Master Status:

Develop Status:

ChaiScript

http://www.chaiscript.com

(c) 2009-2012 Jonathan Turner (c) 2009-2017 Jason Turner

Release under the BSD license, see "license.txt" for details.

Introduction

ChaiScript is one of the only embedded scripting language designed from the ground up to directly target C++ and take advantage of modern C++ development techniques, working with the developer how they would expect it to work. Being a native C++ application, it has some advantages over existing embedded scripting languages:

1. It uses a header-only approach, which makes it easy to integrate with existing projects.
2. It maintains type safety between your C++ application and the user scripts.
3. It supports a variety of C++ techniques including callbacks, overloaded functions, class methods, and stl containers.

Requirements

ChaiScript requires a C++17 compiler to build with support for variadic templates. It has been tested with gcc 7 and clang 6 (with libcxx).

Installation using vcpkg

You can download and install ChaiScript using the vcpkg dependency manager:

git clone https://github.com/Microsoft/vcpkg.git
cd vcpkg
./bootstrap-vcpkg.sh
./vcpkg integrate install
vcpkg install chaiscript

The ChaiScript port in vcpkg is kept up to date by Microsoft team members and community contributors. If the version is out of date, please create an issue or pull request on the vcpkg repository.

Usage

• Add the ChaiScript include directory to your project's header search path
• Add #include <chaiscript/chaiscript.hpp> to your source file
• Instantiate the ChaiScript engine in your application. For example, create a new engine with the name chai like so: chaiscript::ChaiScript chai
• The default behavior is to load the ChaiScript standard library from a loadable module. A second option is to compile the library into your code, see below for an example.

Once instantiated, the engine is ready to start running ChaiScript source. You have two main options for processing ChaiScript source: a line at a time using chai.eval(string) and a file at a time using chai.eval_file(fname)

To make functions in your C++ code visible to scripts, they must be registered with the scripting engine. To do so, call add:

chai.add(chaiscript::fun(&my_function), "my_function_name");

Once registered the function will be visible to scripts as "my_function_name"

Examples

ChaiScript is similar to ECMAScript (aka JavaScript(tm)), but with some modifications to make it easier to use. For usage examples see the "samples" directory, and for more in-depth look at the language, the unit tests in the "unittests" directory cover the most ground.

For examples of how to register parts of your C++ application, see "example.cpp" in the "samples" directory. Example.cpp is verbose and shows every possible way of working with the library. For further documentation generate the doxygen documentation in the build folder or see the website http://www.chaiscript.com.

Grammar

A formal EBNF grammar for ChaiScript is available in grammar/chaiscript.ebnf. To view it as a railroad diagram, paste the grammar into mingodad's railroad diagram generator or bottlecaps.de/rr.

The shortest complete example possible follows:

/// main.cpp

#include <chaiscript/chaiscript.hpp>

double function(int i, double j)
{
  return i * j;
}

int main()
{
  chaiscript::ChaiScript chai;
  chai.add(chaiscript::fun(&function), "function");

  double d = chai.eval<double>("function(3, 4.75);");
}