Run-time dynamic loader generator for C APIs

Generates run-time dynamic loaders from C header files. Useful for when you don't want to have a hard dependency on a particular C library or where dynamic loading is a requirement, like with OpenGL 2.0+ on Windows.

It works in the following way:

1. You provide the generator with a header file, output Jinja2 templates and some additional options
2. The header file is preprocessed and parsed into an AST
3. Output templates are instantiated with access to the AST and then rendered.

With the default templates you get a struct full of function pointers, *_functions along with a function to fill that struct, *_load_functions.

The default templates generate loaders which can be used with any OS-level dynamic loader by passing the *_load_functions function a loader function pointer of type PFN_rbg_get_sym and a user-defined argument void *user_arg.

A simple dynamic loader is provided in loaders/c. You might need to use something more complicated, like combining wglGetProcAddress and GetProcAddress.

Get Python 3.7+, install pipenv and run pipenv install in rubigen's directory. Run the generator using pipenv run python app.py.

Example:

pipenv run python app.py tests/data/simple_decl.h test -oheader=test_binding.h=default_c_binding.h -osource=test_binding.c=default_c_binding.c.j2

Output:

[header] default_c_binding.h.j2 -> test_binding.h
[source] default_c_binding.c.j2 -> test_binding.c

Header file:

#pragma once
/* generated by rubigen, do not edit.
 *
 * parameters:
 *  defines: none
 *  force includes: none
 */

#include "simple_decl.h"

#ifdef __cplusplus
extern "C" {
#endif

/* typedefs */
typedef int (*PFN_test_compute)(int x, int y);

/* functions struct */
typedef struct test_functions_t
{
	PFN_test_compute compute;
} test_functions;

typedef void* (*PFN_rbg_get_sym)(void *user_arg, const char *name);
void test_load_functions(test_functions *f, PFN_rbg_get_sym get_sym, void *user_arg);

#ifdef __cplusplus
} /* extern "C" */
#endif

Source file:

/* generated by rubigen, do not edit. */

#include "test_binding.h"

void test_load_functions(test_functions *f, PFN_rbg_get_sym get_sym, void *user_arg)
{
#if defined(__GNUC__) || defined(__clang__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic"
#elif defined(_MSC_VER)
#pragma warning(push)
#pragma warning(disable: 4055)
#endif
	f->compute = (PFN_test_compute)get_sym(user_arg, "compute");
#if defined(__GNUC__) || defined(__clang__)
#pragma GCC diagnostic pop
#elif defined(_MSC_VER)
#pragma warning(pop)
#endif
}

pipenv run python app.py --help:

usage: app.py [-h] [-I PATH] [-include FORCE_INCLUDES] [-D MACRO[=VAL]] [-T TEMPLATE_DIRS] [-o NAME=FILE=TEMPLATE]
              [--out-prefix OUT_PREFIX] [--show-ast] [--show-preprocessed-source]
              input namespace

positional arguments:
  input                 the path to the input file
  namespace             the namespace the generated bindings should be put in

optional arguments:
  -h, --help            show this help message and exit
  -I PATH               add an include path
  -include FORCE_INCLUDES
                        force inclusion of the specified file at the top of the input file
  -D MACRO[=VAL]        add a preprocessor definition
  -T TEMPLATE_DIRS      add a template directory
  -o NAME=FILE=TEMPLATE
                        generate an output file at FILE using TEMPLATE with the name NAME
  --out-prefix OUT_PREFIX
                        output path prefix
  --show-ast
  --show-preprocessed-source