Reimplement Splay Tree in JavaScript (and add unit tests!).

This is the first step in reimplementing tick processing scripts in
JavaScript. The goal is to have the same source both for Dev Tools and
Golem, so Python implementation will be removed to avoid code
duplication.

The implementation follows the Dev Tools style: namespaces and JSDocs
are used.

Review URL: http://codereview.chromium.org/67151

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1709 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

test/mjsunit/testcfg.py

@@ -32,6 +32,7 @@ import re
 
 
 FLAGS_PATTERN = re.compile(r"//\s+Flags:(.*)")
+FILES_PATTERN = re.compile(r"//\s+Files:(.*)")
 
 
 class MjsunitTestCase(test.TestCase):
@@ -54,6 +55,12 @@ class MjsunitTestCase(test.TestCase):
     flags_match = FLAGS_PATTERN.search(source)
     if flags_match:
       result += flags_match.group(1).strip().split()
+    files_match = FILES_PATTERN.search(source);
+    additional_files = []
+    if files_match:
+      additional_files += files_match.group(1).strip().split()
+    for a_file in additional_files:
+      result.append(join(dirname(self.config.root), '..', a_file))
     framework = join(dirname(self.config.root), 'mjsunit', 'mjsunit.js')
     result += [framework, self.file]
     return result
@@ -76,7 +83,8 @@ class MjsunitTestConfiguration(test.TestConfiguration):
     mjsunit = [current_path + [t] for t in self.Ls(self.root)]
     regress = [current_path + ['regress', t] for t in self.Ls(join(self.root, 'regress'))]
     bugs = [current_path + ['bugs', t] for t in self.Ls(join(self.root, 'bugs'))]
-    all_tests = mjsunit + regress + bugs
+    tools = [current_path + ['tools', t] for t in self.Ls(join(self.root, 'tools'))]
+    all_tests = mjsunit + regress + bugs + tools
     result = []
     for test in all_tests:
       if self.Contains(path, test):

test/mjsunit/tools/splaytree.js

+// 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.
+
+// Load the Splay tree implementation from <project root>/tools.
+// Files: tools/splaytree.js
+
+
+(function testIsEmpty() {
+  var tree = new goog.structs.SplayTree();
+  assertTrue(tree.isEmpty());
+  tree.insert(0, 'value');
+  assertFalse(tree.isEmpty());
+})();
+
+
+(function testExportValues() {
+  var tree = new goog.structs.SplayTree();
+  assertArrayEquals([], tree.exportValues());
+  tree.insert(0, 'value');
+  assertArrayEquals(['value'], tree.exportValues());
+  tree.insert(0, 'value');
+  assertArrayEquals(['value'], tree.exportValues());
+})();
+
+
+function createSampleTree() {
+  // Creates the following tree:
+  //           50
+  //          /  \
+  //         30  60
+  //        /  \   \
+  //       10  40  90
+  //         \    /  \
+  //         20  70 100
+  //        /      \
+  //       15      80
+  //
+  // We can't use the 'insert' method because it also uses 'splay_'.
+  return { key: 50, value: 50,
+      left: { key: 30, value: 30,
+              left: { key: 10, value: 10, left: null,
+                      right: { key: 20, value: 20,
+                               left: { key: 15, value: 15,
+                                       left: null, right: null },
+                               right: null } },
+              right: { key: 40, value: 40, left: null, right: null } },
+      right: { key: 60, value: 60, left: null,
+               right: { key: 90, value: 90,
+                        left: { key: 70, value: 70, left: null,
+                                right: { key: 80, value: 80,
+                                         left: null, right: null } },
+                        right: { key: 100, value: 100,
+                                 left: null, right: null } } } };
+};
+
+
+(function testSplay() {
+  var tree = new goog.structs.SplayTree();
+  tree.root_ = createSampleTree();
+  assertArrayEquals(['50', '30', '60', '10', '40', '90', '20', '70', '100', '15', '80'],
+                    tree.exportValues());
+  tree.splay_(50);
+  assertArrayEquals(['50', '30', '60', '10', '40', '90', '20', '70', '100', '15', '80'],
+                    tree.exportValues());
+  tree.splay_(80);
+  assertArrayEquals(['80', '60', '90', '50', '70', '100', '30', '10', '40', '20', '15'],
+                    tree.exportValues());
+})();
+
+
+(function testInsert() {
+  var tree = new goog.structs.SplayTree();
+  tree.insert(5, 'root');
+  tree.insert(3, 'left');
+  assertArrayEquals(['left', 'root'], tree.exportValues());
+  tree.insert(7, 'right');
+  assertArrayEquals(['right', 'root', 'left'], tree.exportValues());
+})();
+
+
+(function testFind() {
+  var tree = new goog.structs.SplayTree();
+  tree.insert(5, 'root');
+  tree.insert(3, 'left');
+  tree.insert(7, 'right');
+  assertEquals('root', tree.find(5).value);
+  assertEquals('left', tree.find(3).value);
+  assertEquals('right', tree.find(7).value);
+  assertEquals(null, tree.find(0));
+  assertEquals(null, tree.find(100));
+  assertEquals(null, tree.find(-100));
+})();
+
+
+(function testFindMin() {
+  var tree = new goog.structs.SplayTree();
+  assertEquals(null, tree.findMin());
+  tree.insert(5, 'root');
+  tree.insert(3, 'left');
+  tree.insert(7, 'right');
+  assertEquals('left', tree.findMin().value);
+})();
+
+
+(function testFindMax() {
+  var tree = new goog.structs.SplayTree();
+  assertEquals(null, tree.findMax());
+  tree.insert(5, 'root');
+  tree.insert(3, 'left');
+  tree.insert(7, 'right');
+  assertEquals('right', tree.findMax().value);
+})();
+
+
+(function testFindGreatestLessThan() {
+  var tree = new goog.structs.SplayTree();
+  assertEquals(null, tree.findGreatestLessThan(10));
+  tree.insert(5, 'root');
+  tree.insert(3, 'left');
+  tree.insert(7, 'right');
+  assertEquals('right', tree.findGreatestLessThan(10).value);
+  assertEquals('right', tree.findGreatestLessThan(7).value);
+  assertEquals('root', tree.findGreatestLessThan(6).value);
+  assertEquals('left', tree.findGreatestLessThan(4).value);
+  assertEquals(null, tree.findGreatestLessThan(2));
+})();
+
+
+(function testRemove() {
+  var tree = new goog.structs.SplayTree();
+  assertThrows('tree.remove(5)');
+  tree.insert(5, 'root');
+  tree.insert(3, 'left');
+  tree.insert(7, 'right');
+  assertThrows('tree.remove(1)');
+  assertThrows('tree.remove(6)');
+  assertThrows('tree.remove(10)');
+  assertEquals('root', tree.remove(5).value);
+  assertEquals('left', tree.remove(3).value);
+  assertEquals('right', tree.remove(7).value);
+  assertArrayEquals([], tree.exportValues());
+})();

tools/splaytree.js

+// 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.
+
+
+// A namespace stub. It will become more clear how to declare it properly
+// during integration of this script into Dev Tools.
+goog = { structs: {} };
+
+
+/**
+ * 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
+ */
+goog.structs.SplayTree = function() {
+};
+
+
+/**
+ * Pointer to the root node of the tree.
+ *
+ * @type {goog.structs.SplayTree.Node}
+ * @private
+ */
+goog.structs.SplayTree.prototype.root_ = null;
+
+
+/**
+ * @return {boolean} Whether the tree is empty.
+ */
+goog.structs.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.
+ */
+goog.structs.SplayTree.prototype.insert = function(key, value) {
+  if (this.isEmpty()) {
+    this.root_ = new goog.structs.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 goog.structs.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 {goog.structs.SplayTree.Node} The removed node.
+ */
+goog.structs.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 {goog.structs.SplayTree.Node} Node having the specified key.
+ */
+goog.structs.SplayTree.prototype.find = function(key) {
+  if (this.isEmpty()) {
+    return null;
+  }
+  this.splay_(key);
+  return this.root_.key == key ? this.root_ : null;
+};
+
+
+/**
+ * @return {goog.structs.SplayTree.Node} Node having the minimum key value.
+ */
+goog.structs.SplayTree.prototype.findMin = function() {
+  if (this.isEmpty()) {
+    return null;
+  }
+  var current = this.root_;
+  while (current.left) {
+    current = current.left;
+  }
+  return current;
+};
+
+
+/**
+ * @return {goog.structs.SplayTree.Node} Node having the maximum key value.
+ */
+goog.structs.SplayTree.prototype.findMax = function(opt_startNode) {
+  if (this.isEmpty()) {
+    return null;
+  }
+  var current = opt_startNode || this.root_;
+  while (current.right) {
+    current = current.right;
+  }
+  return current;
+};
+
+
+/**
+ * @return {goog.structs.SplayTree.Node} Node having the maximum key value that
+ *     is less or equal to the specified key value.
+ */
+goog.structs.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 values of tree's nodes.
+ */
+goog.structs.SplayTree.prototype.exportValues = function() {
+  var result = [];
+  this.traverse_(function(node) { result.push(node.value); });
+  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
+ */
+goog.structs.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 goog.structs.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;
+};
+
+
+/**
+ * Performs a preorder traversal of the tree.
+ *
+ * @param {function(goog.structs.SplayTree.Node)} f Visitor function.
+ * @private
+ */
+goog.structs.SplayTree.prototype.traverse_ = function(f) {
+  var nodesToVisit = [this.root_];
+  while (nodesToVisit.length > 0) {
+    var node = nodesToVisit.shift();
+    if (node == null) {
+      continue;
+    }
+    f(node);
+    nodesToVisit.push(node.left);
+    nodesToVisit.push(node.right);
+  }
+};
+
+
+/**
+ * Constructs a Splay tree node.
+ *
+ * @param {number} key Key.
+ * @param {*} value Value.
+ */
+goog.structs.SplayTree.Node = function(key, value) {
+  this.key = key;
+  this.value = value;
+};
+
+
+/**
+ * @type {goog.structs.SplayTree.Node}
+ */
+goog.structs.SplayTree.Node.prototype.left = null;
+
+
+/**
+ * @type {goog.structs.SplayTree.Node}
+ */
+goog.structs.SplayTree.Node.prototype.right = null;