Parametrize C++ splay tree with allocator.

Thus, now there is a "generic" SplayTree and its Zone-bound
specialization ZoneSplayTree.

This is needed for my reimplementation of profiler tree generation in
C++. As generation is performed in a separate thread, Zone can't be
used, because it intentionally not thread-safe.

Review URL: http://codereview.chromium.org/660280

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3990 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/globals.h

@@ -261,6 +261,8 @@ template<class Allocator = FreeStoreAllocationPolicy> class ScopeInfo;
 class Script;
 class Slot;
 class Smi;
+template <typename Config, class Allocator = FreeStoreAllocationPolicy>
+    class SplayTree;
 class Statement;
 class String;
 class Struct;

src/heap.h

@@ -30,6 +30,7 @@
 
 #include <math.h>
 
+#include "splay-tree-inl.h"
 #include "zone-inl.h"
 
 

src/splay-tree-inl.h

+// Copyright 2010 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.
+
+#ifndef V8_SPLAY_TREE_INL_H_
+#define V8_SPLAY_TREE_INL_H_
+
+#include "splay-tree.h"
+
+namespace v8 {
+namespace internal {
+
+
+template<typename Config, class Allocator>
+SplayTree<Config, Allocator>::~SplayTree() {
+  NodeDeleter deleter;
+  ForEachNode(&deleter);
+}
+
+
+template<typename Config, class Allocator>
+bool SplayTree<Config, Allocator>::Insert(const Key& key, Locator* locator) {
+  if (is_empty()) {
+    // If the tree is empty, insert the new node.
+    root_ = new Node(key, Config::kNoValue);
+  } else {
+    // Splay on the key to move the last node on the search path
+    // for the key to the root of the tree.
+    Splay(key);
+    // Ignore repeated insertions with the same key.
+    int cmp = Config::Compare(key, root_->key_);
+    if (cmp == 0) {
+      locator->bind(root_);
+      return false;
+    }
+    // Insert the new node.
+    Node* node = new Node(key, Config::kNoValue);
+    if (cmp > 0) {
+      node->left_ = root_;
+      node->right_ = root_->right_;
+      root_->right_ = NULL;
+    } else {
+      node->right_ = root_;
+      node->left_ = root_->left_;
+      root_->left_ = NULL;
+    }
+    root_ = node;
+  }
+  locator->bind(root_);
+  return true;
+}
+
+
+template<typename Config, class Allocator>
+bool SplayTree<Config, Allocator>::Find(const Key& key, Locator* locator) {
+  if (is_empty())
+    return false;
+  Splay(key);
+  if (Config::Compare(key, root_->key_) == 0) {
+    locator->bind(root_);
+    return true;
+  } else {
+    return false;
+  }
+}
+
+
+template<typename Config, class Allocator>
+bool SplayTree<Config, Allocator>::FindGreatestLessThan(const Key& key,
+                                                        Locator* locator) {
+  if (is_empty())
+    return false;
+  // 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.
+  Splay(key);
+  // Now the result is either the root node or the greatest node in
+  // the left subtree.
+  int cmp = Config::Compare(root_->key_, key);
+  if (cmp <= 0) {
+    locator->bind(root_);
+    return true;
+  } else {
+    Node* temp = root_;
+    root_ = root_->left_;
+    bool result = FindGreatest(locator);
+    root_ = temp;
+    return result;
+  }
+}
+
+
+template<typename Config, class Allocator>
+bool SplayTree<Config, Allocator>::FindLeastGreaterThan(const Key& key,
+                                                        Locator* locator) {
+  if (is_empty())
+    return false;
+  // 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.
+  Splay(key);
+  // Now the result is either the root node or the least node in
+  // the right subtree.
+  int cmp = Config::Compare(root_->key_, key);
+  if (cmp >= 0) {
+    locator->bind(root_);
+    return true;
+  } else {
+    Node* temp = root_;
+    root_ = root_->right_;
+    bool result = FindLeast(locator);
+    root_ = temp;
+    return result;
+  }
+}
+
+
+template<typename Config, class Allocator>
+bool SplayTree<Config, Allocator>::FindGreatest(Locator* locator) {
+  if (is_empty())
+    return false;
+  Node* current = root_;
+  while (current->right_ != NULL)
+    current = current->right_;
+  locator->bind(current);
+  return true;
+}
+
+
+template<typename Config, class Allocator>
+bool SplayTree<Config, Allocator>::FindLeast(Locator* locator) {
+  if (is_empty())
+    return false;
+  Node* current = root_;
+  while (current->left_ != NULL)
+    current = current->left_;
+  locator->bind(current);
+  return true;
+}
+
+
+template<typename Config, class Allocator>
+bool SplayTree<Config, Allocator>::Remove(const Key& key) {
+  // Bail if the tree is empty
+  if (is_empty())
+    return false;
+  // Splay on the key to move the node with the given key to the top.
+  Splay(key);
+  // Bail if the key is not in the tree
+  if (Config::Compare(key, root_->key_) != 0)
+    return false;
+  if (root_->left_ == NULL) {
+    // No left child, so the new tree is just the right child.
+    root_ = root_->right_;
+  } else {
+    // Left child exists.
+    Node* right = root_->right_;
+    // Make the original left child the new root.
+    root_ = root_->left_;
+    // Splay to make sure that the new root has an empty right child.
+    Splay(key);
+    // Insert the original right child as the right child of the new
+    // root.
+    root_->right_ = right;
+  }
+  return true;
+}
+
+
+template<typename Config, class Allocator>
+void SplayTree<Config, Allocator>::Splay(const Key& key) {
+  if (is_empty())
+    return;
+  Node dummy_node(Config::kNoKey, Config::kNoValue);
+  // 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.
+  Node* dummy = &dummy_node;
+  Node* left = dummy;
+  Node* right = dummy;
+  Node* current = root_;
+  while (true) {
+    int cmp = Config::Compare(key, current->key_);
+    if (cmp < 0) {
+      if (current->left_ == NULL)
+        break;
+      if (Config::Compare(key, current->left_->key_) < 0) {
+        // Rotate right.
+        Node* temp = current->left_;
+        current->left_ = temp->right_;
+        temp->right_ = current;
+        current = temp;
+        if (current->left_ == NULL)
+          break;
+      }
+      // Link right.
+      right->left_ = current;
+      right = current;
+      current = current->left_;
+    } else if (cmp > 0) {
+      if (current->right_ == NULL)
+        break;
+      if (Config::Compare(key, current->right_->key_) > 0) {
+        // Rotate left.
+        Node* temp = current->right_;
+        current->right_ = temp->left_;
+        temp->left_ = current;
+        current = temp;
+        if (current->right_ == NULL)
+          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_;
+  root_ = current;
+}
+
+
+template <typename Config, class Allocator> template <class Callback>
+void SplayTree<Config, Allocator>::ForEach(Callback* callback) {
+  NodeToPairAdaptor<Callback> callback_adaptor(callback);
+  ForEachNode(&callback_adaptor);
+}
+
+
+template <typename Config, class Allocator> template <class Callback>
+void SplayTree<Config, Allocator>::ForEachNode(Callback* callback) {
+  // Pre-allocate some space for tiny trees.
+  List<Node*, Allocator> nodes_to_visit(10);
+  if (root_ != NULL) nodes_to_visit.Add(root_);
+  int pos = 0;
+  while (pos < nodes_to_visit.length()) {
+    Node* node = nodes_to_visit[pos++];
+    if (node->left() != NULL) nodes_to_visit.Add(node->left());
+    if (node->right() != NULL) nodes_to_visit.Add(node->right());
+    callback->Call(node);
+  }
+}
+
+
+} }  // namespace v8::internal
+
+#endif  // V8_SPLAY_TREE_INL_H_

src/splay-tree.h

+// Copyright 2010 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.
+
+#ifndef V8_SPLAY_TREE_H_
+#define V8_SPLAY_TREE_H_
+
+namespace v8 {
+namespace internal {
+
+
+// A splay tree.  The config type parameter encapsulates the different
+// configurations of a concrete splay tree:
+//
+//   typedef Key: the key type
+//   typedef Value: the value type
+//   static const kNoKey: the dummy key used when no key is set
+//   static const kNoValue: the dummy value used to initialize nodes
+//   int (Compare)(Key& a, Key& b) -> {-1, 0, 1}: comparison function
+//
+// The tree is also parameterized by an allocation policy
+// (Allocator). The policy is used for allocating lists in the C free
+// store or the zone; see zone.h.
+
+// Forward defined as
+// template <typename Config, class Allocator = FreeStoreAllocationPolicy>
+//     class SplayTree;
+template <typename Config, class Allocator>
+class SplayTree {
+ public:
+  typedef typename Config::Key Key;
+  typedef typename Config::Value Value;
+
+  class Locator;
+
+  SplayTree() : root_(NULL) { }
+  ~SplayTree();
+
+  INLINE(void* operator new(size_t size)) {
+    return Allocator::New(static_cast<int>(size));
+  }
+  INLINE(void operator delete(void* p, size_t)) { return Allocator::Delete(p); }
+
+  // Inserts the given key in this tree with the given value.  Returns
+  // true if a node was inserted, otherwise false.  If found the locator
+  // is enabled and provides access to the mapping for the key.
+  bool Insert(const Key& key, Locator* locator);
+
+  // Looks up the key in this tree and returns true if it was found,
+  // otherwise false.  If the node is found the locator is enabled and
+  // provides access to the mapping for the key.
+  bool Find(const Key& key, Locator* locator);
+
+  // Finds the mapping with the greatest key less than or equal to the
+  // given key.
+  bool FindGreatestLessThan(const Key& key, Locator* locator);
+
+  // Find the mapping with the greatest key in this tree.
+  bool FindGreatest(Locator* locator);
+
+  // Finds the mapping with the least key greater than or equal to the
+  // given key.
+  bool FindLeastGreaterThan(const Key& key, Locator* locator);
+
+  // Find the mapping with the least key in this tree.
+  bool FindLeast(Locator* locator);
+
+  // Remove the node with the given key from the tree.
+  bool Remove(const Key& key);
+
+  bool is_empty() { return root_ == NULL; }
+
+  // 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.
+  void Splay(const Key& key);
+
+  class Node {
+   public:
+    Node(const Key& key, const Value& value)
+        : key_(key),
+          value_(value),
+          left_(NULL),
+          right_(NULL) { }
+
+    INLINE(void* operator new(size_t size)) {
+      return Allocator::New(static_cast<int>(size));
+    }
+    INLINE(void operator delete(void* p, size_t)) {
+      return Allocator::Delete(p);
+    }
+
+    Key key() { return key_; }
+    Value value() { return value_; }
+    Node* left() { return left_; }
+    Node* right() { return right_; }
+   private:
+
+    friend class SplayTree;
+    friend class Locator;
+    Key key_;
+    Value value_;
+    Node* left_;
+    Node* right_;
+  };
+
+  // A locator provides access to a node in the tree without actually
+  // exposing the node.
+  class Locator BASE_EMBEDDED {
+   public:
+    explicit Locator(Node* node) : node_(node) { }
+    Locator() : node_(NULL) { }
+    const Key& key() { return node_->key_; }
+    Value& value() { return node_->value_; }
+    void set_value(const Value& value) { node_->value_ = value; }
+    inline void bind(Node* node) { node_ = node; }
+   private:
+    Node* node_;
+  };
+
+  template <class Callback>
+  void ForEach(Callback* callback);
+
+ protected:
+
+  // Resets tree root. Existing nodes become unreachable.
+  void ResetRoot() { root_ = NULL; }
+
+ private:
+
+  template<class Callback>
+  class NodeToPairAdaptor BASE_EMBEDDED {
+   public:
+    explicit NodeToPairAdaptor(Callback* callback)
+        : callback_(callback) { }
+    void Call(Node* node) {
+      callback_->Call(node->key(), node->value());
+    }
+
+   private:
+    Callback* callback_;
+
+    DISALLOW_COPY_AND_ASSIGN(NodeToPairAdaptor);
+  };
+
+  class NodeDeleter BASE_EMBEDDED {
+   public:
+    NodeDeleter() { }
+    void Call(Node* node) { delete node; }
+
+   private:
+
+    DISALLOW_COPY_AND_ASSIGN(NodeDeleter);
+  };
+
+  template <class Callback>
+  void ForEachNode(Callback* callback);
+
+  Node* root_;
+
+  DISALLOW_COPY_AND_ASSIGN(SplayTree);
+};
+
+
+} }  // namespace v8::internal
+
+#endif  // V8_SPLAY_TREE_H_

src/zone-inl.h

@@ -68,227 +68,12 @@ void Zone::adjust_segment_bytes_allocated(int delta) {
 }
 
 
-template <typename C>
-bool ZoneSplayTree<C>::Insert(const Key& key, Locator* locator) {
-  if (is_empty()) {
-    // If the tree is empty, insert the new node.
-    root_ = new Node(key, C::kNoValue);
-  } else {
-    // Splay on the key to move the last node on the search path
-    // for the key to the root of the tree.
-    Splay(key);
-    // Ignore repeated insertions with the same key.
-    int cmp = C::Compare(key, root_->key_);
-    if (cmp == 0) {
-      locator->bind(root_);
-      return false;
-    }
-    // Insert the new node.
-    Node* node = new Node(key, C::kNoValue);
-    if (cmp > 0) {
-      node->left_ = root_;
-      node->right_ = root_->right_;
-      root_->right_ = NULL;
-    } else {
-      node->right_ = root_;
-      node->left_ = root_->left_;
-      root_->left_ = NULL;
-    }
-    root_ = node;
-  }
-  locator->bind(root_);
-  return true;
-}
-
-
-template <typename C>
-bool ZoneSplayTree<C>::Find(const Key& key, Locator* locator) {
-  if (is_empty())
-    return false;
-  Splay(key);
-  if (C::Compare(key, root_->key_) == 0) {
-    locator->bind(root_);
-    return true;
-  } else {
-    return false;
-  }
-}
-
-
-template <typename C>
-bool ZoneSplayTree<C>::FindGreatestLessThan(const Key& key,
-                                            Locator* locator) {
-  if (is_empty())
-    return false;
-  // 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.
-  Splay(key);
-  // Now the result is either the root node or the greatest node in
-  // the left subtree.
-  int cmp = C::Compare(root_->key_, key);
-  if (cmp <= 0) {
-    locator->bind(root_);
-    return true;
-  } else {
-    Node* temp = root_;
-    root_ = root_->left_;
-    bool result = FindGreatest(locator);
-    root_ = temp;
-    return result;
-  }
-}
-
-
-template <typename C>
-bool ZoneSplayTree<C>::FindLeastGreaterThan(const Key& key,
-                                            Locator* locator) {
-  if (is_empty())
-    return false;
-  // 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.
-  Splay(key);
-  // Now the result is either the root node or the least node in
-  // the right subtree.
-  int cmp = C::Compare(root_->key_, key);
-  if (cmp >= 0) {
-    locator->bind(root_);
-    return true;
-  } else {
-    Node* temp = root_;
-    root_ = root_->right_;
-    bool result = FindLeast(locator);
-    root_ = temp;
-    return result;
-  }
-}
-
-
-template <typename C>
-bool ZoneSplayTree<C>::FindGreatest(Locator* locator) {
-  if (is_empty())
-    return false;
-  Node* current = root_;
-  while (current->right_ != NULL)
-    current = current->right_;
-  locator->bind(current);
-  return true;
-}
-
-
-template <typename C>
-bool ZoneSplayTree<C>::FindLeast(Locator* locator) {
-  if (is_empty())
-    return false;
-  Node* current = root_;
-  while (current->left_ != NULL)
-    current = current->left_;
-  locator->bind(current);
-  return true;
-}
-
-
-template <typename C>
-bool ZoneSplayTree<C>::Remove(const Key& key) {
-  // Bail if the tree is empty
-  if (is_empty())
-    return false;
-  // Splay on the key to move the node with the given key to the top.
-  Splay(key);
-  // Bail if the key is not in the tree
-  if (C::Compare(key, root_->key_) != 0)
-    return false;
-  if (root_->left_ == NULL) {
-    // No left child, so the new tree is just the right child.
-    root_ = root_->right_;
-  } else {
-    // Left child exists.
-    Node* right = root_->right_;
-    // Make the original left child the new root.
-    root_ = root_->left_;
-    // Splay to make sure that the new root has an empty right child.
-    Splay(key);
-    // Insert the original right child as the right child of the new
-    // root.
-    root_->right_ = right;
-  }
-  return true;
-}
-
-
-template <typename C>
-void ZoneSplayTree<C>::Splay(const Key& key) {
-  if (is_empty())
-    return;
-  Node dummy_node(C::kNoKey, C::kNoValue);
-  // 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.
-  Node* dummy = &dummy_node;
-  Node* left = dummy;
-  Node* right = dummy;
-  Node* current = root_;
-  while (true) {
-    int cmp = C::Compare(key, current->key_);
-    if (cmp < 0) {
-      if (current->left_ == NULL)
-        break;
-      if (C::Compare(key, current->left_->key_) < 0) {
-        // Rotate right.
-        Node* temp = current->left_;
-        current->left_ = temp->right_;
-        temp->right_ = current;
-        current = temp;
-        if (current->left_ == NULL)
-          break;
-      }
-      // Link right.
-      right->left_ = current;
-      right = current;
-      current = current->left_;
-    } else if (cmp > 0) {
-      if (current->right_ == NULL)
-        break;
-      if (C::Compare(key, current->right_->key_) > 0) {
-        // Rotate left.
-        Node* temp = current->right_;
-        current->right_ = temp->left_;
-        temp->left_ = current;
-        current = temp;
-        if (current->right_ == NULL)
-          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_;
-  root_ = current;
-}
-
-
-template <typename Config> template <class Callback>
-void ZoneSplayTree<Config>::ForEach(Callback* callback) {
-  // Pre-allocate some space for tiny trees.
-  ZoneList<Node*> nodes_to_visit(10);
-  nodes_to_visit.Add(root_);
-  int pos = 0;
-  while (pos < nodes_to_visit.length()) {
-    Node* node = nodes_to_visit[pos++];
-    if (node == NULL) continue;
-    callback->Call(node->key(), node->value());
-    nodes_to_visit.Add(node->left());
-    nodes_to_visit.Add(node->right());
-  }
+template <typename Config>
+ZoneSplayTree<Config>::~ZoneSplayTree() {
+  // Reset the root to avoid unneeded iteration over all tree nodes
+  // in the destructor.  For a zone-allocated tree, nodes will be
+  // freed by the Zone.
+  SplayTree<Config, ZoneListAllocationPolicy>::ResetRoot();
 }
 
 

src/zone.cc

@@ -28,6 +28,7 @@
 #include "v8.h"
 
 #include "zone-inl.h"
+#include "splay-tree-inl.h"
 
 namespace v8 {
 namespace internal {

src/zone.h

@@ -205,98 +205,14 @@ class ZoneScope BASE_EMBEDDED {
 
 
 // A zone splay tree.  The config type parameter encapsulates the
-// different configurations of a concrete splay tree:
-//
-//   typedef Key: the key type
-//   typedef Value: the value type
-//   static const kNoKey: the dummy key used when no key is set
-//   static const kNoValue: the dummy value used to initialize nodes
-//   int (Compare)(Key& a, Key& b) -> {-1, 0, 1}: comparison function
-//
+// different configurations of a concrete splay tree (see splay-tree.h).
+// The tree itself and all its elements are allocated in the Zone.
 template <typename Config>
-class ZoneSplayTree : public ZoneObject {
+class ZoneSplayTree: public SplayTree<Config, ZoneListAllocationPolicy> {
  public:
-  typedef typename Config::Key Key;
-  typedef typename Config::Value Value;
-
-  class Locator;
-
-  ZoneSplayTree() : root_(NULL) { }
-
-  // Inserts the given key in this tree with the given value.  Returns
-  // true if a node was inserted, otherwise false.  If found the locator
-  // is enabled and provides access to the mapping for the key.
-  bool Insert(const Key& key, Locator* locator);
-
-  // Looks up the key in this tree and returns true if it was found,
-  // otherwise false.  If the node is found the locator is enabled and
-  // provides access to the mapping for the key.
-  bool Find(const Key& key, Locator* locator);
-
-  // Finds the mapping with the greatest key less than or equal to the
-  // given key.
-  bool FindGreatestLessThan(const Key& key, Locator* locator);
-
-  // Find the mapping with the greatest key in this tree.
-  bool FindGreatest(Locator* locator);
-
-  // Finds the mapping with the least key greater than or equal to the
-  // given key.
-  bool FindLeastGreaterThan(const Key& key, Locator* locator);
-
-  // Find the mapping with the least key in this tree.
-  bool FindLeast(Locator* locator);
-
-  // Remove the node with the given key from the tree.
-  bool Remove(const Key& key);
-
-  bool is_empty() { return root_ == NULL; }
-
-  // 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.
-  void Splay(const Key& key);
-
-  class Node : public ZoneObject {
-   public:
-    Node(const Key& key, const Value& value)
-        : key_(key),
-          value_(value),
-          left_(NULL),
-          right_(NULL) { }
-    Key key() { return key_; }
-    Value value() { return value_; }
-    Node* left() { return left_; }
-    Node* right() { return right_; }
-   private:
-    friend class ZoneSplayTree;
-    friend class Locator;
-    Key key_;
-    Value value_;
-    Node* left_;
-    Node* right_;
-  };
-
-  // A locator provides access to a node in the tree without actually
-  // exposing the node.
-  class Locator {
-   public:
-    explicit Locator(Node* node) : node_(node) { }
-    Locator() : node_(NULL) { }
-    const Key& key() { return node_->key_; }
-    Value& value() { return node_->value_; }
-    void set_value(const Value& value) { node_->value_ = value; }
-    inline void bind(Node* node) { node_ = node; }
-   private:
-    Node* node_;
-  };
-
-  template <class Callback>
-  void ForEach(Callback* callback);
-
- private:
-  Node* root_;
+  ZoneSplayTree()
+      : SplayTree<Config, ZoneListAllocationPolicy>() {}
+  ~ZoneSplayTree();
 };