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winrt::vector_view_base struct template (C++/WinRT)

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A base class from which you can derive to implement your own custom view, or span, of a contiguous sequence of elements in a general-purpose collection. For more info, and code examples, see Collections with C++/WinRT.

Syntax

template <typename D, typename T, typename Version = winrt::impl::no_collection_version>
struct vector_view_base : iterable_base<D, T, Version>

Template parameters

typename D Your derived type name.

typename T The type of the elements that the vector_view_base views, or spans.

typename Version A type that provides versioning policy and services to the collection.

Requirements

Minimum supported SDK: Windows SDK version 10.0.17763.0 (Windows 10, version 1809)

Namespace: winrt

Header: %WindowsSdkDir%Include<WindowsTargetPlatformVersion>\cppwinrt\winrt\base.h (included by default)

Member functions

Function Description
vector_view_base::First function Retrieves an IIterator representing the first element viewed by the vector_view_base object.
vector_view_base::GetAt function Retrieves the element at the specified index viewed by the vector_view_base object.
vector_view_base::GetMany function Retrieves a collection of elements viewed by the vector_view_base object beginning at the given index.
vector_view_base::IndexOf function Retrieves the index of a specified element viewed by the vector_view_base object.
vector_view_base::Size function Retrieves the number of elements viewed by the vector_view_base object.

Iterators

A vector_view_base is a range, and that range is defined by internal free functions (each of which retrieves an iterator) that are compatible with standard language features. Because of this, you can enumerate the elements viewed by a vector_view_base object with a range-based for statement.

You can also retrieve an IIterator from the vector_view_base::First function, and use that to iterate through the elements viewed by a vector_view_base object.

...
#include <iostream>
using namespace winrt;
using namespace Windows::Foundation::Collections;
...
struct MyVectorView :
    implements<MyVectorView, IVectorView<float>, IIterable<float>>,
    winrt::vector_view_base<MyVectorView, float>
{
    auto& get_container() const noexcept
    {
        return m_values;
    }

private:
    std::vector<float> m_values{ 0.1f, 0.2f, 0.3f };
};
...
IVectorView<float> view{ winrt::make<MyVectorView>() };

for (float el : view)
{
    std::wcout << el << std::endl;
}

IIterator<float> it{ view.First() };
while (it.HasCurrent())
{
    std::wcout << it.Current() << std::endl;
    it.MoveNext();
}

vector_view_base::First function

Retrieves an IIterator representing the first element viewed by the vector_view_base object.

Syntax

auto First();

Return value

An IIterator representing the first element viewed by the vector_view_base object.

vector_view_base::GetAt function

Retrieves the element at the specified index viewed by the vector_view_base object.

Syntax

T GetAt(uint32_t const index) const;

Parameters

index A zero-based element index.

Return value

The element at the specified index viewed by the vector_view_base object.

vector_view_base::GetMany function

Retrieves a collection of elements viewed by the vector_view_base object beginning at the given index.

Syntax

uint32_t GetMany(uint32_t const startIndex, array_view<T> values) const;

Parameters

startIndex A zero-based element index to start at.

values An array_view to copy the items into.

Return value

A value representing the number of elements retrieved.

vector_view_base::IndexOf function

Retrieves the index of a specified element viewed by the vector_view_base object.

Syntax

bool IndexOf(T const& value, uint32_t& index) const noexcept;

Parameters

value The element, viewed by the vector_view_base object, to look for.

index The zero-based index of the element if the element is found, otherwise the number of elements viewed by the vector_view_base object.

Return value

true if the element is found, otherwise false.

vector_view_base::Size function

Retrieves the number of elements viewed by the vector_view_base object.

Syntax

uint32_t Size() const noexcept;

Return value

A value representing the number of elements viewed by the vector_view_base object.

See also