refactor: Update palindrome interface

benchmark/palindrome_benchmark.cpp

@@ -69,7 +69,8 @@ TEST_CASE("Palindrome benchmarking", "[benchmark][palindrome]")
             .run(
                 NAMEOF_RAW(raw::is_palindrome<char>).c_str(),
                 [&palindrome]() {
-                    auto const r{raw::is_palindrome(palindrome)};
+                    auto const r{raw::is_palindrome<char>(
+                        palindrome.data(), palindrome.length())};
 
                     ankerl::nanobench::doNotOptimizeAway(r);
                 })

include/forfun/palindrome.hpp

@@ -12,21 +12,23 @@
 
 #include <algorithm>
 #include <cctype>
+#include <concepts>
 #include <iterator>
 #include <string_view>
+#include <type_traits>
 
 namespace forfun::palindrome {
 
 namespace raw {
 
-template <typename CharT>
+template <std::integral CharT>
 [[clang::no_sanitize("unsigned-integer-overflow")]] [[nodiscard]]
-constexpr auto
-is_palindrome(std::basic_string_view<CharT> const s) noexcept -> bool
+constexpr auto is_palindrome(
+    typename std::basic_string_view<CharT>::const_pointer const s,
+    typename std::basic_string_view<CharT>::size_type const length) noexcept
+    -> bool
 {
-    using SizeType = decltype(s)::size_type;
-
-    auto const length{s.length()};
+    using SizeType = std::remove_const_t<decltype(length)>;
 
     auto end{length - 1};
     auto const mid{length / 2};
@@ -64,7 +66,7 @@ inline auto is_palindrome_ci(std::string_view const s) noexcept -> bool
 
 namespace iterator_based {
 
-template <typename CharT>
+template <std::integral CharT>
 [[nodiscard]]
 constexpr auto
 is_palindrome(std::basic_string_view<CharT> const s) noexcept -> bool
@@ -119,7 +121,7 @@ namespace functional {
 
 /// Adapted from original source:
 /// https://en.cppreference.com/w/cpp/algorithm/equal
-template <typename CharT>
+template <std::integral CharT>
 [[nodiscard]]
 constexpr auto
 is_palindrome(std::basic_string_view<CharT> const s) noexcept -> bool
@@ -135,7 +137,7 @@ namespace bloated {
 
 /// Adapted from original source:
 /// https://en.cppreference.com/w/cpp/algorithm/equal
-template <typename CharT>
+template <std::integral CharT>
 [[nodiscard]]
 constexpr auto
 is_palindrome(std::basic_string_view<CharT> const s) noexcept -> bool

test/palindrome_test.cpp

@@ -4,7 +4,9 @@
 
 // SPDX-License-Identifier: MIT
 
+#include <functional>
 #include <string_view>
+#include <utility>
 
 #include <catch2/catch_message.hpp>
 #include <catch2/catch_template_test_macros.hpp>
@@ -16,16 +18,27 @@
 
 namespace {
 
-[[nodiscard]] inline auto
-is_palindrome_wrapper(std::string_view const s) noexcept -> bool
+template <typename Func, typename BasicStringView>
+[[nodiscard]] constexpr auto is_palindrome_test_wrapper(
+    Func&& func, BasicStringView const s) noexcept -> bool
 {
-    return ::is_palindrome(s.data(), s.size()) != 0;
-}
-
-[[nodiscard]] inline auto
-is_palindrome_ci_wrapper(std::string_view const s) noexcept -> bool
-{
-    return ::is_palindrome_ci(s.data(), s.size()) != 0;
+    if constexpr (std::is_invocable_v<decltype(func), decltype(s)>)
+    {
+        return std::invoke(
+            std::forward<decltype(func)>(func), std::forward<decltype(s)>(s));
+    }
+    // clang-format off
+    else if constexpr (std::is_invocable_v<
+        decltype(func),
+        typename decltype(s)::pointer,
+        typename decltype(s)::size_type>)
+    // clang-format on
+    {
+        return std::invoke(
+            std::forward<decltype(func)>(func),
+            std::forward<decltype(s.data())>(s.data()),
+            std::forward<decltype(s.length())>(s.length()));
+    }
 }
 
 } // namespace
@@ -36,7 +49,7 @@ TEMPLATE_TEST_CASE_SIG(
     "Case-sensitive palindrome check",
     "[palindrome]",
     ((auto is_palindrome), is_palindrome),
-    (is_palindrome_wrapper),
+    (::is_palindrome),
     (forfun::palindrome::functional::is_palindrome<char>),
     (forfun::palindrome::functional::bloated::is_palindrome<char>),
     (forfun::palindrome::iterator_based::is_palindrome<char>),
@@ -59,7 +72,7 @@ TEMPLATE_TEST_CASE_SIG(
 
         CAPTURE(s);
 
-        REQUIRE(is_palindrome(s));
+        REQUIRE(is_palindrome_test_wrapper(is_palindrome, s));
     }
 
     SECTION("Negative")
@@ -78,7 +91,7 @@ TEMPLATE_TEST_CASE_SIG(
 
         CAPTURE(s);
 
-        REQUIRE_FALSE(is_palindrome(s));
+        REQUIRE_FALSE(is_palindrome_test_wrapper(is_palindrome, s));
     }
 }
 
@@ -104,13 +117,13 @@ TEMPLATE_TEST_CASE_SIG(
             U"ABBA"sv,
             U"Xyz 8 zyX"sv,
             U"step on no pets"sv,
-            U"باب"sv,
-            U"亞細亞"sv,
+            U"باب"sv, // Door, in Arabic
+            U"亞細亞"sv, // Asia, in Chinese
             U"19/9/91"sv)};
 
         CAPTURE(s);
 
-        REQUIRE(is_palindrome(s));
+        REQUIRE(is_palindrome_test_wrapper(is_palindrome, s));
     }
 
     SECTION("Negative")
@@ -130,15 +143,15 @@ TEMPLATE_TEST_CASE_SIG(
 
         CAPTURE(s);
 
-        REQUIRE_FALSE(is_palindrome(s));
+        REQUIRE_FALSE(is_palindrome_test_wrapper(is_palindrome, s));
     }
 }
 
 TEMPLATE_TEST_CASE_SIG(
     "Case-insensitive palindrome check",
     "[palindrome]",
     ((auto is_palindrome_ci), is_palindrome_ci),
-    (is_palindrome_ci_wrapper),
+    (::is_palindrome_ci),
     (forfun::palindrome::functional::bloated::is_palindrome_ci),
     (forfun::palindrome::iterator_based::is_palindrome_ci),
     (forfun::palindrome::raw::is_palindrome_ci))
@@ -164,7 +177,7 @@ TEMPLATE_TEST_CASE_SIG(
 
         CAPTURE(s);
 
-        REQUIRE(is_palindrome_ci(s));
+        REQUIRE(is_palindrome_test_wrapper(is_palindrome_ci, s));
     }
 
     SECTION("Negative")
@@ -180,6 +193,6 @@ TEMPLATE_TEST_CASE_SIG(
 
         CAPTURE(s);
 
-        REQUIRE_FALSE(is_palindrome_ci(s));
+        REQUIRE_FALSE(is_palindrome_test_wrapper(is_palindrome_ci, s));
     }
 }