Make boost::iostreams::detail::path constructible from std::filesystem::path

doc/classes/file_descriptor.html

@@ -168,7 +168,7 @@ <H4><CODE>file_descriptor_source::file_descriptor_source</CODE></H4>
 </P>
 
 <P>
-    The second member constructs a <CODE>file_descriptor_source</CODE> to access the file with the given pathname. <CODE>Path</CODE> should be either a string or a Boost.Filesystem path. The parameter <CODE>mode</CODE> has the same interpretation as <CODE>(mode | std::ios_base::in)</CODE> in <CODE>std::basic_filebuf::open</CODE>.<A CLASS="footnote_ref" NAME="note_1_ref" HREF="#note_1"><SUP>[1]</SUP></A>
+    The second member constructs a <CODE>file_descriptor_source</CODE> to access the file with the given pathname. <CODE>Path</CODE> should be either a string, a Boost.Filesystem path or a std::filesystem::path. The parameter <CODE>mode</CODE> has the same interpretation as <CODE>(mode | std::ios_base::in)</CODE> in <CODE>std::basic_filebuf::open</CODE>.<A CLASS="footnote_ref" NAME="note_1_ref" HREF="#note_1"><SUP>[1]</SUP></A>
 </P>
 
 <P>
@@ -308,7 +308,7 @@ <H4><CODE>file_descriptor_sink::file_descriptor_sink</CODE></H4>
 </P>
 
 <P>
-    The second member constructs a <CODE>file_descriptor_sink</CODE> to access the file with the given pathname. <CODE>Path</CODE> should be either a string or a Boost.Filesystem path. The parameter <CODE>mode</CODE> has the same interpretation as <CODE>(mode | std::ios_base::out)</CODE> in <CODE>std::basic_filebuf::open</CODE>.<A CLASS="footnote_ref" NAME="note_1_ref2" HREF="#note_1"><SUP>[1]</SUP></A>
+    The second member constructs a <CODE>file_descriptor_sink</CODE> to access the file with the given pathname. <CODE>Path</CODE> should be either a string, a Boost.Filesystem path or a std::filesystem::path. The parameter <CODE>mode</CODE> has the same interpretation as <CODE>(mode | std::ios_base::out)</CODE> in <CODE>std::basic_filebuf::open</CODE>.<A CLASS="footnote_ref" NAME="note_1_ref2" HREF="#note_1"><SUP>[1]</SUP></A>
 </P>
 
 <P>
@@ -448,7 +448,7 @@ <H4><CODE>file_descriptor::file_descriptor</CODE></H4>
 </P>
 
 <P>
-    The second member constructs a <CODE>file_descriptor</CODE> to access the file with the given pathname. <CODE>Path</CODE> should be either a string or a Boost.Filesystem path. The parameter <CODE>mode</CODE> has the same interpretation as in <CODE>std::basic_filebuf::open</CODE>.<A CLASS="footnote_ref" NAME="note_1_ref3" HREF="#note_1"><SUP>[1]</SUP></A>
+    The second member constructs a <CODE>file_descriptor</CODE> to access the file with the given pathname. <CODE>Path</CODE> should be either a string, a Boost.Filesystem path or a std::filesystem::path. The parameter <CODE>mode</CODE> has the same interpretation as in <CODE>std::basic_filebuf::open</CODE>.<A CLASS="footnote_ref" NAME="note_1_ref3" HREF="#note_1"><SUP>[1]</SUP></A>
 </P>
 
 <P>
@@ -526,4 +526,4 @@ <H4><CODE>file_descriptor::handle</CODE></H4>
 
 <!-- End Footer -->
 
-</BODY>
+</BODY>

include/boost/iostreams/detail/path.hpp

@@ -59,9 +59,9 @@ class path {
         init(p.external_file_string());
     }
 
-    // Constructor taking a boost::filesystem3::path (boost filesystem v3)
+    // Constructor taking a boost::filesystem3::path or a std::filesystem::path
     template<typename Path>
-    explicit path(const Path& p, typename Path::codecvt_type* = 0)
+    explicit path(const Path& p, typename Path::string_type* = 0)
     {
         init(p.native());
     }
@@ -113,9 +113,9 @@ class path {
     }
 #endif
 
-    // Assignment operator taking a boost::filesystem3::path
+    // Assignment operator taking a boost::filesystem3::path or a std::filesystem::path
     template<typename Path>
-    typename sfinae<typename Path::codecvt_type, path&>::type
+    typename sfinae<typename Path::string_type, path&>::type
         operator=(const Path& p)
     {
         init(p.native());

test/Jamfile.v2

@@ -54,6 +54,14 @@ rule compile-fail-iostreams ( sources * : requirements * : target-name ? ) {
         ] ;
 }
 
+lib stdc++fs ;
+lib c++fs ;
+
+exe can_use_stdcxxfs : checks/std_filesystem_libstdcxx.cpp stdc++fs ;
+exe can_use_cxxfs : checks/std_filesystem_libcxx.cpp c++fs ;
+
+explicit can_use_stdcxxfs ;
+explicit can_use_cxxfs ;
 
     local all-tests = 
           [ test-iostreams array_test.cpp ]
@@ -91,7 +99,11 @@ rule compile-fail-iostreams ( sources * : requirements * : target-name ? ) {
           [ test-iostreams line_filter_test.cpp ]
           [ test-iostreams mapped_file_test.cpp 
                 ../build//boost_iostreams ]
-          [ test-iostreams path_test.cpp ]
+          [ test-iostreams
+                path_test.cpp
+                    : [ check-target-builds ../../config/checks//cpp_lib_filesystem
+                        : [ check-target-builds can_use_stdcxxfs : <source>stdc++fs : [ check-target-builds can_use_cxxfs : <source>c++fs ] ]
+                          <define>BOOST_IOSTREAMS_TEST_PATH_WITH_STD_FILESYSTEM ] ]
           [ test-iostreams newline_test.cpp ]
           [ test-iostreams null_test.cpp ]
           [ test-iostreams operation_sequence_test.cpp ]

test/checks/std_filesystem_libcxx.cpp

@@ -0,0 +1,14 @@
+// Copyright John Doe 2020.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
+
+#include <filesystem>
+
+#ifndef _LIBCPP_VERSION
+#error libc++ expected
+#endif
+
+int main()
+{
+    std::filesystem::create_directory(std::filesystem::path("/tmp/cpp_lib_filesystem_link"));
+}

test/checks/std_filesystem_libstdcxx.cpp

@@ -0,0 +1,14 @@
+// Copyright John Doe 2020.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
+
+#include <filesystem>
+
+#ifndef __GLIBCXX__
+#error libstdc++ expected
+#endif
+
+int main()
+{
+    std::filesystem::create_directory(std::filesystem::path("/tmp/cpp_lib_filesystem_link"));
+}

test/path_test.cpp

@@ -5,21 +5,70 @@
 // See http://www.boost.org/libs/iostreams for documentation.
 
 #include <boost/iostreams/detail/path.hpp>
-#include <boost/filesystem/path.hpp>
 
+#include <boost/core/enable_if.hpp>
+#include <boost/filesystem/path.hpp>
+#include <boost/mpl/list.hpp>
+#include <boost/type_traits/is_same.hpp>
 #include <boost/test/test_tools.hpp>
 #include <boost/test/unit_test.hpp>
 
-void path_test()
+#ifdef BOOST_IOSTREAMS_TEST_PATH_WITH_STD_FILESYSTEM
+#include <filesystem>
+#endif
+
+template <typename Path>
+void check_path_invariant(
+    Path const& original_path,
+    boost::iostreams::detail::path const& path,
+    typename boost::enable_if<typename boost::is_same<typename Path::string_type::value_type, char>, void*>::type = NULL)
 {
-    boost::filesystem::path orig("a/b");
-    boost::iostreams::detail::path p(orig);
-    p = orig;
+    BOOST_CHECK(!path.is_wide());
+    BOOST_CHECK(original_path.native() == path.c_str());
+    BOOST_CHECK(std::wstring() == path.c_wstr());
 }
 
-boost::unit_test::test_suite* init_unit_test_suite(int, char* []) 
+template <typename Path>
+void check_path_invariant(
+    Path const& original_path,
+    boost::iostreams::detail::path const& path,
+    typename boost::enable_if<typename boost::is_same<typename Path::string_type::value_type, wchar_t>, void*>::type = NULL)
+{
+    BOOST_CHECK(path.is_wide());
+    BOOST_CHECK(original_path.native() == path.c_wstr());
+    BOOST_CHECK(std::string() == path.c_str());
+}
+
+BOOST_TEST_CASE_TEMPLATE_FUNCTION(construct_from_std_filesystem_path_test, Path)
+{
+    Path const original_path("abc");
+
+    boost::iostreams::detail::path const path(original_path);
+
+    check_path_invariant(original_path, path);
+}
+
+BOOST_TEST_CASE_TEMPLATE_FUNCTION(assign_std_filesystem_path_test, Path)
+{
+    Path const original_path("abc");
+
+    boost::iostreams::detail::path path;
+    path = original_path;
+
+    check_path_invariant(original_path, path);
+}
+
+typedef boost::mpl::list<
+        boost::filesystem::path
+#ifdef BOOST_IOSTREAMS_TEST_PATH_WITH_STD_FILESYSTEM
+        , std::filesystem::path
+#endif
+    > path_types;
+
+boost::unit_test::test_suite* init_unit_test_suite(int, char* [])
 {
-    boost::unit_test::test_suite* test = BOOST_TEST_SUITE("mapped_file test");
-    test->add(BOOST_TEST_CASE(&path_test));
+    boost::unit_test::test_suite* test = BOOST_TEST_SUITE("path test");
+    test->add(BOOST_TEST_CASE_TEMPLATE(construct_from_std_filesystem_path_test, path_types));
+    test->add(BOOST_TEST_CASE_TEMPLATE(assign_std_filesystem_path_test, path_types));
     return test;
 }