Utilities

Detailed Description

Utilities are mostly internal implementation details and should not concern everyday users.

The only functions that might be interesting to some users are: chunk_range, make_vector_from_range and omp_chunk.

Classes
struct	itertools::iterator_facade< Iter, Value, std::forward_iterator_tag, Reference, Difference >
	CRTP base class for various iterator types in itertools. More...
struct	itertools::sentinel_t< Iter >
	Generic sentinel type that can be used to mark the end of a range. More...

Functions
std::pair< std::ptrdiff_t, std::ptrdiff_t >	itertools::chunk_range (std::ptrdiff_t first, std::ptrdiff_t last, long n_chunks, long rank)
	Given an integer range [first, last), divide it as equally as possible into N chunks.
template<typename Iter1, typename Iter2>
std::iterator_traits< Iter1 >::difference_type	itertools::distance (Iter1 first, Iter2 last)
	Calculate the distance between two iterators.
template<typename Iter>
sentinel_t< Iter >	itertools::make_sentinel (Iter it)
	Create an itertools::sentinel_t from an iterator using template type deduction.
template<typename R>
auto	itertools::make_vector_from_range (R const &rg)
	Create a vector from a range.
template<typename R>
auto	itertools::omp_chunk (R &&rg)
	Distribute a range as evenly as possible across all OMP threads.

Function Documentation

chunk_range()

std::pair< std::ptrdiff_t, std::ptrdiff_t > itertools::chunk_range ( std::ptrdiff_t first, std::ptrdiff_t last, long n_chunks, long rank )

inlinenodiscard

#include <itertools/utils.hpp>

Given an integer range [first, last), divide it as equally as possible into N chunks.

It is intended to divide a range among different processes. If the size of the range is not divisible by \( N \) without a remainder, i.e. r = (last - first) % N, then the first r chunks have one more element.

Parameters

first	First value of the range.
last	Last value of the range (excluded).
n_chunks	Number of chunks to divide the range into.
rank	Rank of the calling process.

Returns

Pair of indices specifying the first and last (excluded) value of the chunk assigned to the calling process.

Definition at line 93 of file utils.hpp.

distance()

template<typename Iter1, typename Iter2>

std::iterator_traits< Iter1 >::difference_type itertools::distance ( Iter1 first, Iter2 last )

inlinenodiscard

#include <itertools/utils.hpp>

Calculate the distance between two iterators.

It is similar to std::distance, except that it can be used for two different iterator types, e.g. in case one of them is a const iterator.

Template Parameters

Iter1	Iterator type #1.
Iter2	Iterator type #2.

Parameters

first	Iterator #1.
last	Iterator #2.

Returns

Number of elements between the two iterators.

Definition at line 51 of file utils.hpp.

make_sentinel()

template<typename Iter>

sentinel_t< Iter > itertools::make_sentinel ( Iter it )

nodiscard

#include <itertools/sentinel.hpp>

Create an itertools::sentinel_t from an iterator using template type deduction.

Template Parameters

Iter	Iterator type.

Parameters

it	Iterator to be turned into an itertools::sentinel_t.

Returns

Sentinel object.

Definition at line 50 of file sentinel.hpp.

make_vector_from_range()

template<typename R>

auto itertools::make_vector_from_range ( R const & rg )

nodiscard

#include <itertools/utils.hpp>

Create a vector from a range.

Template Parameters

R	Range type.

Parameters

rg

Range.

Returns

std::vector<T> containing the elements of the range, where T denotes the value type of the range.

Definition at line 69 of file utils.hpp.

omp_chunk()

template<typename R>

auto itertools::omp_chunk

(

R &&

rg

)

#include <itertools/omp_chunk.hpp>

Distribute a range as evenly as possible across all OMP threads.

See chunk_range(std::ptrdiff_t, std::ptrdiff_t, long, long) and slice(R &&, std::ptrdiff_t, std::ptrdiff_t) for more details.

Template Parameters

R	Range type.

Parameters

rg	Range to chunk.

Returns

An itertools::sliced range, containing the chunk of the original range that belongs to the current thread.

Definition at line 41 of file omp_chunk.hpp.