Added support for forwarding/implementation includes to enhance compile time and hide system headers.

CMakeLists.txt

@@ -11,7 +11,7 @@ if(CMAKE_CXX_STANDARD LESS 11)
 endif()
 
 add_library(ghc_filesystem INTERFACE)
-target_sources(ghc_filesystem INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}/include/ghc/filesystem.hpp)
+target_sources(ghc_filesystem INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}/include/ghc/filesystem.hpp ${CMAKE_CURRENT_SOURCE_DIR}/include/ghc/fs_fwd.hpp ${CMAKE_CURRENT_SOURCE_DIR}/include/ghc/fs_impl.hpp)
 target_include_directories(ghc_filesystem INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}/include)
 target_compile_options(ghc_filesystem INTERFACE "$<$<C_COMPILER_ID:MSVC>:/utf-8>")
 target_compile_options(ghc_filesystem INTERFACE "$<$<CXX_COMPILER_ID:MSVC>:/utf-8>")

README.md

@@ -85,7 +85,7 @@ in the standard, and there might be issues in these implementations too.
 
 ## Usage
 
-As it is a header-only library, it should be enough to copy the header
+As it is at first a header-only library, it should be enough to copy the header
 into your project folder oder point your include path to this directory and
 simply include the `filesystem.hpp` header.
 
@@ -135,6 +135,13 @@ without that switch ([see](https://blogs.msdn.microsoft.com/vcblog/2018/04/09/ms
 Be aware too, as a header-only library, it is not hiding the fact, that it
 uses system includes, so they "pollute" your global namespace.
 
+Alternatively, starting from v1.1.0 `ghc::filesystem` can also be used by
+including one of two additional wrapper headers. These allow to include
+a forwarded version in most places (`ghc/fs_fwd.hpp`) while hiding the
+implementation details in a single cpp that includes `ghc/fs_impl.hpp` to
+implement the needed code. That way system includes are only visible from
+inside the cpp, all other places are clean. 
+
 Additionally, starting from v1.1.0, it is possible to add `ghc::filesystem`
 as a git submodule, add the directory to your `CMakeLists.txt` with
 `add_subdirectory()` and then simply use `target_link_libraries(your-target ghc_filesystem)`
@@ -375,6 +382,12 @@ to the expected behavior.
   will be a valid directive.
   Still you can simply only add the header file to you project and include it
   from there.
+* Enhancement ([#10](https://github.com/gulrak/filesystem/issues/10)),
+  support for separation of implementation and forwarded api: Two
+  additional simple includes are added, that can be used to forward
+  `ghc::filesystem` declarations (`fs_fwd.hpp`) and to wrap the
+  implementation into a single cpp (`fs_impl.hpp`)
+
   
 ### [v1.0.10](https://github.com/gulrak/filesystem/releases/tag/v1.0.10)
 

include/ghc/fs_fwd.hpp

@@ -0,0 +1,46 @@
+//---------------------------------------------------------------------------------------
+//
+// ghc::filesystem - A C++17-like filesystem implementation for C++11/C++14
+//
+//---------------------------------------------------------------------------------------
+//
+// Copyright (c) 2018, Steffen Schümann <s.schuemann@pobox.com>
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification,
+// are permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this
+//    list of conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice,
+//    this list of conditions and the following disclaimer in the documentation
+//    and/or other materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors
+//    may be used to endorse or promote products derived from this software without
+//    specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+//---------------------------------------------------------------------------------------
+// fs_fwd.hpp - The forwarding header for the header/implementation seperated usage of
+//              ghc::filesystem.
+// This file can be include at any place, where ghc::filesystem api is needed while
+// not bleeding implementation details (e.g. system includes) into the global namespace,
+// as long as one cpp includes fs_impl.hpp to deliver the matching implementations.
+//---------------------------------------------------------------------------------------
+#ifndef GHC_FILESYSTEM_FWD_H
+#define GHC_FILESYSTEM_FWD_H
+#define GHC_FILESYSTEM_FWD
+#include <ghc/filesystem.hpp>
+#endif // GHC_FILESYSTEM_FWD_H

include/ghc/fs_impl.hpp

@@ -0,0 +1,43 @@
+//---------------------------------------------------------------------------------------
+//
+// ghc::filesystem - A C++17-like filesystem implementation for C++11/C++14
+//
+//---------------------------------------------------------------------------------------
+//
+// Copyright (c) 2018, Steffen Schümann <s.schuemann@pobox.com>
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification,
+// are permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this
+//    list of conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice,
+//    this list of conditions and the following disclaimer in the documentation
+//    and/or other materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors
+//    may be used to endorse or promote products derived from this software without
+//    specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+//---------------------------------------------------------------------------------------
+// fs_impl.hpp - The implementation header for the header/implementation seperated usage of
+//               ghc::filesystem.
+// This file can be used to hide the implementation of ghc::filesystem into a single cpp.
+// The cpp has to include this before including fs_fwd.hpp directly or via a different
+// header to work.
+//---------------------------------------------------------------------------------------
+#define GHC_FILESYSTEM_IMPLEMENTATION
+#include <ghc/filesystem.hpp>

test/CMakeLists.txt

@@ -40,3 +40,6 @@ endif()
 
 add_executable(multifile_test multi1.cpp multi2.cpp catch.hpp)
 target_link_libraries(multifile_test ghc_filesystem)
+
+add_executable(fwd_impl_test fwd_test.cpp impl_test.cpp)
+target_link_libraries(fwd_impl_test ghc_filesystem)

test/filesystem_test.cpp

@@ -64,8 +64,12 @@ using fstream = std::fstream;
 #define GHC_OS_WINDOWS
 #endif
 #else
+#ifdef GHC_FILESYSTEM_FWD_TEST
+#include <ghc/fs_fwd.hpp>
+#else
 #define NOMINMAX
 #include <ghc/filesystem.hpp>
+#endif
 namespace fs {
 using namespace ghc::filesystem;
 using ifstream = ghc::filesystem::ifstream;
@@ -74,7 +78,9 @@ using fstream = ghc::filesystem::fstream;
 }
 #endif
 
+#ifndef GHC_FILESYSTEM_FWD_TEST
 #define CATCH_CONFIG_MAIN
+#endif
 #include "catch.hpp"
 
 //#define TEST_LWG_2935_BEHAVIOUR

test/fwd_test.cpp

@@ -0,0 +1,7 @@
+// This test file is part of the fwd_test.cpp/impl_test.cpp pair
+// and used to test the new optional two-part usage of ghc::filesystem
+// where exactly one cpp includes fs_impl.hpp and all others use
+// fs_fwd.hpp (to test this with maximum functionality, the unit tests
+// are included here, signaling they should only include the fs_fwd.hpp)
+#define GHC_FILESYSTEM_FWD_TEST
+#include "filesystem_test.cpp"

test/impl_test.cpp

@@ -0,0 +1,8 @@
+// This test file is part of the fwd_test.cpp/impl_test.cpp pair
+// and used to test the new optional two-part usage of ghc::filesystem
+// where exactly one cpp includes fs_impl.hpp and all others use
+// fs_fwd.hpp (to test this with maximum functionality, the unit tests
+// are included here, signaling they should only include the fs_fwd.hpp)
+#include <ghc/fs_impl.hpp>
+#define CATCH_CONFIG_MAIN
+#include "catch.hpp"