// __index metamethod handler.
// For proxied tables, return proxies of children, preferably cached
// For proxied strings, return methods
static int l_str_index(lua_State *L)
{
// Look up cached value, and return it if present
aux_push_weak_table(L, 1);
lua_pushvalue(L, 1);
lua_gettable(L, 3);
lua_replace(L, 3);
lua_pushvalue(L, 2);
lua_rawget(L, 3);
if(!lua_isnil(L, 4))
return 1;
lua_pop(L, 1);
// Fetch the proxied value
aux_push_weak_table(L, 0);
lua_pushvalue(L, 1);
lua_rawget(L, 4);
lua_replace(L, 4);
// Handle string methods
if(lua_type(L, 4) == LUA_TSTRING)
{
lua_rawgeti(L, luaT_environindex, 4);
lua_pushvalue(L, 2);
lua_gettable(L, 5);
return 1;
}
// Handle __random, as it shouldn't be cached
if(lua_type(L, 2) == LUA_TSTRING)
{
size_t iLen;
const char* sKey = lua_tolstring(L, 2, &iLen);
if(iLen == 8 && strcmp(sKey, "__random") == 0)
{
aux_push_random_key(L);
lua_replace(L, 2);
lua_settop(L, 2);
return l_str_index(L);
}
}
// Fetch desired value
lua_pushvalue(L, 2);
lua_gettable(L, 4);
lua_replace(L, 4);
// Create new userdata proxy
l_str_new_aux(L);
aux_mk_table(L, 0, 2, 1, 2);
lua_setfenv(L, 4);
// Save to cache and return
lua_pushvalue(L, 2);
lua_pushvalue(L, 4);
lua_rawset(L, 3);
return 1;
}
// Create a new root-level userdata proxy
static int l_str_new(lua_State *L)
{
// Pack extra arguments into a table
int iNArgs = lua_gettop(L);
lua_createtable(L, iNArgs - 2, 0);
lua_replace(L, 1); // Value inserted by __call
for(int i = iNArgs; i >= 3; --i)
lua_rawseti(L, 1, i - 2);
// Make proxy
luaL_checkany(L, 2);
l_str_new_aux(L);
// Save extra arguments as reconstruction information
lua_insert(L, 1);
lua_setfenv(L, 1);
return 1;
}
// Generic string method handler
// The name of the method is stored at upvalue 1
static int l_str_func(lua_State *L)
{
int iArgCount = lua_gettop(L);
lua_checkstack(L, iArgCount + 10);
int iUserdataCount = 0;
// Construct the resulting value
aux_push_weak_table(L, 0);
for(int i = 1; i <= iArgCount; ++i)
{
lua_pushvalue(L, i);
if(lua_type(L, i) == LUA_TUSERDATA)
{
lua_rawget(L, iArgCount + 1);
++iUserdataCount;
}
}
lua_pushvalue(L, luaT_upvalueindex(1));
lua_gettable(L, iArgCount + 2);
lua_replace(L, iArgCount + 1);
lua_call(L, iArgCount, 1);
// Trivial case of result not depending upon any proxies
if(iUserdataCount == 0)
return 1;
// Wrap result in a proxy
l_str_new_aux(L);
// Create and save reconstruction information
lua_createtable(L, iArgCount + 1, 0);
lua_pushvalue(L, luaT_upvalueindex(1));
lua_rawseti(L, -2, 1);
for(int i = 1; i <= iArgCount; ++i)
{
lua_pushvalue(L, i);
lua_rawseti(L, -2, i + 1);
}
lua_setfenv(L, -2);
return 1;
}
