select / select_with_index / select_many / select_many_with_index

Projects elements in a sequence into another form. More...

Functions
template<typename Selector >
auto	coveo::linq::select (Selector &&sel) -> detail::select_impl< detail::indexless_selector_proxy< Selector >>
	Projects elements in sequence into another form. More...
template<typename Selector >
auto	coveo::linq::select_with_index (Selector &&sel) -> detail::select_impl< Selector >
	Projects elements in sequence into another form using element index. More...
template<typename Selector >
auto	coveo::linq::select_many (Selector &&sel) -> detail::select_many_impl< detail::indexless_selector_proxy< Selector >>
	Projects elements in sequence into many values and flattens them. More...
template<typename Selector >
auto	coveo::linq::select_many_with_index (Selector &&sel) -> detail::select_many_impl< Selector >
	Projects elements in sequence into many values using element index and flattens them. More...

Detailed Description

The select operator scans a sequence and projects each of its element into another form using a selector, returning a sequence of the results. A little similar to std::transform().

.NET equivalent: Select / SelectMany

Function Documentation

select()

template<typename Selector >

auto coveo::linq::select

(

Selector &&

sel

)

-> detail::select_impl<detail::indexless_selector_proxy<Selector>>

Produces a new sequence by projecting each element in the source sequence into another form, a little like std::transform().

Use like this:

const std::vector<std::string> STRS = {
    "Life, the Universe and Everything",
    "Hangar",
    "Route",
};

using namespace coveo::linq;
auto seq = from(STRS)
         | select([](const std::string& s) { return s.size(); });
// seq == { 33, 6, 5 }

Parameters

sel	Selector used to project each element in source sequence into another form.

Returns

(Once applied) Sequence of projected values.

select_with_index()

template<typename Selector >

auto coveo::linq::select_with_index

(

Selector &&

sel

)

-> detail::select_impl<Selector>

Produces a new sequence by projecting each element in the source sequence into another form, a little like std::transform(). The selector receives, as second argument, the index of the element in the source sequence.

Use like this:

const std::vector<std::string> STRS = {
    "Life, the Universe and Everything",
    "Hangar",
    "Route",
};

using namespace coveo::linq;
auto seq = from(STRS)
         | select_with_index([](const std::string& s, std::size_t i) { return s.size() * (i + 1); });
// seq == { 33, 12, 15 }

Parameters

sel	Selector used to project each element in source sequence into another form. Receives index of element as second argument.

Returns

(Once applied) Sequence of projected values.

select_many()

template<typename Selector >

auto coveo::linq::select_many

(

Selector &&

sel

)

-> detail::select_many_impl<detail::indexless_selector_proxy<Selector>>

Produces a new sequence by projecting each element in the source sequence into a sequence of new values, then flattens all those sequences.

Use like this:

const std::vector<std::string> STRS = {
    "Life, the Universe and Everything",
    "Hangar",
    "Route",
};

using namespace coveo::linq;
auto seq = from(STRS)
         | select_many([](const std::string& s) {
                           return std::vector<std::size_t>{
                               s.size(),
                               static_cast<std::size_t>(s.front() - 'A'),
                           };
                       });
// seq == { 33, 11, 6, 7, 5, 17 }

Parameters

sel	Selector used to project each element in source sequence into a sequence of values.

Returns

(Once applied) Sequence of flattened projected values.

select_many_with_index()

template<typename Selector >

auto coveo::linq::select_many_with_index

(

Selector &&

sel

)

-> detail::select_many_impl<Selector>

Produces a new sequence by projecting each element in the source sequence into a sequence of new values, then flattens all those sequences. The selector receives, as second argument, the index of the element in the source sequence.

Use like this:

const std::vector<std::string> STRS = {
    "Life, the Universe and Everything",
    "Hangar",
    "Route",
};

using namespace coveo::linq;
auto seq = from(STRS)
         | select_many_with_index([](const std::string& s, std::size_t i) {
                                      return std::vector<std::size_t>{
                                          s.size(),
                                          static_cast<std::size_t>(s.front() - 'A'),
                                          i + 1,
                                      };
                                  });
// seq == { 33, 11, 1, 6, 7, 2, 5, 17, 3 }

Parameters

sel	Selector used to project each element in source sequence into a sequence of values. Receives index of element as second argument.

Returns

(Once applied) Sequence of flattened projected values.