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CppSharp Developers Manual

  1. Introduction ===============

How to compile

Requirements: Windows VS 2012 Up-to-date versions of Clang and LLVM (development versions).

Since C++/CLI is used to interface with the native Clang libraries, for the moment you will need the Windows/VS platform to use this tool.

How to use

Since the generator was designed to be easily extensible, you can use it either as a library or as a command-line interface.

Library interface

With this approach you implement the ILibrary interface and customize the options with C#. This is ideal since you get all the power of the language to do the customizations you want and it is easy to integrate in your IDE build system.

Command-line interface

With this one you call the executable with the right [command-line flags] (Manual.md#command-line-flags) to generate the bindings code. You can still integrate it in your IDE by using the pre-build command features. If you need to customize the build you can pass the path to a compiled assembly with an ILibrary implementation.

  1. Architecture ===============

Driver

The driver is responsible for setting up the needed context for the rest of the tool and for implementing the main logic for parsing the user-provided headers, processing the declarations adn then calling the language-specific generator to generate the bindings.

Parser

Since writing bindings by hand is tedious and error-prone, an automated approach was preferred. The open-source Clang parser is used for the task, providing an AST (Abstract Syntax Tree) of the code, ready to be consumed by the generator.

This is done in Parser.cpp, we walk the AST provided by Clang and mirror it in a .NET-friendly way. Most of this code is pretty straightforward if you are familiar how Clang represents C++ code in AST nodes.

Recommended Clang documentation: http://clang.llvm.org/docs/InternalsManual.html

Generator

After parsing is done, some language-specific binding code needs to be generated.

Different target languages provide different features, so each generator needs to process the declarations in certain ways to provide a good mapping to the target language.

Additionally some of it can be provided directly in the native source code, by annotating the declarations with custom attributes.

Runtime

This implements the C++ implementation-specific behaviours that allow the target language to communicate with the native code. It will usually use an existing FFI that provides support for interacting with C code.

It needs to know about the object layout, virtual tables, RTTI and exception low level details, so it can interoperate with the C++ code.

  1. ABI Internals ===============

Each ABI specifies the internal implementation-specific details of how C++ code works at the machine level, involving things like:

  1. Class Layout
  2. Symbol Naming
  3. Virtual tables
  4. Exceptions
  5. RTTI (Run-time Type Information)

There are two major C++ ABIs currently in use:

  1. Microsoft (VC++ / Clang)
  2. Itanium (GCC / Clang)

Each implementation differs in a lot of low level details, so we have to implement specific code for each one.

The target runtime needs to support calling native methods and this is usually implemented with an FFI (foreign function interface) in the target language VM virtual machine). In .NET this is done via the P/Invoke system.

  1. Similar Tools =================