Transformer - C/C++ code parser and generator

Tool for parsing C/C++ code and generating output using a given Jinja-like template. This might be useful for creating reflection/RTTI frameworks for C/C++ (or you can just wait until 2023 or 2026 year and use standard implementation... ~~or use Java~~)

Currently supported features:

• struct/class fields parsing
• struct/class methods (including constructors) parsing
• enum parsing
• generate output using Jinja-like template
• C++ custom attributes support

WARNING! WIP!

After switching from libclang to libtooling, some of the information in this README file is OUTDATED. At the moment transformer is a fully working tool, but some command line interfaces have changed a little, and also names of some template variables have changed. I will try to update this manual in the near future.

Usage example

Let's imagine that we have some files:

example/simple/source.hpp

#include <vector>

namespace math::geometry
{

struct Point2D
{
	float x;
	float y;
};

struct Point3D : public Point2D
{
	float z;
};

enum class Direction : long
{
	UP = 0,
	DOWN,

	LEFT = -10,
	RIGHT
};

class Shape
{
private:
	std::vector<Point3D> m_points;
};

}

example/simple/template.jinja

We have in file {{ file_path }} {{ length(classes) }} classes:
{% for c in classes %}
	{% if length(c.base_classes) != 0 %}
	{{ c.name }} has {{ length(c.base_classes) }} base class:
	{% endif %}
	{% for b in c.base_classes %}
		- {{ b.name }} from file {{ b.file_path }}
	{% endfor %}
	{% if length(c.base_classes) == 0 %}
	{{ c.name }} does not have base classes :(
	{% endif %}

	{% if length(c.fields) != 0 %}
	{{ c.name }} has {{ length(c.fields) }} fields:
	{% endif %}
	{% for f in c.fields %}
		- {{ f.type }} -> {{ f.name }} (full name is {{ f.full_name }})
	{% endfor %}

	{% if loop.is_last %}
	THE END!
	{% endif %}
{% endfor %}

{% for e in enums %}
Enum {{ e.name }} has type {{ e.integer_type }}:
	{% for c in e.consts %}
	- {{ c.full_name }} has value {{ c.value }}
	{% endfor %}
{% endfor %}

After execution of command transformer example/simple/template.jinja example/simple/source.hpp the output will be:

We have in file example/simple/source.hpp 3 classes:
	Point2D does not have base classes :(

	Point2D has 2 fields:
		- float -> x (full name is math::geometry::Point2D::x)
		- float -> y (full name is math::geometry::Point2D::y)

	Point3D has 1 base class:
		- Point2D from file example/simple/source.hpp

	Point3D has 3 fields:
		- float -> x (full name is math::geometry::Point2D::x)
		- float -> y (full name is math::geometry::Point2D::y)
		- float -> z (full name is math::geometry::Point3D::z)

	Shape does not have base classes :(

	Shape has 1 fields:
		- std::vector<Point3D> -> m_points (full name is math::geometry::Shape::m_points)

	THE END!

Enum Direction has type long:
	- math::geometry::Direction::UP has value 0
	- math::geometry::Direction::DOWN has value 1
	- math::geometry::Direction::LEFT has value -10
	- math::geometry::Direction::RIGHT has value -9

For more information about tool usage execute command:

transformer --help

Beta! RTTI framework for C++

You can also find a more advanced example of creating a RTTI framework for C++ in the directory example/rtti/. Some examples with it:

#include "rtti/ObjectType.h"

struct Point2D
{
	float x;
	float y;
};

struct Point3D : Point2D
{
	float z;
};

// all we need is to inherit from rtti::ObjectType class and use RTTI_OBJECT_TYPE_BODY macro
class Rect : public rtti::ObjectType<Rect>
{
private: // <- we even have access to private fields
	RTTI_OBJECT_TYPE_BODY;

	std::string name;
	Point3D top_left;
	Point3D bot_right;
};

int main()
{
	Rect r {};

	r.object_field("name") = "Hello, Rect!";
	r.object_field("top_left") = 123; // <- wrong type
	r.object_field("bot_right") = { { "x", 12345.f } };
	r.object_field("bot_right").subfield("x") = -1.5f;

	r.object_set_value(
		{
			{ "top_left", {
				{ "x", 123u },
				{ "z", 3.0  },
				{ "y", 5.1f },
			} },
			{ "name", "New name from " __FILE__ },
			{ "some name", 123 - 456 }
		}
	);
}

Requirements

• GCC with C++17 support
• GNU Make for building
• LibClang for parsing C/C++ code

Third-party libs

• inja for parsing and rendering Jinja-like templates
• json required by inja for data input and handling

Downloading and compilation

This is a piece of cake:

git clone --recursive https://github.com/mtiapko/transformer
make

Compiled tool binary will be in bin/ directory.

But!

Be careful, nlohmann/json is very heavy repo (240MB+). But inja requires only source files (only include directory). So you can clone this repo without --recursive if nlohmann/json already exists in your filesystem or manually download only source files and put them in libs/json/include/nlohmann/<header-files>.

Troubleshooting

[ clang ] fatal error: 'stddef.h' file not found

This error occurs when clang looks for headers in gcc directories. You can create symlink, but transformer support arguments for compiler, so you can set system header directory path:

transformer <template-file-path> <source-file-path> --compiler-args -cxx-isystem /usr/lib/clang/<clang-version>/include