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Implementation status

This library is a work-in-progress. We try to stay close to standard library interfaces, but we neither promise full API compatibility with std::ranges:: nor do we currently promise stability between releases of this library. The latter will likely change at some point.

Progress implementing std::views::X equivalents (adaptor objects and factory objects)

Standard adaptors factories Comment
C++20 14/15 5/5 lazy_split not planned
C++23 3/13 1/1
C++26 1/03 --
C++29 1/?? --
extra 1

See below for details. Note that the list of adaptors in C++26 and C++29 is not yet final.

Range adaptor classes

Range adaptors (classes) Equivalent in std:: Remarks
radr::generator<> std::generator<> alias for std::generator if available
radr::borrowing_rad<> std::ranges::subrange, (std::span, std::ranges::ref_view) stores (iterator, sentinel) pair
radr::owning_rad<> std::ranges::owning_view stores rvalues of containers

There are no distinct type templates per adaptor (like e.g. std::ranges::transform_view for std::views::transform in the standard library). Instead all range adaptor objects in this library (see below) return a specialisation of one of the above type templates.

Range adaptor objects

We plan to add equivalent objects for all standard library adaptors.

Range adaptors (objects) C++XY Equivalent in std:: C++XY Differences of radr objects
radr::all C++20 std::views::all C++20
radr::as_const C++20 std::views::as_const C++23 make the range and its elements const
radr::as_rvalue C++20 std::views::as_rvalue C++23 *returns only input ranges in C++20
radr::drop(n) C++20 std::views::drop C++20
radr::drop_while(fn) C++20 std::views::drop_while C++20
radr::elements<I> C++20 std::views::elements C++20
radr::enumerate C++23 std::views::enumerate C++23
radr::filter(fn) C++20 std::views::filter C++20
radr::join C++20 std::views::join C++20
radr::keys C++20 std::views::keys C++20
radr::reverse C++20 std::views::reverse C++20
radr::slice(m, n) C++20 not yet available get subrange between m and n
radr::split(pat) C++20 std::views::split C++20
not planned C++20 std::views::lazy_split C++20 use radr::to_single_pass ╎ radr::split
radr::take(n) C++20 std::views::take C++20
radr::take_while(fn) C++20 std::views::take_while C++20
radr::to_common C++20 std::views::common1 C++20 turns non-common into common
radr::to_single_pass C++20 std::views::to_input1 C++26 demotes range category to input
radr::transform(fn) C++20 std::views::transform C++20
radr::values C++20 std::views::values C++20
radr::unchecked_take(n) C++20 std::views::unchecked_take C++29 turns unsized into sized
radr::zip_with(w) C++23 std::views::zip C++23 see also radr::zip() below

In this library, everything that "you can pipe into", is called an adaptor; everything else is called a factory (can only be at beginning of pipeline). This is different from the somewhat arbitrary use of the words in the standard.

Range factory objects

Range factories (objects) C++XY Equivalent in std:: C++XY Remarks
radr::counted(it, n) C++20 std::views::counted C++20
radr::empty<T> C++20 std::views::empty C++20
radr::iota(val[, bound]) C++20 std::views::iota C++20
radr::istream<Val> C++20 std::views::istream C++20
radr::repeat(val[, bound]) C++20 std::views::repeat C++23 allows indirect storage and static bounds
radr::single(val) C++20 std::views::single C++20 allows indirect storage
radr::zip(v, w) C++23 std::views::zip C++23

The standard library groups counted and zip with "range adaptors" and not "range factories".

For some factories, specialised single-pass versions exist:

Range factories (objects) C++XY
radr::counted_sp(it, n) C++20
radr::iota_sp(val[, bound]) C++20
radr::zip_sp(v, w) C++23

These might have weaker requirements or generate better code than using the multi-pass factory in combination with radr::to_single_pass.

Notable functions

Notable functions CP Remarks
radr::subborrow(r, it, sen[, s]) ✔ Used when creating subranges from other ranges
radr::subborrow(r, i, j) (✔) Position-based slice
radr::borrow(r) (✔) = radr::subborrow(r, r.begin(), r.end(), r.size())

CP denotes functions that you can customise for your own types, e.g. specify a different subrange-type for a specific container.

Footnotes

  1. These range adaptors have relevant differences between std:: and radr::. Usually the names have been chosen differently to highlight this. ↩ ↩2