Feature/std23 repeat

src/tools/std23/views.hpp

@@ -2,3 +2,4 @@
 #include "tools/std23/views/chunk_by.hpp"
 #include "tools/std23/views/stride.hpp"
 #include "tools/std23/views/zip.hpp"
+#include "tools/std23/views/repeat.hpp"

src/tools/std23/views/repeat.hpp

@@ -0,0 +1,235 @@
+#ifndef NJOY_TOOLS_STD23_RANGES_VIEWS_REPEAT
+#define NJOY_TOOLS_STD23_RANGES_VIEWS_REPEAT
+
+#include "tools/std20/detail/views/range_adaptors.hpp"
+#include "tools/std20/iterator/unreachable.hpp"
+#include "tools/std20/views/interface.hpp"
+#include "tools/std20/views/all.hpp"
+#include "tools/std20/views/subrange.hpp"
+#include "tools/std20/views/take.hpp"
+#include "tools/std20/detail/views/semiregular_box.hpp"
+#include "tools/std20/detail/iterator/concepts.hpp"
+#include "tools/std20/views/iota.hpp"
+
+namespace njoy {
+namespace tools {
+namespace std23 {
+inline namespace ranges {
+
+template <typename Type, typename = void>
+struct repeat_view_iterator_difference {
+    using type = std20::detail::iota_diff_t<Type>;
+};
+
+template <typename Type>
+struct repeat_view_iterator_difference<Type, typename std::enable_if<std20::detail::is_signed_integer_like<Type>>::type> 
+{
+    using type = Type;
+};
+
+template <typename Type>
+using repeat_view_iterator_difference_t = typename repeat_view_iterator_difference<Type>::type;
+
+/**
+ *  @brief A range factory that generates a sequence of elements by repeatedly
+ *         producing the same value. Can be either bounded or unbounded (infinite).
+ *
+ *  See https://en.cppreference.com/w/cpp/ranges/repeat_view
+ */
+
+template < typename Type, typename Bound = std20::unreachable_sentinel_t >
+struct repeat_view : public std20::ranges::view_interface< repeat_view< Type, Bound > > {
+    // The Type must be a non-const object
+    static_assert( std::is_object_v<Type> && std20::same_as< Type, std::remove_cv_t< Type > > );
+
+    // The Bound has to be integer like of unbound
+    static_assert( ( std20::detail::is_signed_integer_like< Bound > || 
+                 ( std20::detail::is_integer_like< Bound > && std20::weakly_incrementable< Bound > ) ) ||
+                 ( std20::same_as< Bound, std20::unreachable_sentinel_t > ) );
+
+private:
+
+    std20::detail::semiregular_box< Type > value_;
+    Bound bound_ = Bound();
+
+    struct iterator{
+    friend class repeat_view;
+    private:
+        using IndexT = std::conditional_t<std20::same_as<Bound, std20::unreachable_sentinel_t>, ptrdiff_t, Bound>;
+        const Type* ivalue_ = nullptr;
+        IndexT current_  = IndexT();
+
+    public:
+
+        constexpr explicit iterator(const Type* value, IndexT bound_sentinel = IndexT())
+            : ivalue_(value), current_(bound_sentinel) {}
+
+        using iterator_concept  = std20::random_access_iterator_tag;
+          using iterator_category = std20::random_access_iterator_tag;
+          using value_type        = Type;
+          using difference_type   = repeat_view_iterator_difference_t<IndexT>;
+
+          iterator() = default;
+
+          constexpr const Type& operator*() const noexcept { return *ivalue_; }
+
+          constexpr iterator& operator++() {
+              ++current_;
+              return *this;
+          }
+
+          constexpr iterator operator++(int) {
+              auto tmp = *this;
+              ++*this;
+              return tmp;
+          }
+
+          constexpr iterator& operator--() {
+              --current_;
+              return *this;
+          }
+
+          constexpr iterator operator--(int) {
+              auto tmp = *this;
+              --*this;
+              return tmp;
+          }
+
+          constexpr iterator& operator+=(difference_type n) {
+              current_ += n;
+              return *this;
+          }
+
+          constexpr iterator& operator-=(difference_type n) {
+              current_ -= n;
+              return *this;
+          }
+
+          constexpr const Type& operator[](difference_type n) const noexcept { return *(*this + n); }
+
+          friend constexpr bool operator==(const iterator& left, const iterator& right) {
+              return left.current_ == right.current_;
+          }
+
+          friend constexpr bool operator!=(const iterator& left, const iterator& right) {
+              return !(left.current_ == right.current_);
+          }
+
+          friend constexpr auto operator> (const iterator& left, const iterator& right) {
+              return left.current_ > right.current_;
+          }
+          friend constexpr auto operator< (const iterator& left, const iterator& right) {
+              return right.current_ > left.current_;
+          }
+
+          friend constexpr iterator operator+(iterator i, difference_type n) {
+              i += n;
+              return i;
+          }
+
+          friend constexpr iterator operator+(difference_type n, iterator i) {
+              i += n;
+              return i;
+          }
+
+          friend constexpr iterator operator-(iterator i, difference_type n) {
+              i -= n;
+              return i;
+          }
+
+          friend constexpr difference_type operator-(const iterator& left, const iterator& right) {
+              return static_cast<difference_type>(left.current_) - static_cast<difference_type>(right.current_);
+          }
+
+
+    };
+
+public:
+
+    repeat_view() = default;
+
+    constexpr explicit repeat_view( const Type& value, Bound bound_sentinel = Bound())
+        : value_(std::in_place, value), bound_(bound_sentinel) {
+        }
+
+    constexpr explicit repeat_view(Type&& value, Bound bound_sentinel = Bound())
+        : value_(std::in_place, std::move(value)), bound_(bound_sentinel) {
+    }
+
+    template <class... _TpArgs, class... _BoundArgs, 
+          std::enable_if_t<std20::constructible_from<Type, _TpArgs...> && std20::constructible_from<Bound, _BoundArgs...>, bool> = true>
+    constexpr explicit repeat_view( std::piecewise_construct_t, std::tuple<_TpArgs...> __value_args, 
+                    std::tuple<_BoundArgs...> __bound_args = std::tuple<>{}) 
+        : value_(std::in_place, std::make_from_tuple<Type>(std::move(__value_args))),
+        bound_(std::make_from_tuple<Bound>(std::move(__bound_args))) {
+    }
+
+    constexpr iterator begin() const { return iterator(std::addressof(*value_)); }
+
+    template<typename T=Bound, std::enable_if_t<!std20::same_as<T, std20::unreachable_sentinel_t>, bool> = true> 
+    constexpr iterator end() const
+    {
+        return iterator(std::addressof(*value_), bound_);
+    }
+
+    template<typename T=Bound, std::enable_if_t<std20::same_as<T, std20::unreachable_sentinel_t>, bool> = true> 
+    constexpr std20::unreachable_sentinel_t end() const noexcept 
+    {
+        return std20::unreachable_sentinel; 
+    }
+
+    template<typename T=Bound, std::enable_if_t<!std20::same_as<T, std20::unreachable_sentinel_t>, bool> = true> 
+    constexpr auto size() const
+    {
+	return std::make_unsigned_t<decltype(bound_)>(bound_);
+    }
+};
+
+template < typename Type >
+repeat_view( Type&&, std20::ranges::range_difference_t< Type > ) -> repeat_view< std20::ranges::all_view< Type > >;
+
+} // namespace ranges
+} // namespace std23
+
+namespace std20 {
+inline namespace ranges {
+
+template <typename Type>
+inline constexpr bool enable_borrowed_range<std23::ranges::repeat_view<Type>> = forward_range<Type> && enable_borrowed_range<Type>;
+
+} // namespace ranges
+} // namespace std20
+
+namespace std23 {
+inline namespace ranges {
+namespace detail {
+struct repeat_view_fn {
+
+    template < typename E, typename F >
+    constexpr auto operator()( E&& e, F&& f ) const
+    -> decltype( repeat_view{ std::forward< E >( e ), std::forward< F >( f ) } )
+    {
+        return repeat_view{ std::forward< E >( e ), std::forward< F >( f ) };
+    }
+
+    template < typename E >
+    constexpr auto operator()( E&& e ) const
+    -> decltype( repeat_view{ std::forward< E >( e ) } )
+    {
+        return repeat_view{ std::forward< E >( e ) };
+    }
+
+};
+
+}
+
+namespace views {
+NANO_INLINE_VAR(ranges::detail::repeat_view_fn, repeat)
+}
+} // namespace ranges
+} // namespace std23
+
+} // namespace tools
+} // namespace njoy
+
+#endif

src/tools/std23/views/test/CMakeLists.txt

@@ -2,3 +2,4 @@ add_cpp_test( std23.views.chunk chunk.test.cpp )
 add_cpp_test( std23.views.chunk_by chunk_by.test.cpp )
 add_cpp_test( std23.views.stride stride.test.cpp )
 add_cpp_test( std23.views.zip zip.test.cpp )
+add_cpp_test( std23.views.repeat repeat.test.cpp )

src/tools/std23/views/test/repeat.test.cpp

@@ -0,0 +1,107 @@
+// include Catch2
+#include <catch2/catch_test_macros.hpp>
+
+// what we are testing
+#include "tools/std23/views.hpp"
+
+// other includes
+#include <forward_list>
+#include <list>
+#include <vector>
+#include "tools/std20/algorithm.hpp"
+#include <string_view>
+#include "tools/std20/iterator/unreachable.hpp"
+// convenience typedefs
+using namespace njoy::tools;
+
+SCENARIO( "repeat_view" ) {
+	// Use a single bound limit for all bound tests
+	int boundLimit = 4;
+
+	GIVEN( "Test repeat integer" ) {
+		int repeated = 9;
+		WHEN("Bound repeater"){
+			auto RepeatedInt = std23::views::repeat(repeated, boundLimit);
+			THEN("Check all ints in bound limit"){
+				CHECK(RepeatedInt.size() == boundLimit);
+				for (int i : RepeatedInt){
+					CHECK(i == repeated);
+				}
+			} //THEN
+		} //WHEN
+		WHEN("Unbound repeater"){
+			auto RepeatedInt = std23::views::repeat(repeated);
+			THEN("Check that end is unbound and int is repeated within 2x listed limit"){
+				CHECK( std20::same_as<std::remove_cv_t<decltype(std20::unreachable_sentinel)>, 
+						      decltype(RepeatedInt.end())>);
+				int UnboundLimit = 0; 
+				for (int i : RepeatedInt){
+					UnboundLimit += 1;
+					CHECK(i == repeated);
+					if (UnboundLimit > 2*boundLimit){
+						break;
+					}
+				}
+			} //THEN
+
+		} //WHEN
+	} //GIVEN
+	GIVEN( "Test repeat float" ) {
+		float repeated = 9.0;
+		WHEN("Bound repeater"){
+			auto RepeatedInt = std23::views::repeat(repeated, boundLimit);
+			THEN("Check all ints in bound limit"){
+				CHECK(RepeatedInt.size() == boundLimit);
+				for (float i : RepeatedInt){
+					CHECK(i == repeated);
+				}
+			} //THEN
+		} //WHEN
+		WHEN("Unbound repeater"){
+			auto RepeatedInt = std23::views::repeat(repeated);
+			THEN("Check that end is unbound and int is repeated within 2x listed limit"){
+				CHECK( std20::same_as<std::remove_cv_t<decltype(std20::unreachable_sentinel)>, 
+						      decltype(RepeatedInt.end())>);
+				int UnboundLimit = 0; 
+				for (float i : RepeatedInt){
+					UnboundLimit += 1;
+					CHECK(i == repeated);
+					if (UnboundLimit > 2*boundLimit){
+						break;
+					}
+				}
+			} //THEN
+
+		} //WHEN
+	} //GIVEN
+	GIVEN( "Test repeat string views" ) {
+		using namespace std::literals::string_view_literals;
+		WHEN("Bound repeater"){
+			auto RepeatedInt = std23::views::repeat("testMe"sv, boundLimit);
+			THEN("Check all ints in bound limit"){
+				CHECK(RepeatedInt.size() == boundLimit);
+				for (auto i : RepeatedInt){
+					CHECK(i == "testMe");
+				}
+			} //THEN
+		} //WHEN
+		WHEN("Unbound repeater"){
+			auto RepeatedInt = std23::views::repeat("testMe"sv);
+			THEN("Check that end is unbound and int is repeated within 2x listed limit"){
+				CHECK( std20::same_as<std::remove_cv_t<decltype(std20::unreachable_sentinel)>, 
+						      decltype(RepeatedInt.end())>);
+				int UnboundLimit = 0; 
+				for (auto i : RepeatedInt){
+					UnboundLimit += 1;
+					CHECK(i == "testMe");
+					if (UnboundLimit > 2*boundLimit){
+						break;
+					}
+				}
+			} //THEN
+
+		} //WHEN
+	} //GIVEN
+
+} //SCENARIO
+