chromium/v8/src/base/hashmap-entry.h

// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_BASE_HASHMAP_ENTRY_H_
#define V8_BASE_HASHMAP_ENTRY_H_

#include <cstdint>
#include <type_traits>

#include "src/base/memory.h"

namespace v8 {
namespace base {

// Marker type for hashmaps without a value (i.e. hashsets). These won't
// allocate space for the value in the entry.
struct NoHashMapValue { … };

// HashMap entries are (key, value, hash) triplets, with a boolean indicating if
// they are an empty entry. Some clients may not need to use the value slot
// (e.g. implementers of sets, where the key is the value), in which case they
// should use NoHashMapValue.
template <typename Key, typename Value>
struct TemplateHashMapEntry { … };

// Specialization for pointer-valued keys
TemplateHashMapEntry<Key *, Value>;

// Specialization for Address-valued keys
TemplateHashMapEntry<Address, Value>;

// Specialization for no value.
TemplateHashMapEntry<Key, NoHashMapValue>;

// Specialization for pointer-valued keys and no value.
TemplateHashMapEntry<Key *, NoHashMapValue>;

}  // namespace base
}  // namespace v8

#endif  // V8_BASE_HASHMAP_ENTRY_H_