Platform::Collections::MapView Class

Represents a read-only view into a map, which is a collection of key-value pairs.

Syntax

template <  
   typename K,  
   typename V,  
   typename C = ::std::less<K>>  
ref class MapView sealed;  

Parameters

K
The type of the key in the key-value pair.

V
The type of the value in the key-value pair.

C
A type that provides a function object that can compare two element values as sort keys to determine their relative order in the MapView. By default, std::less<K>.

Remarks

MapView is a concrete C++ implementation of the Windows::Foundation::Collections::IMapView <K,V> interface that is passed across the application binary interface (ABI). For more information, see Collections (C++/CX).

Members

Public Constructors

Name Description
MapView::MapView Initializes a new instance of the MapView class.

Public Methods

Name Description
MapView::First Returns an iterator that is initialized to the first element in the map view.
MapView::HasKey Determines whether the current MapView contains the specified key.
MapView::Lookup Retrieves the element at the specified key in the current MapView object.
MapView::Size Returns the number of elements in the current MapView object.
MapView::Split Splits an original MapView object into two MapView objects.

Inheritance Hierarchy

MapView

Requirements

Header: collection.h

Namespace: Platform::Collections

MapView::First Method

Returns an iterator that specifies the first element in the map view.

Syntax

virtual Windows::Foundation::Collections::IIterator<  
   Windows::Foundation::Collections::IKeyValuePair<K, V>^>^ First();  

Return Value

An iterator that specifies the first element in the map view.

Remarks

A convenient way to hold the iterator returned by First() is to assign the return value to a variable that is declared with the auto type deduction keyword. For example, auto x = myMapView->First();.

MapView::HasKey Method

Determines whether the current MapView contains the specified key.

Syntax


bool HasKey(K key);  

Parameters

key
The key used to locate the MapView element. The type of key is typename K.

Return Value

true if the key is found; otherwise, false.

MapView::Lookup Method

Retrieves the value of type V that is associated with the specified key of type K.

Syntax

V Lookup(K key);  

Parameters

key
The key used to locate an element in the MapView. The type of key is typename K.

Return Value

The value that is paired with the key. The type of the return value is typename V.

MapView::MapView Constructor

Initializes a new instance of the MapView class.

Syntax

explicit MapView(const C& comp = C());  

explicit MapView(const ::std::map<K, V, C>& m);  

explicit MapView(std::map<K, V, C>&& m);  

template <typename InIt> MapView(  
    InIt first,  
    InIt last,  
    const C& comp = C());  

MapView(
    ::std::initializer_list<std::pair<const K, V>> il,  
    const C& comp = C());  

Parameters

InIt
The typename of the current MapView.

comp
A function object that can compare two element values as sort keys to determine their relative order in the MapView.

m
A reference or Lvalues and Rvalues to a map Class that is used to initialize the current MapView.

first
The input iterator of the first element in a range of elements used to initialize the current MapView.

last
The input iterator of the first element after a range of elements used to initialize the current MapView.

il
A std::initializer_list<std::pair<K,V>> whose elements will be inserted into the MapView.

MapView::Size Method

Returns the number of elements in the current MapView object.

Syntax


virtual property unsigned int Size;  

Return Value

The number of elements in the current MapView.

MapView::Split Method

Divides the current MapView object into two MapView objects. This method is non-operational.

Syntax

void Split(  
   Windows::Foundation::Collections::IMapView<  
                         K, V>^ * firstPartition,  
   Windows::Foundation::Collections::IMapView<  
                         K, V>^ * secondPartition);  

Parameters

firstPartition
The first part of the original MapView object.

secondPartition
The second part of the original MapView object.

Remarks

This method is not operational; it does nothing.

See Also

Platform Namespace