THashMappedArray | Unreal Engine 5.7 Documentation

API > API/Runtime > API/Runtime/Chaos

A HashMap using FHashTable to index an array of elements of type TElementType, whcih should be uniquely identified by an object of type TIDType.

E.g., using FMyDataID = int32; struct FMyData { FMyDataID ID; // Every FMyData will require a unique ID if using the default THashMappedArrayTraits float MyValue; };

const int32 HashTableSize = 128; // Must be power of 2 THashMapedArray MyDataMap(HashTableSize);

MyDataMap.Add(1, { 1, 1.0 }); // NOTE: ID passed twice. Once for the hash map and once to construct FMyData MyDataMap.Emplace(2, 2, 2.0); // NOTE: ID passed twice. Once for the hash map and once for forwarding args to FMyData

const FMyData* MyData2 = MyDataMap.Find(2); // MyData2->MyValue == 2.0


Name	THashMappedArray
Type	class
Header File	/Engine/Source/Runtime/Experimental/Chaos/Public/Chaos/Framework/HashMappedArray.h
Include Path	#include "Chaos/Framework/HashMappedArray.h"

Syntax

template<typename TIDType, typename TElementType , typename TTraits>  
class THashMappedArray

Constructors

Name	Remarks	Include Path	Unreal Specifiers
THashMappedArray ( const int32 InHashSize )	Initialize the hash table. InHashSize must be a power of two (asserted)	Chaos/Framework/HashMappedArray.h

Typedefs

Name	Type	Include Path
FElementType	TElementType	Chaos/Framework/HashMappedArray.h
FHashType	uint32	Chaos/Framework/HashMappedArray.h
FIDType	TIDType	Chaos/Framework/HashMappedArray.h
FTraits	TTraits	Chaos/Framework/HashMappedArray.h
FType	THashMappedArray< FIDType, FElementType, FTraits >	Chaos/Framework/HashMappedArray.h

Variables

Protected

Name	Type	Remarks	Include Path	Unreal Specifiers
Elements	TArray< FElementType >		Chaos/Framework/HashMappedArray.h
HashTable	FHashTable		Chaos/Framework/HashMappedArray.h

Functions

Public

Name	Remarks	Include Path
void Add ( const FIDType ID, const FElementType& Element )	Add an element with the specified ID to the map. Asserts if an Element with the same ID is already in the map.	Chaos/Framework/HashMappedArray.h
FElementType & At ( const int32 ElementIndex )	Get the element at ElementIndex (indexed by order in which they were added)	Chaos/Framework/HashMappedArray.h
const FElementType & At ( const int32 ElementIndex ) const	Get the element at ElementIndex (indexed by order in which they were added)	Chaos/Framework/HashMappedArray.h
void Emplace ( const FIDType ID, ArgsType&&... Args )	Add an element with the specified ID to the map.	Chaos/Framework/HashMappedArray.h
TArray< FElementType > ExtractElements()	Move the array elements into an external array and reset.	Chaos/Framework/HashMappedArray.h
const FElementType * Find ( const FIDType ID ) const	Find the element with the specified ID. Roughly O(Max(1,N/M)) for N elements with a hash table of size M.	Chaos/Framework/HashMappedArray.h
FElementType * Find ( const FIDType ID )	Find the element with the specified ID. Roughly O(Max(1,N/M)) for N elements with a hash table of size M.	Chaos/Framework/HashMappedArray.h
int32 Num()	The number of elements that have been added to the map.	Chaos/Framework/HashMappedArray.h
void Remove ( const FIDType ID )		Chaos/Framework/HashMappedArray.h
void Reset ( const int32 InReserveElements )	Clear the hash map and reserve space for the specified number of elements (will not shrink)	Chaos/Framework/HashMappedArray.h
bool TryAdd ( const FIDType ID, const FElementType& Element )	Try to add an element with the specified ID to the map.	Chaos/Framework/HashMappedArray.h
bool TryEmplace ( const FIDType ID, ArgsType&&... Args )	Try to add an element with the specified ID to the map.	Chaos/Framework/HashMappedArray.h

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