libc++ Ranges Status

Overview

This document contains the status of the C++20 Ranges library in libc++. It is used to track both the status of the sub-projects of the ranges library and who is assigned to these sub-projects. This is imperative to effective implementation so that work is not duplicated and implementors are not blocked by each other.

If you are interested in contributing to the libc++ Ranges library, please send a message to the #libcxx channel in the LLVM discord. Please do not start working on any of the assigned items below.

Sub-Projects in the One Ranges Proposal

Section Description Dependencies Assignee Complete
[tuple.helper] Update <tuple> includes. None Unassigned Not started
[range.cmp]
ranges::equal_to
ranges::not_equal_to
ranges::less
ranges::greater
ranges::less_equal
ranges::greater_equal
 None Zoe Carver ✅
[readable.traits]
indirectly_readable_traits
iter_value_t
 None Christopher Di Bella ✅
[incrementable.traits]
incrementable_traits
iter_difference_t
   Christopher Di Bella ✅
[iterator.traits] Updates to iterator_traits
indirectly_readable_traits
incrementable_traits
 Christopher Di Bella ✅
[special.mem.concepts]
no-throw-input-iterator
no-throw-sentinel-for
no-throw-input-range
no-throw-forward-iterator
no-throw-forward-range
[iterator.concepts]
[range.refinements]
 Unassigned Not started
[specialized.algorithms]
ranges::uninitialized_default_construct
ranges::uninitialized_default_construct_n
ranges::uninitialized_value_construct
ranges::uninitialized_value_construct_n
ranges::uninitialized_copy
ranges::uninitialized_copy_n
ranges::uninitialized_move
ranges::uninitialized_move_n
ranges::uninitialized_fill
ranges::uninitialized_fill_n
ranges::construct_at
ranges::destroy
ranges::destroy_at
ranges::destroy_n
 [special.mem.concepts] Unassigned Not started
[strings] Adds begin/end and updates const_iterator. [iterator.concepts] Unassigned Not started
[views.span] Same as [strings] [iterator.concepts] Unassigned Not started
[iterator.cust.move] ranges::iter_move   Zoe Carver ✅
[iterator.cust.swap] ranges::iter_swap iter_value_t Zoe Carver ✅
[iterator.concepts]
indirectly_readable
indirectly_writable
weakly_incrementable
incrementable
input_or_output_iterator
sentinel_for
sized_sentinel_for
input_iterator
output_iterator
forward_iterator
bidirectional_iterator
random_access_iterator
contiguous_iterator
   Various ✅
[indirectcallable.indirectinvocable]
indirectly_unary_invocable
indirectly_regular_unary_invocable
indirectly_unary_predicate
indirectly_binary_predicate
indirectly_equivalence_relation
indirectly_strict_weak_order
 [readable.traits] Louis Dionne ✅
[projected] ranges::projected [iterator.concepts] Louis Dionne ✅
[common.alg.req]: pt. 1
indirectly_movable
indirectly_movable_storable
indirectly_copyable
indirectly_copyable_storable
 [iterator.concepts] Zoe Carver In progress
[common.alg.req]: pt. 2 indirectly_swappable
[iterator.concepts]
[iterator.cust.swap]
 Zoe Carver ✅
[common.alg.req]: pt. 3 indirectly_comparable [projected] Louis Dionne Not started
[common.alg.req]: pt. 4
permutable
mergeable
sortable
 [iterator.concepts] Unassigned Not started
[std.iterator.tags]   [iterator.traits] Unassigned Not started
[range.iter.ops]
ranges::advance
ranges::distance
ranges::next
ranges::prev
 [iterator.concepts] Christopher Di Bella In progress
[predef.iterators] Updates to predefined iterators.
[iterator.concepts]
[iterator.cust.swap]
[iterator.cust.move]
 Unassigned Not started
[move.sentinel]   [predef.iterators] Unassigned Not started
[common.iterator]  
[iterator.concepts]
[iterator.cust.swap]
[iterator.cust.move]
 Zoe Carver ✅
[default.sentinels] std::default_sentinel_t. No dependencies Zoe Carver ✅
[counted.iterator]  
[iterator.concepts]
[iterator.cust.swap]
[iterator.cust.move]
[default.sentinels]
 Zoe Carver ✅
[stream.iterators]   [default.sentinels] Unassigned Not started
[range.access]
ranges::begin
ranges::end
range::cbegin
ranges::cend
ranges::rbegin
ranges::rend
ranges::crbegin
ranges::crend
ranges::size
ranges::ssize
ranges::empty
ranges::data
ranges::cdata
 [iterator.concepts] Christopher Di Bella and Zoe Carver In progress
[range.range]
ranges::range
ranges::borrowed_range
ranges::enable_borrowed_range
ranges::iterator_t
ranges::sentinel_t
ranges::range_difference_t
ranges::range_size_t
ranges::range_value_t
ranges::range_reference_t
ranges::range_rvalue_reference_t
 [range.access] Christopher Di Bella ✅
[range.sized]
ranges::sized_range
ranges::disable_sized_range
[range.primitives]
[range.range]
 Christopher Di Bella ✅
[range.view]
ranges::enable_view
ranges::view_base
ranges::view
 [range.range] Louis Dionne ✅
[range.refinements]
ranges::output_range
ranges::input_range
ranges::forward_range: `D100275
ranges::bidirectional_range
ranges::random_access_range
ranges::contiguous_range
ranges::common_range
 [range.range] Christopher Di Bella ✅
[range.refinements] ranges::viewable_range [range.range] Louis Dionne ✅
[range.utility.helpers]
simple-view
has-arrow
not-same-as
[range.range]
[iterator.concept.input]
 Zoe Carver ✅
[view.interface] ranges::view_interface
[ranges.range]
[range.view]
[range.iterator.op.prev]
[range.refinements]
 Zoe Carver ✅
[range.subrange] ranges::subrange [view.interface] Zoe Carver ✅
[range.dangling]
ranges::dangling
ranges::borrowed_iterator_t
ranges::borrowed_subrange_t
[range.range]
[range.subrange]
 Christopher Di Bella ✅
[range.all] view::all [range.subrange], [range.view.ref] Zoe Carver ✅
[range.view.ref] ref-view [view.interface] Zoe Carver ✅
[range.filter] filter_view [range.all] Louis Dionne Not started
[range.transform] transform_view [range.all] Zoe Carver ✅
[range.iota] iota_view [range.all] Zoe Carver ✅
[range.take] take_view [range.all] Zoe Carver ✅
[range.join] join_view [range.all] Zoe Carver ✅
[range.empty] empty_view [view.interface] Zoe Carver ✅
[range.single] single_view [view.interface] Zoe Carver ✅
[range.split] split_view [range.all] Zoe Carver In Progress
[range.counted] view::counted [range.subrange] Zoe Carver ✅
[range.common] common_view [range.all] Zoe Carver ✅
[range.reverse] reverse_view [range.all] Zoe Carver ✅

Misc. Items and TODOs

(Note: files with required updates will contain the TODO at the beginning of the list item so they can be easily found via global search.)

  • TODO(XX_SPACESHIP_CONCEPTS): when spaceship support is added to various STL types, we need to update some concept tests.

Paper and Issue Status

(Note: stolen from MSVC here.)

Number Name Status First released version
P0896R4 <ranges>    
P1035R7 Input Range Adaptors    
P1207R4 Movability Of Single-Pass Iterators    
P1243R4 Rangify New Algorithms    
P1248R1 Fixing Relations    
P1252R2 Ranges Design Cleanup    
P1391R4 Range Constructor For string_view    
P1456R1 Move-Only Views    
P1474R1 Helpful Pointers For contiguous_iterator    
P1522R1 Iterator Difference Type And Integer Overflow    
P1523R1 Views And Size Types    
P1638R1 basic_istream_view::iterator Should Not Be Copyable    
P1716R3 Range Comparison Algorithms Are Over-Constrained    
P1739R4 Avoiding Template Bloat For Ranges    
P1862R1 Range Adaptors For Non-Copyable Iterators    
P1870R1 safe_range    
P1871R1 disable_sized_sentinel_for    
P1878R1 Constraining Readable Types    
P1970R2 ranges::ssize    
P1983R0 Fixing Minor Ranges Issues    
P1994R1 elements_view Needs Its Own sentinel    
P2091R0 Fixing Issues With Range Access CPOs    
P2106R0 Range Algorithm Result Types    
       
P2325R3 Views should not be required to be default constructible    
P2328R1 join_view should join all views of ranges    
P2210R2 Superior String Splitting    
P2281R1 Clarifying range adaptor objects    
P2367R0 Remove misuses of list-initialization from Clause 24    
       
LWG3169 ranges permutation generators discard useful information    
LWG3173 Enable CTAD for ref-view    
LWG3179 subrange should always model Range    
LWG3180 Inconsistently named return type for ranges::minmax_element    
LWG3183 Normative permission to specialize Ranges variable templates    
LWG3186 ranges removal, partition, and partial_sort_copy algorithms discard useful information    
LWG3191 std::ranges::shuffle synopsis does not match algorithm definition    
LWG3276 Class split_view::outer_iterator::value_type should inherit from view_interface    
LWG3280 View converting constructors can cause constraint recursion and are unneeded    
LWG3281 Conversion from pair-like types to subrange is a silent semantic promotion    
LWG3282 subrange converting constructor should disallow derived to base conversions    
LWG3286 ranges::size is not required to be valid after a call to ranges::begin on an input range    
LWG3291 iota_view::iterator has the wrong iterator_category    
LWG3292 iota_view is under-constrained    
LWG3299 Pointers don’t need customized iterator behavior    
LWG3301 transform_view::iterator has incorrect iterator_category    
LWG3302 Range adaptor objects keys and values are unspecified    
LWG3313 join_view::iterator::operator– is incorrectly constrained    
LWG3323 has-tuple-element helper concept needs convertible_to    
LWG3325 Constrain return type of transformation function for transform_view    
LWG3335 range_size_t and views::all_t    
LWG3355 The memory algorithms should support move-only input iterators introduced by P1207    
LWG3363 drop_while_view should opt-out of sized_range    
LWG3364 Initialize data members of ranges and their iterators    
LWG3381 begin and data must agree for contiguous_range    
LWG3384 transform_view::sentinel has an incorrect operator-    
LWG3385 common_iterator is not sufficiently constrained for non-copyable iterators    
LWG3387 [range.reverse.view] reverse_view<V> unintentionally requires range<const V>    
LWG3388 view iterator types have ill-formed <=> operators    
LWG3389 A move-only iterator still does not have a counted_iterator    
LWG3397 ranges::basic_istream_view::iterator should not provide iterator_category    
LWG3398 tuple_element_t is also wrong for const subrange    
LWG3474 Nesting join_views is broken because of CTAD    
LWG3481 viewable_range mishandles lvalue move-only views    
LWG3500 join_view::iterator::operator->() is bogus    
LWG3505 split_view::outer-iterator::operator++ misspecified    
LWG3517 join_view::iterator’s iter_swap is underconstrained    
LWG3520 iter_move and iter_swap are inconsistent for transform_view::iterator    
LWG3522 Missing requirement on InputIterator template parameter for priority_queue constructors Complete 14.0
LWG3523 iota_view::sentinel is not always iota_view’s sentinel    
LWG3532 split_view<V, P>::inner-iterator<true>::operator++(int) should depend on Base    
LWG3533 Make base() const & consistent across iterator wrappers that supports input_iterators    
LWG3541 indirectly_readable_traits should be SFINAE-friendly for all types    
LWG3543 Definition of when counted_iterators refer to the same sequence isn’t quite right    
LWG3546 common_iterator’s postfix-proxy is not quite right    
LWG3549 view_interface is overspecified to derive from view_base    
LWG3551 borrowed_{iterator,subrange}_t are overspecified    
LWG3553 Useless constraint in split_view::outer-iterator::value_type::begin()    
LWG3555 {transform,elements}_view::iterator::iterator_concept should consider const-qualification of the underlying range