TreeAlgorithms.java

/*
Copyright 2011-2016 Google Inc. All Rights Reserved.

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 com.google.security.zynamics.zylib.types.trees;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Set;

import com.google.common.collect.Sets;

public class TreeAlgorithms {
  /**
   * Tests whether a node dominates another node.
   * 
   * @param node The node of the dominator tree where the search starts.
   * @param target The dominator node.
   * @param source The dominated node.
   * 
   * @return True, if the dominator node dominates the dominated node. False, otherwise.
   */
  public static <ObjectType> boolean dominates(final ITreeNode<ObjectType> node,
      final ITreeNode<ObjectType> target, final ITreeNode<ObjectType> source) {
    if (node.getObject() == source) {
      return false;
    } else if (node.getObject() == target) {
      return true;
    } else {
      for (final ITreeNode<ObjectType> child : node.getChildren()) {
        if (!dominates(child, target, source)) {
          return false;
        }
      }

      return true;
    }
  }

  /**
   * Calculate the dominate relation of a tree node.
   * 
   * @param treeNode The tree node for which the dominate relation is calculated.
   * @return A HashMap of the tree node with all nodes that dominate the tree node.
   */
  public static <NodeType> HashMap<ITreeNode<NodeType>, Set<ITreeNode<NodeType>>> getDominateRelation(
      final ITreeNode<NodeType> treeNode) {
    final HashMap<ITreeNode<NodeType>, Set<ITreeNode<NodeType>>> dominationRelation =
        new HashMap<ITreeNode<NodeType>, Set<ITreeNode<NodeType>>>();

    final HashSet<ITreeNode<NodeType>> hashSet = new HashSet<ITreeNode<NodeType>>();
    hashSet.add(treeNode);
    dominationRelation.put(treeNode, hashSet);

    final DepthFirstIterator<NodeType> iter = new DepthFirstIterator<NodeType>(treeNode);

    while (iter.hasNext()) {
      final ITreeNode<NodeType> currentTreeElement = iter.next();
      final ITreeNode<NodeType> currentTreeElementParent = currentTreeElement.getParent();
      final Set<ITreeNode<NodeType>> currentTreeElementParents =
          Sets.newHashSet(dominationRelation.get(currentTreeElementParent));
      currentTreeElementParents.add(currentTreeElementParent);
      currentTreeElementParents.add(currentTreeElement);
      dominationRelation.put(currentTreeElement, currentTreeElementParents);
    }

    return dominationRelation;
  }

  /**
   * Calculate the dominate relation of a tree node.
   * 
   * @param treeNode The tree node for which the dominate relation is calculated.
   * @return A HashMap of the tree node with all nodes that dominate the tree node.
   */
  // public static <NodeType> HashMap<ITreeNode<NodeType>, List<ITreeNode<NodeType>>>
  // getDominateRelation(final ITreeNode<NodeType> treeNode)
  // {
  // final HashMap<ITreeNode<NodeType>, List<ITreeNode<NodeType>>> dominateRelation = new
  // HashMap<ITreeNode<NodeType>, List<ITreeNode<NodeType>>>();
  //
  // if (treeNode.getChildren().size() == 0)
  // {
  // final ArrayList<ITreeNode<NodeType>> dominates = new ArrayList<ITreeNode<NodeType>>();
  // dominates.add(treeNode);
  // dominateRelation.put(treeNode, dominates);
  // return dominateRelation;
  // }
  //
  // for (final ITreeNode<NodeType> childNode : treeNode.getChildren())
  // {
  // final HashMap<ITreeNode<NodeType>, List<ITreeNode<NodeType>>> tempDominaton =
  // getDominateRelation(childNode);
  // for (final Entry<ITreeNode<NodeType>, List<ITreeNode<NodeType>>> tempDominationEntry :
  // tempDominaton.entrySet())
  // {
  // final List<ITreeNode<NodeType>> dominators = tempDominationEntry.getValue();
  // dominators.add(treeNode);
  // dominateRelation.put(tempDominationEntry.getKey(), dominators);
  // }
  // }
  //
  // final ArrayList<ITreeNode<NodeType>> dominates = new ArrayList<ITreeNode<NodeType>>();
  // dominates.add(treeNode);
  // dominateRelation.put(treeNode, dominates);
  // return dominateRelation;
  // }

}