expect_smaller_range

Detailed Description

Names the range an algorithm should expect to be the shorter one.

Variables
template<int N>
constexpr auto	eve::algo::expect_smaller_range = (expect_smaller_range_key = eve::index<N>)

Variable Documentation

expect_smaller_range

template<int N>

auto eve::algo::expect_smaller_range = (expect_smaller_range_key = eve::index<N>)

inlineconstexpr

Header file #include <eve/module/algo.hpp>

namespace eve::algo
{
  template<int N> inline constexpr auto expect_smaller_range = eve_implementation_defined;
}

Template Parameters

N	Zero-based position of that range among the arguments.

Names the range, by its zero-based position among the arguments, that is expected to run out first. An algorithm that reads two ranges, as eve::algo::set_intersection does, is faster when it is told which of them is the shorter. Shorter is a rough guide rather than a rule, and the choice is to be benchmarked on the data at hand.

std::vector<int> a(1 << 16), b(64), out(64);
 
// b runs out first: the loop is shaped around it.
auto r = set_intersection[expect_smaller_range<1>](a, b, out);

See also

eve::algo::set_intersection