/*******************************************************************************
* Copyright (c) 2005, 2007 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.internal.handlers;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.StringWriter;
import org.eclipse.core.commands.IHandler;
import org.eclipse.core.expressions.Expression;
import org.eclipse.core.expressions.IEvaluationContext;
import org.eclipse.ui.ISources;
import org.eclipse.ui.handlers.IHandlerActivation;
import org.eclipse.ui.handlers.IHandlerService;
import org.eclipse.ui.internal.services.EvaluationResultCache;
/**
* <p>
* A token representing the activation of a handler. This token can later be
* used to cancel that activation. Without this token, then handler will only
* become inactive if the component in which the handler was activated is
* destroyed.
* </p>
* <p>
* This caches the command id and the handler, so that they can later be
* identified.
* </p>
* <p>
* <b>Note:</b> this class has a natural ordering that is inconsistent with
* equals.
* </p>
*
* @since 3.1
*/
final class HandlerActivation extends EvaluationResultCache implements
IHandlerActivation {
/**
* The identifier for the command which the activated handler handles. This
* value is never <code>null</code>.
*/
private final String commandId;
/**
* The depth of services at which this token was created. This is used as a
* final tie-breaker if all other things are equivalent.
*/
private final int depth;
/**
* The handler that has been activated. This value may be <code>null</code>.
*/
private final IHandler handler;
/**
* The handler service from which this handler activation was request. This
* value is never <code>null</code>.
*/
private final IHandlerService handlerService;
/**
* Constructs a new instance of <code>HandlerActivation</code>.
*
* @param commandId
* The identifier for the command which the activated handler
* handles. This value must not be <code>null</code>.
* @param handler `
* The handler that has been activated. This value may be
* <code>null</code>.
* @param expression
* The expression that must evaluate to <code>true</code>
* before this handler is active. This value may be
* <code>null</code> if it is always active.</code>.
* @param depth
* The depth at which this activation was created within the
* services hierarchy. This is used as the final tie-breaker if
* all other conditions are equal. This should be a positive
* integer.
* @param handlerService
* The handler service from which the handler activation was
* requested; must not be <code>null</code>.
* @see ISources
*/
HandlerActivation(final String commandId, final IHandler handler,
final Expression expression, final int depth,
final IHandlerService handlerService) {
super(expression);
if (commandId == null) {
throw new NullPointerException(
"The command identifier for a handler activation cannot be null"); //$NON-NLS-1$
}
if (handlerService == null) {
throw new NullPointerException(
"The handler service for an activation cannot be null"); //$NON-NLS-1$
}
this.commandId = commandId;
this.depth = depth;
this.handler = handler;
this.handlerService = handlerService;
}
public final void clearActive() {
clearResult();
}
/**
* Implement {@link Comparable#compareTo(Object)}.
* <p>
* <b>Note:</b> this class has a natural ordering that is inconsistent with
* equals.
* </p>
*/
public final int compareTo(final Object object) {
final IHandlerActivation activation = (IHandlerActivation) object;
int difference;
// Check the priorities
int thisPriority = this.getSourcePriority();
int thatPriority = activation.getSourcePriority();
// rogue bit problem - ISources.ACTIVE_MENU
int thisLsb = 0;
int thatLsb = 0;
if (((thisPriority & ISources.ACTIVE_MENU) | (thatPriority & ISources.ACTIVE_MENU)) != 0) {
thisLsb = thisPriority & 1;
thisPriority = (thisPriority >> 1) & 0x7fffffff;
thatLsb = thatPriority & 1;
thatPriority = (thatPriority >> 1) & 0x7fffffff;
}
difference = thisPriority - thatPriority;
if (difference != 0) {
return difference;
}
// if all of the higher bits are the same, check the
// difference of the LSB
difference = thisLsb - thatLsb;
if (difference != 0) {
return difference;
}
// Check depth
final int thisDepth = this.getDepth();
final int thatDepth = activation.getDepth();
difference = thisDepth - thatDepth;
return difference;
}
public final String getCommandId() {
return commandId;
}
public final int getDepth() {
return depth;
}
public final IHandler getHandler() {
return handler;
}
public final IHandlerService getHandlerService() {
return handlerService;
}
public final boolean isActive(final IEvaluationContext context) {
return evaluate(context);
}
public final String toString() {
final StringWriter sw = new StringWriter();
final BufferedWriter buffer = new BufferedWriter(sw);
try {
buffer.write("HandlerActivation(commandId="); //$NON-NLS-1$
buffer.write(commandId);
buffer.write(',');
buffer.newLine();
buffer.write("\thandler="); //$NON-NLS-1$
buffer.write(handler==null?"":handler.toString()); //$NON-NLS-1$
buffer.write(',');
buffer.newLine();
buffer.write("\texpression="); //$NON-NLS-1$
Expression exp = getExpression();
buffer.write(exp==null?"":exp.toString()); //$NON-NLS-1$
buffer.write(",sourcePriority="); //$NON-NLS-1$
buffer.write(Integer.toString(getSourcePriority()));
buffer.write(')');
buffer.flush();
} catch (IOException e) {
// we're a string buffer, there should be no IO exception
}
return sw.toString();
}
}