HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse > Class Template Reference

Holds a set of mappings between some key/value pairs. More...

#include <juce_HashMap.h>

Collaboration diagram for HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >:

Classes
class	HashEntry
struct	Iterator
	Iterates over the items in a HashMap. More...

Public Types
typedef TypeOfCriticalSectionToUse::ScopedLockType	ScopedLockType
	Returns the type of scoped lock to use for locking this array. More...

Public Member Functions
	HashMap (int numberOfSlots=defaultHashTableSize, HashFunctionType hashFunction=HashFunctionType())
	Creates an empty hash-map. More...
	~HashMap ()
	Destructor. More...
Iterator	begin () const noexcept
	Returns a start iterator for the values in this tree. More...
void	clear ()
	Removes all values from the map. More...
bool	contains (KeyTypeParameter keyToLookFor) const
	Returns true if the map contains an item with the specied key. More...
bool	containsValue (ValueTypeParameter valueToLookFor) const
	Returns true if the hash contains at least one occurrence of a given value. More...
Iterator	end () const noexcept
	Returns an end iterator for the values in this tree. More...
const TypeOfCriticalSectionToUse &	getLock () const noexcept
	Returns the CriticalSection that locks this structure. More...
int	getNumSlots () const noexcept
	Returns the number of slots which are available for hashing. More...
ValueType &	getReference (KeyTypeParameter keyToLookFor)
	Returns a reference to the value corresponding to a given key. More...
ValueType	operator[] (KeyTypeParameter keyToLookFor) const
	Returns the value corresponding to a given key. More...
void	remapTable (int newNumberOfSlots)
	Remaps the hash-map to use a different number of slots for its hash function. More...
void	remove (KeyTypeParameter keyToRemove)
	Removes an item with the given key. More...
void	removeValue (ValueTypeParameter valueToRemove)
	Removes all items with the given value. More...
void	set (KeyTypeParameter newKey, ValueTypeParameter newValue)
	Adds or replaces an element in the hash-map. More...
int	size () const noexcept
	Returns the current number of items in the map. More...
template<class OtherHashMapType >
void	swapWith (OtherHashMapType &otherHashMap) noexcept
	Efficiently swaps the contents of two hash-maps. More...

Private Types
enum	{ defaultHashTableSize = 101 }
typedef TypeHelpers::ParameterType< KeyType >::type	KeyTypeParameter
typedef TypeHelpers::ParameterType< ValueType >::type	ValueTypeParameter

Private Member Functions
int	generateHashFor (KeyTypeParameter key, int numSlots) const
HashEntry *	getSlot (KeyType key) const noexcept

Static Private Member Functions
static HashEntry *	getEntry (HashEntry *firstEntry, KeyType keyToLookFor) noexcept

Private Attributes
HashFunctionType	hashFunctionToUse
Array< HashEntry * >	hashSlots
TypeOfCriticalSectionToUse	lock
int	totalNumItems

Friends
struct	Iterator

Detailed Description

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>
class HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >

Holds a set of mappings between some key/value pairs.

The types of the key and value objects are set as template parameters. You can also specify a class to supply a hash function that converts a key value into an hashed integer. This class must have the form:

struct MyHashGenerator
{
    int generateHash (MyKeyType key, int upperLimit) const
    {
        // The function must return a value 0 <= x < upperLimit
        return someFunctionOfMyKeyType (key) % upperLimit;
    }
};

Like the Array class, the key and value types are expected to be copy-by-value types, so if you define them to be pointer types, this class won't delete the objects that they point to.

If you don't supply a class for the HashFunctionType template parameter, the default one provides some simple mappings for strings and ints.

HashMap<int, String> hash;
hash.set (1, "item1");
hash.set (2, "item2");

DBG (hash [1]); // prints "item1"
DBG (hash [2]); // prints "item2"

// This iterates the map, printing all of its key -> value pairs..
for (HashMap<int, String>::Iterator i (hash); i.next();)
    DBG (i.getKey() << " -> " << i.getValue());

Template Parameters

HashFunctionType

The class of hash function, which must be copy-constructible.

See also

CriticalSection, DefaultHashFunctions, NamedValueSet, SortedSet

Member Typedef Documentation

KeyTypeParameter

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

typedef TypeHelpers::ParameterType<KeyType>::type HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::KeyTypeParameter

private

ScopedLockType

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

typedef TypeOfCriticalSectionToUse::ScopedLockType HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::ScopedLockType

Returns the type of scoped lock to use for locking this array.

ValueTypeParameter

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

typedef TypeHelpers::ParameterType<ValueType>::type HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::ValueTypeParameter

private

Member Enumeration Documentation

anonymous enum

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

anonymous enum

private

Enumerator
defaultHashTableSize

Constructor & Destructor Documentation

HashMap()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::HashMap ( int  numberOfSlots = defaultHashTableSize, HashFunctionType  hashFunction = HashFunctionType()  )

inlineexplicit

Creates an empty hash-map.

Parameters

numberOfSlots	Specifies the number of hash entries the map will use. This will be the "upperLimit" parameter that is passed to your generateHash() function. The number of hash slots will grow automatically if necessary, or it can be remapped manually using remapTable().
hashFunction	An instance of HashFunctionType, which will be copied and stored to use with the HashMap. This parameter can be omitted if HashFunctionType has a default constructor.

~HashMap()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::~HashMap ( )

inline

Destructor.

Member Function Documentation

begin()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

Iterator HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::begin ( ) const

inlinenoexcept

Returns a start iterator for the values in this tree.

References HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::Iterator::next().

clear()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

void HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::clear ( )

inline

Removes all values from the map.

Note that this will clear the content, but won't affect the number of slots (see remapTable and getNumSlots).

contains()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

bool HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::contains ( KeyTypeParameter  keyToLookFor ) const

inline

Returns true if the map contains an item with the specied key.

containsValue()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

bool HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::containsValue ( ValueTypeParameter  valueToLookFor ) const

inline

Returns true if the hash contains at least one occurrence of a given value.

end()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

Iterator HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::end ( ) const

inlinenoexcept

Returns an end iterator for the values in this tree.

References HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::Iterator::resetToEnd().

generateHashFor()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

int HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::generateHashFor ( KeyTypeParameter  key, int  numSlots  ) const

inlineprivate

References juce::isPositiveAndBelow(), and jassert.

getEntry()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

static HashEntry* HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::getEntry ( HashEntry *  firstEntry, KeyType  keyToLookFor  )

inlinestaticprivatenoexcept

getLock()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

const TypeOfCriticalSectionToUse& HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::getLock ( ) const

inlinenoexcept

Returns the CriticalSection that locks this structure.

To lock, you can call getLock().enter() and getLock().exit(), or preferably use an object of ScopedLockType as an RAII lock for it.

getNumSlots()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

int HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::getNumSlots ( ) const

inlinenoexcept

Returns the number of slots which are available for hashing.

Each slot corresponds to a single hash-code, and each one can contain multiple items.

See also

getNumSlots()

getReference()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

ValueType& HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::getReference ( KeyTypeParameter  keyToLookFor )

inline

Returns a reference to the value corresponding to a given key.

If the map doesn't contain the key, a default instance of the value type is added to the map and a reference to this is returned.

Parameters

keyToLookFor

the key of the item being requested

getSlot()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

HashEntry* HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::getSlot ( KeyType  key ) const

inlineprivatenoexcept

References Array< ElementType, TypeOfCriticalSectionToUse, minimumAllocatedSize >::getUnchecked(), and JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR.

operator[]()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

ValueType HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::operator[] ( KeyTypeParameter  keyToLookFor ) const

inline

Returns the value corresponding to a given key.

If the map doesn't contain the key, a default instance of the value type is returned.

Parameters

keyToLookFor

the key of the item being requested

remapTable()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

void HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::remapTable ( int  newNumberOfSlots )

inline

Remaps the hash-map to use a different number of slots for its hash function.

Each slot corresponds to a single hash-code, and each one can contain multiple items.

See also

getNumSlots()

References Array< ElementType, TypeOfCriticalSectionToUse, minimumAllocatedSize >::getUnchecked(), Array< ElementType, TypeOfCriticalSectionToUse, minimumAllocatedSize >::insertMultiple(), HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::HashEntry::nextEntry, and Array< ElementType, TypeOfCriticalSectionToUse, minimumAllocatedSize >::set().

remove()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

void HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::remove ( KeyTypeParameter  keyToRemove )

inline

Removes an item with the given key.

References HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::HashEntry::nextEntry.

removeValue()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

void HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::removeValue ( ValueTypeParameter  valueToRemove )

inline

Removes all items with the given value.

References HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::HashEntry::nextEntry.

set()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

void HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::set ( KeyTypeParameter  newKey, ValueTypeParameter  newValue  )

inline

Adds or replaces an element in the hash-map.

If there's already an item with the given key, this will replace its value. Otherwise, a new item will be added to the map.

size()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

int HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::size ( ) const

inlinenoexcept

Returns the current number of items in the map.

swapWith()

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

template<class OtherHashMapType >

void HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::swapWith ( OtherHashMapType &  otherHashMap )

inlinenoexcept

Efficiently swaps the contents of two hash-maps.

Friends And Related Function Documentation

Iterator

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

friend struct Iterator

friend

Member Data Documentation

hashFunctionToUse

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

HashFunctionType HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::hashFunctionToUse

private

hashSlots

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

Array<HashEntry*> HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::hashSlots

private

lock

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

TypeOfCriticalSectionToUse HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::lock

private

totalNumItems

template<typename KeyType, typename ValueType, class HashFunctionType = DefaultHashFunctions, class TypeOfCriticalSectionToUse = DummyCriticalSection>

int HashMap< KeyType, ValueType, HashFunctionType, TypeOfCriticalSectionToUse >::totalNumItems

private

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

• juce_HashMap.h