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_(nullptr), allocator_(allocator) {}
40 ~SplayTree();
41
42 V8_INLINE void* operator new(
43 size_t size, AllocationPolicy allocator = AllocationPolicy()) {
44 return allocator.New(static_cast<int>(size));
45 }
46 V8_INLINE void operator delete(void* p) { AllocationPolicy::Delete(p); }
47 // Please the MSVC compiler. We should never have to execute this.
48 V8_INLINE void operator delete(void* p, AllocationPolicy policy) {
49 UNREACHABLE();
50 }
51
52 AllocationPolicy allocator() { return allocator_; }
53
54 // Checks if there is a mapping for the key.
55 bool Contains(const Key& key);
56
57 // Inserts the given key in this tree with the given value. Returns
58 // true if a node was inserted, otherwise false. If found the locator
59 // is enabled and provides access to the mapping for the key.
60 bool Insert(const Key& key, Locator* locator);
61
62 // Looks up the key in this tree and returns true if it was found,
63 // otherwise false. If the node is found the locator is enabled and
64 // provides access to the mapping for the key.
65 bool Find(const Key& key, Locator* locator);
66
67 // Finds the mapping with the greatest key less than or equal to the
68 // given key.
69 bool FindGreatestLessThan(const Key& key, Locator* locator);
70
71 // Find the mapping with the greatest key in this tree.
72 bool FindGreatest(Locator* locator);
73
74 // Finds the mapping with the least key greater than or equal to the
75 // given key.
76 bool FindLeastGreaterThan(const Key& key, Locator* locator);
77
78 // Find the mapping with the least key in this tree.
79 bool FindLeast(Locator* locator);
80
81 // Move the node from one key to another.
82 bool Move(const Key& old_key, const Key& new_key);
83
84 // Remove the node with the given key from the tree.
85 bool Remove(const Key& key);
86
87 // Remove all keys from the tree.
88 void Clear() { ResetRoot(); }
89
90 bool is_empty() { return root_ == nullptr; }
91
92 // Perform the splay operation for the given key. Moves the node with
93 // the given key to the top of the tree. If no node has the given
94 // key, the last node on the search path is moved to the top of the
95 // tree.
96 void Splay(const Key& key);
97
98 class Node {
99 public:
100 Node(const Key& key, const Value& value)
101 : key_(key), value_(value), left_(nullptr), right_(nullptr) {}
102
103 V8_INLINE void* operator new(size_t size, AllocationPolicy allocator) {
104 return allocator.New(static_cast<int>(size));
105 }
106 V8_INLINE void operator delete(void* p) {
107 return AllocationPolicy::Delete(p);
108 }
109 // Please the MSVC compiler. We should never have to execute
110 // this.
111 V8_INLINE void operator delete(void* p, AllocationPolicy allocator) {
112 UNREACHABLE();
113 }
114
115 Key key() { return key_; }
116 Value value() { return value_; }
117 Node* left() { return left_; }
118 Node* right() { return right_; }
119
120 private:
121 friend class SplayTree;
122 friend class Locator;
123 Key key_;
124 Value value_;
125 Node* left_;
126 Node* right_;
127 };
128
129 // A locator provides access to a node in the tree without actually
130 // exposing the node.
131 class Locator {
132 public:
133 explicit Locator(Node* node) : node_(node) { }
134 Locator() : node_(nullptr) {}
135 const Key& key() { return node_->key_; }
136 Value& value() { return node_->value_; }
137 void set_value(const Value& value) { node_->value_ = value; }
138 inline void bind(Node* node) { node_ = node; }
139
140 private:
141 Node* node_;
142 };
143
144 template <class Callback>
145 void ForEach(Callback* callback);
146
147 protected:
148 // Resets tree root. Existing nodes become unreachable.
149 void ResetRoot() { root_ = nullptr; }
150
151 private:
152 // Search for a node with a given key. If found, root_ points
153 // to the node.
154 bool FindInternal(const Key& key);
155
156 // Inserts a node assuming that root_ is already set up.
157 void InsertInternal(int cmp, Node* node);
158
159 // Removes root_ node.
160 void RemoveRootNode(const Key& key);
161
162 template <class Callback>
163 class NodeToPairAdaptor {
164 public:
165 explicit NodeToPairAdaptor(Callback* callback)
166 : callback_(callback) { }
167 void Call(Node* node) {
168 callback_->Call(node->key(), node->value());
169 }
170
171 private:
172 Callback* callback_;
173
174 DISALLOW_COPY_AND_ASSIGN(NodeToPairAdaptor);
175 };
176
177 class NodeDeleter {
178 public:
179 NodeDeleter() = default;
180 void Call(Node* node) { AllocationPolicy::Delete(node); }
181
182 private:
183 DISALLOW_COPY_AND_ASSIGN(NodeDeleter);
184 };
185
186 template <class Callback>
187 void ForEachNode(Callback* callback);
188
189 Node* root_;
190 AllocationPolicy allocator_;
191
192 DISALLOW_COPY_AND_ASSIGN(SplayTree);
193};
194
195
196} // namespace internal
197} // namespace v8
198
199#endif // V8_SPLAY_TREE_H_
200