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/interpreter/tags/reactive-pattern-matching/src/edu/vub/at/objects/natives/NATMethod.java

http://ambienttalk.googlecode.com/
Java | 188 lines | 95 code | 25 blank | 68 comment | 4 complexity | e5463bc1b682f5e842fc3e43c6f96d8c MD5 | raw file
  1/**
  2 * AmbientTalk/2 Project
  3 * NATMethod.java created on Jul 24, 2006 at 11:30:35 PM
  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;
 29
 30import edu.vub.at.eval.PartialBinder;
 31import edu.vub.at.exceptions.InterpreterException;
 32import edu.vub.at.exceptions.XTypeMismatch;
 33import edu.vub.at.objects.ATClosure;
 34import edu.vub.at.objects.ATContext;
 35import edu.vub.at.objects.ATMethod;
 36import edu.vub.at.objects.ATObject;
 37import edu.vub.at.objects.ATTable;
 38import edu.vub.at.objects.coercion.NativeTypeTags;
 39import edu.vub.at.objects.grammar.ATBegin;
 40import edu.vub.at.objects.grammar.ATSymbol;
 41import edu.vub.at.objects.mirrors.PrimitiveMethod;
 42import edu.vub.at.signals.natives.NATLiftedBehavior;
 43import edu.vub.at.util.logging.Logging;
 44
 45/**
 46 * NATMethod implements methods as named functions which are in fact simply containers
 47 * for a name, a table of arguments and a body.
 48 * 
 49 * @author smostinc
 50 * @author tvcutsem
 51 */
 52public class NATMethod extends NATByCopy implements ATMethod {
 53
 54	private final ATSymbol 	name_;
 55	private final ATTable 	parameters_;
 56	private final ATBegin	body_;
 57	private final ATTable	annotations_;
 58	
 59	// partial function denoting a parameter binding algorithm specialized for this method's parameter list
 60	private final PartialBinder parameterBindingFunction_;
 61	
 62	/** construct a new method. This method may raise an exception if the parameter list is illegal. */
 63	public NATMethod(ATSymbol name, ATTable parameters, ATBegin body, ATTable annotations) throws InterpreterException {
 64		name_ 		= name;
 65		parameters_ = parameters;
 66		body_ 		= body;
 67		annotations_= annotations;
 68		
 69		// calculate the parameter binding strategy to use using partial evaluation
 70		parameterBindingFunction_ =
 71			PartialBinder.calculateResidual(name_.base_text().asNativeText().javaValue, parameters);
 72	}
 73	
 74	/**
 75	 * Constructor to be used by primitive methods only.
 76	 */
 77	protected NATMethod(ATSymbol name, ATTable parameters, PrimitiveMethod.PrimitiveBody body, ATTable annotations) {
 78		name_ 		= name;
 79		parameters_ = parameters;
 80		body_ 		= body;
 81		annotations_= annotations;
 82		
 83		PartialBinder parameterBindingFunction;
 84		try {
 85			// calculate the parameter binding strategy to use using partial evaluation
 86			parameterBindingFunction = PartialBinder.calculateResidual(name_.base_text().asNativeText().javaValue, parameters);
 87		} catch (InterpreterException e) {
 88			parameterBindingFunction = null;
 89			// this indicates a bug, primitive methods should not contain erroneous parameter lists
 90			Logging.VirtualMachine_LOG.fatal("error creating primitive method: ",e);
 91		}
 92		parameterBindingFunction_ = parameterBindingFunction;
 93	}
 94
 95	public ATClosure base_wrap(ATObject lexicalScope, ATObject dynamicReceiver) throws InterpreterException {
 96		return new NATClosure(this, lexicalScope, dynamicReceiver);
 97	}
 98	
 99	public ATSymbol base_name() {
100		return name_;
101	}
102
103	public ATTable base_parameters() {
104		return parameters_;
105	}
106
107	public ATBegin base_bodyExpression() {
108		return body_;
109	}
110	
111	public ATTable base_annotations() throws InterpreterException {
112		return annotations_;
113	}
114	
115	/**
116	 * To apply a function, first bind its parameters to the evaluated arguments within a new call frame.
117	 * This call frame is lexically nested within the current lexical scope.
118	 * 
119	 * This method is invoked via the following paths:
120	 *  - either by directly 'calling a function', in which case this method is applied via NATClosure.base_apply.
121	 *    The closure ensures that the context used is the lexical scope, not the dynamic scope of invocation.
122	 *  - or by 'invoking a method' through an object, in which case this method is applied via NATObject.meta_invoke.
123	 *    The enclosing object ensures that the context is properly initialized with the implementor, the dynamic receiver
124	 *    and the implementor's parent.
125	 * 
126	 * @param arguments the evaluated actual arguments
127	 * @param ctx the context in which to evaluate the method body, where a call frame will be inserted first
128	 * @return the value of evaluating the function body
129	 */
130	public ATObject base_apply(ATTable arguments, ATContext ctx) throws InterpreterException {
131		if(! base_annotations().base_contains(NativeTypeTags._LIFTED_).asNativeBoolean().javaValue) {
132			boolean		shouldBeLifted	= false;
133			ATObject[] 	argumentsArray 	= arguments.asNativeTable().elements_;
134
135			for (int argIndex = 0; argIndex < argumentsArray.length; argIndex++) {
136				ATObject currentArgument = argumentsArray[argIndex];
137			
138				if (currentArgument.isBehavior()) {
139					shouldBeLifted = true;
140
141					break;
142				}
143			}
144
145			if(shouldBeLifted) {
146				return NATLiftedBehavior.fromClosure(new NATClosure(this, ctx), argumentsArray);
147			} // else
148		}
149		
150		NATCallframe cf = new NATCallframe(ctx.base_lexicalScope());
151		ATContext evalCtx = ctx.base_withLexicalEnvironment(cf);
152		PartialBinder.defineParamsForArgs(parameterBindingFunction_, evalCtx, arguments);
153		return body_.meta_eval(evalCtx);
154	}
155	
156	/**
157	 * Applies the method in the context given, without first inserting a call frame to bind parameters.
158	 * Arguments are bound directly in the given lexical scope.
159	 * 
160	 * This method is often invoked via its enclosing closure when used to implement various language
161	 * constructs such as object:, mirror:, extend:with: etc.
162	 * 
163	 * @param arguments the evaluated actual arguments
164	 * @param ctx the context in which to evaluate the method body, to be used as-is
165	 * @return the value of evaluating the function body
166	 */
167	public ATObject base_applyInScope(ATTable arguments, ATContext ctx) throws InterpreterException {
168		PartialBinder.defineParamsForArgs(parameterBindingFunction_, ctx, arguments);
169		return body_.meta_eval(ctx);
170	}
171
172	public NATText meta_print() throws InterpreterException {
173		return NATText.atValue("<method:"+name_.meta_print().javaValue+">");
174	}
175	
176	public ATObject meta_clone() throws InterpreterException {
177		return this;
178	}
179
180	public ATMethod asMethod() throws XTypeMismatch {
181		return this;
182	}
183	
184    public ATTable meta_typeTags() throws InterpreterException {
185    	return NATTable.of(NativeTypeTags._METHOD_, NativeTypeTags._ISOLATE_);
186    }
187
188}