Add case_insensitive_less (issue #81)

include/cpp-sort/comparators/case_insensitive_less.h

@@ -0,0 +1,130 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Morwenn
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef CPPSORT_COMPARATORS_CASE_INSENSITIVE_LESS_H_
+#define CPPSORT_COMPARATORS_CASE_INSENSITIVE_LESS_H_
+
+////////////////////////////////////////////////////////////
+// Headers
+////////////////////////////////////////////////////////////
+#include <algorithm>
+#include <iterator>
+#include <locale>
+#include <type_traits>
+#include <utility>
+#include <cpp-sort/utility/static_const.h>
+
+namespace cppsort
+{
+    namespace detail
+    {
+        ////////////////////////////////////////////////////////////
+        // Case insensitive comparison for char sequences
+
+        template<typename CharT>
+        struct char_less
+        {
+            const std::ctype<CharT>& ct;
+
+            char_less(const std::ctype<CharT>& ct):
+                ct(ct)
+            {}
+
+            auto operator()(CharT lhs, CharT rhs) const
+                -> bool
+            {
+              return ct.tolower(lhs) < ct.tolower(rhs);
+            }
+        };
+
+        template<typename T>
+        auto case_insensitive_less(const T& lhs, const T& rhs, const std::locale loc)
+            -> bool
+        {
+            using char_type = std::decay_t<decltype(*std::begin(lhs))>;
+            const auto& ct = std::use_facet<std::ctype<char_type>>(loc);
+
+            return std::lexicographical_compare(std::begin(lhs), std::end(lhs),
+                                                std::begin(rhs), std::end(rhs),
+                                                char_less<char_type>(ct));
+        }
+
+        template<typename T>
+        auto case_insensitive_less(const T& lhs, const T& rhs)
+            -> bool
+        {
+            std::locale loc;
+            return case_insensitive_less(lhs, rhs, loc);
+        }
+
+        ////////////////////////////////////////////////////////////
+        // Customization point
+
+        class case_insensitive_less_locale_fn
+        {
+            private:
+
+                const std::locale& loc;
+
+            public:
+
+                explicit case_insensitive_less_locale_fn(const std::locale& loc):
+                    loc(loc)
+                {}
+
+                template<typename T, typename U>
+                constexpr auto operator()(T&& lhs, U&& rhs) const
+                    noexcept(noexcept(case_insensitive_less(std::forward<T>(lhs), std::forward<U>(rhs), loc)))
+                    -> decltype(case_insensitive_less(std::forward<T>(lhs), std::forward<U>(rhs), loc))
+                {
+                    return case_insensitive_less(std::forward<T>(lhs), std::forward<U>(rhs), loc);
+                }
+        };
+
+        struct case_insensitive_less_fn
+        {
+            template<typename T, typename U>
+            constexpr auto operator()(T&& lhs, U&& rhs) const
+                noexcept(noexcept(case_insensitive_less(std::forward<T>(lhs), std::forward<U>(rhs))))
+                -> decltype(case_insensitive_less(std::forward<T>(lhs), std::forward<U>(rhs)))
+            {
+                return case_insensitive_less(std::forward<T>(lhs), std::forward<U>(rhs));
+            }
+
+            inline auto operator()(const std::locale& loc) const
+                -> case_insensitive_less_locale_fn
+            {
+                return case_insensitive_less_locale_fn(loc);
+            }
+        };
+    }
+
+    namespace
+    {
+        constexpr auto&& case_insensitive_less = utility::static_const<
+            detail::case_insensitive_less_fn
+        >::value;
+    }
+}
+
+#endif // CPPSORT_COMPARATORS_CASE_INSENSITIVE_LESS_H_

testsuite/CMakeLists.txt

@@ -28,6 +28,7 @@ set(
 set(
     COMPARATORS_TESTS
 
+    comparators/case_insensitive_less.cpp
     comparators/natural_less.cpp
     comparators/total_less.cpp
 )

testsuite/comparators/case_insensitive_less.cpp

@@ -0,0 +1,69 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Morwenn
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include <array>
+#include <string>
+#include <catch.hpp>
+#include <cpp-sort/comparators/case_insensitive_less.h>
+#include <cpp-sort/sort.h>
+
+TEST_CASE( "case-insensitive string comparison with case_insensitive_less" )
+{
+    std::array<std::string, 9> array = {
+        "awry",
+        "Banana",
+        "greaTEr",
+        "bounTy",
+        "eXpected",
+        "aROma",
+        "excellent",
+        "GreaT",
+        "aROused"
+    };
+
+    std::array<std::string, 9> expected = {
+        "aROma",
+        "aROused",
+        "awry",
+        "Banana",
+        "bounTy",
+        "excellent",
+        "eXpected",
+        "GreaT",
+        "greaTEr"
+    };
+
+    SECTION( "implicit global locale" )
+    {
+        cppsort::sort(array, cppsort::case_insensitive_less);
+        CHECK( array == expected );
+    }
+
+    SECTION( "explicit global locale" )
+    {
+        std::locale locale;
+        cppsort::sort(array, cppsort::case_insensitive_less(locale));
+        CHECK( array == expected );
+    }
+}
+