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static int latebind_func_index(lua_State *L)
{
const luaL_Reg *llib;
/* name @ top of stack */
const char *name = lua_tostring (L, -1);
luaL_argcheck(L, lua_istable(L, -2) && lua_getmetatable(L, -2), -2,
"latebind table expected");
/* lookup late bound func(s), lua_objlen allows check of multiple luaL_Reg */
for(int i = lua_objlen(L, -1); i > 0; i--) {
lua_rawgeti (L, -1, i);
llib = (const luaL_Reg *) lua_touserdata (L, -1);
lua_pop(L, 1);
if(!llib)
continue;
for (; llib->name; llib++) {
if(!name || strcmp(name, llib->name) == 0) {
/* if function is used it is added to the base table */
lua_pushcclosure(L, llib->func, 0);
if(!name) /* nil name binds all functions in table immediately */
lua_setfield (L, -4, llib->name);
else {
lua_pushvalue(L, -1); /* dupe closure */
lua_setfield (L, -5, llib->name);
/* returns the closure */
return 1;
}
}
}
}
lua_pop(L, 2); /* base table is top of stack */
return 0;
}
static int latebind_func_pairs(lua_State *L)
{
luaL_argcheck(L, lua_istable(L, 1), 1, "table expected");
lua_getglobal(L, "pairs"); /* function to be called / returned */
lua_createtable(L, 0, 15);
lua_getmetatable (L, 1);
lua_setmetatable (L, 3);
lua_pushnil(L); /*nil name retrieves all late bound functions */
latebind_func_index(L);
lua_pushnil(L); /* remove metatable */
lua_setmetatable (L, 3);
/* clone base table */
lua_pushnil(L); /* first key */
while(lua_next(L, 1) != 0) {
lua_pushvalue(L, -2); /* dupe key */
lua_insert(L, -2); /* Stk = kkv */
lua_settable(L, 3);
}
lua_call(L, 1, 3); /* pairs(t_cloned) */
return 3;
}
LUALIB_API void (luaL_register) (lua_State *L, const char *libname,
const luaL_Reg *l) {
if(!libname)
{
/* if there is no libname register normally */
luaI_openlib(L, libname, l, 0);
return;
}
/* store this table instead of of the passed luaL_Reg table */
static const struct luaL_reg late_lib [] =
{
{"__latebind", latebind_func_index},
{NULL, NULL}
};
static const struct luaL_reg late_meta [] =
{
{"__index", latebind_func_index},
{"__pairs", latebind_func_pairs},
{NULL, NULL}
};
luaI_openlib(L, libname, late_lib, 0);
if(!lua_getmetatable(L, -1))
lua_createtable(L, 5, 2);
luaI_openlib(L, NULL, late_meta, 0);
/* address of luaL_Reg is stored in numbered [1] key indices of metatable */
lua_pushlightuserdata (L, (void *) l);
lua_rawseti (L, -2, lua_objlen(L, -2) + 1);
lua_setmetatable(L, -2);
}
