Function generic_reader

Source/Misc/lua/src/lua.c:11161–11176

** Reader for generic `load' function: `lua_load' uses the ** stack for internal stuff, so the reader cannot change the ** stack top. Instead, it keeps its resulting string in a ** reserved slot inside the stack. */

** reserved slot inside the stack.
*/
static const char *generic_reader (lua_State *L, void *ud, size_t *size) {
(void)ud;  /* to avoid warnings */
luaL_checkstack(L, 2, "too many nested functions");
lua_pushvalue(L, 1);  /* get function */
lua_call(L, 0, 1);  /* call it */
if (lua_isnil(L, -1)) {
*size = 0;
return NULL;
}
else if (lua_isstring(L, -1)) {
lua_replace(L, 3);  /* save string in a reserved stack slot */
return lua_tolstring(L, 3, size);
}
else luaL_error(L, "reader function must return a string");
return NULL;  /* to avoid warnings */
}


static int luaB_load (lua_State *L) {