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/interpreter/tags/at2dist041108/src/edu/vub/at/exceptions/XTypeMismatch.java

http://ambienttalk.googlecode.com/
Java | 102 lines | 28 code | 10 blank | 64 comment | 0 complexity | e8183efe26b7abf606f29e62711211bb MD5 | raw file
  1/**
  2 * AmbientTalk/2 Project
  3 * XTypeMismatch.java created on Jul 13, 2006 at 9:43:54 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.exceptions;
 29
 30import edu.vub.at.eval.Evaluator;
 31import edu.vub.at.objects.ATObject;
 32import edu.vub.at.objects.ATTypeTag;
 33import edu.vub.at.objects.coercion.NativeTypeTags;
 34
 35/**
 36 * XTypeMismatch instances are thrown when a value conversion failed. Value conversions occur 
 37 * when the interpreter expects arguments of a particular interface type (e.g. an ATClosure to
 38 * apply) and the passed argument has another type. The following cases can be distinguished: 
 39 * <ul>
 40 *   <li> The argument is of a different native ambienttalk type and therefore cannot be used. 
 41 *   In this case, an XTypeMismatch exception will be thrown.</li>
 42 *   <li> The argument is an ambienttalk object. At this point, the coercer will attempt to 
 43 *   coerce the object into the correct type, which is possible only if the object has the 
 44 *   correct native type. Otherwise, an XTypeMismatch exception will be thrown.</li>
 45 *   <li>The target type is a Java interface. The conversion automatically succeeds if the passed
 46 *   argument is a JavaObject wrapper for an object which implements the interface. If the passed
 47 *   argument is an ambienttalk object, the coercer will be able to dynamically synthetise a 
 48 *   proxy implementing the interface. If the argument is of a native ambienttalk type however, 
 49 *   an XTypeMismatch exception will be thrown.</li>
 50 *   <li>The target type is a Java class. If the passed argument is not a JavaObject wrapper for
 51 *   an instance of this class (or one of its subclasses), an XTypeMismatch exception will be 
 52 *   thrown.</li>
 53 * </ul>
 54 * 
 55 * @author smostinc
 56 * @author tvcutsem
 57 */
 58public class XTypeMismatch extends InterpreterException {
 59
 60	private static final long serialVersionUID = -3135452124227872807L;
 61	
 62	private final ATObject failedObject_;
 63    private final Class expectedType_;
 64
 65    /**
 66     * Creates a new type mismatch exception given the expected type and the object that could not be coerced to this type.
 67     * @param expectedType a Java Class denoting the type the object was being coerced into.
 68     * @param failedObject the ambienttalk value that could not be coerced into the correct type
 69     */
 70	public XTypeMismatch(Class expectedType, ATObject failedObject) {
 71		expectedType_ = expectedType;
 72		failedObject_ = failedObject;
 73	}
 74
 75	/**
 76	 * @return the ambienttalk value that could not be coerced into the correct type.
 77	 */
 78	public ATObject getFailedObject() {
 79		return failedObject_;
 80	}
 81	
 82	/**
 83	 * @return a Java Class denoting the type the object was being coerced into.
 84	 */
 85	public Class getExpectedType() {
 86		return expectedType_;
 87	}
 88	
 89	/**
 90	 * @return a textual description of the type mismatch exception.
 91	 */
 92	public String getMessage() {
 93		String obj = Evaluator.toString(failedObject_);
 94		return "Type mismatch: expected " + Evaluator.valueNameOf(expectedType_)
 95		           + ", given " + obj + " (type: " + Evaluator.valueNameOf(failedObject_.getClass())+ ")";
 96	}
 97	
 98	public ATTypeTag getType() {
 99		return NativeTypeTags._TYPEMISMATCH_;
100	}
101
102}