std::experimental::ranges::find,std::experimental::ranges::find_if, (3) - Linux Man Pages

std::experimental::ranges::find,std::experimental::ranges::find_if,: std::experimental::ranges::find,std::experimental::ranges::find_if,

NAME

std::experimental::ranges::find,std::experimental::ranges::find_if, - std::experimental::ranges::find,std::experimental::ranges::find_if,

Synopsis


Defined in header <experimental/ranges/algorithm>
template< InputIterator I, Sentinel<I> S, class T, class Proj =
ranges::identity >


requires IndirectRelation<ranges::equal_to<>, projected<I, Proj>,    (1) (ranges TS)
const T*>


I find(I first, S last, const T& value, Proj proj Proj{});
template< InputRange R, class T, class Proj ranges::identity >


requires IndirectRelation<ranges::equal_to<>,
projected<ranges::iterator_t<R>, Proj>, const T*>                    (2) (ranges TS)


ranges::safe_iterator_t<R> find(R&& r, const T& value, Proj proj =
Proj{});
template< InputIterator I, Sentinel<I> S, class Proj =
ranges::identity,
                                                               (3) (ranges TS)
IndirectUnaryPredicate<projected<I, Proj>> Pred >


I find_if(I first, S last, Pred pred, Proj proj Proj{});
template< InputRange R, class Proj ranges::identity,


IndirectUnaryPredicate<projected<ranges::iterator_t<R>, Proj>> Pred
                                                                   (4) (ranges TS)


ranges::safe_iterator_t<R> find_if(R&& r, Pred pred, Proj proj =
Proj{});
template< InputIterator I, Sentinel<I> S, class Proj =
ranges::identity,
                                                               (5) (ranges TS)
IndirectUnaryPredicate<projected<I, Proj>> Pred >


I find_if_not(I first, S last, Pred pred, Proj proj Proj{});
template< InputRange R, class Proj ranges::identity,


IndirectUnaryPredicate<projected<ranges::iterator_t<R>, Proj>> Pred
                                                                   (6) (ranges TS)


ranges::safe_iterator_t<R> find_if_not(R&& r, Pred pred, Proj proj =
Proj{});


Returns the first element in the range [first, last) that satisfies specific
criteria:


1) find searches for an element whose projected value is equal to value (i.e., value
== ranges::invoke(proj, *i)).
3) find_if searches for an element for whose projected value predicate p returns
true (i.e., ranges::invoke(pred, ranges::invoke(proj, *i))) is true).
5) find_if_not searches for an element for whose projected value predicate q returns
false (i.e., ranges::invoke(pred, ranges::invoke(proj, *i))) is false).
2,4,6) Same as (1,3,5), but uses r as the source range, as if using ranges::begin(r)
as first and ranges::end(r) as last.


Notwithstanding the declarations depicted above, the actual number and order of
template parameters for algorithm declarations is unspecified. Thus, if explicit
template arguments are used when calling an algorithm, the program is probably
non-portable.

Parameters


first, last - the range of elements to examine
          - the range of elements to examine
value       - value to compare the projected elements to
pred        - predicate to apply to the projected elements
proj        - projection to apply to the elements

Return value


Iterator to the first element satisfying the condition. If no such element is found,
returns an iterator that compares equal to last.

Complexity


At most last - first applications of the predicate and projection.

Possible implementation

First version


template< InputIterator I, Sentinel<I> S, class T, class Proj ranges::identity >
  requires IndirectRelation<ranges::equal_to<>, projected<I, Proj>, const T*>
I find(I first, S last, const T& value, Proj proj Proj{})
{
 for (; first != last; ++first) {
  if (ranges::invoke(proj, *first) == value) break;
 }
 return first;
}

Second version


template< InputIterator I, Sentinel<I> S, class Proj ranges::identity,
    IndirectUnaryPredicate<projected<I, Proj>> Pred >
I find_if(I first, S last, Pred pred, Proj proj Proj{})
{
 for (; first != last; ++first) {
  if (ranges::invoke(pred, ranges::invoke(proj, *first))) break;
 }
 return first;
}
                            Third version
template< InputIterator I, Sentinel<I> S, class Proj ranges::identity,
    IndirectUnaryPredicate<projected<I, Proj>> Pred >
I find_if_not(I first, S last, Pred pred, Proj proj Proj{})
{
 for (; first != last; ++first) {
  if (!ranges::invoke(pred, ranges::invoke(proj, *first))) break;
 }
 return first;
}

Example


 This section is incomplete
 Reason: no example

See also


find
find_if       finds the first element satisfying specific criteria
find_if_not   (function template)
(C++11)
        finds the first two adjacent items that are equal (or satisfy a given
adjacent_find predicate)
        (function template)
find_end      finds the last sequence of elements in a certain range
        (function template)
find_first_of searches for any one of a set of elements
        (function template)
mismatch      finds the first position where two ranges differ
        (function template)
search        searches for a range of elements
        (function template)