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/*******************************************************************************
* Copyright (c) 2005, 2017 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.cheatsheets.composite.model;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.osgi.util.NLS;
import org.eclipse.ui.internal.cheatsheets.Messages;
import org.eclipse.ui.internal.cheatsheets.composite.parser.IStatusContainer;
import org.eclipse.ui.internal.provisional.cheatsheets.ICompositeCheatSheetTask;
/**
* Class to keep track of dependencies between tasks
*/
public class TaskDependencies {
private class Dependency {
private AbstractTask sourceTask;
private String requiredTaskId;
public Dependency(AbstractTask sourceTask, String requiredTaskId) {
this.sourceTask = sourceTask;
this.requiredTaskId = requiredTaskId;
}
public AbstractTask getSourceTask() {
return sourceTask;
}
public String getRequiredTaskId() {
return requiredTaskId;
}
}
private List<Dependency> dependencies;
private Map<String, AbstractTask> taskIdMap = new HashMap<>();
public void saveId(AbstractTask task) {
String id = task.getId();
if (id != null) {
taskIdMap.put(id, task);
}
}
public AbstractTask getTask(String id) {
return taskIdMap.get(id);
}
public TaskDependencies() {
dependencies = new ArrayList<>();
}
/**
* Register a dependency between tasks
* @param sourceTask a task which cannot be started until another task is completed
* @param requiredTaskId the id of the task which must be completed first
*/
public void addDependency(AbstractTask sourceTask, String requiredTaskId) {
dependencies.add(new Dependency(sourceTask, requiredTaskId));
}
/**
* Resolve all of the dependencies updating the individual tasks
* @param model The composite cheat sheet
* @param status An object used to add error status
*/
public void resolveDependencies(IStatusContainer status) {
for (Iterator<Dependency> dependencyIterator = dependencies.iterator(); dependencyIterator.hasNext();) {
Dependency dep = dependencyIterator.next();
AbstractTask sourceTask = dep.getSourceTask();
AbstractTask requiredTask = getTask(dep.requiredTaskId);
if (requiredTask == null) {
String message = NLS.bind(Messages.ERROR_PARSING_INVALID_ID, (new Object[] {dep.getRequiredTaskId()}));
status.addStatus(IStatus.ERROR, message, null);
} else if (!sourceTask.requiresTask(requiredTask)) {
sourceTask.addRequiredTask(requiredTask);
}
}
checkForCircularities (status);
}
/**
* Check for circular dependencies using the following algorithm.
* 1. Create a set of all the tasks which have an id (tasks without id cannot be in a cycle).;
* 2. Remove from the set any tasks which depend on no other task, these cannot be part of a cycle
* 3. Remove from the set any tasks which only depend on tasks already removed, these cannot be
* part of a cycle.
* 4. Repeat step 3 until not further tasks can be removed
* 5. Any tasks remaining are part of a cycle or depend on a task in a cycle
* @param model
* @param status
*/
private void checkForCircularities (IStatusContainer status) {
Set<ICompositeCheatSheetTask> tasks = new HashSet<>();
// Combine steps 1 + 2
for (Iterator<AbstractTask> idIterator = taskIdMap.values().iterator(); idIterator.hasNext();) {
AbstractTask nextTask = idIterator.next();
if (nextTask.getRequiredTasks().length > 0) {
tasks.add(nextTask);
}
}
boolean makingProgress = true;
while (makingProgress) {
// Use a new set to store the tasks which are still cycle candidates to avoid
// iterating over and deleting from the same set.
Set<ICompositeCheatSheetTask> remainingTasks = new HashSet<>();
makingProgress = false;
for (Iterator<ICompositeCheatSheetTask> taskIterator = tasks.iterator(); taskIterator.hasNext()
&& !makingProgress;) {
boolean mayBeInCycle = false;
ICompositeCheatSheetTask nextTask = taskIterator.next();
ICompositeCheatSheetTask[] requiredTasks = nextTask.getRequiredTasks();
for (int i = 0; i < requiredTasks.length; i++) {
if (tasks.contains(requiredTasks[i])) {
mayBeInCycle = true;
}
}
if (mayBeInCycle) {
remainingTasks.add(nextTask);
} else {
makingProgress = true;
}
}
tasks = remainingTasks;
}
if (!tasks.isEmpty()) {
status.addStatus(IStatus.ERROR, Messages.ERROR_PARSING_CYCLE_DETECTED, null);
// Detect one of the cycles and report its members
List<ICompositeCheatSheetTask> cycle = new ArrayList<>();
ICompositeCheatSheetTask cycleStartTask = tasks.iterator().next();
while (!cycle.contains(cycleStartTask)) {
cycle.add(cycleStartTask);
ICompositeCheatSheetTask[] requiredTasks = cycleStartTask.getRequiredTasks();
for (int i = 0; i < requiredTasks.length; i++) {
if (tasks.contains(requiredTasks[i])) {
cycleStartTask=requiredTasks[i];
}
}
}
// Now the list contains a cycle and possibly additional tasks at the start
// of the list
boolean cycleStarted = false;
String thisTask = null;
String lastTask = null;
String firstTask = null;
for (Iterator<ICompositeCheatSheetTask> cycleIterator = cycle.iterator(); cycleIterator.hasNext();) {
ICompositeCheatSheetTask task = cycleIterator.next();
if (task == cycleStartTask) {
cycleStarted = true;
firstTask = task.getName();
}
if (cycleStarted) {
// Save the name of this task
lastTask = thisTask;
thisTask = task.getName();
if (lastTask != null) {
String message = NLS.bind(Messages.ERROR_PARSING_CYCLE_CONTAINS, (new Object[] {lastTask, thisTask}));
status.addStatus(IStatus.ERROR, message, null);
}
}
}
String message = NLS.bind(Messages.ERROR_PARSING_CYCLE_CONTAINS, (new Object[] {thisTask, firstTask}));
status.addStatus(IStatus.ERROR, message, null);
}
}
}
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