A small wrapper that exposes the run_parinfer function from rust-parinfer to lua

parinfer_lua_bridge.c

#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>
#include "lua.h"
#include "lualib.h"
#include "lauxlib.h"



 //We declare a function pointer for the function to import (int myfunction(int) )
 typedef const char * (*external_function)(const char *);


static int run_parinfer (lua_State *L) {

  /*Open rust-parinfer shared object library (dynamic)
  libcparinfer.so must be placed under /user/local/lib.
  It can be made more flexible using lua/c interop
 
 
  void* dlh = dlopen("/user/local/lib/libcparinfer.so", RTLD_LAZY );
  if (dlh == NULL) {
    fprintf(stderr, "%s", dlerror());
    exit(1);
  }

  //We resolve the function symbol to use
  external_function prf  = dlsym(dlh, "run_parinfer");

  //The string returned from run_parinfer represents a json object
    const char *json_obj= luaL_checkstring (L, 1);

    //push the results to lua stack
    lua_pushstring (L, prf (json_obj));

    //return number of results
    return 1;
}


static const struct luaL_Reg parinfer_lua_bridge [] = {
      {"runParinfer", run_parinfer},
      {NULL, NULL}  /* sentinel */
    };

//expose the library to lua 
int luaopen_parinfer_lua_bridge (lua_State *L){
    luaL_newlib(L, parinfer_lua_bridge);
    return 1;
}

//Compile with gcc parinfer_lua_bridge.c -shared -o parinfer_lua_bridge.so -ldl -fPIC -llua5.2 -I/usr/include/lua5.2/
//Las line might not be nessesary. Check lua wiki
//Minimal test. This is lua code but compiled from fennel programming language
/*
local mylib = require(("parinfer_lua_bridge"))
local json = require(("json"))
local ppr = require(("pl.pretty"))
local test_me = ({[("mode")] = ("indent"), [("options")] = ({}), [("text")] = ("(defn foo\n  [arg\n   ret")})
return ppr.dump(mylib.runParinfer(json.encode(test_me)))
*/