LRUHashMap< K, V, MAXENTRIES > Class Template Reference

#include <lruhashmap.h>

Detailed Description

template<typename K, typename V, Int MAXENTRIES>
class maxon::LRUHashMap< K, V, MAXENTRIES >

LRUHashMap is a specialized HashMap which is able to restrict the number of elements in the HashMap. The map keeps the LRU (last recently used) elements and destroys the most unused values if a the number of elements exceeds the limit (MAXENTRIES). The class can be used to cache a limited number of elements.

Template Parameters

K	KEY type of the hash map.
V	VALUE type of the hash map.
MAXENTRIES	Initial maximum number of elements to store.

Public Member Functions
	~LRUHashMap ()
template<typename KEY >
ResultRef< V >	InsertKey (KEY &&key, Bool &created=BoolLValue())
template<typename KEY >
const V *	FindValue (const KEY &key) const
template<typename KEY >
V *	FindValue (const KEY &key)
Int	GetCount () const
void	SetCapacity (Int maxCapacity)
Int	GetCapacity () const
void	Reset ()
template<typename KEY >
ResultOk< void >	Erase (const KEY &key)

Private Types
using	ListNodeType = BaseListNode< V >
using	LastNodeHead = BaseListHead< V, ListNodeType >
using	Entry = typename HashMap< K, ListNodeType >::Entry
using	Allocator = BlockArrayAllocator< SIZEOF(Entry)>
using	HashMapType = HashMap< K, ListNodeType, DefaultCompare, HashMapKeyValuePair, DefaultAllocator, HASHMAP_MODE::DEFAULT, 16, 10, Allocator >

Private Member Functions
void	UpdateEntry (typename HashMapType::Entry *entry) const
void	RemoveOldest ()

Private Attributes
HashMapType	_hashMap
LastNodeHead	_lastUsed
Int	_maxCapacity

Member Typedef Documentation

ListNodeType

using ListNodeType = BaseListNode<V>

private

LastNodeHead

using LastNodeHead = BaseListHead<V, ListNodeType>

private

Entry

using Entry = typename HashMap<K, ListNodeType>::Entry

private

Allocator

using Allocator = BlockArrayAllocator<SIZEOF(Entry)>

private

HashMapType

using HashMapType = HashMap<K, ListNodeType, DefaultCompare, HashMapKeyValuePair, DefaultAllocator, HASHMAP_MODE::DEFAULT, 16, 10, Allocator>

private

Constructor & Destructor Documentation

~LRUHashMap()

~LRUHashMap

(

)

Member Function Documentation

InsertKey()

ResultRef<V> InsertKey	(	KEY &&	key,
		Bool &	created = BoolLValue()
	)

Finds the value associated with the given key, or creates a corresponding entry if it doesn't exist yet. The value of a new entry has to be initialized afterwards (but its default constructor has already been invoked).

Parameters

[in]	key	Key of the value to find or create.
[out]	created	This will be set to true if a new entry has been created successfully, otherwise it will be set to false.

Returns

Pointer to value for the given key, or nullptr if an entry didn't exist and allocation of a new entry failed.

FindValue() [1/2]

const V* FindValue

(

const KEY &

key

)

const

Finds the value associated with the given key in this map.

Template Parameters

KEY	Type of key.

Parameters

[in]

key

Key to search for.

Returns

Pointer to value for the given key, or nullptr if no entry exists for the key.

FindValue() [2/2]

V* FindValue

(

const KEY &

key

)

Finds the value associated with the given key in this map.

Template Parameters

KEY	Type of key.

Parameters

[in]

key

Key to search for.

Returns

Pointer to value for the given key, or nullptr if no entry exists for the key.

GetCount()

Int GetCount

(

void

)

const

Returns the number of entries in this map.

Returns

Number of entries.

SetCapacity()

void SetCapacity

(

Int

maxCapacity

)

Sets the maximum capacity of this map.

Parameters

[in]

maxCapacity

Maximum capacity of the map.

GetCapacity()

Int GetCapacity

(

)

const

Returns the maximum capacity of this map.

Returns

Maximum capacity.

Reset()

void Reset

(

void

)

Resets the map. This destructs all entries and frees any memory held by the map, so the map will be in a state as if it had been newly constructed.

See also

Flush()

Erase()

ResultOk<void> Erase

(

const KEY &

key

)

Removes an entry with the given key from this HashMap (if possible). In case of a multi-map, this only removes a single entry. The type KEY of the given key need not be the same as K, but then you have to provide an additional class KEYHASH to compute the hash code of the specified key (function KEYHASH::GetHashCode(const KEY&)), and to compare a key of type KEY with a key of type K for equality (function KEYHASH::IsEqual(const KEY&, const K&)) unless the default HASH class is already able to do so.

Template Parameters

KEY	Type of key.

Parameters

[in]

key

An entry having this key shall be removed.

Returns

Always true for a HashMap (even if key isn't contained in the map). For a general map, false indicates an out-of-memory condition on removal, but this cannot happen for a HashMap.

UpdateEntry()

void UpdateEntry ( typename HashMapType::Entry *  entry ) const

private

RemoveOldest()

void RemoveOldest ( )

private

Member Data Documentation

_hashMap

HashMapType _hashMap

private

_lastUsed

LastNodeHead _lastUsed

private

_maxCapacity

Int _maxCapacity

private