/*******************************************************************************
* Copyright (c) 2006, 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.expressions;
import java.util.Collection;
import org.eclipse.core.expressions.EvaluationResult;
import org.eclipse.core.expressions.Expression;
import org.eclipse.core.expressions.ExpressionInfo;
import org.eclipse.core.expressions.IEvaluationContext;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.ui.ISources;
import org.eclipse.ui.IWorkbenchWindow;
/**
* <p>
* An expression that can control the activation of a handler derived from a
* viewer contribution. The viewer contribution is linked to a menu with a
* particular identifier, as well as some other criteria. This expression checks
* the target menu id, and contains a child expression for the other criteria.
* </p>
* <p>
* This class is not intended for use outside of the
* <code>org.eclipse.ui.workbench</code> plug-in.
* </p>
*
* @see ISources#ACTIVE_MENU_NAME
* @since 3.2
*/
public final class LegacyViewerContributionExpression extends
WorkbenchWindowExpression {
/**
* The seed for the hash code for all schemes.
*/
private static final int HASH_INITIAL = LegacyViewerContributionExpression.class
.getName().hashCode();
/**
* The child expression for this viewer contribution. This value may be
* <code>null</code> if there are no criteria beyond the menu id.
*/
private final Expression expression;
/**
* The identifier of the menu to which this viewer contribution applies.
* This value is never <code>null</code>.
*/
private final String targetId;
/**
* Constructs a new {@link LegacyViewerContributionExpression}.
*
* @param targetId
* The identifier of the menu to which this viewer contribution
* applies; never <code>null</code>.
* @param window
* The workbench window which must be active for this expression
* to evaluate to <code>true</code>; may be <code>null</code>
* if the window should be disregarded.
* @param childExpression
* The child expression for this viewer contribution; may be
* <code>null</code>.
*/
public LegacyViewerContributionExpression(final String targetId,
final IWorkbenchWindow window, final Expression childExpression) {
super(window);
if (targetId == null) {
throw new NullPointerException("The targetId cannot be null"); //$NON-NLS-1$
}
this.targetId = targetId;
this.expression = childExpression;
}
public final void collectExpressionInfo(final ExpressionInfo info) {
super.collectExpressionInfo(info);
info.addVariableNameAccess(ISources.ACTIVE_MENU_NAME);
if (expression != null) {
expression.collectExpressionInfo(info);
}
}
protected final int computeHashCode() {
int hashCode = HASH_INITIAL * HASH_FACTOR + hashCode(getWindow());
hashCode = hashCode * HASH_FACTOR + hashCode(expression);
hashCode = hashCode * HASH_FACTOR + hashCode(targetId);
return hashCode;
}
public final boolean equals(final Object object) {
if (object instanceof LegacyViewerContributionExpression) {
final LegacyViewerContributionExpression that = (LegacyViewerContributionExpression) object;
return equals(this.targetId, that.targetId)
&& equals(this.expression, that.expression)
&& equals(this.getWindow(), that.getWindow());
}
return false;
}
public final EvaluationResult evaluate(final IEvaluationContext context)
throws CoreException {
final EvaluationResult result = super.evaluate(context);
if (result == EvaluationResult.FALSE) {
return result;
}
final Object value = context.getVariable(ISources.ACTIVE_MENU_NAME);
if (value instanceof String) {
final String menuId = (String) value;
if (targetId.equals(menuId)) {
if (expression == null) {
return EvaluationResult.TRUE;
}
return expression.evaluate(context);
}
} else if (value instanceof Collection) {
final Collection menuIds = (Collection) value;
if (menuIds.contains(targetId)) {
if (expression == null) {
return EvaluationResult.TRUE;
}
return expression.evaluate(context);
}
}
return EvaluationResult.FALSE;
}
public final String toString() {
final StringBuffer buffer = new StringBuffer();
buffer.append("ViewerContributionExpression("); //$NON-NLS-1$
buffer.append(targetId);
buffer.append(',');
buffer.append(expression);
buffer.append(',');
buffer.append(getWindow());
buffer.append(')');
return buffer.toString();
}
}