/*******************************************************

* Copyright (c) 2022, ArrayFire

* All rights reserved.

*

* This file is distributed under 3-clause BSD license.

* The complete license agreement can be obtained at:

* http://arrayfire.com/licenses/BSD-3-Clause

********************************************************/

#include <common/deterministicHash.hpp>

#include <nonstd/span.hpp>

#include <numeric>

#include <string>

using nonstd::span;

using std::accumulate;

using std::string;

size_t deterministicHash(const void* data, size_t byteSize, size_t prevHash) {

// Fowler-Noll-Vo "1a" 32 bit hash

// https://en.wikipedia.org/wiki/Fowler-Noll-Vo_hash_function

const auto* byteData = static_cast<const uint8_t*>(data);

return accumulate(

byteData, byteData + byteSize, prevHash,

[&](size_t hash, uint8_t data) { return (hash ^ data) * FNV1A_PRIME; });

}

size_t deterministicHash(const string& data, const size_t prevHash) {

return deterministicHash(data.data(), data.size(), prevHash);

}

size_t deterministicHash(span<const string> list, const size_t prevHash) {

size_t hash = prevHash;

for (auto s : list) { hash = deterministicHash(s.data(), s.size(), hash); }

return hash;

}

size_t deterministicHash(span<const arrayfire::common::Source> list) {

// Combine the different source codes, via their hashes

size_t hash = FNV1A_BASE_OFFSET;

for (auto s : list) {

size_t h = s.hash ? s.hash : deterministicHash(s.ptr, s.length);

hash = deterministicHash(&h, sizeof(size_t), hash);

}

return hash;

}