CPP2D

(Clang based) C++ to D language converter

Objective

The goal is to take a C++ project and convert all the source code to D language.

License

Copyright Loïc HAMOT, 2016

Distributed under the Boost Software License, Version 1.0.

See ./LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt

Continuous integration

• Ubuntu

• Windows

Already handled C++ features

Majority of C++ code is already convertible to D.

A not exhaustive list:

• class
  • constructor/destructor
  • virtual
  • abstract
  • override
  • initialization list
  • call base constructor
• Operator overloading
  • member
  • free
    • left or right
• Template
  • function
  • function specialization
  • class
  • class/struct specialization
  • class/struct partial specialization
• arrays
  • static
  • dynamic
  • std::vector (partially)
  • std::array (partially)
• preprocessor
  • function-like macro
  • declaration-like macro
  • simple #ifdef/else/endif

Some samples here : https://github.com/lhamot/CPP2D/wiki/Conversion-samples

Requirements

• cmake >= 2.6
• Tested with gcc 4.8.4 (Ubuntu 14.04.3), Visual Studio 2015 (Windows 7 & 10), and clang (macOS 10.14)
• Tested with LLVM/clang 6.0.1

How to install it?

1. Install clang : http://clang.llvm.org/get_started.html
2. Check out CPP2D from : https://github.com/lhamot/CPP2D.git
3. Run cmake in the root directory of CPP2D
   1. Set the build type if needed (Debug;Release;MinSizeRel;RelWithDebInfo)
   2. Set the path to LLVM using CMAKE_PREFIX_PATH.
   3. Generate
4. Run make

How to use it?

Be aware than this project is far to be finished. Do not expect a fully working D project immediately. That you can expect is a great help to the conversion of your project, doing all the simple repetitive job, which is not so bad.

CPP2D work like any clang tools. This could help you:

• http://clang.llvm.org/docs/HowToSetupToolingForLLVM.html

There is two way to use CPP2D:

1. Without compilation database

1. Go to the destination directory (D project)
2. Call CPP2D.exe [options] <source0> [... <sourceN>] -- [compiler options]
   • The double dashes are needed to inform cpp2d you don't need a compilation database
   • <sourceN> are C++ source files
   • [compiler options] are options forwarded to the compiler, like includes path, preprocessor definitions and so on.
   • [options] can be -macro-stmt and -macro-exec which are for macro handling

2. With compilation database

It seems to be impossible to generate a compilation database under windows...

If you are not under windows, and you are using cmake to compile your project:

• Add this code in your(s) CMakeFiles.txt

if(CMAKE_EXPORT_COMPILE_COMMANDS STREQUAL "ON")
    include_directories(${LLVM_PATH}/lib/clang/3.9.0/include)
endif()

# Go to project build directory
$ cd project/build/directory
# Run cmake, asking it to generate a compilation database
$ cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON path/to/project/sources
# You will obtain a compilation database
# Link it to the source project
$ ln -s $PWD/compile_commands.json path/to/project/source/
# Convert files, calling cpp2d
$ cd path/to/project/source
$ project/build/directory/CPP2D/cpp2d source1.cpp source2.cpp source3.cpp
# You will find D files in the project/build/directory
# You also need to copy the cpp_std.d file to your D source directory
$ cp project/build/directory/CPP2D/cpp_std.d dproject/source

Need for more documentation? You can search here :

• http://eli.thegreenplace.net/2014/05/21/compilation-databases-for-clang-based-tools

Future of the project?

Small C++ project are almost fully convertible to D, but many things have to be done for the bigger ones.

Main missing features are:

• Better macro handling
• Namespace/Module handling
• External library handling, and specifically the stdlib
• Variadic template
  • Not tried to do yet
• Better conservation of comments
• Porting constness
  • Hard because D containers seem to not be const correct
• Handling const ref function argument
  • Hard because, unlike in C++, in D we can't pass a rvalue to a const ref parameter

Other possible enhancements

• CMake : Create a cmake to compile a project linked to LLVM/clang in a cross-platform way seems to be not straightforward. If you can enhance my CMakeLists, please do it!
• Clang integration : Maybe there is a better way to integrate CPP2D with clang, like make it a real clang tool, in clang/tools, or clang/tools/extra.

Want to try?

• http://nogane.net/cpp2d

Want to help?

I would be happy to get some help on this project. If you are interested, do not hesitate to :

• Reach us on the mailing list: https://groups.google.com/forum/#!forum/cpp2d
• Contact me at [email protected]
• Or just checkout and enjoy ;)