Fix std::views::zip support (issue #40)

Author: Morwenn

include/gfx/timsort.hpp

@@ -89,14 +89,13 @@ struct run {
 template <typename RandomAccessIterator>
 class TimSort {
     using iter_t = RandomAccessIterator;
-    using value_t = typename std::iterator_traits<iter_t>::value_type;
-    using diff_t = typename std::iterator_traits<iter_t>::difference_type;
+    using diff_t = std::iter_difference_t<iter_t>;
 
     static constexpr int MIN_MERGE = 32;
     static constexpr int MIN_GALLOP = 7;
 
     int minGallop_ = MIN_GALLOP;
-    std::vector<value_t> tmp_; // temp storage for merges
+    std::vector<std::iter_value_t<iter_t>> tmp_; // temp storage for merges
     std::vector<run<RandomAccessIterator>> pending_;
 
     template <typename Compare, typename Projection>
@@ -344,14 +343,14 @@ class TimSort {
     }
 
     static void rotateLeft(iter_t first, iter_t last) {
-        auto tmp = std::ranges::iter_move(first);
+        std::iter_value_t<iter_t> tmp = std::ranges::iter_move(first);
         auto [_, last_1] = std::ranges::move(std::ranges::next(first), last, first);
         *last_1 = std::move(tmp);
     }
 
     static void rotateRight(iter_t first, iter_t last) {
         auto last_1 = std::ranges::prev(last);
-        auto tmp = std::ranges::iter_move(last_1);
+        std::iter_value_t<iter_t> tmp = std::ranges::iter_move(last_1);
         std::ranges::move_backward(first, last_1, last);
         *first = std::move(tmp);
     }

tests/CMakeLists.txt

@@ -118,6 +118,16 @@ add_executable(cxx_20_tests
 configure_tests(cxx_20_tests)
 target_compile_features(cxx_20_tests PRIVATE cxx_std_20)
 
+# Tests requiring C++23 support
+if ("cxx_std_23" IN_LIST CMAKE_CXX_COMPILE_FEATURES)
+    add_executable(cxx_23_tests
+        cxx_23_tests.cpp
+        verbose_abort.cpp
+    )
+    configure_tests(cxx_23_tests)
+    target_compile_features(cxx_23_tests PRIVATE cxx_std_23)
+endif()
+
 # Windows-specific tests
 if (WIN32)
     add_executable(windows_tests
@@ -135,6 +145,9 @@ catch_discover_tests(cxx_98_tests EXTRA_ARGS --rng-seed ${RNG_SEED})
 catch_discover_tests(cxx_11_tests EXTRA_ARGS --rng-seed ${RNG_SEED})
 catch_discover_tests(cxx_17_tests EXTRA_ARGS --rng-seed ${RNG_SEED})
 catch_discover_tests(cxx_20_tests EXTRA_ARGS --rng-seed ${RNG_SEED})
+if ("cxx_std_23" IN_LIST CMAKE_CXX_COMPILE_FEATURES)
+    catch_discover_tests(cxx_23_tests EXTRA_ARGS --rng-seed ${RNG_SEED})
+endif()
 if (WIN32)
     catch_discover_tests(windows_tests EXTRA_ARGS --rng-seed ${RNG_SEED})
 endif()

tests/cxx_23_tests.cpp

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2024 Morwenn.
+ * SPDX-License-Identifier: MIT
+ */
+#include <array>
+#include <deque>
+#include <iterator>
+#include <numeric>
+#include <ranges>
+#include <vector>
+#include <catch2/catch_test_macros.hpp>
+#include <gfx/timsort.hpp>
+#include "test_helpers.hpp"
+
+TEST_CASE( "support for std::ranges::views::zip" )
+{
+    SECTION( "zip two small collections" ) {
+        // issue #40
+        std::vector<int> vec = {4, 2, 3, 1};
+        std::array<char, 4> arr = {'A', 'C', 'B', 'D'};
+        auto zipped = std::views::zip(vec, arr);
+
+        gfx::timsort(
+            zipped, {},
+            [](std::tuple<int&, char&> const& pair) {
+                return std::get<0>(pair);
+            }
+        );
+        CHECK( std::ranges::is_sorted(vec) );
+        CHECK( std::ranges::is_sorted(arr, std::ranges::greater{}) );
+    }
+
+    SECTION( "zip two big collections" ) {
+        std::vector<int> vec(3000);
+        std::deque<long long int> deq(3000);
+        std::iota(vec.begin(), vec.end(), -500);
+        std::ranges::reverse(vec);
+        std::iota(deq.begin(), deq.end(), -500);
+
+        auto zipped = std::views::zip(vec, deq);
+        test_helpers::shuffle(zipped);
+
+        gfx::timsort(zipped);
+        CHECK( std::ranges::is_sorted(vec) );
+        CHECK( std::ranges::is_sorted(deq, std::ranges::greater{}) );
+    }
+}