Added std formatter for path view, but as no current standard library

implements formatters for filesystem paths, no idea if it works or not.

Author: ned14

include/llfio/revision.hpp

@@ -1,4 +1,4 @@
 // Note the second line of this file must ALWAYS be the git SHA, third line ALWAYS the git SHA update time
-#define LLFIO_PREVIOUS_COMMIT_REF    2ff292feda4aaece95ffcc5bc35095281ca45dfd
-#define LLFIO_PREVIOUS_COMMIT_DATE   "2024-08-29 10:58:20 +00:00"
-#define LLFIO_PREVIOUS_COMMIT_UNIQUE 2ff292fe
+#define LLFIO_PREVIOUS_COMMIT_REF    c9e6f6c8accb5ce8a36607191955ad59e5cba099
+#define LLFIO_PREVIOUS_COMMIT_DATE   "2024-08-29 11:02:08 +00:00"
+#define LLFIO_PREVIOUS_COMMIT_UNIQUE c9e6f6c8

include/llfio/v2.0/path_view.hpp

@@ -34,6 +34,11 @@ Distributed under the Boost Software License, Version 1.0.
 #include <compare>
 #endif
 
+#if __cplusplus >= 202600L || _HAS_CXX26
+#include <format>
+#define LLFIO_PATH_VIEW_HAVE_FORMAT 1
+#endif
+
 #include "quickcpplib/algorithm/hash.hpp"
 #include "quickcpplib/algorithm/string.hpp"
 
@@ -3199,6 +3204,55 @@ static_assert(std::is_trivially_copyable<path_view>::value, "path_view is not a
 
 LLFIO_V2_NAMESPACE_END
 
+#if LLFIO_PATH_VIEW_HAVE_FORMAT
+template <class charT> struct std::formatter<LLFIO_V2_NAMESPACE::path_view_component, charT>
+{
+  std::formatter<std::filesystem::path, charT> fmt;
+  constexpr void set_debug_format() { fmt.set_debug_format(); }
+  constexpr typename std::basic_format_parse_context<charT>::iterator parse(std::basic_format_parse_context<charT> &ctx) { return fmt.parse(ctx); }
+  template <class FormatContext> typename FormatContext::iterator format(const LLFIO_V2_NAMESPACE::path_view_component &pv, FormatContext &ctx) const
+  {
+    return LLFIO_V2_NAMESPACE::visit(
+    [&](auto sv)
+    {
+      using type = typename decltype(sv)::value_type;
+      if constexpr(std::is_same_v<type, std::byte>)
+      {
+        return fmt.format(std::filesystem::path(QUICKCPPLIB_NAMESPACE::algorithm::string::to_hex_string((const char *) v.data(), v.size())), ctx);
+      }
+      else
+      {
+        return fmt.format(std::filesystem::path(sv), ctx);
+      }
+    },
+    pv);
+  }
+};
+template <class charT> struct std::formatter<LLFIO_V2_NAMESPACE::path_view, charT>
+{
+  std::formatter<std::filesystem::path, charT> fmt;
+  constexpr void set_debug_format() { fmt.set_debug_format(); }
+  constexpr typename std::basic_format_parse_context<charT>::iterator parse(std::basic_format_parse_context<charT> &ctx) { return fmt.parse(ctx); }
+  template <class FormatContext> typename FormatContext::iterator format(const LLFIO_V2_NAMESPACE::path_view &pv, FormatContext &ctx) const
+  {
+    return LLFIO_V2_NAMESPACE::visit(
+    [&](auto sv)
+    {
+      using type = typename decltype(sv)::value_type;
+      if constexpr(std::is_same_v<type, std::byte>)
+      {
+        return fmt.format(std::filesystem::path(QUICKCPPLIB_NAMESPACE::algorithm::string::to_hex_string((const char *) v.data(), v.size())), ctx);
+      }
+      else
+      {
+        return fmt.format(std::filesystem::path(sv), ctx);
+      }
+    },
+    pv);
+  }
+};
+#endif
+
 #if LLFIO_HEADERS_ONLY == 1 && !defined(DOXYGEN_SHOULD_SKIP_THIS)
 #define LLFIO_INCLUDED_BY_HEADER 1
 #include "detail/impl/path_view.ipp"

test/tests/path_view.cpp

@@ -357,6 +357,17 @@ static inline void TestPathView()
     BOOST_CHECK(zbuff.allocator().deleted == 1);
     BOOST_CHECK(zbuff.allocator().sig == 0);  // default initialised
   }
+
+#if LLFIO_PATH_VIEW_HAVE_FORMAT
+  {
+    std::string a, b;
+    std::format_to(std::back_inserter(a), std::filesystem::path("a/b/c"));
+    std::format_to(std::back_inserter(b), llfio::path_view("a/b/c"));
+    std::cout << "std::format(path) = " << a << std::endl;
+    std::cout << "std::format(path_view) = " << b << std::endl;
+    BOOST_CHECK(a == b);
+  }
+#endif
 }
 
 KERNELTEST_TEST_KERNEL(integration, llfio, path_view, path_view, "Tests that llfio::path_view() works as expected", TestPathView())