue_ifFalse_(
 95				new NativeClosure(this) {
 96					public ATObject base_apply(ATTable args) throws InterpreterException {
 97						return NATText.atValue("{ "+ body_.meta_print().javaValue + " }");
 98					}
 99				},
100				new NativeClosure(this) {
101					public ATObject base_apply(ATTable args) throws InterpreterException {
102						  return NATText.atValue(Evaluator.printElements(arguments_.asNativeTable(), "{ |", ", ", " | ").javaValue +
103			                       body_.meta_print().javaValue+"}");
104					}
105				}).asNativeText();
106	}
107	
108}