Function AddFieldInfoTable

library/LuaTypes.cpp:1488–1548

}

static void AddFieldInfoTable(lua_State *state, int ftable_idx, struct_identity *pstruct)
{
    Lua::StackUnwinder base{state};

    // metatable
    lua_newtable(state);
    int ix_meta = lua_gettop(state);

    // field info table (name -> struct_field_info*)
    lua_newtable(state);
    int ix_fieldinfo = lua_gettop(state);

    // field iter table (int <-> name)
    lua_newtable(state);
    int ix_fielditer = lua_gettop(state);
    IndexFields(state, base, pstruct, IndexFieldsFlags::RAW);

    PushStructMethod(state, ix_meta, ix_fielditer, meta_fieldinfo_next);
    // change upvalue 1 to the field info table since we don't need the original
    lua_pushvalue(state, ix_fieldinfo);
    lua_setupvalue(state, -2, 1);
    SetPairsMethod(state, ix_meta, "__pairs");

    // field table (name -> table representation of struct_field_info)
    lua_newtable(state);
    int ix_fields = lua_gettop(state);

    // wrapper table (empty, indexes into field table with metamethods)
    lua_newtable(state);
    int ix_wrapper = lua_gettop(state);

    // set up metatable for the wrapper
    // use field table for __index
    lua_pushstring(state, "__index");
    lua_pushvalue(state, ix_fieldinfo);
    lua_pushcclosure(state, meta_fieldinfo_index, 1);
    lua_settable(state, ix_meta);

    // use change_error() for __newindex
    lua_pushstring(state, "__newindex");
    lua_getfield(state, LUA_REGISTRYINDEX, DFHACK_CHANGEERROR_NAME);
    lua_settable(state, ix_meta);

    lua_pushvalue(state, ix_meta);
    lua_setmetatable(state, ix_wrapper);

    // convert field info table (struct_field_info) to field table (lua tables)
    lua_pushnil(state);  // initial key for next()
    while (lua_next(state, ix_fieldinfo)) {
        auto field = static_cast<const struct_field_info*>(lua_touserdata(state, -1));
        lua_pushvalue(state, -2);  // field name
        PushFieldInfoSubTable(state, field);
        lua_settable(state, ix_fields);
        lua_pop(state, 1); // struct_field_info
    }

    // lua_pushvalue(state, ix_fields);
    // freeze_table(state); // TODO: figure out why this creates an __index cycle for nonexistent fields