Unordered Map Concept

Concept of a distributed unordered map container. More...

Collaboration diagram for Unordered Map Concept:

Classes
class	dash::UnorderedMapLocalRef< Key, Mapped, Hash, Pred, LMemSpace >
	Local view specifier of a dynamic map container with support for workload balancing. More...
class	dash::UnorderedMap< Key, Mapped, Hash, Pred, LocalMemType >
	Usage examples: More...

Detailed Description

Concept of a distributed unordered map container.

Description

Different from regular maps, elements in unordered map containers are not sorted in any particular order, but organized into buckets depending on their hash values. Unordered maps allow for fast access to individual elements as the storage location of a key in global and/or local memory can be resolved directly from its hash value.

Extends concepts:

• Container Concept
• DashSequentialContainerConcept
• DashDynamicContainerConcept

Container properties:

• Associative: Elements are referenced by their key and not by their absolute position in the container.
• Unordered: Elements follow no order and are organized using hash tables.
• Map: Each element associates a key to a mapped value: Keys identify the elements which contain the mapped value.
• Unique keys: No to elements can have equivalent keys.
• Allocator-aware: The container uses an allocator object to manage acquisition and release of storage space.

Iterator validity:

• All iterators in the container remain valid after the insertion unless it forces a rehash. In this case, all iterators in the container are invalidated.
• A rehash is forced if the new container size after the insertion operation would increase above its capacity threshold.
• References to elements in the map container remain valid in all cases, even after a rehash.

Member types

Type	Definition
STL
key_type	First template parameter Key
mapped_type	Second template parameter Mapped
compare_type	Third template parameter Compare
allocator_type	Fourth template parameter AllocatorType
value_type	std::pair<const key_type, mapped_type>
difference_type	A signed integral type, identical to iterator_traits<iterator>::difference_type
size_type	Unsigned integral type to represent any non-negative value of difference_type
reference	value_type &
const_reference	const value_type &
pointer	allocator_traits<allocator_type>::pointer
const_pointer	allocator_traits<allocator_type>::const_pointer
iterator	A bidirectional iterator to value_type
const_iterator	A bidirectional iterator to const value_type
reverse_iterator	reverse_iterator<iterator>
const_reverse_iterator	reverse_iterator<const_iterator>
DASH-specific
index_type	A signed integgral type to represent positions in global index space
view_type	Proxy type for views on map elements, implements DashUnorderedMapConcept
local_type	Proxy type for views on map elements that are local to the calling unit

Member functions

Function	Return type	Definition
Initialization
operator=	self &	Assignment operator
Iterators
begin	iterator	Iterator to first element in the map
end	iterator	Iterator past last element in the map
Capacity
size	size_type	Number of elements in the map
max_size	size_type	Maximum number of elements the map can hold
empty	bool	Whether the map is empty, i.e. size is 0
Modifiers
emplace	iterator	Construct and insert element at given position
insert	iterator	Insert elements before given position
erase	iterator	Erase elements at position or in range
swap	void	Swap content
clear	void	Clear the map's content
Views (DASH specific)
local	local_type	View on map elements local to calling unit