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

  1/**
  2 * AmbientTalk/2 Project
  3 * AGApplication.java created on 26-jul-2006 at 16:13:31
  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.objects.ATClosure;
 34import edu.vub.at.objects.ATContext;
 35import edu.vub.at.objects.ATObject;
 36import edu.vub.at.objects.ATTable;
 37import edu.vub.at.objects.grammar.ATApplication;
 38import edu.vub.at.objects.grammar.ATExpression;
 39import edu.vub.at.objects.natives.NATTable;
 40import edu.vub.at.objects.natives.NATText;
 41
 42/**
 43 * The native implementation of an application AG element.
 44 * 
 45 * @author tvc
 46 */
 47public final class AGApplication extends AGExpression implements ATApplication {
 48
 49	private final ATExpression funExp_;
 50	private final ATTable arguments_;
 51	
 52	public AGApplication(ATExpression fun, ATTable arg) {
 53		funExp_ = fun;
 54		arguments_ = arg;
 55	}
 56	
 57	public ATExpression base_function() { return funExp_; }
 58
 59	public ATTable base_arguments() { return arguments_; }
 60
 61	/**
 62	 * To evaluate a function application, evaluate the receiver expression to a function, then evaluate the arguments
 63	 * to the function application eagerly and apply the function.
 64	 * 
 65	 * AGAPL(fun,arg).eval(ctx) = fun.eval(ctx).apply(map eval(ctx) over arg)
 66	 * 
 67	 * @return the return value of the applied function.
 68	 */
 69	public ATObject meta_eval(ATContext ctx) throws InterpreterException {
 70		// calls of the form f(x) are transformed into ctx.lex.call(`f, [x])
 71		if(funExp_.isSymbol()) {
 72			NATTable args = Evaluator.evaluateArguments(arguments_.asNativeTable(), ctx);
 73			ATObject result = null;
 74			InvocationStack stack = InvocationStack.getInvocationStack();
 75			try {
 76				stack.functionCalled(this, null, args);
 77				result = ctx.base_lexicalScope().impl_callAccessor(funExp_.asSymbol(), args);
 78			} finally {
 79				stack.funcallReturned(result);
 80			}
 81			return result;
 82		// calls of the form (expr)(x) are transformed into expr.eval(ctx).apply([x])
 83		} else {
 84			ATClosure clo = funExp_.meta_eval(ctx).asClosure();
 85			NATTable args = Evaluator.evaluateArguments(arguments_.asNativeTable(), ctx);
 86			ATObject result = null;
 87			InvocationStack stack = InvocationStack.getInvocationStack();
 88			try {
 89				stack.functionCalled(this, clo, args);
 90				result = clo.base_apply(args);
 91			} finally {
 92				stack.funcallReturned(result);
 93			}
 94			return result;
 95		}
 96	}
 97
 98	/**
 99	 * Quoting an application results in a new quoted application.
100	 * 
101	 * AGAPL(sel,arg).quote(ctx) = AGAPL(sel.quote(ctx), arg.quote(ctx))
102	 */
103	public ATObject meta_quote(ATContext ctx) throws InterpreterException {
104		return new AGApplication(funExp_.meta_quote(ctx).asExpression(),
105				                arguments_.meta_quote(ctx).asTable());
106	}
107	
108	public NATText meta_print() throws InterpreterException {
109		return NATText.atValue(funExp_.meta_print().javaValue + Evaluator.printAsList(arguments_).javaValue);
110	}
111
112}