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author | Jonathan Wakely <jwakely@redhat.com> | 2020-02-26 15:19:43 +0000 |
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committer | Jonathan Wakely <jwakely@redhat.com> | 2020-02-26 15:19:43 +0000 |
commit | 8017d95c7f55b98bcee1caf0216fdfd7fd613849 (patch) | |
tree | 1809954a9a655bb8e75f52ca13ca84aaee3736c7 /libstdc++-v3/include | |
parent | 4a305fa2fd4c9d553b26efa00f868aa1e4416a9f (diff) | |
download | gcc-8017d95c7f55b98bcee1caf0216fdfd7fd613849.zip gcc-8017d95c7f55b98bcee1caf0216fdfd7fd613849.tar.gz gcc-8017d95c7f55b98bcee1caf0216fdfd7fd613849.tar.bz2 |
libstdc++: Add __maybe_const_t and __maybe_empty_t aliases
This introduces a couple of convenience alias templates to be used for
some repeated patterns using std::conditional_t.
* include/std/ranges (__detail::__maybe_empty_t): Define new helper
alias.
(__detail::__maybe_const_t): Likewise.
(__adaptor::_RangeAdaptor): Use __maybe_empty_t.
(transform_view, take_view, take_while_view, elements_view): Use
__maybe_const_t.
(join_view, split_view): Use both.
Diffstat (limited to 'libstdc++-v3/include')
-rw-r--r-- | libstdc++-v3/include/std/ranges | 53 |
1 files changed, 29 insertions, 24 deletions
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index a7f4da9..d832663 100644 --- a/libstdc++-v3/include/std/ranges +++ b/libstdc++-v3/include/std/ranges @@ -1029,6 +1029,13 @@ namespace views namespace __detail { struct _Empty { }; + + template<bool _NonEmpty, typename _Tp> + using __maybe_empty_t = conditional_t<_NonEmpty, _Tp, _Empty>; + + template<bool _Const, typename _Tp> + using __maybe_const_t = conditional_t<_Const, const _Tp, _Tp>; + } // namespace __detail namespace views @@ -1058,8 +1065,8 @@ namespace views { protected: [[no_unique_address]] - conditional_t<!is_default_constructible_v<_Callable>, - _Callable, __detail::_Empty> _M_callable; + __detail::__maybe_empty_t<!is_default_constructible_v<_Callable>, + _Callable> _M_callable; public: constexpr @@ -1552,9 +1559,8 @@ namespace views struct _Iterator { private: - using _Parent - = conditional_t<_Const, const transform_view, transform_view>; - using _Base = conditional_t<_Const, const _Vp, _Vp>; + using _Parent = __detail::__maybe_const_t<_Const, transform_view>; + using _Base = __detail::__maybe_const_t<_Const, _Vp>; static constexpr auto _S_iter_concept() @@ -1760,9 +1766,8 @@ namespace views struct _Sentinel { private: - using _Parent - = conditional_t<_Const, const transform_view, transform_view>; - using _Base = conditional_t<_Const, const _Vp, _Vp>; + using _Parent = __detail::__maybe_const_t<_Const, transform_view>; + using _Base = __detail::__maybe_const_t<_Const, _Vp>; constexpr range_difference_t<_Base> __distance_from(const _Iterator<_Const>& __i) const @@ -1886,7 +1891,7 @@ namespace views struct _Sentinel { private: - using _Base = conditional_t<_Const, const _Vp, _Vp>; + using _Base = __detail::__maybe_const_t<_Const, _Vp>; using _CI = counted_iterator<iterator_t<_Base>>; sentinel_t<_Base> _M_end = sentinel_t<_Base>(); @@ -2025,7 +2030,7 @@ namespace views struct _Sentinel { private: - using _Base = conditional_t<_Const, const _Vp, _Vp>; + using _Base = __detail::__maybe_const_t<_Const, _Vp>; sentinel_t<_Base> _M_end = sentinel_t<_Base>(); const _Pred* _M_pred = nullptr; @@ -2258,8 +2263,8 @@ namespace views struct _Iterator { private: - using _Parent = conditional_t<_Const, const join_view, join_view>; - using _Base = conditional_t<_Const, const _Vp, _Vp>; + using _Parent = __detail::__maybe_const_t<_Const, join_view>; + using _Base = __detail::__maybe_const_t<_Const, _Vp>; static constexpr bool _S_ref_is_glvalue = is_reference_v<range_reference_t<_Base>>; @@ -2450,8 +2455,8 @@ namespace views struct _Sentinel { private: - using _Parent = conditional_t<_Const, const join_view, join_view>; - using _Base = conditional_t<_Const, const _Vp, _Vp>; + using _Parent = __detail::__maybe_const_t<_Const, join_view>; + using _Base = __detail::__maybe_const_t<_Const, _Vp>; constexpr bool __equal(const _Iterator<_Const>& __i) const @@ -2482,8 +2487,8 @@ namespace views // XXX: _M_inner is "present only when !is_reference_v<_InnerRange>" [[no_unique_address]] - conditional_t<!is_reference_v<_InnerRange>, - views::all_t<_InnerRange>, __detail::_Empty> _M_inner; + __detail::__maybe_empty_t<!is_reference_v<_InnerRange>, + views::all_t<_InnerRange>> _M_inner; public: join_view() = default; @@ -2585,8 +2590,8 @@ namespace views struct _OuterIter { private: - using _Parent = conditional_t<_Const, const split_view, split_view>; - using _Base = conditional_t<_Const, const _Vp, _Vp>; + using _Parent = __detail::__maybe_const_t<_Const, split_view>; + using _Base = __detail::__maybe_const_t<_Const, _Vp>; constexpr bool __at_end() const @@ -2618,8 +2623,8 @@ namespace views // XXX: _M_current is present only if "V models forward_range" [[no_unique_address]] - conditional_t<forward_range<_Vp>, - iterator_t<_Base>, __detail::_Empty> _M_current; + __detail::__maybe_empty_t<forward_range<_Vp>, + iterator_t<_Base>> _M_current; public: using iterator_concept = conditional_t<forward_range<_Base>, @@ -2732,7 +2737,7 @@ namespace views struct _InnerIter { private: - using _Base = conditional_t<_Const, const _Vp, _Vp>; + using _Base = __detail::__maybe_const_t<_Const, _Vp>; constexpr bool __at_end() const @@ -2858,8 +2863,8 @@ namespace views // XXX: _M_current is "present only if !forward_range<V>" [[no_unique_address]] - conditional_t<!forward_range<_Vp>, - iterator_t<_Vp>, __detail::_Empty> _M_current; + __detail::__maybe_empty_t<!forward_range<_Vp>, iterator_t<_Vp>> + _M_current; public: @@ -3223,7 +3228,7 @@ namespace views template<bool _Const> struct _Iterator { - using _Base = conditional_t<_Const, const _Vp, _Vp>; + using _Base = __detail::__maybe_const_t<_Const, _Vp>; iterator_t<_Base> _M_current = iterator_t<_Base>(); |