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/*******************************************************************************
 * Copyright (c) 2004, 2008 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.jface.bindings;

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.StringWriter;

import org.eclipse.core.commands.ParameterizedCommand;
import org.eclipse.jface.util.Util;

/**
 * 

* A binding is a link between user input and the triggering of a particular * command. The most common example of a binding is a keyboard shortcut, but * there are also mouse and gesture bindings. *

*

* Bindings are linked to particular conditions within the application. Some of * these conditions change infrequently (e.g., locale, scheme), while some will * tend to change quite frequently (e.g., context). This allows the bindings to * be tailored to particular situations. For example, a set of bindings may be * appropriate only inside a text editor. Or, perhaps, a set of bindings might * be appropriate only for a given locale, such as bindings that coexist with * the Input Method Editor (IME) on Chinese locales. *

*

* It is also possible to remove a particular binding. This is typically done as * part of user configuration (e.g., user changing keyboard shortcuts). However, * it can also be helpful when trying to change a binding on a particular locale * or platform. An "unbinding" is really just a binding with no command * identifier. For it to unbind a particular binding, it must match that binding * in its context identifier and scheme identifier. Subclasses (e.g., * KeyBinding) may require other properties to match (e.g., * keySequence). If these properties match, then this is an * unbinding. Note: the locale and platform can be different. *

*

* For example, imagine you have a key binding that looks like this: *

*
 * KeyBinding(command, scheme, context, "Ctrl+Shift+F")
 * 
*

* On GTK+, the "Ctrl+Shift+F" interferes with some native behaviour. To change * the binding, we first unbind the "Ctrl+Shift+F" key sequence by * assigning it a null command on the gtk platform. We then create a new binding * that maps the command to the "Esc Ctrl+F" key sequence. *

*
 *     KeyBinding("Ctrl+Shift+F",null,scheme,context,null,gtk,null,SYSTEM)
 *     KeyBinding("Esc Ctrl+F",parameterizedCommand,scheme,context,null,gtk,SYSTEM)
 * 
*

* Bindings are intended to be immutable objects. *

* * @since 1.4 */ public abstract class Binding { /** * The constant integer hash code value meaning the hash code has not yet * been computed. */ private static final int HASH_CODE_NOT_COMPUTED = -1; /** * A factor for computing the hash code for all key bindings. */ private final static int HASH_FACTOR = 89; /** * The seed for the hash code for all key bindings. */ private final static int HASH_INITIAL = Binding.class.getName().hashCode(); /** * The type of binding that is defined by the system (i.e., by the * application developer). In the case of an application based on the * Eclipse workbench, this is the registry. */ public static final int SYSTEM = 0; /** * The type of binding that is defined by the user (i.e., by the end user of * the application). In the case of an application based on the Eclipse * workbench, this is the preference store. */ public static final int USER = 1; /** * The parameterized command to which this binding applies. This value may * be null if this binding is meant to "unbind" an existing * binding. */ private final ParameterizedCommand command; /** * The context identifier to which this binding applies. This context must * be active before this key binding becomes active. This value will never * be null. */ private final String contextId; /** * The hash code for this key binding. This value is computed lazily, and * marked as invalid when one of the values on which it is based changes. */ private transient int hashCode = HASH_CODE_NOT_COMPUTED; /** * The locale in which this binding applies. This value may be * null if this binding is meant to apply to all locales. * This string should be in the same format returned by * Locale.getDefault().toString(). */ private final String locale; /** * The platform on which this binding applies. This value may be * null if this binding is meant to apply to all platforms. * This string should be in the same format returned by * SWT.getPlatform. */ private final String platform; /** * The identifier of the scheme in which this binding applies. This value * will never be null. */ private final String schemeId; /** * The string representation of this binding. This string is for debugging * purposes only, and is not meant to be displayed to the user. This value * is computed lazily. */ protected transient String string = null; /** * The type of binding this represents. This is used to distinguish between * different priority levels for bindings. For example, in our case, * USER bindings override SYSTEM bindings. */ private final int type; /** * Constructs a new instance of Binding. * * @param command * The parameterized command to which this binding applies; this * value may be null if the binding is meant to * "unbind" a previously defined binding. * @param schemeId * The scheme to which this binding belongs; this value must not * be null. * @param contextId * The context to which this binding applies; this value must not * be null. * @param locale * The locale to which this binding applies; this value may be * null if it applies to all locales. * @param platform * The platform to which this binding applies; this value may be * null if it applies to all platforms. * @param windowManager * The window manager to which this binding applies; this value * may be null if it applies to all window * managers. This value is currently ignored. * @param type * The type of binding. This should be either SYSTEM * or USER. */ protected Binding(final ParameterizedCommand command, final String schemeId, final String contextId, final String locale, final String platform, final String windowManager, final int type) { if (schemeId == null) { throw new NullPointerException("The scheme cannot be null"); //$NON-NLS-1$ } if (contextId == null) { throw new NullPointerException("The context cannot be null"); //$NON-NLS-1$ } if ((type != SYSTEM) && (type != USER)) { throw new IllegalArgumentException( "The type must be SYSTEM or USER"); //$NON-NLS-1$ } this.command = command; this.schemeId = schemeId.intern(); this.contextId = contextId.intern(); this.locale = (locale == null) ? null : locale.intern(); this.platform = (platform == null) ? null : platform.intern(); this.type = type; } /** * Tests whether this binding is intended to delete another binding. The * receiver must have a null command identifier. * * @param binding * The binding to test; must not be null. * This binding must be a SYSTEM binding. * @return true if the receiver deletes the binding defined by * the argument. */ final boolean deletes(final Binding binding) { boolean deletes = true; deletes &= Util.equals(getContextId(), binding.getContextId()); deletes &= Util.equals(getTriggerSequence(), binding .getTriggerSequence()); if (getLocale() != null) { deletes &= !Util.equals(getLocale(), binding.getLocale()); } if (getPlatform() != null) { deletes &= !Util.equals(getPlatform(), binding.getPlatform()); } deletes &= (binding.getType() == SYSTEM); deletes &= Util.equals(getParameterizedCommand(), null); return deletes; } /** * Tests whether this binding is equal to another object. Bindings are only * equal to other bindings with equivalent values. * * @param object * The object with which to compare; may be null. * @return true if the object is a binding with equivalent * values for all of its properties; false otherwise. */ public final boolean equals(final Object object) { if (this == object) { return true; } if (!(object instanceof Binding)) { return false; } final Binding binding = (Binding) object; if (!Util.equals(getParameterizedCommand(), binding .getParameterizedCommand())) { return false; } if (!Util.equals(getContextId(), binding.getContextId())) { return false; } if (!Util.equals(getTriggerSequence(), binding.getTriggerSequence())) { return false; } if (!Util.equals(getLocale(), binding.getLocale())) { return false; } if (!Util.equals(getPlatform(), binding.getPlatform())) { return false; } if (!Util.equals(getSchemeId(), binding.getSchemeId())) { return false; } return (getType() == binding.getType()); } /** * Returns the parameterized command to which this binding applies. If the * identifier is null, then this binding is "unbinding" an * existing binding. * * @return The fully-parameterized command; may be null. */ public final ParameterizedCommand getParameterizedCommand() { return command; } /** * Returns the identifier of the context in which this binding applies. * * @return The context identifier; never null. */ public final String getContextId() { return contextId; } /** * Returns the locale in which this binding applies. If the locale is * null, then this binding applies to all locales. This * string is the same format as returned by * Locale.getDefault().toString(). * * @return The locale; may be null. */ public final String getLocale() { return locale; } /** * Returns the platform on which this binding applies. If the platform is * null, then this binding applies to all platforms. This * string is the same format as returned by SWT.getPlatform(). * * @return The platform; may be null. */ public final String getPlatform() { return platform; } /** * Returns the identifier of the scheme in which this binding applies. * * @return The scheme identifier; never null. */ public final String getSchemeId() { return schemeId; } /** * Returns the sequence of trigger for a given binding. The triggers can be * anything, but above all it must be hashable. This trigger sequence is * used by the binding manager to distinguish between different bindings. * * @return The object representing an input event that will trigger this * binding; must not be null. */ public abstract TriggerSequence getTriggerSequence(); /** * Returns the type for this binding. As it stands now, this value will * either be SYSTEM or USER. In the future, * more types might be added. * * @return The type for this binding. */ public final int getType() { return type; } /** * Computes the hash code for this key binding based on all of its * attributes. * * @return The hash code for this key binding. */ public final int hashCode() { if (hashCode == HASH_CODE_NOT_COMPUTED) { hashCode = HASH_INITIAL; hashCode = hashCode * HASH_FACTOR + Util.hashCode(getParameterizedCommand()); hashCode = hashCode * HASH_FACTOR + Util.hashCode(getContextId()); hashCode = hashCode * HASH_FACTOR + Util.hashCode(getTriggerSequence()); hashCode = hashCode * HASH_FACTOR + Util.hashCode(getLocale()); hashCode = hashCode * HASH_FACTOR + Util.hashCode(getPlatform()); hashCode = hashCode * HASH_FACTOR + Util.hashCode(getSchemeId()); hashCode = hashCode * HASH_FACTOR + Util.hashCode(getType()); if (hashCode == HASH_CODE_NOT_COMPUTED) { hashCode++; } } return hashCode; } /** * The string representation of this binding -- for debugging purposes only. * This string should not be shown to an end user. This should be overridden * by subclasses that add properties. * * @return The string representation; never null. */ public String toString() { if (string == null) { final StringWriter sw = new StringWriter(); final BufferedWriter stringBuffer = new BufferedWriter(sw); try { stringBuffer.write("Binding("); //$NON-NLS-1$ stringBuffer.write(getTriggerSequence().toString()); stringBuffer.write(','); stringBuffer.newLine(); stringBuffer.write('\t'); stringBuffer.write(command==null?"":command.toString()); //$NON-NLS-1$ stringBuffer.write(','); stringBuffer.newLine(); stringBuffer.write('\t'); stringBuffer.write(schemeId); stringBuffer.write(','); stringBuffer.newLine(); stringBuffer.write('\t'); stringBuffer.write(contextId); stringBuffer.write(','); stringBuffer.write(locale==null?"":locale); //$NON-NLS-1$ stringBuffer.write(','); stringBuffer.write(platform==null?"":platform); //$NON-NLS-1$ stringBuffer.write(','); stringBuffer.write((type == SYSTEM) ? "system" : "user"); //$NON-NLS-1$//$NON-NLS-2$ stringBuffer.write(')'); stringBuffer.flush(); } catch (IOException e) { // shouldn't get this } string = sw.toString(); } return string; } }




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