return {
    header = [=[
        #ifndef COMPAT53_H_
        #define COMPAT53_H_

        #include <stddef.h>
        #include <limits.h>
        #include <string.h>
        #if defined(__cplusplus) && !defined(COMPAT53_LUA_CPP)
        extern "C" {
        #endif
        #include <lua.h>
        #include <lauxlib.h>
        #include <lualib.h>
        #if defined(__cplusplus) && !defined(COMPAT53_LUA_CPP)
        }
        #endif


        #undef COMPAT53_INCLUDE_SOURCE
        #if defined(COMPAT53_PREFIX)
        /* - change the symbol names of functions to avoid linker conflicts
         * - compat-5.3.c needs to be compiled (and linked) separately
         */
        #  if !defined(COMPAT53_API)
        #    define COMPAT53_API extern
        #  endif
        #else /* COMPAT53_PREFIX */
        /* - make all functions static and include the source.
         * - compat-5.3.c doesn't need to be compiled (and linked) separately
         */
        #  define COMPAT53_PREFIX compat53
        #  undef COMPAT53_API
        #  if defined(__GNUC__) || defined(__clang__)
        #    define COMPAT53_API __attribute__((__unused__)) static
        #  else
        #    define COMPAT53_API static
        #  endif
        #  define COMPAT53_INCLUDE_SOURCE
        #endif /* COMPAT53_PREFIX */

        #define COMPAT53_CONCAT_HELPER(a, b) a##b
        #define COMPAT53_CONCAT(a, b) COMPAT53_CONCAT_HELPER(a, b)



        /* declarations for Lua 5.1 */
        #if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM == 501

        /* XXX not implemented:
         * lua_arith (new operators)
         * lua_upvalueid
         * lua_upvaluejoin
         * lua_version
         * lua_yieldk
         */

        #ifndef LUA_OK
        #  define LUA_OK 0
        #endif
        #ifndef LUA_OPADD
        #  define LUA_OPADD 0
        #endif
        #ifndef LUA_OPSUB
        #  define LUA_OPSUB 1
        #endif
        #ifndef LUA_OPMUL
        #  define LUA_OPMUL 2
        #endif
        #ifndef LUA_OPDIV
        #  define LUA_OPDIV 3
        #endif
        #ifndef LUA_OPMOD
        #  define LUA_OPMOD 4
        #endif
        #ifndef LUA_OPPOW
        #  define LUA_OPPOW 5
        #endif
        #ifndef LUA_OPUNM
        #  define LUA_OPUNM 6
        #endif
        #ifndef LUA_OPEQ
        #  define LUA_OPEQ 0
        #endif
        #ifndef LUA_OPLT
        #  define LUA_OPLT 1
        #endif
        #ifndef LUA_OPLE
        #  define LUA_OPLE 2
        #endif

        /* LuaJIT/Lua 5.1 does not have the updated
         * error codes for thread status/function returns (but some patched versions do)
         * define it only if it's not found
         */
        #if !defined(LUA_ERRGCMM)
        /* Use + 2 because in some versions of Lua (Lua 5.1)
         * LUA_ERRFILE is defined as (LUA_ERRERR+1)
         * so we need to avoid it (LuaJIT might have something at this
         * integer value too)
         */
        #  define LUA_ERRGCMM (LUA_ERRERR + 2)
        #endif /* LUA_ERRGCMM define */

        typedef size_t lua_Unsigned;

        typedef struct luaL_Buffer_53 {
          luaL_Buffer b; /* make incorrect code crash! */
          char *ptr;
          size_t nelems;
          size_t capacity;
          lua_State *L2;
        } luaL_Buffer_53;
        #define luaL_Buffer luaL_Buffer_53

        /* In PUC-Rio 5.1, userdata is a simple FILE*
         * In LuaJIT, it's a struct where the first member is a FILE*
         * We can't support the `closef` member
         */
        typedef struct luaL_Stream {
          FILE *f;
        } luaL_Stream;

        #define lua_absindex COMPAT53_CONCAT(COMPAT53_PREFIX, _absindex)
        COMPAT53_API int lua_absindex (lua_State *L, int i);

        #define lua_arith COMPAT53_CONCAT(COMPAT53_PREFIX, _arith)
        COMPAT53_API void lua_arith (lua_State *L, int op);

        #define lua_compare COMPAT53_CONCAT(COMPAT53_PREFIX, _compare)
        COMPAT53_API int lua_compare (lua_State *L, int idx1, int idx2, int op);

        #define lua_copy COMPAT53_CONCAT(COMPAT53_PREFIX, _copy)
        COMPAT53_API void lua_copy (lua_State *L, int from, int to);

        #define lua_getuservalue(L, i) \
          (lua_getfenv((L), (i)), lua_type((L), -1))
        #define lua_setuservalue(L, i) \
          (luaL_checktype((L), -1, LUA_TTABLE), lua_setfenv((L), (i)))

        #define lua_len COMPAT53_CONCAT(COMPAT53_PREFIX, _len)
        COMPAT53_API void lua_len (lua_State *L, int i);

        #define lua_pushstring(L, s) \
          (lua_pushstring((L), (s)), lua_tostring((L), -1))

        #ifndef luaL_newlibtable
        #  define luaL_newlibtable(L, l) \
          (lua_createtable((L), 0, sizeof((l))/sizeof(*(l))-1))
        #endif
        #ifndef luaL_newlib
        #  define luaL_newlib(L, l) \
          (luaL_newlibtable((L), (l)), luaL_register((L), NULL, (l)))
        #endif

        #define lua_pushglobaltable(L) \
          lua_pushvalue((L), LUA_GLOBALSINDEX)

        #define lua_rawgetp COMPAT53_CONCAT(COMPAT53_PREFIX, _rawgetp)
        COMPAT53_API int lua_rawgetp (lua_State *L, int i, const void *p);

        #define lua_rawsetp COMPAT53_CONCAT(COMPAT53_PREFIX, _rawsetp)
        COMPAT53_API void lua_rawsetp(lua_State *L, int i, const void *p);

        #define lua_rawlen(L, i) lua_objlen((L), (i))

        #define lua_tointeger(L, i) lua_tointegerx((L), (i), NULL)

        #define lua_tonumberx COMPAT53_CONCAT(COMPAT53_PREFIX, _tonumberx)
        COMPAT53_API lua_Number lua_tonumberx (lua_State *L, int i, int *isnum);

        #define luaL_checkversion COMPAT53_CONCAT(COMPAT53_PREFIX, L_checkversion)
        COMPAT53_API void luaL_checkversion (lua_State *L);

        #define lua_load COMPAT53_CONCAT(COMPAT53_PREFIX, _load_53)
        COMPAT53_API int lua_load (lua_State *L, lua_Reader reader, void *data, const char* source, const char* mode);

        #define luaL_loadfilex COMPAT53_CONCAT(COMPAT53_PREFIX, L_loadfilex)
        COMPAT53_API int luaL_loadfilex (lua_State *L, const char *filename, const char *mode);

        #define luaL_loadbufferx COMPAT53_CONCAT(COMPAT53_PREFIX, L_loadbufferx)
        COMPAT53_API int luaL_loadbufferx (lua_State *L, const char *buff, size_t sz, const char *name, const char *mode);

        #define luaL_checkstack COMPAT53_CONCAT(COMPAT53_PREFIX, L_checkstack_53)
        COMPAT53_API void luaL_checkstack (lua_State *L, int sp, const char *msg);

        #define luaL_getsubtable COMPAT53_CONCAT(COMPAT53_PREFIX, L_getsubtable)
        COMPAT53_API int luaL_getsubtable (lua_State* L, int i, const char *name);

        #define luaL_len COMPAT53_CONCAT(COMPAT53_PREFIX, L_len)
        COMPAT53_API lua_Integer luaL_len (lua_State *L, int i);

        #define luaL_setfuncs COMPAT53_CONCAT(COMPAT53_PREFIX, L_setfuncs)
        COMPAT53_API void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup);

        #define luaL_setmetatable COMPAT53_CONCAT(COMPAT53_PREFIX, L_setmetatable)
        COMPAT53_API void luaL_setmetatable (lua_State *L, const char *tname);

        #define luaL_testudata COMPAT53_CONCAT(COMPAT53_PREFIX, L_testudata)
        COMPAT53_API void *luaL_testudata (lua_State *L, int i, const char *tname);

        #define luaL_traceback COMPAT53_CONCAT(COMPAT53_PREFIX, L_traceback)
        COMPAT53_API void luaL_traceback (lua_State *L, lua_State *L1, const char *msg, int level);

        #define luaL_fileresult COMPAT53_CONCAT(COMPAT53_PREFIX, L_fileresult)
        COMPAT53_API int luaL_fileresult (lua_State *L, int stat, const char *fname);

        #define luaL_execresult COMPAT53_CONCAT(COMPAT53_PREFIX, L_execresult)
        COMPAT53_API int luaL_execresult (lua_State *L, int stat);

        #define lua_callk(L, na, nr, ctx, cont) \
          ((void)(ctx), (void)(cont), lua_call((L), (na), (nr)))
        #define lua_pcallk(L, na, nr, err, ctx, cont) \
          ((void)(ctx), (void)(cont), lua_pcall((L), (na), (nr), (err)))

        #define lua_resume(L, from, nargs) \
          ((void)(from), lua_resume((L), (nargs)))

        #define luaL_buffinit COMPAT53_CONCAT(COMPAT53_PREFIX, _buffinit_53)
        COMPAT53_API void luaL_buffinit (lua_State *L, luaL_Buffer_53 *B);

        #define luaL_prepbuffsize COMPAT53_CONCAT(COMPAT53_PREFIX, _prepbufsize_53)
        COMPAT53_API char *luaL_prepbuffsize (luaL_Buffer_53 *B, size_t s);

        #define luaL_addlstring COMPAT53_CONCAT(COMPAT53_PREFIX, _addlstring_53)
        COMPAT53_API void luaL_addlstring (luaL_Buffer_53 *B, const char *s, size_t l);

        #define luaL_addvalue COMPAT53_CONCAT(COMPAT53_PREFIX, _addvalue_53)
        COMPAT53_API void luaL_addvalue (luaL_Buffer_53 *B);

        #define luaL_pushresult COMPAT53_CONCAT(COMPAT53_PREFIX, _pushresult_53)
        COMPAT53_API void luaL_pushresult (luaL_Buffer_53 *B);

        #undef luaL_buffinitsize
        #define luaL_buffinitsize(L, B, s) \
          (luaL_buffinit((L), (B)), luaL_prepbuffsize((B), (s)))

        #undef luaL_prepbuffer
        #define luaL_prepbuffer(B) \
          luaL_prepbuffsize((B), LUAL_BUFFERSIZE)

        #undef luaL_addchar
        #define luaL_addchar(B, c) \
          ((void)((B)->nelems < (B)->capacity || luaL_prepbuffsize((B), 1)), \
           ((B)->ptr[(B)->nelems++] = (c)))

        #undef luaL_addsize
        #define luaL_addsize(B, s) \
          ((B)->nelems += (s))

        #undef luaL_addstring
        #define luaL_addstring(B, s) \
          luaL_addlstring((B), (s), strlen((s)))

        #undef luaL_pushresultsize
        #define luaL_pushresultsize(B, s) \
          (luaL_addsize((B), (s)), luaL_pushresult((B)))

        #if defined(LUA_COMPAT_APIINTCASTS)
        #define lua_pushunsigned(L, n) \
          lua_pushinteger((L), (lua_Integer)(n))
        #define lua_tounsignedx(L, i, is) \
          ((lua_Unsigned)lua_tointegerx((L), (i), (is)))
        #define lua_tounsigned(L, i) \
          lua_tounsignedx((L), (i), NULL)
        #define luaL_checkunsigned(L, a) \
          ((lua_Unsigned)luaL_checkinteger((L), (a)))
        #define luaL_optunsigned(L, a, d) \
          ((lua_Unsigned)luaL_optinteger((L), (a), (lua_Integer)(d)))
        #endif

        #endif /* Lua 5.1 only */



        /* declarations for Lua 5.1 and 5.2 */
        #if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM <= 502

        typedef int lua_KContext;

        typedef int (*lua_KFunction)(lua_State *L, int status, lua_KContext ctx);

        #define lua_dump(L, w, d, s) \
          ((void)(s), lua_dump((L), (w), (d)))

        #define lua_getfield(L, i, k) \
          (lua_getfield((L), (i), (k)), lua_type((L), -1))

        #define lua_gettable(L, i) \
          (lua_gettable((L), (i)), lua_type((L), -1))

        #define lua_pushlstring COMPAT53_CONCAT(COMPAT53_PREFIX, _pushlstring_53)
        COMPAT53_API const char *lua_pushlstring (lua_State *L, const char *s, size_t len);

        #define lua_geti COMPAT53_CONCAT(COMPAT53_PREFIX, _geti)
        COMPAT53_API int lua_geti (lua_State *L, int index, lua_Integer i);

        #define lua_getextraspace COMPAT53_CONCAT(COMPAT53_PREFIX, _getextraspace)
        COMPAT53_API void *lua_getextraspace (lua_State *L);

        #define lua_isinteger COMPAT53_CONCAT(COMPAT53_PREFIX, _isinteger)
        COMPAT53_API int lua_isinteger (lua_State *L, int index);

        #define lua_tointegerx COMPAT53_CONCAT(COMPAT53_PREFIX, _tointegerx_53)
        COMPAT53_API lua_Integer lua_tointegerx (lua_State *L, int i, int *isnum);

        #define lua_numbertointeger(n, p) \
          ((*(p) = (lua_Integer)(n)), 1)

        #define lua_rawget(L, i) \
          (lua_rawget((L), (i)), lua_type((L), -1))

        #define lua_rawgeti(L, i, n) \
          (lua_rawgeti((L), (i), (n)), lua_type((L), -1))

        #define lua_rotate COMPAT53_CONCAT(COMPAT53_PREFIX, _rotate)
        COMPAT53_API void lua_rotate (lua_State *L, int idx, int n);

        #define lua_seti COMPAT53_CONCAT(COMPAT53_PREFIX, _seti)
        COMPAT53_API void lua_seti (lua_State *L, int index, lua_Integer i);

        #define lua_stringtonumber COMPAT53_CONCAT(COMPAT53_PREFIX, _stringtonumber)
        COMPAT53_API size_t lua_stringtonumber (lua_State *L, const char *s);

        #define luaL_tolstring COMPAT53_CONCAT(COMPAT53_PREFIX, L_tolstring)
        COMPAT53_API const char *luaL_tolstring (lua_State *L, int idx, size_t *len);

        #define luaL_getmetafield(L, o, e) \
          (luaL_getmetafield((L), (o), (e)) ? lua_type((L), -1) : LUA_TNIL)

        #define luaL_newmetatable(L, tn) \
          (luaL_newmetatable((L), (tn)) ? (lua_pushstring((L), (tn)), lua_setfield((L), -2, "__name"), 1) : 0)

        #define luaL_requiref COMPAT53_CONCAT(COMPAT53_PREFIX, L_requiref_53)
        COMPAT53_API void luaL_requiref (lua_State *L, const char *modname,
                                         lua_CFunction openf, int glb );

        #endif /* Lua 5.1 and Lua 5.2 */



        /* declarations for Lua 5.2 */
        #if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM == 502

        /* XXX not implemented:
         * lua_isyieldable
         * lua_arith (new operators)
         * lua_pushfstring (new formats)
         */

        #define lua_getglobal(L, n) \
          (lua_getglobal((L), (n)), lua_type((L), -1))

        #define lua_getuservalue(L, i) \
          (lua_getuservalue((L), (i)), lua_type((L), -1))

        #define lua_rawgetp(L, i, p) \
          (lua_rawgetp((L), (i), (p)), lua_type((L), -1))

        #define LUA_KFUNCTION(_name) \
          static int (_name)(lua_State *L, int status, lua_KContext ctx); \
          static int (_name ## _52)(lua_State *L) { \
            lua_KContext ctx; \
            int status = lua_getctx(L, &ctx); \
            return (_name)(L, status, ctx); \
          } \
          static int (_name)(lua_State *L, int status, lua_KContext ctx)

        #define lua_pcallk(L, na, nr, err, ctx, cont) \
          lua_pcallk((L), (na), (nr), (err), (ctx), cont ## _52)

        #define lua_callk(L, na, nr, ctx, cont) \
          lua_callk((L), (na), (nr), (ctx), cont ## _52)

        #define lua_yieldk(L, nr, ctx, cont) \
          lua_yieldk((L), (nr), (ctx), cont ## _52)

        #ifdef lua_call
        #  undef lua_call
        #  define lua_call(L, na, nr) \
          (lua_callk)((L), (na), (nr), 0, NULL)
        #endif

        #ifdef lua_pcall
        #  undef lua_pcall
        #  define lua_pcall(L, na, nr, err) \
          (lua_pcallk)((L), (na), (nr), (err), 0, NULL)
        #endif

        #ifdef lua_yield
        #  undef lua_yield
        #  define lua_yield(L, nr) \
          (lua_yieldk)((L), (nr), 0, NULL)
        #endif

        #endif /* Lua 5.2 only */



        /* other Lua versions */
        #if !defined(LUA_VERSION_NUM) || LUA_VERSION_NUM < 501 || LUA_VERSION_NUM > 504

        #  error "unsupported Lua version (i.e. not Lua 5.1, 5.2, 5.3, or 5.4)"

        #endif /* other Lua versions except 5.1, 5.2, 5.3, and 5.4 */



        /* helper macro for defining continuation functions (for every version
         * *except* Lua 5.2) */
        #ifndef LUA_KFUNCTION
        #define LUA_KFUNCTION(_name) \
          static int (_name)(lua_State *L, int status, lua_KContext ctx)
        #endif


        #if defined(COMPAT53_INCLUDE_SOURCE)
        #  include "compat-5.3.c"
        #endif


        #endif /* COMPAT53_H_ */
    ]=],
    source = [=[
        #include <stddef.h>
        #include <stdlib.h>
        #include <string.h>
        #include <ctype.h>
        #include <errno.h>
        #include <stdio.h>
        #include "compat-5.3.h"

        /* don't compile it again if it already is included via compat53.h */
        #ifndef COMPAT53_C_
        #define COMPAT53_C_



        /* definitions for Lua 5.1 only */
        #if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM == 501

        #ifndef COMPAT53_FOPEN_NO_LOCK
        #  if defined(_MSC_VER)
        #    define COMPAT53_FOPEN_NO_LOCK 1
        #  else /* otherwise */
        #    define COMPAT53_FOPEN_NO_LOCK 0
        #  endif /* VC++ only so far */
        #endif /* No-lock fopen_s usage if possible */

        #if defined(_MSC_VER) && COMPAT53_FOPEN_NO_LOCK
        #  include <share.h>
        #endif /* VC++ _fsopen for share-allowed file read */

        #ifndef COMPAT53_HAVE_STRERROR_R
        #  if (!defined(_WIN32)) && \
              ((defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L) || \
              (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 600) || \
              defined(__APPLE__))
        #    define COMPAT53_HAVE_STRERROR_R 1
        #  else /* none of the defines matched: define to 0 */
        #    define COMPAT53_HAVE_STRERROR_R 0
        #  endif /* have strerror_r of some form */
        #endif /* strerror_r */

        #ifndef COMPAT53_HAVE_STRERROR_S
        #  if defined(_MSC_VER) || (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L && \
              defined(__STDC_LIB_EXT1__) && __STDC_LIB_EXT1__)
        #    define COMPAT53_HAVE_STRERROR_S 1
        #  else /* not VC++ or C11 */
        #    define COMPAT53_HAVE_STRERROR_S 0
        #  endif /* strerror_s from VC++ or C11 */
        #endif /* strerror_s */

        #ifndef COMPAT53_LUA_FILE_BUFFER_SIZE
        #  define COMPAT53_LUA_FILE_BUFFER_SIZE 4096
        #endif /* Lua File Buffer Size */


        static char* compat53_strerror (int en, char* buff, size_t sz) {
        #if COMPAT53_HAVE_STRERROR_R
          /* use strerror_r here, because it's available on these specific platforms */
          if (sz > 0) {
            buff[0] = '\0';
            /* we don't care whether the GNU version or the XSI version is used: */
            if (strerror_r(en, buff, sz)) {
              /* Yes, we really DO want to ignore the return value!
               * GCC makes that extra hard, not even a (void) cast will do. */
            }
            if (buff[0] == '\0') {
              /* Buffer is unchanged, so we probably have called GNU strerror_r which
               * returned a static constant string. Chances are that strerror will
               * return the same static constant string and therefore be thread-safe. */
              return strerror(en);
            }
          }
          return buff; /* sz is 0 *or* strerror_r wrote into the buffer */
        #elif COMPAT53_HAVE_STRERROR_S
          /* for MSVC and other C11 implementations, use strerror_s since it's
           * provided by default by the libraries */
          strerror_s(buff, sz, en);
          return buff;
        #else
          /* fallback, but strerror is not guaranteed to be threadsafe due to modifying
           * errno itself and some impls not locking a static buffer for it ... but most
           * known systems have threadsafe errno: this might only change if the locale
           * is changed out from under someone while this function is being called */
          (void)buff;
          (void)sz;
          return strerror(en);
        #endif
        }


        COMPAT53_API int lua_absindex (lua_State *L, int i) {
          if (i < 0 && i > LUA_REGISTRYINDEX)
            i += lua_gettop(L) + 1;
          return i;
        }


        static void compat53_call_lua (lua_State *L, char const code[], size_t len,
                                       int nargs, int nret) {
          lua_rawgetp(L, LUA_REGISTRYINDEX, (void*)code);
          if (lua_type(L, -1) != LUA_TFUNCTION) {
            lua_pop(L, 1);
            if (luaL_loadbuffer(L, code, len, "=none"))
              lua_error(L);
            lua_pushvalue(L, -1);
            lua_rawsetp(L, LUA_REGISTRYINDEX, (void*)code);
          }
          lua_insert(L, -nargs-1);
          lua_call(L, nargs, nret);
        }


        static const char compat53_arith_code[] =
          "local op,a,b=...\n"
          "if op==0 then return a+b\n"
          "elseif op==1 then return a-b\n"
          "elseif op==2 then return a*b\n"
          "elseif op==3 then return a/b\n"
          "elseif op==4 then return a%b\n"
          "elseif op==5 then return a^b\n"
          "elseif op==6 then return -a\n"
          "end\n";

        COMPAT53_API void lua_arith (lua_State *L, int op) {
          if (op < LUA_OPADD || op > LUA_OPUNM)
            luaL_error(L, "invalid 'op' argument for lua_arith");
          luaL_checkstack(L, 5, "not enough stack slots");
          if (op == LUA_OPUNM)
            lua_pushvalue(L, -1);
          lua_pushnumber(L, op);
          lua_insert(L, -3);
          compat53_call_lua(L, compat53_arith_code,
                            sizeof(compat53_arith_code)-1, 3, 1);
        }


        static const char compat53_compare_code[] =
          "local a,b=...\n"
          "return a<=b\n";

        COMPAT53_API int lua_compare (lua_State *L, int idx1, int idx2, int op) {
          int result = 0;
          switch (op) {
            case LUA_OPEQ:
              return lua_equal(L, idx1, idx2);
            case LUA_OPLT:
              return lua_lessthan(L, idx1, idx2);
            case LUA_OPLE:
              luaL_checkstack(L, 5, "not enough stack slots");
              idx1 = lua_absindex(L, idx1);
              idx2 = lua_absindex(L, idx2);
              lua_pushvalue(L, idx1);
              lua_pushvalue(L, idx2);
              compat53_call_lua(L, compat53_compare_code,
                                sizeof(compat53_compare_code)-1, 2, 1);
              result = lua_toboolean(L, -1);
              lua_pop(L, 1);
              return result;
            default:
              luaL_error(L, "invalid 'op' argument for lua_compare");
          }
          return 0;
        }


        COMPAT53_API void lua_copy (lua_State *L, int from, int to) {
          int abs_to = lua_absindex(L, to);
          luaL_checkstack(L, 1, "not enough stack slots");
          lua_pushvalue(L, from);
          lua_replace(L, abs_to);
        }


        COMPAT53_API void lua_len (lua_State *L, int i) {
          switch (lua_type(L, i)) {
            case LUA_TSTRING:
              lua_pushnumber(L, (lua_Number)lua_objlen(L, i));
              break;
            case LUA_TTABLE:
              if (!luaL_callmeta(L, i, "__len"))
                lua_pushnumber(L, (lua_Number)lua_objlen(L, i));
              break;
            case LUA_TUSERDATA:
              if (luaL_callmeta(L, i, "__len"))
                break;
              /* FALLTHROUGH */
            default:
              luaL_error(L, "attempt to get length of a %s value",
                         lua_typename(L, lua_type(L, i)));
          }
        }


        COMPAT53_API int lua_rawgetp (lua_State *L, int i, const void *p) {
          int abs_i = lua_absindex(L, i);
          lua_pushlightuserdata(L, (void*)p);
          lua_rawget(L, abs_i);
          return lua_type(L, -1);
        }

        COMPAT53_API void lua_rawsetp (lua_State *L, int i, const void *p) {
          int abs_i = lua_absindex(L, i);
          luaL_checkstack(L, 1, "not enough stack slots");
          lua_pushlightuserdata(L, (void*)p);
          lua_insert(L, -2);
          lua_rawset(L, abs_i);
        }


        COMPAT53_API lua_Number lua_tonumberx (lua_State *L, int i, int *isnum) {
          lua_Number n = lua_tonumber(L, i);
          if (isnum != NULL) {
            *isnum = (n != 0 || lua_isnumber(L, i));
          }
          return n;
        }


        COMPAT53_API void luaL_checkversion (lua_State *L) {
          (void)L;
        }


        COMPAT53_API void luaL_checkstack (lua_State *L, int sp, const char *msg) {
          if (!lua_checkstack(L, sp+LUA_MINSTACK)) {
            if (msg != NULL)
              luaL_error(L, "stack overflow (%s)", msg);
            else {
              lua_pushliteral(L, "stack overflow");
              lua_error(L);
            }
          }
        }


        COMPAT53_API int luaL_getsubtable (lua_State *L, int i, const char *name) {
          int abs_i = lua_absindex(L, i);
          luaL_checkstack(L, 3, "not enough stack slots");
          lua_pushstring(L, name);
          lua_gettable(L, abs_i);
          if (lua_istable(L, -1))
            return 1;
          lua_pop(L, 1);
          lua_newtable(L);
          lua_pushstring(L, name);
          lua_pushvalue(L, -2);
          lua_settable(L, abs_i);
          return 0;
        }


        COMPAT53_API lua_Integer luaL_len (lua_State *L, int i) {
          lua_Integer res = 0;
          int isnum = 0;
          luaL_checkstack(L, 1, "not enough stack slots");
          lua_len(L, i);
          res = lua_tointegerx(L, -1, &isnum);
          lua_pop(L, 1);
          if (!isnum)
            luaL_error(L, "object length is not an integer");
          return res;
        }


        COMPAT53_API void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup) {
          luaL_checkstack(L, nup+1, "too many upvalues");
          for (; l->name != NULL; l++) {  /* fill the table with given functions */
            int i;
            lua_pushstring(L, l->name);
            for (i = 0; i < nup; i++)  /* copy upvalues to the top */
              lua_pushvalue(L, -(nup + 1));
            lua_pushcclosure(L, l->func, nup);  /* closure with those upvalues */
            lua_settable(L, -(nup + 3)); /* table must be below the upvalues, the name and the closure */
          }
          lua_pop(L, nup);  /* remove upvalues */
        }


        COMPAT53_API void luaL_setmetatable (lua_State *L, const char *tname) {
          luaL_checkstack(L, 1, "not enough stack slots");
          luaL_getmetatable(L, tname);
          lua_setmetatable(L, -2);
        }


        COMPAT53_API void *luaL_testudata (lua_State *L, int i, const char *tname) {
          void *p = lua_touserdata(L, i);
          luaL_checkstack(L, 2, "not enough stack slots");
          if (p == NULL || !lua_getmetatable(L, i))
            return NULL;
          else {
            int res = 0;
            luaL_getmetatable(L, tname);
            res = lua_rawequal(L, -1, -2);
            lua_pop(L, 2);
            if (!res)
              p = NULL;
          }
          return p;
        }


        static int compat53_countlevels (lua_State *L) {
          lua_Debug ar;
          int li = 1, le = 1;
          /* find an upper bound */
          while (lua_getstack(L, le, &ar)) { li = le; le *= 2; }
          /* do a binary search */
          while (li < le) {
            int m = (li + le)/2;
            if (lua_getstack(L, m, &ar)) li = m + 1;
            else le = m;
          }
          return le - 1;
        }

        static int compat53_findfield (lua_State *L, int objidx, int level) {
          if (level == 0 || !lua_istable(L, -1))
            return 0;  /* not found */
          lua_pushnil(L);  /* start 'next' loop */
          while (lua_next(L, -2)) {  /* for each pair in table */
            if (lua_type(L, -2) == LUA_TSTRING) {  /* ignore non-string keys */
              if (lua_rawequal(L, objidx, -1)) {  /* found object? */
                lua_pop(L, 1);  /* remove value (but keep name) */
                return 1;
              }
              else if (compat53_findfield(L, objidx, level - 1)) {  /* try recursively */
                lua_remove(L, -2);  /* remove table (but keep name) */
                lua_pushliteral(L, ".");
                lua_insert(L, -2);  /* place '.' between the two names */
                lua_concat(L, 3);
                return 1;
              }
            }
            lua_pop(L, 1);  /* remove value */
          }
          return 0;  /* not found */
        }

        static int compat53_pushglobalfuncname (lua_State *L, lua_Debug *ar) {
          int top = lua_gettop(L);
          lua_getinfo(L, "f", ar);  /* push function */
          lua_pushvalue(L, LUA_GLOBALSINDEX);
          if (compat53_findfield(L, top + 1, 2)) {
            lua_copy(L, -1, top + 1);  /* move name to proper place */
            lua_pop(L, 2);  /* remove pushed values */
            return 1;
          }
          else {
            lua_settop(L, top);  /* remove function and global table */
            return 0;
          }
        }

        static void compat53_pushfuncname (lua_State *L, lua_Debug *ar) {
          if (*ar->namewhat != '\0')  /* is there a name? */
            lua_pushfstring(L, "function " LUA_QS, ar->name);
          else if (*ar->what == 'm')  /* main? */
              lua_pushliteral(L, "main chunk");
          else if (*ar->what == 'C') {
            if (compat53_pushglobalfuncname(L, ar)) {
              lua_pushfstring(L, "function " LUA_QS, lua_tostring(L, -1));
              lua_remove(L, -2);  /* remove name */
            }
            else
              lua_pushliteral(L, "?");
          }
          else
            lua_pushfstring(L, "function <%s:%d>", ar->short_src, ar->linedefined);
        }

        #define COMPAT53_LEVELS1 12  /* size of the first part of the stack */
        #define COMPAT53_LEVELS2 10  /* size of the second part of the stack */

        COMPAT53_API void luaL_traceback (lua_State *L, lua_State *L1,
                                          const char *msg, int level) {
          lua_Debug ar;
          int top = lua_gettop(L);
          int numlevels = compat53_countlevels(L1);
          int mark = (numlevels > COMPAT53_LEVELS1 + COMPAT53_LEVELS2) ? COMPAT53_LEVELS1 : 0;
          if (msg) lua_pushfstring(L, "%s\n", msg);
          lua_pushliteral(L, "stack traceback:");
          while (lua_getstack(L1, level++, &ar)) {
            if (level == mark) {  /* too many levels? */
              lua_pushliteral(L, "\n\t...");  /* add a '...' */
              level = numlevels - COMPAT53_LEVELS2;  /* and skip to last ones */
            }
            else {
              lua_getinfo(L1, "Slnt", &ar);
              lua_pushfstring(L, "\n\t%s:", ar.short_src);
              if (ar.currentline > 0)
                lua_pushfstring(L, "%d:", ar.currentline);
              lua_pushliteral(L, " in ");
              compat53_pushfuncname(L, &ar);
              lua_concat(L, lua_gettop(L) - top);
            }
          }
          lua_concat(L, lua_gettop(L) - top);
        }


        COMPAT53_API int luaL_fileresult (lua_State *L, int stat, const char *fname) {
          const char *serr = NULL;
          int en = errno;  /* calls to Lua API may change this value */
          char buf[512] = { 0 };
          if (stat) {
            lua_pushboolean(L, 1);
            return 1;
          }
          else {
            lua_pushnil(L);
            serr = compat53_strerror(en, buf, sizeof(buf));
            if (fname)
              lua_pushfstring(L, "%s: %s", fname, serr);
            else
              lua_pushstring(L, serr);
            lua_pushnumber(L, (lua_Number)en);
            return 3;
          }
        }


        static int compat53_checkmode (lua_State *L, const char *mode, const char *modename, int err) {
          if (mode && strchr(mode, modename[0]) == NULL) {
            lua_pushfstring(L, "attempt to load a %s chunk (mode is '%s')", modename, mode);
            return err;
          }
          return LUA_OK;
        }


        typedef struct {
          lua_Reader reader;
          void *ud;
          int has_peeked_data;
          const char *peeked_data;
          size_t peeked_data_size;
        } compat53_reader_data;


        static const char *compat53_reader (lua_State *L, void *ud, size_t *size) {
          compat53_reader_data *data = (compat53_reader_data *)ud;
          if (data->has_peeked_data) {
            data->has_peeked_data = 0;
            *size = data->peeked_data_size;
            return data->peeked_data;
          } else
            return data->reader(L, data->ud, size);
        }


        COMPAT53_API int lua_load (lua_State *L, lua_Reader reader, void *data, const char *source, const char *mode) {
          int status = LUA_OK;
          compat53_reader_data compat53_data = { 0, NULL, 1, 0, 0 };
          compat53_data.reader = reader;
          compat53_data.ud = data;
          compat53_data.peeked_data = reader(L, data, &(compat53_data.peeked_data_size));
          if (compat53_data.peeked_data && compat53_data.peeked_data_size &&
              compat53_data.peeked_data[0] == LUA_SIGNATURE[0]) /* binary file? */
              status = compat53_checkmode(L, mode, "binary", LUA_ERRSYNTAX);
          else
              status = compat53_checkmode(L, mode, "text", LUA_ERRSYNTAX);
          if (status != LUA_OK)
            return status;
          /* we need to call the original 5.1 version of lua_load! */
        #undef lua_load
          return lua_load(L, compat53_reader, &compat53_data, source);
        #define lua_load COMPAT53_CONCAT(COMPAT53_PREFIX, _load_53)
        }


        typedef struct {
          int n;  /* number of pre-read characters */
          FILE *f;  /* file being read */
          char buff[COMPAT53_LUA_FILE_BUFFER_SIZE];  /* area for reading file */
        } compat53_LoadF;


        static const char *compat53_getF (lua_State *L, void *ud, size_t *size) {
          compat53_LoadF *lf = (compat53_LoadF *)ud;
          (void)L;  /* not used */
          if (lf->n > 0) {  /* are there pre-read characters to be read? */
            *size = lf->n;  /* return them (chars already in buffer) */
            lf->n = 0;  /* no more pre-read characters */
          }
          else {  /* read a block from file */
            /* 'fread' can return > 0 *and* set the EOF flag. If next call to
               'compat53_getF' called 'fread', it might still wait for user input.
               The next check avoids this problem. */
            if (feof(lf->f)) return NULL;
            *size = fread(lf->buff, 1, sizeof(lf->buff), lf->f);  /* read block */
          }
          return lf->buff;
        }


        static int compat53_errfile (lua_State *L, const char *what, int fnameindex) {
          char buf[512] = {0};
          const char *serr = compat53_strerror(errno, buf, sizeof(buf));
          const char *filename = lua_tostring(L, fnameindex) + 1;
          lua_pushfstring(L, "cannot %s %s: %s", what, filename, serr);
          lua_remove(L, fnameindex);
          return LUA_ERRFILE;
        }


        static int compat53_skipBOM (compat53_LoadF *lf) {
          const char *p = "\xEF\xBB\xBF";  /* UTF-8 BOM mark */
          int c;
          lf->n = 0;
          do {
            c = getc(lf->f);
            if (c == EOF || c != *(const unsigned char *)p++) return c;
            lf->buff[lf->n++] = (char)c;  /* to be read by the parser */
          } while (*p != '\0');
          lf->n = 0;  /* prefix matched; discard it */
          return getc(lf->f);  /* return next character */
        }


        /*
        ** reads the first character of file 'f' and skips an optional BOM mark
        ** in its beginning plus its first line if it starts with '#'. Returns
        ** true if it skipped the first line.  In any case, '*cp' has the
        ** first "valid" character of the file (after the optional BOM and
        ** a first-line comment).
        */
        static int compat53_skipcomment (compat53_LoadF *lf, int *cp) {
          int c = *cp = compat53_skipBOM(lf);
          if (c == '#') {  /* first line is a comment (Unix exec. file)? */
            do {  /* skip first line */
              c = getc(lf->f);
            } while (c != EOF && c != '\n');
            *cp = getc(lf->f);  /* skip end-of-line, if present */
            return 1;  /* there was a comment */
          }
          else return 0;  /* no comment */
        }


        COMPAT53_API int luaL_loadfilex (lua_State *L, const char *filename, const char *mode) {
          compat53_LoadF lf;
          int status, readstatus;
          int c;
          int fnameindex = lua_gettop(L) + 1;  /* index of filename on the stack */
          if (filename == NULL) {
            lua_pushliteral(L, "=stdin");
            lf.f = stdin;
          }
          else {
            lua_pushfstring(L, "@%s", filename);
        #if defined(_MSC_VER)
            /* This code is here to stop a deprecation error that stops builds
             * if a certain macro is defined. While normally not caring would
             * be best, some header-only libraries and builds can't afford to
             * dictate this to the user. A quick check shows that fopen_s this
             * goes back to VS 2005, and _fsopen goes back to VS 2003 .NET,
             * possibly even before that so we don't need to do any version
             * number checks, since this has been there since forever.  */

            /* TO USER: if you want the behavior of typical fopen_s/fopen,
             * which does lock the file on VC++, define the macro used below to 0 */
        #if COMPAT53_FOPEN_NO_LOCK
            lf.f = _fsopen(filename, "r", _SH_DENYNO); /* do not lock the file in any way */
            if (lf.f == NULL)
              return compat53_errfile(L, "open", fnameindex);
        #else /* use default locking version */
            if (fopen_s(&lf.f, filename, "r") != 0)
              return compat53_errfile(L, "open", fnameindex);
        #endif /* Locking vs. No-locking fopen variants */
        #else
            lf.f = fopen(filename, "r"); /* default stdlib doesn't forcefully lock files here */
            if (lf.f == NULL) return compat53_errfile(L, "open", fnameindex);
        #endif
          }
          if (compat53_skipcomment(&lf, &c))  /* read initial portion */
            lf.buff[lf.n++] = '\n';  /* add line to correct line numbers */
          if (c == LUA_SIGNATURE[0] && filename) {  /* binary file? */
        #if defined(_MSC_VER)
            if (freopen_s(&lf.f, filename, "rb", lf.f) != 0)
              return compat53_errfile(L, "reopen", fnameindex);
        #else
            lf.f = freopen(filename, "rb", lf.f);  /* reopen in binary mode */
            if (lf.f == NULL) return compat53_errfile(L, "reopen", fnameindex);
        #endif
            compat53_skipcomment(&lf, &c);  /* re-read initial portion */
          }
          if (c != EOF)
            lf.buff[lf.n++] = (char)c;  /* 'c' is the first character of the stream */
          status = lua_load(L, &compat53_getF, &lf, lua_tostring(L, -1), mode);
          readstatus = ferror(lf.f);
          if (filename) fclose(lf.f);  /* close file (even in case of errors) */
          if (readstatus) {
            lua_settop(L, fnameindex);  /* ignore results from 'lua_load' */
            return compat53_errfile(L, "read", fnameindex);
          }
          lua_remove(L, fnameindex);
          return status;
        }


        COMPAT53_API int luaL_loadbufferx (lua_State *L, const char *buff, size_t sz, const char *name, const char *mode) {
          int status = LUA_OK;
          if (sz > 0 && buff[0] == LUA_SIGNATURE[0]) {
            status = compat53_checkmode(L, mode, "binary", LUA_ERRSYNTAX);
          }
          else {
            status = compat53_checkmode(L, mode, "text", LUA_ERRSYNTAX);
          }
          if (status != LUA_OK)
            return status;
          return luaL_loadbuffer(L, buff, sz, name);
        }


        #if !defined(l_inspectstat) && \
            (defined(unix) || defined(__unix) || defined(__unix__) || \
             defined(__TOS_AIX__) || defined(_SYSTYPE_BSD) || \
             (defined(__APPLE__) && defined(__MACH__)))
        /* some form of unix; check feature macros in unistd.h for details */
        #  include <unistd.h>
        /* check posix version; the relevant include files and macros probably
         * were available before 2001, but I'm not sure */
        #  if defined(_POSIX_VERSION) && _POSIX_VERSION >= 200112L
        #    include <sys/wait.h>
        #    define l_inspectstat(stat,what) \
          if (WIFEXITED(stat)) { stat = WEXITSTATUS(stat); } \
          else if (WIFSIGNALED(stat)) { stat = WTERMSIG(stat); what = "signal"; }
        #  endif
        #endif

        /* provide default (no-op) version */
        #if !defined(l_inspectstat)
        #  define l_inspectstat(stat,what) ((void)0)
        #endif


        COMPAT53_API int luaL_execresult (lua_State *L, int stat) {
          const char *what = "exit";
          if (stat == -1)
            return luaL_fileresult(L, 0, NULL);
          else {
            l_inspectstat(stat, what);
            if (*what == 'e' && stat == 0)
              lua_pushboolean(L, 1);
            else
              lua_pushnil(L);
            lua_pushstring(L, what);
            lua_pushinteger(L, stat);
            return 3;
          }
        }


        COMPAT53_API void luaL_buffinit (lua_State *L, luaL_Buffer_53 *B) {
          /* make it crash if used via pointer to a 5.1-style luaL_Buffer */
          B->b.p = NULL;
          B->b.L = NULL;
          B->b.lvl = 0;
          /* reuse the buffer from the 5.1-style luaL_Buffer though! */
          B->ptr = B->b.buffer;
          B->capacity = LUAL_BUFFERSIZE;
          B->nelems = 0;
          B->L2 = L;
        }


        COMPAT53_API char *luaL_prepbuffsize (luaL_Buffer_53 *B, size_t s) {
          if (B->capacity - B->nelems < s) { /* needs to grow */
            char* newptr = NULL;
            size_t newcap = B->capacity * 2;
            if (newcap - B->nelems < s)
              newcap = B->nelems + s;
            if (newcap < B->capacity) /* overflow */
              luaL_error(B->L2, "buffer too large");
            newptr = (char*)lua_newuserdata(B->L2, newcap);
            memcpy(newptr, B->ptr, B->nelems);
            if (B->ptr != B->b.buffer)
              lua_replace(B->L2, -2); /* remove old buffer */
            B->ptr = newptr;
            B->capacity = newcap;
          }
          return B->ptr+B->nelems;
        }


        COMPAT53_API void luaL_addlstring (luaL_Buffer_53 *B, const char *s, size_t l) {
          memcpy(luaL_prepbuffsize(B, l), s, l);
          luaL_addsize(B, l);
        }


        COMPAT53_API void luaL_addvalue (luaL_Buffer_53 *B) {
          size_t len = 0;
          const char *s = lua_tolstring(B->L2, -1, &len);
          if (!s)
            luaL_error(B->L2, "cannot convert value to string");
          if (B->ptr != B->b.buffer)
            lua_insert(B->L2, -2); /* userdata buffer must be at stack top */
          luaL_addlstring(B, s, len);
          lua_remove(B->L2, B->ptr != B->b.buffer ? -2 : -1);
        }


        void luaL_pushresult (luaL_Buffer_53 *B) {
          lua_pushlstring(B->L2, B->ptr, B->nelems);
          if (B->ptr != B->b.buffer)
            lua_replace(B->L2, -2); /* remove userdata buffer */
        }


        #endif /* Lua 5.1 */



        /* definitions for Lua 5.1 and Lua 5.2 */
        #if defined( LUA_VERSION_NUM ) && LUA_VERSION_NUM <= 502


        COMPAT53_API const char *lua_pushlstring (lua_State *L, const char *s, size_t len) {
        #undef lua_pushlstring
          lua_pushlstring(L, len > 0 ? s : "", len);
        #define lua_pushlstring COMPAT53_CONCAT(COMPAT53_PREFIX, _pushlstring_53)
          return lua_tostring(L, -1);
        }


        COMPAT53_API int lua_geti (lua_State *L, int index, lua_Integer i) {
          index = lua_absindex(L, index);
          lua_pushinteger(L, i);
          lua_gettable(L, index);
          return lua_type(L, -1);
        }


        #ifndef LUA_EXTRASPACE
        #define LUA_EXTRASPACE (sizeof(void*))
        #endif

        COMPAT53_API void *lua_getextraspace (lua_State *L) {
          int is_main = 0;
          void *ptr = NULL;
          luaL_checkstack(L, 4, "not enough stack slots available");
          lua_pushliteral(L, "__compat53_extraspace");
          lua_pushvalue(L, -1);
          lua_rawget(L, LUA_REGISTRYINDEX);
          if (!lua_istable(L, -1)) {
            lua_pop(L, 1);
            lua_createtable(L, 0, 2);
            lua_createtable(L, 0, 1);
            lua_pushliteral(L, "k");
            lua_setfield(L, -2, "__mode");
            lua_setmetatable(L, -2);
            lua_pushvalue(L, -2);
            lua_pushvalue(L, -2);
            lua_rawset(L, LUA_REGISTRYINDEX);
          }
          lua_replace(L, -2);
          is_main = lua_pushthread(L);
          lua_rawget(L, -2);
          ptr = lua_touserdata(L, -1);
          if (!ptr) {
            lua_pop(L, 1);
            ptr = lua_newuserdata(L, LUA_EXTRASPACE);
            if (is_main) {
              memset(ptr, '\0', LUA_EXTRASPACE);
              lua_pushthread(L);
              lua_pushvalue(L, -2);
              lua_rawset(L, -4);
              lua_pushboolean(L, 1);
              lua_pushvalue(L, -2);
              lua_rawset(L, -4);
            } else {
              void* mptr = NULL;
              lua_pushboolean(L, 1);
              lua_rawget(L, -3);
              mptr = lua_touserdata(L, -1);
              if (mptr)
                memcpy(ptr, mptr, LUA_EXTRASPACE);
              else
                memset(ptr, '\0', LUA_EXTRASPACE);
              lua_pop(L, 1);
              lua_pushthread(L);
              lua_pushvalue(L, -2);
              lua_rawset(L, -4);
            }
          }
          lua_pop(L, 2);
          return ptr;
        }


        COMPAT53_API int lua_isinteger (lua_State *L, int index) {
          if (lua_type(L, index) == LUA_TNUMBER) {
            lua_Number n = lua_tonumber(L, index);
            lua_Integer i = lua_tointeger(L, index);
            if (i == n)
              return 1;
          }
          return 0;
        }


        COMPAT53_API lua_Integer lua_tointegerx (lua_State *L, int i, int *isnum) {
          int ok = 0;
          lua_Number n = lua_tonumberx(L, i, &ok);
          if (ok) {
            if (n == (lua_Integer)n) {
              if (isnum)
                *isnum = 1;
              return (lua_Integer)n;
            }
          }
          if (isnum)
            *isnum = 0;
          return 0;
        }


        static void compat53_reverse (lua_State *L, int a, int b) {
          for (; a < b; ++a, --b) {
            lua_pushvalue(L, a);
            lua_pushvalue(L, b);
            lua_replace(L, a);
            lua_replace(L, b);
          }
        }


        COMPAT53_API void lua_rotate (lua_State *L, int idx, int n) {
          int n_elems = 0;
          idx = lua_absindex(L, idx);
          n_elems = lua_gettop(L)-idx+1;
          if (n < 0)
            n += n_elems;
          if ( n > 0 && n < n_elems) {
            luaL_checkstack(L, 2, "not enough stack slots available");
            n = n_elems - n;
            compat53_reverse(L, idx, idx+n-1);
            compat53_reverse(L, idx+n, idx+n_elems-1);
            compat53_reverse(L, idx, idx+n_elems-1);
          }
        }


        COMPAT53_API void lua_seti (lua_State *L, int index, lua_Integer i) {
          luaL_checkstack(L, 1, "not enough stack slots available");
          index = lua_absindex(L, index);
          lua_pushinteger(L, i);
          lua_insert(L, -2);
          lua_settable(L, index);
        }


        #if !defined(lua_str2number)
        #  define lua_str2number(s, p)  strtod((s), (p))
        #endif

        COMPAT53_API size_t lua_stringtonumber (lua_State *L, const char *s) {
          char* endptr;
          lua_Number n = lua_str2number(s, &endptr);
          if (endptr != s) {
            while (*endptr != '\0' && isspace((unsigned char)*endptr))
              ++endptr;
            if (*endptr == '\0') {
              lua_pushnumber(L, n);
              return endptr - s + 1;
            }
          }
          return 0;
        }


        COMPAT53_API const char *luaL_tolstring (lua_State *L, int idx, size_t *len) {
          if (!luaL_callmeta(L, idx, "__tostring")) {
            int t = lua_type(L, idx), tt = 0;
            char const* name = NULL;
            switch (t) {
              case LUA_TNIL:
                lua_pushliteral(L, "nil");
                break;
              case LUA_TSTRING:
              case LUA_TNUMBER:
                lua_pushvalue(L, idx);
                break;
              case LUA_TBOOLEAN:
                if (lua_toboolean(L, idx))
                  lua_pushliteral(L, "true");
                else
                  lua_pushliteral(L, "false");
                break;
              default:
                tt = luaL_getmetafield(L, idx, "__name");
                name = (tt == LUA_TSTRING) ? lua_tostring(L, -1) : lua_typename(L, t);
                lua_pushfstring(L, "%s: %p", name, lua_topointer(L, idx));
                if (tt != LUA_TNIL)
                  lua_replace(L, -2);
                break;
            }
          } else {
            if (!lua_isstring(L, -1))
              luaL_error(L, "'__tostring' must return a string");
          }
          return lua_tolstring(L, -1, len);
        }


        COMPAT53_API void luaL_requiref (lua_State *L, const char *modname,
                                         lua_CFunction openf, int glb) {
          luaL_checkstack(L, 3, "not enough stack slots available");
          luaL_getsubtable(L, LUA_REGISTRYINDEX, "_LOADED");
          if (lua_getfield(L, -1, modname) == LUA_TNIL) {
            lua_pop(L, 1);
            lua_pushcfunction(L, openf);
            lua_pushstring(L, modname);
            lua_call(L, 1, 1);
            lua_pushvalue(L, -1);
            lua_setfield(L, -3, modname);
          }
          if (glb) {
            lua_pushvalue(L, -1);
            lua_setglobal(L, modname);
          }
          lua_replace(L, -2);
        }


        #endif /* Lua 5.1 and 5.2 */


        #endif /* COMPAT53_C_ */


        /*********************************************************************
        * This file contains parts of Lua 5.2's and Lua 5.3's source code:
        *
        * Copyright (C) 1994-2014 Lua.org, PUC-Rio.
        *
        * Permission is hereby granted, free of charge, to any person obtaining
        * a copy of this software and associated documentation files (the
        * "Software"), to deal in the Software without restriction, including
        * without limitation the rights to use, copy, modify, merge, publish,
        * distribute, sublicense, and/or sell copies of the Software, and to
        * permit persons to whom the Software is furnished to do so, subject to
        * the following conditions:
        *
        * The above copyright notice and this permission notice shall be
        * included in all copies or substantial portions of the Software.
        *
        * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
        * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
        * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
        * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
        * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
        * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
        * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
        *********************************************************************/


    ]=]
}
