87 lines
3.0 KiB
C++
87 lines
3.0 KiB
C++
// Copyright (c) 2011 The Chromium 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 BASE_HASH_HASH_H_
|
|
#define BASE_HASH_HASH_H_
|
|
|
|
#include <stddef.h>
|
|
#include <stdint.h>
|
|
|
|
#include <limits>
|
|
#include <string>
|
|
#include <utility>
|
|
|
|
#include "base/base_export.h"
|
|
#include "base/containers/span.h"
|
|
#include "base/logging.h"
|
|
#include "base/strings/string16.h"
|
|
#include "base/strings/string_piece.h"
|
|
|
|
namespace base {
|
|
|
|
// WARNING: This hash functions should not be used for any cryptographic
|
|
// purpose.
|
|
|
|
// Deprecated: Computes a hash of a memory buffer, use FastHash() instead.
|
|
// If you need to persist a change on disk or between computers, use
|
|
// PersistentHash().
|
|
// TODO(https://crbug.com/1025358): Migrate client code to new hash function.
|
|
BASE_EXPORT uint32_t Hash(const void* data, size_t length);
|
|
BASE_EXPORT uint32_t Hash(const std::string& str);
|
|
BASE_EXPORT uint32_t Hash(const string16& str);
|
|
|
|
// Really *fast* and high quality hash.
|
|
// Recommended hash function for general use, we pick the best performant
|
|
// hash for each build target.
|
|
// It is prone to be updated whenever a newer/faster hash function is
|
|
// publicly available.
|
|
// May changed without warning, do not expect stability of outputs.
|
|
BASE_EXPORT size_t FastHash(base::span<const uint8_t> data);
|
|
inline size_t FastHash(StringPiece str) {
|
|
return FastHash(as_bytes(make_span(str)));
|
|
}
|
|
|
|
// Computes a hash of a memory buffer. This hash function must not change so
|
|
// that code can use the hashed values for persistent storage purposes or
|
|
// sending across the network. If a new persistent hash function is desired, a
|
|
// new version will have to be added in addition.
|
|
//
|
|
// WARNING: This hash function should not be used for any cryptographic purpose.
|
|
BASE_EXPORT uint32_t PersistentHash(base::span<const uint8_t> data);
|
|
BASE_EXPORT uint32_t PersistentHash(const void* data, size_t length);
|
|
BASE_EXPORT uint32_t PersistentHash(const std::string& str);
|
|
|
|
// Hash pairs of 32-bit or 64-bit numbers.
|
|
BASE_EXPORT size_t HashInts32(uint32_t value1, uint32_t value2);
|
|
BASE_EXPORT size_t HashInts64(uint64_t value1, uint64_t value2);
|
|
|
|
template <typename T1, typename T2>
|
|
inline size_t HashInts(T1 value1, T2 value2) {
|
|
// This condition is expected to be compile-time evaluated and optimised away
|
|
// in release builds.
|
|
if (sizeof(T1) > sizeof(uint32_t) || (sizeof(T2) > sizeof(uint32_t)))
|
|
return HashInts64(value1, value2);
|
|
|
|
return HashInts32(static_cast<uint32_t>(value1),
|
|
static_cast<uint32_t>(value2));
|
|
}
|
|
|
|
// A templated hasher for pairs of integer types. Example:
|
|
//
|
|
// using MyPair = std::pair<int32_t, int32_t>;
|
|
// std::unordered_set<MyPair, base::IntPairHash<MyPair>> set;
|
|
template <typename T>
|
|
struct IntPairHash;
|
|
|
|
template <typename Type1, typename Type2>
|
|
struct IntPairHash<std::pair<Type1, Type2>> {
|
|
size_t operator()(std::pair<Type1, Type2> value) const {
|
|
return HashInts(value.first, value.second);
|
|
}
|
|
};
|
|
|
|
} // namespace base
|
|
|
|
#endif // BASE_HASH_HASH_H_
|