Added helper headers to dynamically select std::filesystem or ghc::filesystem into the namespace fs.

This commit is contained in:
Steffen Schuemann 2019-03-24 15:16:36 +01:00
parent d4eae36f7c
commit de2c1187a4
4 changed files with 211 additions and 0 deletions

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@ -143,6 +143,12 @@ 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.
There is an additional header named `ghc/fs_std.hpp` that implements this
dynamic selection of a filesystem implementation, that you can include
instead of `ghc/filesystem.hpp` when you want std::filesystem where
available and ghc::filesystem where not.
### Using it as Forwarding-/Implementation-Header
Alternatively, starting from v1.1.0 `ghc::filesystem` can also be used by
@ -157,6 +163,43 @@ into a Windows-DLL, as a DLL interface with C++ standard templates in interfaces
is a different beast. If someone is willing to give it a try, I might integrate
a PR but currently working on that myself is not a priority.
If you use the forwarding/implementation approach, you can still use the dynamic
switching like this:
```cpp
#if defined(__cplusplus) && __cplusplus >= 201703L && defined(__has_include) && __has_include(<filesystem>)
#include <filesystem>
namespace fs {
using namespace std::filesystem;
using ifstream = std::ifstream;
using ofstream = std::ofstream;
using fstream = std::fstream;
}
#else
#include <ghc/fs-fwd.hpp>
namespace fs {
using namespace ghc::filesystem;
using ifstream = ghc::filesystem::ifstream;
using ofstream = ghc::filesystem::ofstream;
using fstream = ghc::filesystem::fstream;
}
#endif
```
and in the implementation hiding cpp, you might use (before any include that includes `ghc/fs_fwd.hpp`
to take precedence:
```cpp
#if !(defined(__cplusplus) && __cplusplus >= 201703L && defined(__has_include) && __has_include(<filesystem>))
#include <ghc/fs_impl.hpp>
#endif
```
There are additional helper headers, named `ghc/fs_std_fwd.hpp` and `ghc/fs_std_impl.hpp`
that use this technique, so you can simply include them if you want to dynamically select
the filesystem implementation.
### Git Submodule
Starting from v1.1.0, it is possible to add `ghc::filesystem`

59
include/ghc/fs_std.hpp Normal file
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@ -0,0 +1,59 @@
//---------------------------------------------------------------------------------------
//
// 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_std.hpp - The dynamic switching header for that includes std::filesystem if detected
// or ghc::filesystem if not, and makes the resulting API available in the
// namespace fs.
//---------------------------------------------------------------------------------------
#ifndef GHC_FILESYSTEM_STD_H
#if defined(__cplusplus) && __cplusplus >= 201703L && defined(__has_include) && __has_include(<filesystem>)
#include <filesystem>
namespace fs {
using namespace std::filesystem;
using ifstream = std::ifstream;
using ofstream = std::ofstream;
using fstream = std::fstream;
}
#else
#include <ghc/filesystem.hpp>
namespace fs {
using namespace ghc::filesystem;
using ifstream = ghc::filesystem::ifstream;
using ofstream = ghc::filesystem::ofstream;
using fstream = ghc::filesystem::fstream;
}
#endif
#endif // GHC_FILESYSTEM_STD_H

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@ -0,0 +1,63 @@
//---------------------------------------------------------------------------------------
//
// 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_std_fwd.hpp - The forwarding header for the header/implementation seperated usage of
// ghc::filesystem that uses std::filesystem if it detects it.
// This file can be include at any place, where fs::filesystem api is needed while
// not bleeding implementation details (e.g. system includes) into the global namespace,
// as long as one cpp includes fs_std_impl.hpp to deliver the matching implementations.
//---------------------------------------------------------------------------------------
#ifndef GHC_FILESYSTEM_STD_FWD_H
#define GHC_FILESYSTEM_STD_FWD_H
#if defined(__cplusplus) && __cplusplus >= 201703L && defined(__has_include) && __has_include(<filesystem>)
#include <filesystem>
namespace fs {
using namespace std::filesystem;
using ifstream = std::ifstream;
using ofstream = std::ofstream;
using fstream = std::fstream;
}
#else
#define GHC_FILESYSTEM_FWD
#include <ghc/filesystem.hpp>
namespace fs {
using namespace ghc::filesystem;
using ifstream = ghc::filesystem::ifstream;
using ofstream = ghc::filesystem::ofstream;
using fstream = ghc::filesystem::fstream;
}
#endif
#endif // GHC_FILESYSTEM_STD_FWD_H

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@ -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_std_impl.hpp - The implementation header for the header/implementation seperated usage of
// ghc::filesystem that does nothing if std::filesystem is detected.
// 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_std_fwd.hpp directly or via a different
// header to work.
//---------------------------------------------------------------------------------------
#if !(defined(__cplusplus) && __cplusplus >= 201703L && defined(__has_include) && __has_include(<filesystem>))
#define GHC_FILESYSTEM_IMPLEMENTATION
#include <ghc/filesystem.hpp>
#endif