77 lines
2.6 KiB
C
77 lines
2.6 KiB
C
|
/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
|
|||
|
|
* Use of this file is governed by the BSD 3-clause license that
|
|||
|
|
* can be found in the LICENSE.txt file in the project root.
|
|||
|
|
*/
|
|||
|
|
|
|||
|
|
#pragma once
|
|||
|
|
|
|||
|
|
#include "antlr4-common.h"
|
|||
|
|
|
|||
|
|
namespace antlr4 {
|
|||
|
|
namespace misc {
|
|||
|
|
|
|||
|
|
class ANTLR4CPP_PUBLIC MurmurHash {
|
|||
|
|
|
|||
|
|
private:
|
|||
|
|
static const size_t DEFAULT_SEED = 0;
|
|||
|
|
|
|||
|
|
/// Initialize the hash using the default seed value.
|
|||
|
|
/// Returns the intermediate hash value.
|
|||
|
|
public:
|
|||
|
|
static size_t initialize();
|
|||
|
|
|
|||
|
|
/// Initialize the hash using the specified seed.
|
|||
|
|
static size_t initialize(size_t seed);
|
|||
|
|
|
|||
|
|
/// Update the intermediate hash value for the next input {@code value}.
|
|||
|
|
/// <param name="hash"> the intermediate hash value </param>
|
|||
|
|
/// <param name="value"> the value to add to the current hash </param>
|
|||
|
|
/// Returns the updated intermediate hash value.
|
|||
|
|
static size_t update(size_t hash, size_t value);
|
|||
|
|
|
|||
|
|
/**
|
|||
|
|
* Update the intermediate hash value for the next input {@code value}.
|
|||
|
|
*
|
|||
|
|
* @param hash the intermediate hash value
|
|||
|
|
* @param value the value to add to the current hash
|
|||
|
|
* @return the updated intermediate hash value
|
|||
|
|
*/
|
|||
|
|
template <class T>
|
|||
|
|
static size_t update(size_t hash, Ref<T> const& value) {
|
|||
|
|
return update(hash, value != nullptr ? value->hashCode() : 0);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
template <class T>
|
|||
|
|
static size_t update(size_t hash, T *value) {
|
|||
|
|
return update(hash, value != nullptr ? value->hashCode() : 0);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/// <summary>
|
|||
|
|
/// Apply the final computation steps to the intermediate value {@code hash}
|
|||
|
|
/// to form the final result of the MurmurHash 3 hash function.
|
|||
|
|
/// </summary>
|
|||
|
|
/// <param name="hash"> the intermediate hash value </param>
|
|||
|
|
/// <param name="entryCount"> the number of calls to update() before calling finish() </param>
|
|||
|
|
/// <returns> the final hash result </returns>
|
|||
|
|
static size_t finish(size_t hash, size_t entryCount);
|
|||
|
|
|
|||
|
|
/// Utility function to compute the hash code of an array using the MurmurHash3 algorithm.
|
|||
|
|
///
|
|||
|
|
/// @param <T> the array element type </param>
|
|||
|
|
/// <param name="data"> the array data </param>
|
|||
|
|
/// <param name="seed"> the seed for the MurmurHash algorithm </param>
|
|||
|
|
/// <returns> the hash code of the data </returns>
|
|||
|
|
template<typename T> // where T is C array type
|
|||
|
|
static size_t hashCode(const std::vector<Ref<T>> &data, size_t seed) {
|
|||
|
|
size_t hash = initialize(seed);
|
|||
|
|
for (auto entry : data) {
|
|||
|
|
hash = update(hash, entry->hashCode());
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
return finish(hash, data.size());
|
|||
|
|
}
|
|||
|
|
};
|
|||
|
|
|
|||
|
|
} // namespace atn
|
|||
|
|
} // namespace antlr4
|