// Copyright 2009 the V8 project authors. All rights reserved.

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

//

//     * Redistributions of source code must retain the above copyright

//       notice, this list of conditions and the following disclaimer.

//     * Redistributions in binary form must reproduce the above

//       copyright notice, this list of conditions and the following

//       disclaimer in the documentation and/or other materials provided

//       with the distribution.

//     * Neither the name of Google Inc. nor the names of its

//       contributors may be used to endorse or promote products derived

//       from this software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// This benchmark is based on a JavaScript log processing module used

// by the V8 profiler to generate execution time profiles for runs of

// JavaScript applications, and it effectively measures how fast the

// JavaScript engine is at allocating nodes and reclaiming the memory

// used for old nodes. Because of the way splay trees work, the engine

// also has to deal with a lot of changes to the large tree object

// graph.

// Configuration.

var kSplayTreeSize = 8000;

var kSplayTreeModifications = 80;

var kSplayTreePayloadDepth = 5;

var splayTree = null;

function GeneratePayloadTree(depth, key) {

  if (depth == 0) {

    return {

      array  : [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ],

      string : 'String for key ' + key + ' in leaf node'

    };

  } else {

    return {

      left:  GeneratePayloadTree(depth - 1, key),

      right: GeneratePayloadTree(depth - 1, key)

    };

  }

}

function GenerateKey() {

  // The benchmark framework guarantees that Math.random is

  // deterministic; see base.js.

  return Math.random();

}

function InsertNewNode() {

  // Insert new node with a unique key.

  var key;

  do {

    key = GenerateKey();

  } while (splayTree.find(key) != null);

  splayTree.insert(key, GeneratePayloadTree(kSplayTreePayloadDepth, key));

  return key;

}

function SplaySetup() {

  splayTree = new SplayTree();

  for (var i = 0; i < kSplayTreeSize; i++) InsertNewNode();

}

function SplayTearDown() {

  // Allow the garbage collector to reclaim the memory

  // used by the splay tree no matter how we exit the

  // tear down function.

  var keys = splayTree.exportKeys();

  splayTree = null;

  // Verify that the splay tree has the right size.

  var length = keys.length;

  if (length != kSplayTreeSize) {

    throw new Error("Splay tree has wrong size");

  }

  // Verify that the splay tree has sorted, unique keys.

  for (var i = 0; i < length - 1; i++) {

    if (keys[i] >= keys[i + 1]) {

      throw new Error("Splay tree not sorted");

    }

  }

}

function SplayRun() {

  // Replace a few nodes in the splay tree.

  for (var i = 0; i < kSplayTreeModifications; i++) {

    var key = InsertNewNode();

    var greatest = splayTree.findGreatestLessThan(key);

    if (greatest == null) splayTree.remove(key);

    else splayTree.remove(greatest.key);

  }

}

/**

 * Constructs a Splay tree.  A splay tree is a self-balancing binary

 * search tree with the additional property that recently accessed

 * elements are quick to access again. It performs basic operations

 * such as insertion, look-up and removal in O(log(n)) amortized time.

 *

 * @constructor

 */

function SplayTree() {

};

/**

 * Pointer to the root node of the tree.

 *

 * @type {SplayTree.Node}

 * @private

 */

SplayTree.prototype.root_ = null;

/**

 * @return {boolean} Whether the tree is empty.

 */

SplayTree.prototype.isEmpty = function() {

  return !this.root_;

};

/**

 * Inserts a node into the tree with the specified key and value if

 * the tree does not already contain a node with the specified key. If

 * the value is inserted, it becomes the root of the tree.

 *

 * @param {number} key Key to insert into the tree.

 * @param {*} value Value to insert into the tree.

 */

SplayTree.prototype.insert = function(key, value) {

  if (this.isEmpty()) {

    this.root_ = new SplayTree.Node(key, value);

    return;

  }

  // Splay on the key to move the last node on the search path for

  // the key to the root of the tree.

  this.splay_(key);

  if (this.root_.key == key) {

    return;

  }

  var node = new SplayTree.Node(key, value);

  if (key > this.root_.key) {

    node.left = this.root_;

    node.right = this.root_.right;

    this.root_.right = null;

  } else {

    node.right = this.root_;

    node.left = this.root_.left;

    this.root_.left = null;

  }

  this.root_ = node;

};

/**

 * Removes a node with the specified key from the tree if the tree

 * contains a node with this key. The removed node is returned. If the

 * key is not found, an exception is thrown.

 *

 * @param {number} key Key to find and remove from the tree.

 * @return {SplayTree.Node} The removed node.

 */

SplayTree.prototype.remove = function(key) {

  if (this.isEmpty()) {

    throw Error('Key not found: ' + key);

  }

  this.splay_(key);

  if (this.root_.key != key) {

    throw Error('Key not found: ' + key);

  }

  var removed = this.root_;

  if (!this.root_.left) {

    this.root_ = this.root_.right;

  } else {

    var right = this.root_.right;

    this.root_ = this.root_.left;

    // Splay to make sure that the new root has an empty right child.

    this.splay_(key);

    // Insert the original right child as the right child of the new

    // root.

    this.root_.right = right;

  }

  return removed;

};

/**

 * Returns the node having the specified key or null if the tree doesn't contain

 * a node with the specified key.

 *

 * @param {number} key Key to find in the tree.

 * @return {SplayTree.Node} Node having the specified key.

 */

SplayTree.prototype.find = function(key) {

  if (this.isEmpty()) {

    return null;

  }

  this.splay_(key);

  return this.root_.key == key ? this.root_ : null;

};

/**

 * @return {SplayTree.Node} Node having the maximum key value that

 *     is less or equal to the specified key value.

 */

SplayTree.prototype.findGreatestLessThan = function(key) {

  if (this.isEmpty()) {

    return null;

  }

  // Splay on the key to move the node with the given key or the last

  // node on the search path to the top of the tree.

  this.splay_(key);

  // Now the result is either the root node or the greatest node in

  // the left subtree.

  if (this.root_.key <= key) {

    return this.root_;

  } else if (this.root_.left) {

    return this.findMax(this.root_.left);

  } else {

    return null;

  }

};

/**

 * @return {Array<*>} An array containing all the keys of tree's nodes.

 */

SplayTree.prototype.exportKeys = function() {

  var result = [];

  if (!this.isEmpty()) {

    this.root_.traverse_(function(node) { result.push(node.key); });

  }

  return result;

};

/**

 * Perform the splay operation for the given key. Moves the node with

 * the given key to the top of the tree.  If no node has the given

 * key, the last node on the search path is moved to the top of the

 * tree. This is the simplified top-down splaying algorithm from:

 * "Self-adjusting Binary Search Trees" by Sleator and Tarjan

 *

 * @param {number} key Key to splay the tree on.

 * @private

 */

SplayTree.prototype.splay_ = function(key) {

  if (this.isEmpty()) {

    return;

  }

  // Create a dummy node.  The use of the dummy node is a bit

  // counter-intuitive: The right child of the dummy node will hold

  // the L tree of the algorithm.  The left child of the dummy node

  // will hold the R tree of the algorithm.  Using a dummy node, left

  // and right will always be nodes and we avoid special cases.

  var dummy, left, right;

  dummy = left = right = new SplayTree.Node(null, null);

  var current = this.root_;

  while (true) {

    if (key < current.key) {

      if (!current.left) {

        break;

      }

      if (key < current.left.key) {

        // Rotate right.

        var tmp = current.left;

        current.left = tmp.right;

        tmp.right = current;

        current = tmp;

        if (!current.left) {

          break;

        }

      }

      // Link right.

      right.left = current;

      right = current;

      current = current.left;

    } else if (key > current.key) {

      if (!current.right) {

        break;

      }

      if (key > current.right.key) {

        // Rotate left.

        var tmp = current.right;

        current.right = tmp.left;

        tmp.left = current;

        current = tmp;

        if (!current.right) {

          break;

        }

      }

      // Link left.

      left.right = current;

      left = current;

      current = current.right;

    } else {

      break;

    }

  }

  // Assemble.

  left.right = current.left;

  right.left = current.right;

  current.left = dummy.right;

  current.right = dummy.left;

  this.root_ = current;

};

/**

 * Constructs a Splay tree node.

 *

 * @param {number} key Key.

 * @param {*} value Value.

 */

SplayTree.Node = function(key, value) {

  this.key = key;

  this.value = value;

};

/**

 * @type {SplayTree.Node}

 */

SplayTree.Node.prototype.left = null;

/**

 * @type {SplayTree.Node}

 */

SplayTree.Node.prototype.right = null;

/**

 * Performs an ordered traversal of the subtree starting at

 * this SplayTree.Node.

 *

 * @param {function(SplayTree.Node)} f Visitor function.

 * @private

 */

SplayTree.Node.prototype.traverse_ = function(f) {

  var current = this;

  while (current) {

    var left = current.left;

    if (left) left.traverse_(f);

    f(current);

    current = current.right;

  }

};

SplaySetup();

SplayRun();

SplayTearDown();