nelua as C library

libmylib.c

/* Generated by Nelua 0.2.0-dev */
/* Compile command: gcc "libmylib.c" -o "libmylib" -Wall -fwrapv -g -lm */
/* Compile hash: 3ubsTFvAUFqRHss7xDS1yGaiVwdM */
/* ------------------------------ DECLARATIONS ------------------------------ */
// moved to here:
#ifndef MYLIB_H
#define MYLIB_H

#ifdef __GNUC__
#pragma GCC diagnostic error   "-Wimplicit-function-declaration"
#pragma GCC diagnostic error   "-Wimplicit-int"
#pragma GCC diagnostic ignored "-Wincompatible-pointer-types"
#pragma GCC diagnostic ignored "-Wmissing-braces"
#pragma GCC diagnostic ignored "-Wmissing-field-initializers"
#pragma GCC diagnostic ignored "-Wtype-limits"
#pragma GCC diagnostic ignored "-Wunused-parameter"
#if defined(__clang__)
#pragma GCC diagnostic ignored "-Wunused"
#else
#pragma GCC diagnostic ignored "-Wunused-variable"
#pragma GCC diagnostic ignored "-Wunused-function"
#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
#pragma GCC diagnostic ignored "-Wdiscarded-qualifiers"
#endif
#endif
#if __STDC_VERSION__ >= 201112L
#define nelua_static_assert _Static_assert
#else
#define nelua_static_assert(x, y)
#endif
nelua_static_assert(sizeof(void*) == 8, "Nelua and C disagree on architecture size");
// moved to top
// #ifndef MYLIB_H
// #define MYLIB_H
#ifdef _WIN32
#define nelua_cexport __declspec(dllexport) extern
#elif defined(__GNUC__)
#define nelua_cexport __attribute__((visibility ("default"))) extern
#else
#define nelua_cexport extern
#endif
nelua_cexport int mylib_sum(int a, int b);
/* ------------------------------ DEFINITIONS ------------------------------- */
#endif /* MYLIB_H */
#ifdef MYLIB_IMPL
int mylib_sum(int a, int b) {
  return (a + b);
}
#endif /* MYLIB_IMPL */

libmylib.lua

-- note: the extension of this file is actually libmylib.nelua, 
--  I changed to .lua just to activate Github syntax highlighting.

-- reference:
-- 
-- creating C libraries with nelua:
-- https://nelua.io/overview/#exporting-named-c-functions
-- https://github.com/edubart/nelua-lang/blob/master/tests/libmylib.nelua
-- https://github.com/edubart/nelua-lang/blob/master/tests/mylib_test.nelua
-- 
-- I used `-P noentrypoint` to not define the `main` function:
-- https://github.com/edubart/nelua-lang/blob/50989179b3f19c216dc438475e7acfe63b83c359/nelua/cgenerator.lua#L1651
--
-- about including C files:
-- https://stackoverflow.com/a/11334387
-- 
-- about single-header libraries:
-- https://nicolashollmann.de/blog/single-header-libraries/
--
-- command to transpile to C lib:
-- $ nelua libmylib.nelua -o libmylib -c -P noentrypoint

-- don't use GC and set prefix
## pragmas.nogc = true
## pragmas.unitname = 'mylib'

-- sets MYLIB_H, needs to be moved manually to the top
##[=[ cemitdecl[[
#ifndef MYLIB_H
#define MYLIB_H
]]
]=]

-- unset MYLIB_H
## cemitdef'#endif /* MYLIB_H */'

-- set MYLIB_IMPL, which "guards" the implementation
## cemitdef'#ifdef MYLIB_IMPL'

-- let's define a function!
local function sum(a: cint, b: cint): cint <cexport>
  return a + b
end

-- unset MYLIB_IMPL, no functions should be declared after this
## cemitdef'#endif /* MYLIB_IMPL */'
  

test.c

#include <stdio.h>
#define MYLIB_IMPL
#include "libmylib.c"

int main() {
  int x = mylib_sum(1, 2);
  printf("-> %d\n", x);
  return 0;
}

// command:
// $ gcc test.c -o test
//
// output:
// $ ./test
// -> 3