BinarySearchTree.java :  » Code-Analyzer » soot » soot » toolkits » purity » Java Open Source

package soot.toolkits.purity;

/**
 * This example is from the article A Combined Pointer and Purity Analysis for
 * Java Programs" by Alexandru Salcianu and Martin Rinard.
 * It is supposed to demonstrate the purity analysis (-annot-purity)
 *
 * by Antoine Mine, 2005/02/08
 */

import java.util.*;

public class BinarySearchTree {
    Node root;
    int size;

    static class Node {
  Node left;
  Node right;
  Comparable info;
    }

    static final class Wrapper {
  Object o;
  Wrapper(Object o) {
      this.o = o;
  }
  public boolean equals(Object o) {
      if (!(o instanceof Wrapper)) return false;
      return this.o == ((Wrapper)o).o;
  }
  public int hashCode() {
      return System.identityHashCode(o);
  }
    }

    boolean repOk() {
  if (root==null) return size==0;
  if (!isTree()) return false;
  if (numNodes(root)!=size) return false;
  if (!isOrdered(root,null,null)) return false;
  return true;
    }

    boolean isTree() {
  Set visited = new HashSet();
  visited.add(new Wrapper(root));
  LinkedList workList = new LinkedList();
  workList.add(root);
  while (!workList.isEmpty()) {
      Node current = (Node)workList.removeFirst();
      if (current.left!=null) {
    if (!visited.add(new Wrapper(current.left))) return false;
    workList.add(current.left);
      }
      if (current.right!=null) {
    if (!visited.add(new Wrapper(current.right))) return false;
    workList.add(current.right);
      }
  }
  return true;
    }

    int numNodes(Node n) {
  if (n==null) return 0;
  return 1 + numNodes(n.left) + numNodes(n.right);
    }

    boolean isOrdered(Node n, Comparable min, Comparable max) {
  if ((min!=null && n.info.compareTo(min)<=0) ||
      (max!=null && n.info.compareTo(max)>=0)) return false;
  if (n.left!=null)
      if (!isOrdered(n.left,min,n.info)) return false;
  if (n.right!=null)
      if (!isOrdered(n.right,n.info,max)) return false;
  return true;
    }

    static Node create(int i) {
  if (i==0) return null;
  Node n = new Node();
  n.left  = create(i-1);
  n.right = create(i-1);
  return n;
    }

    public static void main(String[] args) {
  BinarySearchTree x = new BinarySearchTree();
  x.root = create(5);
  x.repOk();
    }

}