diff options
Diffstat (limited to 'src/corelib/global/q20algorithm.h')
| -rw-r--r-- | src/corelib/global/q20algorithm.h | 123 |
1 files changed, 117 insertions, 6 deletions
diff --git a/src/corelib/global/q20algorithm.h b/src/corelib/global/q20algorithm.h index 16e97e4a8f..24d801b2cd 100644 --- a/src/corelib/global/q20algorithm.h +++ b/src/corelib/global/q20algorithm.h @@ -12,9 +12,9 @@ // W A R N I N G // ------------- // -// This file is not part of the Qt API. Types and functions defined -// in this file will behave exactly as their std counterparts. You -// may use these definitions in your own code, but be aware that we +// This file is not part of the Qt API. Types and functions defined in this +// file can reliably be replaced by their std counterparts, once available. +// You may use these definitions in your own code, but be aware that we // will remove them once Qt depends on the C++ version that supports // them in namespace std. There will be NO deprecation warning, the // definitions will JUST go away. @@ -26,6 +26,117 @@ QT_BEGIN_NAMESPACE +namespace q20 { +// like std::<algorithm> (ie. not ranged, but constexpr) +#ifdef __cpp_lib_constexpr_algorithms +using std::copy; +using std::copy_if; +using std::copy_n; +using std::fill; +using std::fill_n; +using std::is_sorted_until; +using std::is_sorted; +using std::transform; +#else +template <typename InputIterator, typename OutputIterator> +constexpr OutputIterator +copy(InputIterator first, InputIterator last, OutputIterator dest) +{ + while (first != last) { + *dest = *first; + ++first; + ++dest; + } + return dest; +} + +template <typename InputIterator, typename OutputIterator, typename UnaryPredicate> +constexpr OutputIterator +copy_if(InputIterator first, InputIterator last, OutputIterator dest, UnaryPredicate pred) +{ + while (first != last) { + if (pred(*first)) { + *dest = *first; + ++dest; + } + ++first; + } + return dest; +} + +template <typename InputIterator, typename Size, typename OutputIterator> +constexpr OutputIterator +copy_n(InputIterator first, Size n, OutputIterator dest) +{ + while (n > Size{0}) { + *dest = *first; + ++first; + ++dest; + --n; + } + return dest; +} + +template <typename ForwardIterator, typename Value> +constexpr void +fill(ForwardIterator first, ForwardIterator last, const Value &value) +{ + while (first != last) { + *first = value; + ++first; + } +} + +template <typename OutputIterator, typename Size, typename Value> +constexpr OutputIterator +fill_n(OutputIterator first, Size n, const Value &value) +{ + while (n > Size{0}) { + *first = value; + ++first; + --n; + } + return first; +} + +template <typename ForwardIterator, typename BinaryPredicate = std::less<>> +constexpr ForwardIterator +is_sorted_until(ForwardIterator first, ForwardIterator last, BinaryPredicate p = {}) +{ + if (first == last) + return first; + auto prev = first; + while (++first != last) { + if (p(*first, *prev)) + return first; + prev = first; + } + return first; +} + +template <typename ForwardIterator, typename BinaryPredicate = std::less<>> +constexpr bool is_sorted(ForwardIterator first, ForwardIterator last, BinaryPredicate p = {}) +{ + return q20::is_sorted_until(first, last, p) == last; +} + +template <typename InputIterator, typename OutputIterator, typename UnaryFunction> +constexpr OutputIterator +transform(InputIterator first, InputIterator last, OutputIterator dest, UnaryFunction op) +{ + while (first != last) { + *dest = op(*first); + ++first; + ++dest; + } + return dest; +} + +// binary transform missing on purpose (no users) + +#endif +} + namespace q20::ranges { // like std::ranges::{any,all,none}_of, just unconstrained, so no range-overload #ifdef __cpp_lib_ranges @@ -36,7 +147,7 @@ using std::ranges::none_of; [[maybe_unused]] inline constexpr struct { // Niebloid template <typename InputIterator, typename Sentinel, typename Predicate, typename Projection = q20::identity> - constexpr bool operator()(InputIterator first, Sentinel last, Predicate pred, Projection proj = {}) const + [[maybe_unused]] constexpr bool operator()(InputIterator first, Sentinel last, Predicate pred, Projection proj = {}) const { while (first != last) { if (std::invoke(pred, std::invoke(proj, *first))) @@ -49,7 +160,7 @@ using std::ranges::none_of; [[maybe_unused]] inline constexpr struct { // Niebloid template <typename InputIterator, typename Sentinel, typename Predicate, typename Projection = q20::identity> - constexpr bool operator()(InputIterator first, Sentinel last, Predicate pred, Projection proj = {}) const + [[maybe_unused]] constexpr bool operator()(InputIterator first, Sentinel last, Predicate pred, Projection proj = {}) const { while (first != last) { if (!std::invoke(pred, std::invoke(proj, *first))) @@ -62,7 +173,7 @@ using std::ranges::none_of; [[maybe_unused]] inline constexpr struct { // Niebloid template <typename InputIterator, typename Sentinel, typename Predicate, typename Projection = q20::identity> - constexpr bool operator()(InputIterator first, Sentinel last, Predicate pred, Projection proj = {}) const + [[maybe_unused]] constexpr bool operator()(InputIterator first, Sentinel last, Predicate pred, Projection proj = {}) const { while (first != last) { if (std::invoke(pred, std::invoke(proj, *first))) |