default_hasher.h

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#pragma once
 
#include "di/container/hash/hasher.h"
#include "di/util/exchange.h"
 
namespace di::container {
struct DefaultHasher {
    constexpr void write(vocab::Span<byte const> data) noexcept {
        // For now, this is a simple hash function. This is apparently used by Java.
        // See https://computinglife.wordpress.com/2008/11/20/why-do-hash-functions-use-prime-numbers/.
        for (auto const byte : data) {
            m_hash = (m_hash * 31U) + di::to_integer<u8>(byte);
        }
    }
 
    constexpr auto finish() noexcept -> u64 { return util::exchange(m_hash, 0); }
 
private:
    u64 m_hash { 0 };
};
}
 
namespace di {
using container::DefaultHasher;
}