/*
* Sets up [-1]<->[-2] two-way lookups, and ensures the lookup table exists.
* Pops the both values off the stack.
*/
static void set_deep_lookup( lua_State* L)
{
STACK_GROW( L, 3);
STACK_CHECK( L); // a b
push_registry_subtable( L, DEEP_LOOKUP_KEY); // a b {}
STACK_MID( L, 1);
lua_insert( L, -3); // {} a b
lua_pushvalue( L, -1); // {} a b b
lua_pushvalue( L,-3); // {} a b b a
lua_rawset( L, -5); // {} a b
lua_rawset( L, -3); // {}
lua_pop( L, 1); //
STACK_END( L, -2);
}
/*
* Sets up [-1]<->[-2] two-way lookups, and ensures the lookup table exists.
* Pops the both values off the stack.
*/
void set_deep_lookup( lua_State *L ) {
STACK_GROW(L,3);
STACK_CHECK(L)
#if 1
push_registry_subtable( L, DEEP_LOOKUP_KEY );
#else
/* ..to be removed.. */
lua_pushlightuserdata( L, DEEP_LOOKUP_KEY );
lua_rawget( L, LUA_REGISTRYINDEX );
if (lua_isnil(L,-1)) {
// First time here; let's make the lookup
//
lua_pop(L,1);
lua_newtable(L);
lua_pushlightuserdata( L, DEEP_LOOKUP_KEY );
lua_pushvalue(L,-2);
//
// [-3]: {} (2nd ref)
// [-2]: DEEP_LOOKUP_KEY
// [-1]: {}
lua_rawset( L, LUA_REGISTRYINDEX );
//
// [-1]: lookup table (empty)
}
#endif
STACK_MID(L,1)
lua_insert(L,-3);
// [-3]: lookup table
// [-2]: A
// [-1]: B
lua_pushvalue( L,-1 ); // B
lua_pushvalue( L,-3 ); // A
lua_rawset( L, -5 ); // B->A
lua_rawset( L, -3 ); // A->B
lua_pop( L,1 );
STACK_END(L,-2)
}
/*
* Get a unique ID for metatable at [i].
*/
static
uint_t get_mt_id( lua_State *L, int i ) {
static uint_t last_id= 0;
uint_t id;
i= STACK_ABS(L,i);
STACK_GROW(L,3);
STACK_CHECK(L)
push_registry_subtable( L, REG_MTID );
lua_pushvalue(L, i);
lua_rawget( L, -2 );
//
// [-2]: reg[REG_MTID]
// [-1]: nil/uint
id= lua_tointeger(L,-1); // 0 for nil
lua_pop(L,1);
STACK_MID(L,1)
if (id==0) {
MUTEX_LOCK( &mtid_lock );
id= ++last_id;
MUTEX_UNLOCK( &mtid_lock );
/* Create two-way references: id_uint <-> table
*/
lua_pushvalue(L,i);
lua_pushinteger(L,id);
lua_rawset( L, -3 );
lua_pushinteger(L,id);
lua_pushvalue(L,i);
lua_rawset( L, -3 );
}
lua_pop(L,1); // remove 'reg[REG_MTID]' reference
STACK_END(L,0)
return id;
}
