source: trunk/autoquest-core-tasktrees/src/main/java/de/ugoe/cs/autoquest/tasktrees/temporalrelation/SequenceForTaskDetectionRule.java @ 1129

//   Copyright 2012 Georg-August-Universität Göttingen, Germany
//
//   Licensed under the Apache License, Version 2.0 (the "License");
//   you may not use this file except in compliance with the License.
//   You may obtain a copy of the License at
//
//       http://www.apache.org/licenses/LICENSE-2.0
//
//   Unless required by applicable law or agreed to in writing, software
//   distributed under the License is distributed on an "AS IS" BASIS,
//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//   See the License for the specific language governing permissions and
//   limitations under the License.

package de.ugoe.cs.autoquest.tasktrees.temporalrelation;

import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import de.ugoe.cs.autoquest.tasktrees.nodeequality.NodeEquality;
import de.ugoe.cs.autoquest.tasktrees.nodeequality.NodeEqualityRuleManager;
import de.ugoe.cs.autoquest.tasktrees.treeifc.IIteration;
import de.ugoe.cs.autoquest.tasktrees.treeifc.ISelection;
import de.ugoe.cs.autoquest.tasktrees.treeifc.ISequence;
import de.ugoe.cs.autoquest.tasktrees.treeifc.ITaskTreeBuilder;
import de.ugoe.cs.autoquest.tasktrees.treeifc.ITaskTreeNode;
import de.ugoe.cs.autoquest.tasktrees.treeifc.ITaskTreeNodeFactory;
import de.ugoe.cs.autoquest.usageprofiles.Trie;
import de.ugoe.cs.autoquest.usageprofiles.TrieProcessor;
import de.ugoe.cs.util.StopWatch;
import de.ugoe.cs.util.console.Console;

/**
 * <p>
 * TODO comment
 * </p>
 * 
 * @author Patrick Harms
 */
class SequenceForTaskDetectionRule implements TemporalRelationshipRule {
    
    /**
     * <p>
     * the task tree node factory to be used for creating substructures for the temporal
     * relationships identified during rule
     * </p>
     */
    private ITaskTreeNodeFactory taskTreeNodeFactory;
    /**
     * <p>
     * the task tree builder to be used for creating substructures for the temporal relationships
     * identified during rule application
     * </p>
     */
    private ITaskTreeBuilder taskTreeBuilder;

    /**
     * <p>
     * the node comparator to be used for comparing task tree nodes
     * </p>
     */
    private TaskTreeNodeComparator nodeComparator;

    /**
     * <p>
     * instantiates the rule and initializes it with a node equality rule manager and the minimal
     * node equality identified sublist must have to consider them as iterated.
     * </p>
     */
    SequenceForTaskDetectionRule(NodeEqualityRuleManager nodeEqualityRuleManager,
                                 NodeEquality            minimalNodeEquality,
                                 ITaskTreeNodeFactory    taskTreeNodeFactory,
                                 ITaskTreeBuilder        taskTreeBuilder)
    {
        this.taskTreeNodeFactory = taskTreeNodeFactory;
        this.taskTreeBuilder = taskTreeBuilder;
        
        this.nodeComparator =
            new TaskTreeNodeComparator(nodeEqualityRuleManager, minimalNodeEquality);
    }

    /* (non-Javadoc)
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return "SequenceForTaskDetectionRule";
    }

    /*
     * (non-Javadoc)
     * 
     * @see de.ugoe.cs.tasktree.temporalrelation.TemporalRelationshipRule#apply(TaskTreeNode,
     * boolean)
     */
    @Override
    public RuleApplicationResult apply(ITaskTreeNode parent, boolean finalize) {
        if (!(parent instanceof ISequence)) {
            return null;
        }

        if (!finalize) {
            // the rule is always feasible as tasks may occur at any time
            RuleApplicationResult result = new RuleApplicationResult();
            result.setRuleApplicationStatus(RuleApplicationStatus.FEASIBLE);
            return result;
        }

        List<ITaskTreeNode> children = parent.getChildren();
        List<ISequence> sessions = new LinkedList<ISequence>();
        
        for (ITaskTreeNode child : children) {
            if (child instanceof ISequence) {
                sessions.add((ISequence) child);
            }
            else {
                Console.println("provided parent is no parent of sessions");
                return null;
            }
        }
        
        RuleApplicationData appData = new RuleApplicationData(sessions);

        boolean finished = false;
        
        // this is the real rule application. Loop while something is replaced.
        do {
            System.out.println();
            
            appData.getStopWatch().start("whole loop");
            detectAndReplaceIterations(appData);
            //mergeEqualTasks(appData);
            appData.getStopWatch().start("task replacement");
            detectAndReplaceTasks(appData);
            appData.getStopWatch().stop("task replacement");
            appData.getStopWatch().stop("whole loop");
            
            //((TaskTreeNodeComparator) nodeComparator).getStopWatch().dumpStatistics(System.out);
            //((TaskTreeNodeComparator) nodeComparator).getStopWatch().reset();
            
            appData.getStopWatch().dumpStatistics(System.out);
            appData.getStopWatch().reset();
            
            finished = (appData.getReplacementCounter() == 0);
        }
        while (!finished);
        
        System.out.println("created " + appData.getResult().getNewlyCreatedParentNodes().size() +
                           " new parent nodes\n");
        
        if (appData.getResult().getNewlyCreatedParentNodes().size() > 0) {
            appData.getResult().setRuleApplicationStatus(RuleApplicationStatus.FINISHED);
        }
        
        return appData.getResult();
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param appData
     */
    private void detectAndReplaceIterations(RuleApplicationData appData) {
        System.out.print("detecting iterations");
        appData.getStopWatch().start("detecting iterations");
        
        List<ISequence> sessions = appData.getSessions();
        int foundIterations = 0;
        
        for (ISequence session : sessions) {
            foundIterations += detectAndReplaceIterations(session, appData);
        }
        
        appData.getStopWatch().stop("detecting iterations");
        System.out.println(" --> found " + foundIterations);
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param appData
     */
    private int detectAndReplaceIterations(ISequence           session,
                                           RuleApplicationData appData)
    {
        int count = 0;
        
        TemporalRelationshipRule rule = new SimpleIterationDetectionRule
            (nodeComparator, taskTreeNodeFactory, taskTreeBuilder);

        RuleApplicationResult result = rule.apply(session, true);
            
        if ((result != null) && (result.getNewlyCreatedParentNodes() != null)) {
            for (ITaskTreeNode newParent : result.getNewlyCreatedParentNodes()) {
                appData.getResult().addNewlyCreatedParentNode(newParent);
                if (newParent instanceof IIteration) {
                    count++;
                }
            }
        }
        
        return count;
    }

//    /**
//     * <p>
//     * TODO: comment
//     * </p>
//     *
//     * @param appData
//     */
//    private void mergeEqualTasks(RuleApplicationData appData) {
//        System.out.println("merging equal tasks");
//        appData.getStopWatch().start("merging equal tasks");
//        
//        int replacements = 0;
//        List<ISequence> sessions = appData.getSessions();
//        
//        IdentityHashMap<ITaskTreeNode, ITaskTreeNode> replacedChildren =
//            new IdentityHashMap<ITaskTreeNode, ITaskTreeNode>();
//        
//        for (int sessionIdx1 = 0; sessionIdx1 < sessions.size(); sessionIdx1++) {
//            List<ITaskTreeNode> children1 = appData.getSessions().get(sessionIdx1).getChildren();
//            for (int childIdx1 = 0; childIdx1 < children1.size(); childIdx1++) {
//                // this is the child of which we search equal other children to merge and to
//                // replace with one single unique node
//                ITaskTreeNode child1 = children1.get(childIdx1);
//                
//                if (replacedChildren.containsKey(child1)) {
//                    continue;
//                }
//                
//                // now search for all other children that are equal. Also record the session they
//                // belong to as well as the index in that session
//                List<ITaskTreeNode> equalChildren = new LinkedList<ITaskTreeNode>();
//                List<Integer> sessionIndexes = new LinkedList<Integer>();
//                List<Integer> childIndexes = new LinkedList<Integer>();
//
//                // add all information about the current child
//                equalChildren.add(child1);
//                sessionIndexes.add(sessionIdx1);
//                childIndexes.add(childIdx1);
//                
//                for (int sessionIdx2 = sessionIdx1; sessionIdx2 < sessions.size(); sessionIdx2++) {
//                    List<ITaskTreeNode> children2 =
//                          appData.getSessions().get(sessionIdx2).getChildren();
//                    
//                    int startIndex = (sessionIdx1 == sessionIdx2) ? childIdx1 + 1 : 0;
//                    
//                    for (int childIdx2 = startIndex; childIdx2 < children2.size(); childIdx2++) {
//                        ITaskTreeNode child2 = children2.get(childIdx2);
//                        
//                        if ((child1 != child2) && (nodeComparator.equals(child1, child2))) {
//                            // this is an equal child --> record its occurrence
//                            equalChildren.add(child2);
//                            sessionIndexes.add(sessionIdx2);
//                            childIndexes.add(childIdx2);
//                        }
//                    }
//                }
//                
//                // now merge the found children
//                if (equalChildren.size() > 1) {
//                    ITaskTreeNode replacement =
//                        mergeVariantsOfTasks(child1.toString(), equalChildren);
//
//                    for (int i = 0; i < sessionIndexes.size(); i++) {
//                        taskTreeBuilder.setChild(appData.getSessions().get(sessionIndexes.get(i)),
//                                                 childIndexes.get(i), replacement);
//                    
//                        replacements++;
//                    }
//                    
//                    // remember the replacement to prevent comparison of merged nodes
//                    replacedChildren.put(replacement, replacement);
//                    
//                    System.out.println
//                        ("replaced " + sessionIndexes.size() + " occurrences of " + child1);
//                }
//            }
//        }
//
//        appData.getStopWatch().stop("merging equal tasks");
//        
//        System.out.println("replaced " + replacements + " equal tasks with unique replacements");
//    }
//
    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param appData
     */
    private void detectAndReplaceTasks(RuleApplicationData appData) {
        System.out.println("detecting and replacing tasks");
        appData.getStopWatch().start("detecting tasks");
        
        getSequencesOccuringMostOften(appData);

        appData.getStopWatch().stop("detecting tasks");
        appData.getStopWatch().start("replacing tasks");
        
        replaceSequencesOccurringMostOften(appData);
        
        appData.getStopWatch().stop("replacing tasks");
        System.out.println("detected and replaced " + appData.getLastFoundTasks().size() + " tasks");
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param i
     * @return
     */
    private void getSequencesOccuringMostOften(RuleApplicationData appData) {
        System.out.println("determining most prominent tasks");

        Tasks tasks;
        boolean createNewTrie = (appData.getLastTrie() == null) ||
            appData.getReplacementCounter() > 0; // tree has changed
        
        do {
            if (createNewTrie) {
                createNewTrie(appData);
            }
            
            MaxCountAndLongestTasksFinder finder = new MaxCountAndLongestTasksFinder();
            appData.getLastTrie().process(finder);
        
            tasks = finder.getFoundTasks();
            
            createNewTrie = false;
            
            for (List<ITaskTreeNode> task : tasks) {
                if (task.size() >= appData.getTrainedSequenceLength()) {
                    // Trie must be recreated with a longer sequence length to be sure that
                    // the found sequences occurring most often are found in their whole length
                    appData.setTrainedSequenceLength(appData.getTrainedSequenceLength() + 1);
                    createNewTrie = true;
                    break;
                }
            }
        }
        while (createNewTrie);
        
        appData.setLastFoundTasks(tasks);

        System.out.println("found " + appData.getLastFoundTasks().size() + " tasks occurring " +
                           appData.getLastFoundTasks().getOccurrenceCount() + " times");
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param parent
     * @return
     */
    private void createNewTrie(RuleApplicationData appData) {
        System.out.println("training trie with a maximum sequence length of " +
                           appData.getTrainedSequenceLength());

        appData.getStopWatch().start("training trie");
        appData.setLastTrie(new Trie<ITaskTreeNode>(nodeComparator));
    
        List<ISequence> sessions = appData.getSessions();
        
        for (ISequence session : sessions) {
            trainTrie(session, appData);
        }
        
        appData.getStopWatch().stop("training trie");
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param trie
     * @param parent
     */
    private void trainTrie(ISequence session, RuleApplicationData appData) {
        List<ITaskTreeNode> children = session.getChildren();
        
        if ((children != null) && (children.size() > 0)) {
            appData.getLastTrie().train(children, appData.getTrainedSequenceLength());
        }
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param appData
     */
    private void replaceSequencesOccurringMostOften(RuleApplicationData appData) {
        appData.resetReplacementCounter();

        if ((appData.getLastFoundTasks().size() > 0) &&
            (appData.getLastFoundTasks().getOccurrenceCount() > 1))
        {
            System.out.println("replacing tasks occurrences with merged variants of all versions");

            for (List<ITaskTreeNode> task : appData.getLastFoundTasks()) {
                String taskId = "task " + RuleUtils.getNewId();
                System.out.println("replacing " + taskId + ": " + task);

                appData.clearTaskOccurrences();
                determineVariantsOfTaskOccurrences(task, appData.getSessions(), appData);
                
                appData.getStopWatch().start("merging task nodes");
                ITaskTreeNode taskReplacement = mergeVariantsOfTaskOccurrence(taskId, appData);
                appData.getStopWatch().stop("merging task nodes");

                appData.resetReplacementCounter();
                replaceTaskOccurrences(task, taskReplacement, appData.getSessions(), appData);

                if (appData.getReplacementCounter() > 0) {
                    appData.getResult().addNewlyCreatedParentNode(taskReplacement);
                }

                if (appData.getReplacementCounter() <
                    appData.getLastFoundTasks().getOccurrenceCount())
                {
                    System.out.println(taskId + ": replaced task only " +
                                       appData.getReplacementCounter() +
                                       " times instead of expected " +
                                       appData.getLastFoundTasks().getOccurrenceCount());
                }
            }
        }
        
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param tree
     */
    private void determineVariantsOfTaskOccurrences(List<ITaskTreeNode> task,
                                                    List<ISequence>     sessions,
                                                    RuleApplicationData appData)
    {
        for (ISequence session : sessions) {
            int index = -1;
                
            List<ITaskTreeNode> children = session.getChildren();

            do {
                index = getSubListIndex(children, task, ++index);

                if (index > -1) {
                    ISequence taskOccurrence = RuleUtils.getSubSequenceInRange
                            (session, index, index + task.size() - 1, null,
                             taskTreeNodeFactory, taskTreeBuilder);

                    appData.addTaskOccurrence(taskOccurrence);

                    // let the index point to the last element the belongs the identified occurrence
                    index += task.size() - 1;
                }
            }
            while (index > -1);
        }
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param appData
     * @return
     */
    private ITaskTreeNode mergeVariantsOfTaskOccurrence(String              taskId,
                                                        RuleApplicationData appData)
    {
        return mergeVariantsOfTasks(taskId, appData.getTaskOccurrences());
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param appData
     * @return
     */
    private ITaskTreeNode mergeVariantsOfTasks(String description, List<ITaskTreeNode> variants) {
        // merge but preserve lexically distinct variants
        TaskTreeNodeMerger merger = new TaskTreeNodeMerger
            (taskTreeNodeFactory, taskTreeBuilder, nodeComparator);
        
        merger.mergeTaskNodes(variants);
        
        if (variants.size() == 1) {
            ITaskTreeNode replacement = variants.get(0);
            taskTreeBuilder.setDescription(replacement, description);
            return replacement;
        }
        else {
            ISelection selection = taskTreeNodeFactory.createNewSelection();
            taskTreeBuilder.setDescription(selection, "variants of task " + description);
            
            for (ITaskTreeNode variant : variants) {
                taskTreeBuilder.addChild(selection, variant);
            }
            
            return selection;
        }
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param task
     * @param parent
     * @param treeBuilder
     * @param nodeFactory
     * @param result
     */
    private void replaceTaskOccurrences(List<ITaskTreeNode> task,
                                        ITaskTreeNode       replacement,
                                        List<ISequence>     sessions,
                                        RuleApplicationData appData)
    {
        // now check the children themselves for an occurrence of the task
        for (int i = 0; i < sessions.size(); i++) {
            ISequence session = sessions.get(i);
            
            int index = -1;
        
            List<ITaskTreeNode> children = session.getChildren();

            do {
                index = getSubListIndex(children, task, ++index);

                if (index > -1) {
                    if ((!(replacement instanceof ISequence)) ||
                        (task.size() < children.size()))
                    {
                        for (int j = index; j < index + task.size(); j++) {
                            taskTreeBuilder.removeChild(session, index);
                        }

                        taskTreeBuilder.addChild(session, index, replacement);
                        appData.incrementReplacementCounter();

                        children = session.getChildren();
                    }
                    else {
                        // the whole list of children is an occurrence of this task. So ask the
                        // caller of the method to replace the whole node
                        sessions.set(i, (ISequence) replacement);
                        appData.incrementReplacementCounter();
                        break;
                    }
                }
            }
            while (index > -1);
        }
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param trie
     * @param object
     * @return
     */
    private int getSubListIndex(List<ITaskTreeNode> list,
                                List<ITaskTreeNode> subList,
                                int                 startIndex)
    {
        boolean matchFound;
        int result = -1;
        
        for (int i = startIndex; i <= list.size() - subList.size(); i++) {
            matchFound = true;
            
            for (int j = 0; j < subList.size(); j++) {
                if (!nodeComparator.equals(list.get(i + j), subList.get(j))) {
                    matchFound = false;
                    break;
                }
            }
            
            if (matchFound) {
                result = i;
                break;
            }
        }
        
        return result;
    }
    
    /**
     * <p>
     * TODO comment
     * </p>
     * 
     * @author Patrick Harms
     */
    private class MaxCountAndLongestTasksFinder implements TrieProcessor<ITaskTreeNode> {
        
        /**
         * 
         */
        private int currentCount;
        
        /**
         * 
         */
        private List<List<ITaskTreeNode>> foundTasks = new LinkedList<List<ITaskTreeNode>>();

        /**
         * <p>
         * TODO: comment
         * </p>
         *
         * @param maxCount
         */
        public MaxCountAndLongestTasksFinder() {
            super();
            this.currentCount = 0;
        }

        /* (non-Javadoc)
         * @see de.ugoe.cs.autoquest.usageprofiles.TrieProcessor#process(java.util.List, int)
         */
        @Override
        public TrieProcessor.Result process(List<ITaskTreeNode> task, int count) {
            if (task.size() < 2) {
                // ignore single nodes
                return TrieProcessor.Result.CONTINUE;
            }
            
            if (count < 2) {
                // ignore singular occurrences
                return TrieProcessor.Result.SKIP_NODE;
            }

            if (this.currentCount > count) {
                // ignore this children of this node, as they may have only smaller counts than
                // the already found tasks
                return TrieProcessor.Result.SKIP_NODE;
            }
            
            if (this.currentCount < count) {
                // the provided task occurs more often that all tasks found so far.
                // clear all found tasks and use the new count as the one searched for
                foundTasks.clear();
                this.currentCount = count;
            }
            
            if (this.currentCount == count) {
                // the task is of interest. Sort it into the other found tasks so that
                // the longest come first
                boolean added = false;
                for (int i = 0; i < foundTasks.size(); i++) {
                    if (foundTasks.get(i).size() < task.size()) {
                        // defensive copy
                        foundTasks.add(i, new LinkedList<ITaskTreeNode>(task)); // defensive copy
                        added = true;
                        break;
                    }
                }
                
                if (!added) {
                    foundTasks.add(new LinkedList<ITaskTreeNode>(task)); // defensive copy
                }
            }
            
            return TrieProcessor.Result.CONTINUE;
        }

        /**
         * <p>
         * TODO: comment
         * </p>
         *
         * @return
         */
        public Tasks getFoundTasks() {
            removePermutationsOfShorterTasks();
            return new Tasks(currentCount, foundTasks);
        }

        /**
         * <p>
         * TODO: comment
         * </p>
         *
         */
        private void removePermutationsOfShorterTasks() {
            // now iterate the sorted list and for each task remove all other tasks that are shorter
            // (i.e. come later in the sorted list) and that represent a subpart of the task
            for (int i = 0; i < foundTasks.size(); i++) {
                for (int j = i + 1; j < foundTasks.size();) {
                    if (foundTasks.get(j).size() < foundTasks.get(i).size()) {
                        // found a task that is a potential subtask. Check for this and remove the
                        // subtask if needed
                        List<ITaskTreeNode> longTask = foundTasks.get(i);
                        List<ITaskTreeNode> shortTask = foundTasks.get(j);
                        
                        if (getSubListIndex(longTask, shortTask, 0) > -1) {
                            foundTasks.remove(j);
                        }
                        else {
                            j++;
                        }
                    }
                    else {
                        j++;
                    }
                }
            }
        }

    }
    
    /**
     * 
     */
    private class RuleApplicationData {
        
        /**
         * 
         */
        private List<ISequence> sessions;
        
        /**
         * 
         */
        private Trie<ITaskTreeNode> lastTrie;
        
        /**
         * default and minimum trained sequence length is 3
         */
        private int trainedSequenceLength = 3;
        
        /**
         * 
         */
        private Tasks lastFoundTasks = new Tasks(Integer.MAX_VALUE, null);
        
        /**
         * 
         */
        private List<ITaskTreeNode> taskOccurrences = new LinkedList<ITaskTreeNode>();
        
        /**
         * 
         */
        private int replacementCounter;
        
        /**
         * 
         */
        private RuleApplicationResult result = new RuleApplicationResult();
        
        /**
         * 
         */
        private StopWatch stopWatch = new StopWatch();
        
        /**
         * 
         */
        private RuleApplicationData(List<ISequence> sessions) {
            this.sessions = sessions;
        }

        /**
         * @return the tree
         */
        private List<ISequence> getSessions() {
            return sessions;
        }

        /**
         * @param lastTrie the lastTrie to set
         */
        private void setLastTrie(Trie<ITaskTreeNode> lastTrie) {
            this.lastTrie = lastTrie;
        }

        /**
         * @return the lastTrie
         */
        private Trie<ITaskTreeNode> getLastTrie() {
            return lastTrie;
        }

        /**
         * @param trainedSequenceLength the trainedSequenceLength to set
         */
        private void setTrainedSequenceLength(int trainedSequenceLength) {
            this.trainedSequenceLength = trainedSequenceLength;
        }

        /**
         * @return the trainedSequenceLength
         */
        private int getTrainedSequenceLength() {
            return trainedSequenceLength;
        }

        /**
         * @param lastFoundSequences the lastFoundSequences to set
         */
        private void setLastFoundTasks(Tasks lastFoundSequences) {
            this.lastFoundTasks = lastFoundSequences;
        }

        /**
         * @return the lastFoundSequences
         */
        private Tasks getLastFoundTasks() {
            return lastFoundTasks;
        }

        /**
         * @return the taskOccurrences
         */
        private void clearTaskOccurrences() {
            taskOccurrences.clear();
        }

        /**
         * @return the taskOccurrences
         */
        private void addTaskOccurrence(ITaskTreeNode taskOccurrence) {
            taskOccurrences.add(taskOccurrence);
        }

        /**
         * @return the taskOccurrences
         */
        private List<ITaskTreeNode> getTaskOccurrences() {
            return taskOccurrences;
        }

        /**
         *
         */
        private void resetReplacementCounter() {
            replacementCounter = 0;
        }

        /**
         *
         */
        private void incrementReplacementCounter() {
            replacementCounter++;
        }

        /**
         *
         */
        private int getReplacementCounter() {
            return replacementCounter;
        }
        
        /**
         * @return the result
         */
        private RuleApplicationResult getResult() {
            return result;
        }

        /**
         * @return the stopWatch
         */
        private StopWatch getStopWatch() {
            return stopWatch;
        }

    }
    

    /**
     * <p>
     * TODO comment
     * </p>
     * 
     * @author Patrick Harms
     */
    private class Tasks implements Iterable<List<ITaskTreeNode>> {
        
        /**
         * 
         */
        private int occurrenceCount;
        
        /**
         * 
         */
        private List<List<ITaskTreeNode>> sequences;

        /**
         * <p>
         * TODO: comment
         * </p>
         *
         * @param occurrenceCount
         * @param sequences
         */
        private Tasks(int occurrenceCount, List<List<ITaskTreeNode>> sequences) {
            super();
            this.occurrenceCount = occurrenceCount;
            this.sequences = sequences;
        }

        /**
         * <p>
         * TODO: comment
         * </p>
         *
         * @return
         */
        private int getOccurrenceCount() {
            return occurrenceCount;
        }

        /**
         * <p>
         * TODO: comment
         * </p>
         *
         * @return
         */
        private int size() {
            return this.sequences.size();
        }

        /**
         * 
         */

        /* (non-Javadoc)
         * @see java.lang.Iterable#iterator()
         */
        @Override
        public Iterator<List<ITaskTreeNode>> iterator() {
            return this.sequences.iterator();
        }

    }

}