Function meta_assign

library/LuaWrapper.cpp:822–933

* Method: assign data between objects. */

 * Method: assign data between objects.
 */
static int meta_assign(lua_State *state)
{
    int argc = lua_gettop(state);

    if (argc != 2)
        luaL_error(state, "Usage: target:assign(src) or df.assign(target,src)");

    if (!lua_istable(state, 2))
    {
        const type_identity *id1, *id2;
        check_type_compatible(state, 1, 2, &id1, &id2, "df.assign()", false, false);

        if (!id1->copy(get_object_ref(state, 1), get_object_ref(state, 2)))
            luaL_error(state, "No copy support for %s", id1->getFullName().c_str());
    }
    else
    {
        const type_identity *id = get_object_identity(state, 1, "df.assign()", false);

        if (lua_getmetatable(state, 2))
            luaL_error(state, "cannot use lua tables with metatable in df.assign()");

        int base = lua_gettop(state);

        // x:assign{ assign = foo } => x:assign(foo)
        bool has_assign = false;

        lua_pushstring(state, "assign");
        lua_dup(state);
        lua_rawget(state, 2);

        if (!lua_isnil(state,-1))
        {
            has_assign = true;
            lua_getfield(state, LUA_REGISTRYINDEX, DFHACK_ASSIGN_NAME);
            lua_pushvalue(state, 1);
            lua_pushvalue(state, base+2);
            lua_call(state, 2, 0);
        }

        lua_pop(state, 1);

        // new is used by autovivification and should be skipped
        lua_pushstring(state, "new");

        if (id->isContainer())
        {
            // check resize field
            lua_pushstring(state, "resize");
            lua_dup(state);
            lua_rawget(state, 2);

            if (lua_isnil(state,-1) && !has_assign)
            {
                /*
                 * no assign && nil or missing resize field => 1-based lua array
                 */
                int size = lua_rawlen(state, 2);