Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2010 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.ui.texteditor; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import org.eclipse.core.runtime.Assert; import org.eclipse.core.runtime.ListenerList; import org.eclipse.jface.preference.IPreferenceStore; import org.eclipse.jface.util.IPropertyChangeListener; import org.eclipse.jface.util.PropertyChangeEvent; /** * Preference store that composes multiple preference stores in a * chain and serves a preference value from the first preference store in the * chain that contains the preference. * <p> * This preference store is read-only i.e. write access * throws an {@link java.lang.UnsupportedOperationException}.</p> * * @since 3.0 */ public class ChainedPreferenceStore implements IPreferenceStore { /** Child preference stores. */ private IPreferenceStore[] fPreferenceStores; /** Listeners on this chained preference store. */ private ListenerList fClientListeners = new ListenerList(ListenerList.IDENTITY); /** Listeners on the child preference stores. */ private List fChildListeners = new ArrayList(); /** * Listener on the chained preference stores. Forwards only the events * that are visible to clients. */ private class PropertyChangeListener implements IPropertyChangeListener { /** Preference store to listen too. */ private IPreferenceStore fPreferenceStore; /** * Initialize with the given preference store. * * @param preferenceStore the preference store */ public PropertyChangeListener(IPreferenceStore preferenceStore) { setPreferenceStore(preferenceStore); } /* * @see org.eclipse.jface.util.IPropertyChangeListener#propertyChange(org.eclipse.jface.util.PropertyChangeEvent) */ public void propertyChange(PropertyChangeEvent event) { IPreferenceStore childPreferenceStore = getPreferenceStore(); handlePropertyChangeEvent(childPreferenceStore, event); } /** * Registers this listener on the preference store. */ public void register() { getPreferenceStore().addPropertyChangeListener(this); } /** * Unregisters this listener from the preference store. */ public void unregister() { getPreferenceStore().removePropertyChangeListener(this); } /** * Returns the preference store. * * @return the preference store */ public IPreferenceStore getPreferenceStore() { return fPreferenceStore; } /** * Sets the preference store. * * @param preferenceStore the preference store to set */ public void setPreferenceStore(IPreferenceStore preferenceStore) { fPreferenceStore = preferenceStore; } } /** * Sets the chained preference stores. * * @param preferenceStores the chained preference stores to set */ public ChainedPreferenceStore(IPreferenceStore[] preferenceStores) { Assert.isTrue(preferenceStores != null && preferenceStores.length > 0); fPreferenceStores = new IPreferenceStore[preferenceStores.length]; System.arraycopy(preferenceStores, 0, fPreferenceStores, 0, preferenceStores.length); // Create listeners for (int i = 0, length = fPreferenceStores.length; i < length; i++) { PropertyChangeListener listener = new PropertyChangeListener(fPreferenceStores[i]); fChildListeners.add(listener); } } /* * @see org.eclipse.jface.preference.IPreferenceStore#addPropertyChangeListener(org.eclipse.jface.util.IPropertyChangeListener) */ public void addPropertyChangeListener(IPropertyChangeListener listener) { if (fClientListeners.size() == 0) { registerChildListeners(); } fClientListeners.add(listener); } /* * @see org.eclipse.jface.preference.IPreferenceStore#removePropertyChangeListener(org.eclipse.jface.util.IPropertyChangeListener) */ public void removePropertyChangeListener(IPropertyChangeListener listener) { fClientListeners.remove(listener); if (fClientListeners.size() == 0) { unregisterChildListeners(); } } /* * @see org.eclipse.jface.preference.IPreferenceStore#contains(java.lang.String) */ public boolean contains(String name) { return getVisibleStore(name) != null; } /* * @see org.eclipse.jface.preference.IPreferenceStore#firePropertyChangeEvent(java.lang.String, java.lang.Object, java.lang.Object) */ public void firePropertyChangeEvent(String name, Object oldValue, Object newValue) { firePropertyChangeEvent(new PropertyChangeEvent(this, name, oldValue, newValue)); } /** * Fire the given property change event. * * @param event the property change event */ private void firePropertyChangeEvent(PropertyChangeEvent event) { Object[] listeners = fClientListeners.getListeners(); for (int i = 0; i < listeners.length; i++) ((IPropertyChangeListener) listeners[i]).propertyChange(event); } /* * @see org.eclipse.jface.preference.IPreferenceStore#getBoolean(java.lang.String) */ public boolean getBoolean(String name) { IPreferenceStore visibleStore = getVisibleStore(name); if (visibleStore != null) return visibleStore.getBoolean(name); return BOOLEAN_DEFAULT_DEFAULT; } /* * @see org.eclipse.jface.preference.IPreferenceStore#getDefaultBoolean(java.lang.String) */ public boolean getDefaultBoolean(String name) { IPreferenceStore visibleStore = getVisibleStore(name); if (visibleStore != null) return visibleStore.getDefaultBoolean(name); return BOOLEAN_DEFAULT_DEFAULT; } /* * @see org.eclipse.jface.preference.IPreferenceStore#getDefaultDouble(java.lang.String) */ public double getDefaultDouble(String name) { IPreferenceStore visibleStore = getVisibleStore(name); if (visibleStore != null) return visibleStore.getDefaultDouble(name); return DOUBLE_DEFAULT_DEFAULT; } /* * @see org.eclipse.jface.preference.IPreferenceStore#getDefaultFloat(java.lang.String) */ public float getDefaultFloat(String name) { IPreferenceStore visibleStore = getVisibleStore(name); if (visibleStore != null) return visibleStore.getDefaultFloat(name); return FLOAT_DEFAULT_DEFAULT; } /* * @see org.eclipse.jface.preference.IPreferenceStore#getDefaultInt(java.lang.String) */ public int getDefaultInt(String name) { IPreferenceStore visibleStore = getVisibleStore(name); if (visibleStore != null) return visibleStore.getDefaultInt(name); return INT_DEFAULT_DEFAULT; } /* * @see org.eclipse.jface.preference.IPreferenceStore#getDefaultLong(java.lang.String) */ public long getDefaultLong(String name) { IPreferenceStore visibleStore = getVisibleStore(name); if (visibleStore != null) return visibleStore.getDefaultLong(name); return LONG_DEFAULT_DEFAULT; } /* * @see org.eclipse.jface.preference.IPreferenceStore#getDefaultString(java.lang.String) */ public String getDefaultString(String name) { IPreferenceStore visibleStore = getVisibleStore(name); if (visibleStore != null) return visibleStore.getDefaultString(name); return STRING_DEFAULT_DEFAULT; } /* * @see org.eclipse.jface.preference.IPreferenceStore#getDouble(java.lang.String) */ public double getDouble(String name) { IPreferenceStore visibleStore = getVisibleStore(name); if (visibleStore != null) return visibleStore.getDouble(name); return DOUBLE_DEFAULT_DEFAULT; } /* * @see org.eclipse.jface.preference.IPreferenceStore#getFloat(java.lang.String) */ public float getFloat(String name) { IPreferenceStore visibleStore = getVisibleStore(name); if (visibleStore != null) return visibleStore.getFloat(name); return FLOAT_DEFAULT_DEFAULT; } /* * @see org.eclipse.jface.preference.IPreferenceStore#getInt(java.lang.String) */ public int getInt(String name) { IPreferenceStore visibleStore = getVisibleStore(name); if (visibleStore != null) return visibleStore.getInt(name); return INT_DEFAULT_DEFAULT; } /* * @see org.eclipse.jface.preference.IPreferenceStore#getLong(java.lang.String) */ public long getLong(String name) { IPreferenceStore visibleStore = getVisibleStore(name); if (visibleStore != null) return visibleStore.getLong(name); return LONG_DEFAULT_DEFAULT; } /* * @see org.eclipse.jface.preference.IPreferenceStore#getString(java.lang.String) */ public String getString(String name) { IPreferenceStore visibleStore = getVisibleStore(name); if (visibleStore != null) return visibleStore.getString(name); return STRING_DEFAULT_DEFAULT; } /* * @see org.eclipse.jface.preference.IPreferenceStore#isDefault(java.lang.String) */ public boolean isDefault(String name) { IPreferenceStore visibleStore = getVisibleStore(name); if (visibleStore != null) return visibleStore.isDefault(name); return false; } /* * @see org.eclipse.jface.preference.IPreferenceStore#needsSaving() */ public boolean needsSaving() { throw new UnsupportedOperationException(); } /* * @see org.eclipse.jface.preference.IPreferenceStore#putValue(java.lang.String, java.lang.String) */ public void putValue(String name, String value) { throw new UnsupportedOperationException(); } /* * @see org.eclipse.jface.preference.IPreferenceStore#setDefault(java.lang.String, double) */ public void setDefault(String name, double value) { throw new UnsupportedOperationException(); } /* * @see org.eclipse.jface.preference.IPreferenceStore#setDefault(java.lang.String, float) */ public void setDefault(String name, float value) { throw new UnsupportedOperationException(); } /* * @see org.eclipse.jface.preference.IPreferenceStore#setDefault(java.lang.String, int) */ public void setDefault(String name, int value) { throw new UnsupportedOperationException(); } /* * @see org.eclipse.jface.preference.IPreferenceStore#setDefault(java.lang.String, long) */ public void setDefault(String name, long value) { throw new UnsupportedOperationException(); } /* * @see org.eclipse.jface.preference.IPreferenceStore#setDefault(java.lang.String, java.lang.String) */ public void setDefault(String name, String defaultObject) { throw new UnsupportedOperationException(); } /* * @see org.eclipse.jface.preference.IPreferenceStore#setDefault(java.lang.String, boolean) */ public void setDefault(String name, boolean value) { throw new UnsupportedOperationException(); } /* * @see org.eclipse.jface.preference.IPreferenceStore#setToDefault(java.lang.String) */ public void setToDefault(String name) { throw new UnsupportedOperationException(); } /* * @see org.eclipse.jface.preference.IPreferenceStore#setValue(java.lang.String, double) */ public void setValue(String name, double value) { throw new UnsupportedOperationException(); } /* * @see org.eclipse.jface.preference.IPreferenceStore#setValue(java.lang.String, float) */ public void setValue(String name, float value) { throw new UnsupportedOperationException(); } /* * @see org.eclipse.jface.preference.IPreferenceStore#setValue(java.lang.String, int) */ public void setValue(String name, int value) { throw new UnsupportedOperationException(); } /* * @see org.eclipse.jface.preference.IPreferenceStore#setValue(java.lang.String, long) */ public void setValue(String name, long value) { throw new UnsupportedOperationException(); } /* * @see org.eclipse.jface.preference.IPreferenceStore#setValue(java.lang.String, java.lang.String) */ public void setValue(String name, String value) { throw new UnsupportedOperationException(); } /* * @see org.eclipse.jface.preference.IPreferenceStore#setValue(java.lang.String, boolean) */ public void setValue(String name, boolean value) { throw new UnsupportedOperationException(); } /** * Handle property change event from the child listener with the given child preference store. * * @param childPreferenceStore the child preference store * @param event the event */ private void handlePropertyChangeEvent(IPreferenceStore childPreferenceStore, PropertyChangeEvent event) { String property = event.getProperty(); Object oldValue = event.getOldValue(); Object newValue = event.getNewValue(); IPreferenceStore visibleStore = getVisibleStore(property); /* * Assume that the property is there but has no default value (its owner relies on the default-default value) * see https://bugs.eclipse.org/bugs/show_bug.cgi?id=52827 */ if (visibleStore == null && newValue != null) visibleStore = childPreferenceStore; if (visibleStore == null) { // no visible store if (oldValue != null) // removal in child, last in chain -> removal in this chained preference store firePropertyChangeEvent(event); } else if (visibleStore == childPreferenceStore) { // event from visible store if (oldValue != null) { // change in child, visible store -> change in this chained preference store firePropertyChangeEvent(event); } else { // insertion in child IPreferenceStore oldVisibleStore = null; int i = 0; int length = fPreferenceStores.length; while (i < length && fPreferenceStores[i++] != visibleStore) { // do nothing } while (oldVisibleStore == null && i < length) { if (fPreferenceStores[i].contains(property)) oldVisibleStore = fPreferenceStores[i]; i++; } if (oldVisibleStore == null) { // insertion in child, first in chain -> insertion in this chained preference store firePropertyChangeEvent(event); } else { // insertion in child, not first in chain oldValue = getOtherValue(property, oldVisibleStore, newValue); if (!oldValue.equals(newValue)) // insertion in child, different old value -> change in this chained preference store firePropertyChangeEvent(property, oldValue, newValue); // else: insertion in child, same old value -> no change in this chained preference store } } } else { // event from other than the visible store boolean eventBeforeVisibleStore = false; for (int i = 0, length = fPreferenceStores.length; i < length; i++) { IPreferenceStore store = fPreferenceStores[i]; if (store == visibleStore) break; if (store == childPreferenceStore) { eventBeforeVisibleStore = true; break; } } if (eventBeforeVisibleStore) { // removal in child, before visible store /* * The original event's new value can be non-null (removed assertion). * see https://bugs.eclipse.org/bugs/show_bug.cgi?id=69419 */ newValue = getOtherValue(property, visibleStore, oldValue); if (!newValue.equals(oldValue)) // removal in child, before visible store, different old value -> change in this chained preference store firePropertyChangeEvent(property, oldValue, newValue); // else: removal in child, before visible store, same old value -> no change in this chained preference store } // else: event behind visible store -> no change in this chained preference store } } /** * Returns an object of the same dynamic type as <code>thisValue</code>, the returned object * encapsulates the value of the <code>property</code> from the preference <code>store</code>. * * @param property the name of the considered property * @param store the preference store * @param thisValue the given value * @return the other value */ private Object getOtherValue(String property, IPreferenceStore store, Object thisValue) { if (thisValue instanceof Boolean) return store.getBoolean(property) ? Boolean.TRUE : Boolean.FALSE; else if (thisValue instanceof Double) return new Double(store.getDouble(property)); else if (thisValue instanceof Float) return new Float(store.getFloat(property)); else if (thisValue instanceof Integer) return new Integer(store.getInt(property)); else if (thisValue instanceof Long) return new Long(store.getLong(property)); else if (thisValue instanceof String) return store.getString(property); return store.getString(property); } /** * Returns the preference store from which the given property's value * is visible. * * @param property the name of the property * @return the preference store from which the property's value is visible, * <code>null</code> if the property is unknown */ private IPreferenceStore getVisibleStore(String property) { IPreferenceStore visibleStore = null; for (int i = 0, length = fPreferenceStores.length; i < length && visibleStore == null; i++) { IPreferenceStore store = fPreferenceStores[i]; if (store.contains(property)) visibleStore = store; } return visibleStore; } /** * Register the child listeners on the child preference stores. */ private void registerChildListeners() { Iterator iter = fChildListeners.iterator(); while (iter.hasNext()) { PropertyChangeListener listener = (PropertyChangeListener) iter.next(); listener.register(); } } /** * Unregister the child listeners from the child preference stores. */ private void unregisterChildListeners() { Iterator iter = fChildListeners.iterator(); while (iter.hasNext()) { PropertyChangeListener listener = (PropertyChangeListener) iter.next(); listener.unregister(); } } }