range-v3

Range library for C++11/14/17. This code is the basis of a formal proposal to add range support to the C++ standard library.

About:

Why does C++ need another range library? Simply put, the existing solutions haven't kept up with the rapid evolution of C++. Range v3 is a library for the future C++. Not only does it work well with today's C++ -- move semantics, lambdas, automatically deduced types and all -- it also anticipates tomorrow's C++ with Concepts.

Range v3 forms the basis of a proposal to add range support to the standard library (N4128: Ranges for the Standard Library). It also will be the reference implementation for an upcoming Technical Specification. These are the first steps toward turning ranges into an international standard.

Documentation:

Check out the (woefully incomplete) documentation here.

Other resources (mind the dates, the library probably has changed since then):

• Usage:

  • Talk: CppCon 2015: Eric Niebler "Ranges for the Standard Library", 2015.
  • A slice of Python in C++, 07.12.2014.
  • Actions (back then called Container Algorithms), 23.11.2014.
  • Range comprehensions, 27.04.2014.
  • Input iterators vs input ranges, 07.11.2013.

• Design / Implementation:

  • Rationale behind range-v3: N4128: Ranges for the standard library Revision 1, 2014.
  • Ranges TS: N4560: C++ Extensions for Ranges, 2015.
  • Implementation of customization points in range-v3:
    • N4381: Suggested Design for Customization Points, 2015.
    • P0386: Inline variables, 2016.
    • Customization Point Design in C++11 and Beyond, 2014.
  • Proxy iterators in range-v3:
    • D0022: Proxy Iterators for the Ranges Extensions.
    • To Be or Not to Be (an Iterator), 2015.
    • Iterators++: Part1, 2015.
    • Iterators++: Part2, 2015.
    • Iterators++: Part3, 2015.
  • Metaprogramming utilities:
    • See the meta documentation, the library has changed significantly since the 2014 blog post.
  • Concept emulation layer: Concept checking in C++11, 2013.
  • C++Now 2014: Eric Niebler "C++11 Library Design", 2014.

License:

Most of the source code in this project are mine, and those are under the Boost Software License. Parts are taken from Alex Stepanov's Elements of Programming, Howard Hinnant's libc++, and from the SGI STL. Please see the attached LICENSE file and the CREDITS file for the licensing and acknowledgments.

Supported Compilers

The code is known to work on the following compilers:

• clang 3.6.2 (or later)
• GCC 4.9.4 (or later) (C++14 support requires GCC 5.2; C++14 "extended constexpr" support is poor before 6.1.)
• "Clang with Microsoft CodeGen" (Clang/C2) VS2015 Update 3 (or later)

Development Status: This code is fairly stable, well-tested, and suitable for casual use, although currently lacking documentation. No promise is made about support or long-term stability. This code will evolve without regard to backwards compatibility.

Build status

• on Travis-CI:
• on AppVeyor:

Release Notes:

• 0.2.1 March 22, 2017 New in this release:
  • view::cartesian_product
  • action::reverse
• 0.2.0 March 13, 2017 Bring many interfaces into sync with the Ranges TS.

  • Many interfaces are simply renamed. The following table shows the old names and the new. (All names are in the ranges::v3 namespace.)

    Old Name	New Name
    indirect_swap	iter_swap
    indirect_move	iter_move
    iterator_value_t	value_type_t
    iterator_reference_t	reference_t
    iterator_difference_t	difference_type_t
    iterator_size_t	size_type_t
    iterator_rvalue_reference_t	rvalue_reference_t
    iterator_common_reference_t	iter_common_reference_t
    range_value_t	range_value_type_t
    range_difference_t	range_difference_type_t
    range_size_t	range_size_type_t
    range_iterator_t	iterator_t
    range_sentinel_t	sentinel_t

  • common_iterator now requires that its two types (Iterator and Sentinel) are different. Use common_iterator_t<I, S> to get the old behavior (i.e., if the two types are the same, it is an alias for I; otherwise, it is common_iterator<I, S>).

  • The following iterator adaptors now work with iterators that return proxies from their postfix increment operator (i.e., operator++(int)):

    • common_iterator
    • counted_iterator

  • The following customization points are now implemented per the Ranges TS spec and will no longer find the associated unconstrained overload in namespace std:::

    • ranges::begin
    • ranges::end
    • ranges::size
    • ranges::swap
    • ranges::iter_swap

    (In practice, this has very little effect but it may effect overloading in rare situations.)

  • ranges::is_swappable now only takes one template parameter. The new ranges::is_swappable_with<T, U> tests whether T and U are swappable. ranges::is_swappable<T> is equivalent to ranges::is_swappable_with<T &, T &>.

  • The following object concepts have changed to conform with the Ranges TS specification, and approved changes (see P0547):

    • Destructible
    • Constructible
    • DefaultConstructible
    • MoveConstructible
    • MoveConstructible
    • Movable
    • Assignable

  • The View concept is no longer satisfied by reference types.

  • The syntax for defining a concept has changed slightly. See utility/iterator_concepts.hpp for examples.

• 0.1.1 Small tweak to Writable concept to fix #537.
• 0.1.0 March 8, 2017, Begin semantic versioning

Say Thanks!

I do this work because I love it and because I love C++ and want it to be as excellent as I know it can be. If you like my work and are looking for a way to say thank you, you can leave a supportive comment on my blog. Or you could leave me some kudos on my Open Hub range-v3 contribution page. Just click the Give Kudos button here.