| /******************************************************************************* |
| * Copyright (c) 2009 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.e4.core.internal.contexts; |
| |
| import java.util.List; |
| import org.eclipse.e4.core.contexts.IContextFunction; |
| import org.eclipse.e4.core.contexts.IEclipseContext; |
| import org.eclipse.e4.core.internal.contexts.EclipseContext.Scheduled; |
| |
| public class ValueComputation extends Computation { |
| |
| static class CycleException extends RuntimeException { |
| private static final long serialVersionUID = 1L; |
| private final String cycleMessage; |
| |
| CycleException(String cycleMessage) { |
| super("Cycle while computing value"); //$NON-NLS-1$ |
| this.cycleMessage = cycleMessage; |
| } |
| |
| String getCycleMessage() { |
| return cycleMessage; |
| } |
| |
| public String toString() { |
| return "\n" + cycleMessage + '\n'; //$NON-NLS-1$ |
| } |
| } |
| |
| private Object cachedValue; |
| private IEclipseContext context; |
| private String name; |
| private boolean valid; |
| private IContextFunction function; |
| private EclipseContext originatingContext; |
| private boolean computing; // cycle detection |
| |
| public ValueComputation(IEclipseContext context, IEclipseContext originatingContext, String name, IContextFunction computedValue) { |
| this.context = context; |
| this.originatingContext = (EclipseContext) originatingContext; |
| this.name = name; |
| this.function = computedValue; |
| } |
| |
| public int hashCode() { |
| final int prime = 31; |
| int result = 1; |
| result = prime * result + ((context == null) ? 0 : context.hashCode()); |
| result = prime * result + ((function == null) ? 0 : function.hashCode()); |
| result = prime * result + ((name == null) ? 0 : name.hashCode()); |
| result = prime * result + ((originatingContext == null) ? 0 : originatingContext.hashCode()); |
| return result; |
| } |
| |
| public boolean equals(Object obj) { |
| if (this == obj) |
| return true; |
| if (obj == null) |
| return false; |
| if (getClass() != obj.getClass()) |
| return false; |
| ValueComputation other = (ValueComputation) obj; |
| if (context == null) { |
| if (other.context != null) |
| return false; |
| } else if (!context.equals(other.context)) |
| return false; |
| if (function == null) { |
| if (other.function != null) |
| return false; |
| } else if (!function.equals(other.function)) |
| return false; |
| if (name == null) { |
| if (other.name != null) |
| return false; |
| } else if (!name.equals(other.name)) |
| return false; |
| if (originatingContext == null) { |
| if (other.originatingContext != null) |
| return false; |
| } else if (!originatingContext.equals(other.originatingContext)) |
| return false; |
| return true; |
| } |
| |
| protected void doHandleInvalid(ContextChangeEvent event, List<Scheduled> scheduled) { |
| valid = false; |
| cachedValue = null; |
| int eventType = event.getEventType(); |
| // if the originating context is being disposed, remove this value computation completely |
| if (eventType == ContextChangeEvent.DISPOSE) { |
| IEclipseContext eventsContext = event.getContext(); |
| if (originatingContext.equals(eventsContext)) { |
| removeAll(); |
| return; |
| } |
| return; |
| } |
| if (event.getName().equals(name)) |
| originatingContext.removeLocalValueComputations(name); |
| originatingContext.invalidate(name, eventType == ContextChangeEvent.DISPOSE ? ContextChangeEvent.REMOVED : eventType, event.getOldValue(), scheduled); |
| } |
| |
| public Object get() { |
| if (valid) |
| return cachedValue; |
| if (this.computing) |
| throw new CycleException(this.toString()); |
| |
| Computation oldComputation = EclipseContext.currentComputation.get(); |
| EclipseContext.currentComputation.set(this); |
| computing = true; |
| try { |
| cachedValue = function.compute(originatingContext); |
| valid = true; |
| } catch (CycleException ex) { |
| throw new CycleException(ex.getCycleMessage() + '\n' + this.toString()); |
| } finally { |
| computing = false; |
| EclipseContext.currentComputation.set(oldComputation); |
| } |
| startListening(); |
| return cachedValue; |
| } |
| |
| public String toString() { |
| StringBuffer result = new StringBuffer(); |
| result.append("ValueComputation("); //$NON-NLS-1$ |
| result.append(context); |
| result.append('/'); |
| result.append(originatingContext); |
| result.append(','); |
| result.append(name); |
| result.append(')'); |
| return result.toString(); |
| } |
| } |