default_if_empty

Ensures a sequence has at least one element. More...

Functions
template<typename = void>
auto	coveo::linq::default_if_empty () -> detail::default_if_empty_impl_0<>
	Ensures sequence has at least one element. More...
template<typename T >
auto	coveo::linq::default_if_empty (const T &obj) -> detail::default_if_empty_impl_1< T >
	Ensures sequence has at least one element, specifying said element. More...

Detailed Description

The default_if_empty operator either returns the source sequence or, if that sequence is empty, a new sequence with a single, default element.

.NET equivalent: DefaultIfEmpty

Function Documentation

default_if_empty() [1/2]

template<typename = void>

auto coveo::linq::default_if_empty

(

)

-> detail::default_if_empty_impl_0<>

Either returns the source sequence or, if that sequence is empty, a new sequence containing a single, default element.

Use like this:

const std::vector<int> THREE = { 42, 23, 66 };
const std::vector<int> EMPTY;

using namespace coveo::linq;
auto seq1 = from(THREE)
          | default_if_empty();
auto seq2 = from(EMPTY)
          | default_if_empty();
// seq1 == { 42, 23, 66 }
// seq2 == { 0 }

Returns

(Once applied) Source sequence, or sequence with single, default element.

default_if_empty() [2/2]

template<typename T >

auto coveo::linq::default_if_empty

(

const T &

obj

)

-> detail::default_if_empty_impl_1<T>

Either returns the source sequence or, if that sequence is empty, a new sequence containing the provided default element.

Use like this:

const std::vector<int> THREE = { 42, 23, 66 };
const std::vector<int> EMPTY;

using namespace coveo::linq;
auto seq1 = from(THREE)
          | default_if_empty(11);
auto seq2 = from(EMPTY)
          | default_if_empty(11);
// seq1 == { 42, 23, 66 }
// seq2 == { 11 }

Parameters

obj	Default element to use if sequence is empty.

Returns

(Once applied) Source sequence, or sequence with single element obj.