tsl::hh::power_of_two_growth_policy< GrowthFactor > Class Template Reference

#include <hopscotch_growth_policy.h>

Public Member Functions
	power_of_two_growth_policy (std::size_t &min_bucket_count_in_out)
std::size_t	bucket_for_hash (std::size_t hash) const noexcept
std::size_t	next_bucket_count () const
std::size_t	max_bucket_count () const
void	clear () noexcept

Static Private Member Functions
static std::size_t	round_up_to_power_of_two (std::size_t value)
static constexpr bool	is_power_of_two (std::size_t value)

Private Attributes
std::size_t	m_mask

Detailed Description

template<std::size_t GrowthFactor>
class tsl::hh::power_of_two_growth_policy< GrowthFactor >

Grow the hash table by a factor of GrowthFactor keeping the bucket count to a power of two. It allows the table to use a mask operation instead of a modulo operation to map a hash to a bucket.

GrowthFactor must be a power of two >= 2.

Constructor & Destructor Documentation

power_of_two_growth_policy()

template<std::size_t GrowthFactor>

tsl::hh::power_of_two_growth_policy< GrowthFactor >::power_of_two_growth_policy ( std::size_t & min_bucket_count_in_out )

inlineexplicit

Called on the hash table creation and on rehash. The number of buckets for the table is passed in parameter. This number is a minimum, the policy may update this value with a higher value if needed (but not lower).

If 0 is given, min_bucket_count_in_out must still be 0 after the policy creation and bucket_for_hash must always return 0 in this case.

Member Function Documentation

bucket_for_hash()

template<std::size_t GrowthFactor>

std::size_t tsl::hh::power_of_two_growth_policy< GrowthFactor >::bucket_for_hash ( std::size_t hash ) const

inlinenoexcept

Return the bucket [0, bucket_count()) to which the hash belongs. If bucket_count() is 0, it must always return 0.

clear()

template<std::size_t GrowthFactor>

void tsl::hh::power_of_two_growth_policy< GrowthFactor >::clear ( )

inlinenoexcept

Reset the growth policy as if it was created with a bucket count of 0. After a clear, the policy must always return 0 when bucket_for_hash is called.

is_power_of_two()

template<std::size_t GrowthFactor>

static constexpr bool tsl::hh::power_of_two_growth_policy< GrowthFactor >::is_power_of_two ( std::size_t value )

inlinestaticconstexprprivate

max_bucket_count()

template<std::size_t GrowthFactor>

std::size_t tsl::hh::power_of_two_growth_policy< GrowthFactor >::max_bucket_count ( ) const

inline

Return the maximum number of buckets supported by the policy.

next_bucket_count()

template<std::size_t GrowthFactor>

std::size_t tsl::hh::power_of_two_growth_policy< GrowthFactor >::next_bucket_count ( ) const

inline

Return the bucket count to use when the bucket array grows on rehash.

round_up_to_power_of_two()

template<std::size_t GrowthFactor>

static std::size_t tsl::hh::power_of_two_growth_policy< GrowthFactor >::round_up_to_power_of_two ( std::size_t value )

inlinestaticprivate

Member Data Documentation

m_mask

template<std::size_t GrowthFactor>

std::size_t tsl::hh::power_of_two_growth_policy< GrowthFactor >::m_mask

private

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

• src/hopscotch_growth_policy.h