1// Copyright 2010 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef V8_SPLAY_TREE_H_
6#define V8_SPLAY_TREE_H_
7
8#include "src/allocation.h"
9
10namespace v8 {
11namespace internal {
12
13
14// A splay tree.  The config type parameter encapsulates the different
15// configurations of a concrete splay tree:
16//
17//   typedef Key: the key type
18//   typedef Value: the value type
19//   static const Key kNoKey: the dummy key used when no key is set
20//   static Value kNoValue(): the dummy value used to initialize nodes
21//   static int (Compare)(Key& a, Key& b) -> {-1, 0, 1}: comparison function
22//
23// The tree is also parameterized by an allocation policy
24// (Allocator). The policy is used for allocating lists in the C free
25// store or the zone; see zone.h.
26
27// Forward defined as
28// template <typename Config, class Allocator = FreeStoreAllocationPolicy>
29//     class SplayTree;
30template <typename Config, class AllocationPolicy>
31class SplayTree {
32 public:
33  typedef typename Config::Key Key;
34  typedef typename Config::Value Value;
35
36  class Locator;
37
38  explicit SplayTree(AllocationPolicy allocator = AllocationPolicy())
39      : root_(NULL), allocator_(allocator) {}
40  ~SplayTree();
41
42  INLINE(void* operator new(size_t size,
43                            AllocationPolicy allocator = AllocationPolicy())) {
44    return allocator.New(static_cast<int>(size));
45  }
46  INLINE(void operator delete(void* p)) {
47    AllocationPolicy::Delete(p);
48  }
49  // Please the MSVC compiler.  We should never have to execute this.
50  INLINE(void operator delete(void* p, AllocationPolicy policy)) {
51    UNREACHABLE();
52  }
53
54  AllocationPolicy allocator() { return allocator_; }
55
56  // Checks if there is a mapping for the key.
57  bool Contains(const Key& key);
58
59  // Inserts the given key in this tree with the given value.  Returns
60  // true if a node was inserted, otherwise false.  If found the locator
61  // is enabled and provides access to the mapping for the key.
62  bool Insert(const Key& key, Locator* locator);
63
64  // Looks up the key in this tree and returns true if it was found,
65  // otherwise false.  If the node is found the locator is enabled and
66  // provides access to the mapping for the key.
67  bool Find(const Key& key, Locator* locator);
68
69  // Finds the mapping with the greatest key less than or equal to the
70  // given key.
71  bool FindGreatestLessThan(const Key& key, Locator* locator);
72
73  // Find the mapping with the greatest key in this tree.
74  bool FindGreatest(Locator* locator);
75
76  // Finds the mapping with the least key greater than or equal to the
77  // given key.
78  bool FindLeastGreaterThan(const Key& key, Locator* locator);
79
80  // Find the mapping with the least key in this tree.
81  bool FindLeast(Locator* locator);
82
83  // Move the node from one key to another.
84  bool Move(const Key& old_key, const Key& new_key);
85
86  // Remove the node with the given key from the tree.
87  bool Remove(const Key& key);
88
89  // Remove all keys from the tree.
90  void Clear() { ResetRoot(); }
91
92  bool is_empty() { return root_ == NULL; }
93
94  // Perform the splay operation for the given key. Moves the node with
95  // the given key to the top of the tree.  If no node has the given
96  // key, the last node on the search path is moved to the top of the
97  // tree.
98  void Splay(const Key& key);
99
100  class Node {
101   public:
102    Node(const Key& key, const Value& value)
103        : key_(key),
104          value_(value),
105          left_(NULL),
106          right_(NULL) { }
107
108    INLINE(void* operator new(size_t size, AllocationPolicy allocator)) {
109      return allocator.New(static_cast<int>(size));
110    }
111    INLINE(void operator delete(void* p)) {
112      return AllocationPolicy::Delete(p);
113    }
114    // Please the MSVC compiler.  We should never have to execute
115    // this.
116    INLINE(void operator delete(void* p, AllocationPolicy allocator)) {
117      UNREACHABLE();
118    }
119
120    Key key() { return key_; }
121    Value value() { return value_; }
122    Node* left() { return left_; }
123    Node* right() { return right_; }
124
125   private:
126    friend class SplayTree;
127    friend class Locator;
128    Key key_;
129    Value value_;
130    Node* left_;
131    Node* right_;
132  };
133
134  // A locator provides access to a node in the tree without actually
135  // exposing the node.
136  class Locator BASE_EMBEDDED {
137   public:
138    explicit Locator(Node* node) : node_(node) { }
139    Locator() : node_(NULL) { }
140    const Key& key() { return node_->key_; }
141    Value& value() { return node_->value_; }
142    void set_value(const Value& value) { node_->value_ = value; }
143    inline void bind(Node* node) { node_ = node; }
144
145   private:
146    Node* node_;
147  };
148
149  template <class Callback>
150  void ForEach(Callback* callback);
151
152 protected:
153  // Resets tree root. Existing nodes become unreachable.
154  void ResetRoot() { root_ = NULL; }
155
156 private:
157  // Search for a node with a given key. If found, root_ points
158  // to the node.
159  bool FindInternal(const Key& key);
160
161  // Inserts a node assuming that root_ is already set up.
162  void InsertInternal(int cmp, Node* node);
163
164  // Removes root_ node.
165  void RemoveRootNode(const Key& key);
166
167  template<class Callback>
168  class NodeToPairAdaptor BASE_EMBEDDED {
169   public:
170    explicit NodeToPairAdaptor(Callback* callback)
171        : callback_(callback) { }
172    void Call(Node* node) {
173      callback_->Call(node->key(), node->value());
174    }
175
176   private:
177    Callback* callback_;
178
179    DISALLOW_COPY_AND_ASSIGN(NodeToPairAdaptor);
180  };
181
182  class NodeDeleter BASE_EMBEDDED {
183   public:
184    NodeDeleter() { }
185    void Call(Node* node) { AllocationPolicy::Delete(node); }
186
187   private:
188    DISALLOW_COPY_AND_ASSIGN(NodeDeleter);
189  };
190
191  template <class Callback>
192  void ForEachNode(Callback* callback);
193
194  Node* root_;
195  AllocationPolicy allocator_;
196
197  DISALLOW_COPY_AND_ASSIGN(SplayTree);
198};
199
200
201}  // namespace internal
202}  // namespace v8
203
204#endif  // V8_SPLAY_TREE_H_
205