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/*******************************************************************************
* Copyright (c) 2001, 2005 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.jem.internal.beaninfo.vm;
/*
* $RCSfile: FeatureDescriptorEquality.java,v $
* $Revision: 1.5 $ $Date: 2005/08/24 20:31:29 $
*/
import java.beans.*;
import java.util.*;
import java.lang.reflect.*;
/**
* This object is used to test for semantic equality (equals())
* between feature objects. It is needed because Feature's don't
* provide a semantic equality, only an identity equality. Need
* semantic equality so that keys in map can be found equal
* semantically.
*/
public class FeatureDescriptorEquality {
protected FeatureDescriptor fFeature;
private HashMap fValues; // The key/values for this feature. We grab them out
// so that we don't have to keep re-getting them for equality
// compares. This is done the first time needed in the equals
// statement.
private int fHashCode = 0; // Hashcode of this equality object. The hashcode for the feature is expensive
// so we will calculate it once (the assumption is that
// features once created aren't changed, which for our
// purposes here in beaninfo land is good).
protected static HashMap MAP_EQUALITY = new HashMap(10); // Map from descriptor to equality type.
static {
try {
MAP_EQUALITY.put(FeatureDescriptor.class, (FeatureDescriptorEquality.class).getConstructor(new Class[] {FeatureDescriptor.class}));
} catch (NoSuchMethodException e) {
}
// Need to set up the others.
BeanDescriptorEquality.INIT();
EventSetDescriptorEquality.INIT();
IndexedPropertyDescriptorEquality.INIT();
MethodDescriptorEquality.INIT();
ParameterDescriptorEquality.INIT();
}
/**
* Create the appropriate descriptor equality for this object.
*/
public static FeatureDescriptorEquality createEquality(FeatureDescriptor descr) {
try {
return (FeatureDescriptorEquality) ((Constructor) MAP_EQUALITY.get(descr.getClass())).newInstance(new Object[] {descr});
} catch (IllegalAccessException e) {
} catch (InstantiationException e) {
} catch (InvocationTargetException e) {
e.printStackTrace();
}
return null;
}
public FeatureDescriptorEquality() {
}
/**
* NOTE: Every subclass needs to implement an override for the methods:
* calculateHashCode
* equals
* clearFeature - if it has any cache values
*/
public FeatureDescriptorEquality(FeatureDescriptor feature) {
setFeature(feature);
}
public final void setFeature(FeatureDescriptor feature) {
clearFeature();
fFeature = feature;
}
/**
* A new feature is being set into this object,
* clear any cache members so that they can be reconstructed.
*
* NOTE: Subclasses - remember to call super.clearFeature();
*/
protected void clearFeature() {
fValues = null;
fHashCode = 0;
}
public final int hashCode() {
if (fHashCode == 0)
fHashCode = calculateHashCode();
return fHashCode;
}
protected final HashMap values() {
if (fValues == null) {
fValues = new HashMap(5);
Enumeration keys = fFeature.attributeNames();
while (keys.hasMoreElements()) {
String key = (String) keys.nextElement();
fValues.put(key, fFeature.getValue(key));
}
}
return fValues;
}
/**
* Calculate the hashcode for the current feature, add this
* to the hashcode received from super.calculateHashCode
* and return the new value.
*
* NOTE: for subclasses, it is MANDITORY that the first line be:
* int hashcode = super.calculateHashCode();
* and the last line be:
* return hashcode*31 + (your calculated hashcode for just this subclass);
*/
protected int calculateHashCode() {
int hashcode = 0;
if (fFeature.getName() != null)
hashcode += fFeature.getName().hashCode();
if (fFeature.getDisplayName() != fFeature.getName())
hashcode += fFeature.getDisplayName().hashCode();
if (fFeature.getShortDescription() != fFeature.getDisplayName())
hashcode += fFeature.getShortDescription().hashCode();
hashcode += (fFeature.isExpert() ? Boolean.TRUE : Boolean.FALSE).hashCode();
hashcode += (fFeature.isHidden() ? Boolean.TRUE : Boolean.FALSE).hashCode();
hashcode += (fFeature.isPreferred() ? Boolean.TRUE : Boolean.FALSE).hashCode();
hashcode += values().hashCode();
return hashcode;
}
/**
* equals: See if this is equal semantically.
*
* NOTE: Every subclass needs to implement this and
* the first few lines should be:
* if (identityTest())
* return true;
* if (!super.equals(obj))
* return false;
*/
public boolean equals(Object obj) {
if (identityTest(obj))
return true;
if (!(obj instanceof FeatureDescriptorEquality))
return false;
FeatureDescriptorEquality ofe = (FeatureDescriptorEquality) obj;
FeatureDescriptor of = ofe.fFeature;
if (fFeature.getClass() != of.getClass())
return false;
if (!fFeature.getName().equals(of.getName()))
return false;
if (!fFeature.getDisplayName().equals(of.getDisplayName()))
return false;
if (!fFeature.getShortDescription().equals(of.getShortDescription()))
return false;
if (fFeature.isExpert() != of.isExpert() ||
fFeature.isHidden() != of.isHidden() ||
fFeature.isPreferred() != of.isPreferred())
return false;
if (!values().equals(ofe.values()))
return false;
return true;
}
/*
* Identity test: Tests for quick identity of
* descriptors. If this returns true, then
* no other tests required.
*/
protected boolean identityTest(Object obj) {
if (!(obj instanceof FeatureDescriptorEquality))
return false;
if (this == obj)
return true;
if (((FeatureDescriptorEquality) obj).fFeature == fFeature)
return true;
return false;
}
}
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