1// Copyright 2016 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_BASE_HASHMAP_ENTRY_H_
6#define V8_BASE_HASHMAP_ENTRY_H_
7
8#include <cstdint>
9
10namespace v8 {
11namespace base {
12
13// HashMap entries are (key, value, hash) triplets, with a boolean indicating if
14// they are an empty entry. Some clients may not need to use the value slot
15// (e.g. implementers of sets, where the key is the value).
16template <typename Key, typename Value>
17struct TemplateHashMapEntry {
18  Key key;
19  Value value;
20  uint32_t hash;  // The full hash value for key
21
22  TemplateHashMapEntry(Key key, Value value, uint32_t hash)
23      : key(key), value(value), hash(hash), exists_(true) {}
24
25  bool exists() const { return exists_; }
26
27  void clear() { exists_ = false; }
28
29 private:
30  bool exists_;
31};
32
33// Specialization for pointer-valued keys
34template <typename Key, typename Value>
35struct TemplateHashMapEntry<Key*, Value> {
36  Key* key;
37  Value value;
38  uint32_t hash;  // The full hash value for key
39
40  TemplateHashMapEntry(Key* key, Value value, uint32_t hash)
41      : key(key), value(value), hash(hash) {}
42
43  bool exists() const { return key != nullptr; }
44
45  void clear() { key = nullptr; }
46};
47
48// TODO(leszeks): There could be a specialisation for void values (e.g. for
49// sets), which omits the value field
50
51}  // namespace base
52}  // namespace v8
53
54#endif  // V8_BASE_HASHMAP_ENTRY_H_
55