Reflang - Modern C++ reflection using libclang
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Latest commit 1e00e79 Dec 31, 2016

README.md

Reflang - Modern C++ reflection using libclang

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TL;DR

Reflang is a reflection library & tool for modern C++.

The tool parses your C++ code using libclang, then generates human-readable code around it to enable reflection.

The library is extremely lightweight, containing utility interfaces, classes & functions.

Reflang's library has no dependencies other than C++14 with STL. Reflang's tool's only other dependency is libclang (which is not required after code generation).

More details

Functions

Suppose you have the following function:

	bool Func(int a, float b);

With Reflang you could do:

	// Note: no need to include header of Func().
	std::vector<IFunction*> functions = reflang::registry::GetFunctionByName("Func");
	IFunction* f = functions[0];
	Object ret = (*f)(1234, 5678.0f);
	if (ret.GetT<bool>())
	{
		// ...
	}

Classes

Suppose you have the following class:

	class MyClass
	{
	public:
		int field = 0;
		static int static_field;
		void method();
		static void static_method();
	};

With Reflang you could do:

	reflang::Class<MyClass> metadata;
	MyClass c;

	// Modify / use c's 'field'.
	reflang::Reference ref = metadata.GetField(c, "field");
	ref.GetT<int>() = 10;

	// Modify / use 'static_field'.
	ref = metadata.GetStaticField("static_field")
	ref.GetT<int>() = 10;

	// Execute 'method()'.
	auto methods = metadata.GetMethod("method");
	(*methods[0])(c);

	// Execute 'static_method()'.
	auto methods = metadata.GetStaticMethod("static_method");
	(*methods[0])();

Or even without #includeing MyClass:

	// Note: no need to include header of MyClass.
	IClass* metadata = reflang::registry::GetClassByName("MyClass");

	// Assign 10 to MyClass::static_field.
	metadata->GetStaticField("static_field").GetT<int>() = 10;

	// Invoke MyClass::static_method().
	auto static_methods = metadata->GetStaticMethod("static_method");
	(*static_methods[0])();

	reflang::Reference c = // get Reference wrapping a MyClass from somewhere.

	// Assign 10 to c.field.
	metadata->GetField(c, "field").GetT<int>() = 10;

	// Invoke c.method().
	auto methods = metadata->GetMethod("method");
	(*methods[0])(c);

Enums

Suppose you have the following enum:

	enum class MyEnum
	{
		Value1 = 4,
		Value2,
		Value3,
		Value4 = Value3,
		Value5 = 0,
		Value6 = 12
	};

With Reflang you could do:

	for (auto it : reflang::Enum<MyEnum>::Iterate())
	{
		// Do something with MyEnum values...
	}

	std::string string_value = reflang::Enum<MyEnum>::Translate(MyEnum::Value2);
	// string_value == "Value2".

	MyEnum e
	if (reflang::Enum<MyEnum>::TryTranslate(string_value, e))
	{
		// e == MyEnum::Value2.
	}

Or even without #includeing MyEnum:

	// Note: no need to include header of MyEnum.
	IEnum* e = reglang::registry::GetEnumByName("MyEnum");

	// Iterate over {"Value1", "Value2", "Value3", "Value5", "Value6"}.
	for (const auto& s : e->GetStringValues())
	{
		// ...
	}

	// Iterate over {4, 5, 6, 0, 12}.
	for (const auto& s : e->GetStringValues())
	{
		// ...
	}

How it works

Reflang is made of 2 components:

  • Code generator, which uses libclang to parse your C++ code and generate reflection information. You can easily integrate this tool in your build process;
  • Support library, which allows generic and abstract coding ("find class by name", "invoke function by name", etc).

Reflang understands your code exactly like clang does, so which results in accurate parsing of your code.

End-to-end Examples

Check out the tests/ directory, which shows pretty much all features supported by Reflang.

Each test has 4 files:

  • X.src.hpp -- source code which will be used for reflection;
  • X.gen.hpp -- generated reflection code declarations for X.src.hpp;
  • X.gen.cpp -- generated reflection code definitions for X.src.hpp;
  • X.test.cpp -- test code which tests the above.

Using

This section is incomplete. Please check later for more elaborated documentation.

Rough instructions:

  • Clone the repository;
  • Build it using CMake;
  • A new executable, reflang is now available - use it to generate code;
  • Link your program with the generated code and with libreflang, which has been built by CMake as well;
  • Profit.

Examples of running the tool:

# print help
$ ./reflang

# generate code for test.hpp, write both hpp and cpp to stdout
$ ./reflang test.hpp

# specify output files
$ ./reflang --out-cpp test.reflang.cpp --out-hpp test.reflang.hpp test.hpp

# only list classes, functions, etc available for generation
$ ./reflang --list-only true test.hpp

# only generate code for classes, functions, etc not in std::
$ ./reflang --exclude "std::.*" test.hpp

# only generate code for classes, functions, etc beginning with My
$ ./reflang --include "My.*" test.hpp

# pass flags supported by libclang
$ ./reflang test.hpp -- -std=c++14 -DSOMETHING -I./include/

Supported Features & Limitations

  Feature
Supported: Invoking global / namespace functions
Supported: Function overloads
Supported: Iterating classes' fields
Supported: Iterating classes' static fields
Supported: Iterating classes' methods
Supported: Iterating classes' static methods
Supported: Getting a class field / method / statics by name
Supported: Iterating enum values
Supported: Get vector of enum values
Supported: Get vector of enum string names
Supported: Converting enum <-> string
Supported: Use class / function / enum without #include (through registry)
Soon: Get function's / method's argument names & types
Soon: Get function's / method's return type
Soon: Overloaded class methods
Soon: Construct classes through reflection
Soon: Find types by regex
Soon: Respect functions / methods default values
Soon: Support for operators
Not supported: template classes / functions
Not supported: Functions taking non-const reference arguments (yet?)
Not supported: Functions taking rvalue references arguments
Not supported: Private methods / fields
Not supported: Anything in anonymous namespace

Bugs, pull requests, feedback

Please check this section later.

Kind Words & Donations

Please check this section later.