folly::detail::integral_hasher< I > Struct Template Reference

#include <Hash.h>

Public Types
using	folly_is_avalanching = bool_constant<(sizeof(I) >=8||sizeof(size_t)==4)>

Public Member Functions
size_t	operator() (I const &i) const noexcept

Detailed Description

template<typename I>
struct folly::detail::integral_hasher< I >

Definition at line 316 of file Hash.h.

Member Typedef Documentation

template<typename I>

using folly::detail::integral_hasher< I >::folly_is_avalanching = bool_constant<(sizeof(I) >= 8 || sizeof(size_t) == 4)>

Definition at line 318 of file Hash.h.

Member Function Documentation

template<typename I>

size_t folly::detail::integral_hasher< I >::operator() ( I const &  i ) const

inlinenoexcept

Definition at line 320 of file Hash.h.

                                               {
    static_assert(sizeof(I) <= 16, "Input type is too wide");
    /* constexpr */ if (sizeof(I) <= 4) {
      auto const i32 = static_cast<int32_t>(i); // impl accident: sign-extends
      auto const u32 = static_cast<uint32_t>(i32);
      return static_cast<size_t>(hash::jenkins_rev_mix32(u32));
    } else if (sizeof(I) <= 8) {
      auto const u64 = static_cast<uint64_t>(i);
      return static_cast<size_t>(hash::twang_mix64(u64));
    } else {
      auto const u = to_unsigned(i);
      auto const hi = static_cast<uint64_t>(u >> sizeof(I) * 4);
      auto const lo = static_cast<uint64_t>(u);
      return hash::hash_128_to_64(hi, lo);
    }
  }

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The documentation for this struct was generated from the following file:

• proxygen/folly/folly/hash/Hash.h