aboutsummaryrefslogtreecommitdiffstats
path: root/library/cpp/containers/flat_hash/lib/size_fitters.h
blob: 86bd617342d21516a30e191dd0db68e1c695804a (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
#pragma once

#include "concepts/size_fitter.h"

#include <util/system/yassert.h>
#include <util/generic/bitops.h>

namespace NFlatHash {

class TAndSizeFitter {
public:
    size_t EvalIndex(size_t hs, size_t sz) const noexcept {
        Y_ASSERT(Mask_ == sz - 1);
        return (hs & Mask_);
    }

    size_t EvalSize(size_t sz) const noexcept {
        return FastClp2(sz);
    }

    void Update(size_t sz) noexcept {
        Y_ASSERT((sz & (sz - 1)) == 0);
        Mask_ = sz - 1;
    }

private:
    size_t Mask_ = 0;
};

static_assert(NConcepts::SizeFitterV<TAndSizeFitter>);

class TModSizeFitter {
public:
    constexpr size_t EvalIndex(size_t hs, size_t sz) const noexcept {
        return hs % sz;
    }

    constexpr size_t EvalSize(size_t sz) const noexcept {
        return sz;
    }

    constexpr void Update(size_t) noexcept {}
};

static_assert(NConcepts::SizeFitterV<TModSizeFitter>);

}  // NFlatHash