gcc/libstdc++-v3
Patrick Palka a25321ca06 libstdc++: Reimplement range adaptors [PR99433]
This rewrites our range adaptor implementation for more comprehensible
error messages, improved SFINAE behavior and conformance to P2281.

The diagnostic improvements mostly come from using appropriately named
functors instead of lambdas in the generic implementation of partial
application and composition of range adaptors, and in the definition of
each of the standard range adaptors.  This makes their pretty printed
types much shorter and more self-descriptive.

The improved SFINAE behavior comes from constraining the range adaptors'
member functions appropriately.  This improvement fixes PR99433, and is
also necessary in order to implement the wording changes of P2281.

Finally, P2281 clarified that partial application and composition of
range adaptors behaves like a perfect forwarding call wrapper.  This
patch implements this, except that we don't bother adding overloads for
forwarding captured state entities as non-const lvalues, since it seems
sufficient to handle the const lvalue and non-const rvalue cases for now,
given the current set of standard range adaptors.  But such overloads
can be easily added if they turn out to be needed.

libstdc++-v3/ChangeLog:

	PR libstdc++/99433
	* include/std/ranges (__adaptor::__maybe_refwrap): Remove.
	(__adaptor::__adaptor_invocable): New concept.
	(__adaptor::__adaptor_partial_app_viable): New concept.
	(__adaptor::_RangeAdaptorClosure): Rewrite, turning it into a
	non-template base class.
	(__adaptor::_RangeAdaptor): Rewrite, turning it into a CRTP base
	class template.
	(__adaptor::_Partial): New class template that represents
	partial application of a range adaptor non-closure.
	(__adaptor::__pipe_invocable): New concept.
	(__adaptor::_Pipe): New class template.
	(__detail::__can_ref_view): New concept.
	(__detail::__can_subrange): New concept.
	(all): Replace the lambda here with ...
	(_All): ... this functor.  Add appropriate constraints.
	(__detail::__can_filter_view): New concept.
	(filter, _Filter): As in all/_All.
	(__detail::__can_transform): New concept.
	(transform, _Transform): As in all/_All.
	(__detail::__can_take_view): New concept.
	(take, _Take): As in all/_All.
	(__detail::__can_take_while_view): New concept.
	(take_while, _TakeWhile): As in all/_All.
	(__detail::__can_drop_view): New concept.
	(drop, _Drop): As in all/_All.
	(__detail::__can_drop_while_view): New concept.
	(drop_while, _DropWhile): As in all/_All.
	(__detail::__can_join_view): New concept.
	(join, _Join): As in all/_All.
	(__detail::__can_split_view): New concept.
	(split, _Split): As in all/_All.  Rename template parameter
	_Fp to _Pattern.
	(__detail::__already_common): New concept.
	(__detail::__can_common_view): New concept.
	(common, _Common): As in all/_All.
	(__detail::__can_reverse_view): New concept.
	(reverse, _Reverse): As in all/_All.
	(__detail::__can_elements_view): New concept.
	(elements, _Elements): As in all/_All.
	(keys, values): Adjust.
	* testsuite/std/ranges/adaptors/99433.cc: New test.
	* testsuite/std/ranges/adaptors/all.cc: No longer expect that
	adding empty range adaptor closure objects to a pipeline doesn't
	increase the size of the pipeline.
	(test05): New test.
	* testsuite/std/ranges/adaptors/common.cc (test03): New test.
	* testsuite/std/ranges/adaptors/drop.cc (test09): New test.
	* testsuite/std/ranges/adaptors/drop_while.cc (test04): New test.
	* testsuite/std/ranges/adaptors/elements.cc (test04): New test.
	* testsuite/std/ranges/adaptors/filter.cc (test06): New test.
	* testsuite/std/ranges/adaptors/join.cc (test09): New test.
	* testsuite/std/ranges/adaptors/p2281.cc: New test.
	* testsuite/std/ranges/adaptors/reverse.cc (test07): New test.
	* testsuite/std/ranges/adaptors/split.cc (test01, test04):
	Adjust.
	(test09): New test.
	* testsuite/std/ranges/adaptors/split_neg.cc (test01): Adjust
	expected error message.
	(test02): Likewise.  Extend test.
	* testsuite/std/ranges/adaptors/take.cc (test06): New test.
	* testsuite/std/ranges/adaptors/take_while.cc (test05): New test.
	* testsuite/std/ranges/adaptors/transform.cc (test07, test08):
	New test.
2021-04-08 10:40:19 -04:00
..
config libstdc++: Remove symbols for new std::call_once implementation [PR 99341] 2021-03-16 12:25:28 +00:00
doc libstdc++: Adjust link to PSTL upstream (again) 2021-03-29 14:14:00 +01:00
include libstdc++: Reimplement range adaptors [PR99433] 2021-04-08 10:40:19 -04:00
libsupc++ libstdc++: Fix doxygen markup for group close commands 2021-04-06 16:43:24 +01:00
po
python libstdc++: Fix find_type helper to work consistently 2021-03-11 17:52:56 +00:00
scripts libstdc++: Add simd testsuite 2021-01-27 16:37:26 +00:00
src libstdc++: Fix filesystem::path construction from COW string [PR 99805] 2021-04-07 16:39:24 +01:00
testsuite libstdc++: Reimplement range adaptors [PR99433] 2021-04-08 10:40:19 -04:00
acinclude.m4
aclocal.m4
ChangeLog libstdc++: Remove bogus ChangeLog entry 2021-04-08 12:18:01 +01:00
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ChangeLog-2020 libstdc++: Fix typo in ChangeLog-2020 2021-01-13 11:02:13 +00:00
config.h.in
configure Update GNU/Hurd configure support 2021-01-05 16:04:14 -07:00
configure.ac
configure.host
crossconfig.m4
fragment.am
linkage.m4
Makefile.am
Makefile.in
README

file: libstdc++-v3/README

New users may wish to point their web browsers to the file
index.html in the 'doc/html' subdirectory.  It contains brief
building instructions and notes on how to configure the library in
interesting ways.