multidim

Multidim algorithms library

Multidim provides equivalent algorithms for most of the algorithms in the C++ algorithms library (<algorithm> and <numeric>).

Because of the ‘fake’ references (e.g. array_ref and dynarray_ref) used in Multidim, many of the functions provided in the C++ algorithms library may not work with Multidim’s iterators. Hence, Multidim provides its own algorithms that mimic those in the standard. See this page for the differences between Multidim’s iterators and a LegacyRandomAccessIterator.

Unlike many functions in the C++ algorithms library, functions in Multidim’s algorithms library have the following relaxation in requirements:

• std::iterator_traits<Iter>::reference need not be a real reference
• std::iterator_traits<Iter>::value_type is never used; this means that:
  • no Multidim algorithm demands a functor that takes in a std::iterator_traits<Iter>::value_type & or const std::iterator_traits<Iter>::value_type &
  • no Multidim algorithm constructs temporary elements (i.e. all modifying operations may only do move/copy assignment or swaps)

As such, whenever an algorithm in std:: may be used, the equivalent algorithm in multidim:: (if it exists) will most likely work too. However, there are a few std:: algorithms that do not have an equivalent, or require stronger iterator category requirements, in multidim:: because Multidim algorithms must never construct temporary elements.

Note: The Multidim algorithms library does not provide overloads for execution policies.

For the algorithms listed below, if the remarks column contains “Equivalent”, it means that code that use Multidim’s references with the std:: algorithm will probably work (even though it may be undefined behaviour).

Non-modifying sequence operations

Standard Algorithm	Multidim Algorithm	Remarks
std::all_of std::any_of std::none_of	multidim::all_of multidim::any_of multidim::none_of	Equivalent
std::for_each std::for_each_n	multidim::for_each multidim::for_each_n	Equivalent
-	multidim::for_eachs multidim::for_eachs_n	Like for_each/for_each_n, but allows multiple sequences to be iterated together
std::count_if std::count_if	multidim::count_if multidim::count_if	Equivalent
std::mismatch	multidim::mismatch	Equivalent
std::find std::find_if std::find_if_not	multidim::find multidim::find_if multidim::find_if_not	Equivalent
std::find_end	multidim::find_end	Equivalent
std::find_first_of	multidim::find_first_of	Equivalent
std::adjacent_find	multidim::adjacent_find	Equivalent
std::search	multidim::search	Equivalent, but Multidim does not provide the Searcher overload
std::search_n	multidim::search_n	Equivalent
-	multidim::find_consecutive multidim::find_consecutive_if	Finds a range of consecutive elements satisfying specific criteria; similar to multidim::search_n

Modifying sequence operations

Standard Algorithm	Multidim Algorithm	Remarks
std::copy std::copy_if std::copy_n std::copy_backward	multidim::copy multidim::copy_if multidim::copy_n multidim::copy_backward	Equivalent
std::move std::move_backward	multidim::move multidim::move_if multidim::move_n multidim::move_backward	Equivalent, but Multidim provides the extra versions move_if and move_n that are like copy_if and copy_n but moves elements
std::fill std::fill_n	multidim::fill multidim::fill_n	Equivalent
std::transform	-	Not provided by Multidim as the unary operation returns by value, which would construct a temporary; use multidim::for_eachs instead
std::generate std::generate_n	-	Not provided by Multidim as the generator returns by value, which would construct a temporary
std::remove std::remove_if	multidim::remove multidim::remove_if	Equivalent
std::remove_copy std::remove_copy_if	multidim::remove_copy multidim::remove_copy_if	Equivalent
std::replace std::replace_if	multidim::replace multidim::replace_if	Equivalent
std::replace_copy std::replace_copy_if	multidim::replace_copy multidim::replace_copy_if	Equivalent
std::swap	-	Use argument dependent lookup (ADL) to swap instead
std::swap_ranges	multidim::swap_ranges	Equivalent
std::iter_swap	multidim::iter_swap	Equivalent
std::reverse std::reverse_copy	multidim::reverse multidim::reverse_copy	Equivalent
std::rotate std::rotate_copy	multidim::rotate multidim::rotate_copy	Equivalent
std::shift_left std::shift_right	multidim::shift_left multidim::shift_right	Equivalent
std::unique	multidim::unique	Equivalent
std::unique_copy	multidim::unique_copy	Multidim requires either InputIt or OutputIt to satisfy LegacyForwardIterator

Randomizing sequence operations

Standard Algorithm	Multidim Algorithm	Remarks
std::shuffle	multidim::shuffle	Equivalent
std::sample	multidim::sample	Equivalent

Partitioning operations

Standard Algorithm	Multidim Algorithm	Remarks
std::is_partitioned	multidim::is_partitioned	Equivalent
std::partition	multidim::partition	Equivalent
std::partition_copy	multidim::partition_copy	Equivalent
std::stable_partition	multidim::stable_partition	The O(N) algorithm is not provided by Multidim because it allocates additional memory; an O(N log N) algorithm that does not allocate memory is used instead, and it only requires LegacyForwardIterator but not LegacyBidirectionalIterator
std::partition_point	multidim::partition_point	Equivalent

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