package main import ( "github.com/yuin/gopher-lua" "time" ) const luaDateTypeName = "date" const timeFormat = "2006-01-02" // Registers my date type to given L. func luaRegisterDates(L *lua.LState) { mt := L.NewTypeMetatable(luaDateTypeName) L.SetGlobal("date", mt) L.SetField(mt, "new", L.NewFunction(luaDateNew)) L.SetField(mt, "now", L.NewFunction(luaDateNow)) L.SetField(mt, "__index", L.NewFunction(luaDate__index)) L.SetField(mt, "__tostring", L.NewFunction(luaDate__tostring)) L.SetField(mt, "__eq", L.NewFunction(luaDate__eq)) L.SetField(mt, "__lt", L.NewFunction(luaDate__lt)) L.SetField(mt, "__le", L.NewFunction(luaDate__le)) L.SetField(mt, "__add", L.NewFunction(luaDate__add)) L.SetField(mt, "__sub", L.NewFunction(luaDate__sub)) L.SetField(mt, "__metatable", lua.LString("protected")) } func TimeToLua(L *lua.LState, date *time.Time) *lua.LUserData { ud := L.NewUserData() ud.Value = date L.SetMetatable(ud, L.GetTypeMetatable(luaDateTypeName)) return ud } // Checks whether the first lua argument is a *LUserData with *Time and returns this *Time. func luaCheckTime(L *lua.LState, n int) *time.Time { ud := L.CheckUserData(n) if date, ok := ud.Value.(*time.Time); ok { return date } L.ArgError(n, "date expected") return nil } func luaWeakCheckTime(L *lua.LState, n int) *time.Time { v := L.Get(n) if ud, ok := v.(*lua.LUserData); ok { if date, ok := ud.Value.(*time.Time); ok { return date } } return nil } func luaWeakCheckTableFieldInt(L *lua.LState, T *lua.LTable, n int, name string, def int) int { lv := T.RawGetString(name) if lv == lua.LNil { return def } if i, ok := lv.(lua.LNumber); ok { return int(i) } L.ArgError(n, "table field '"+name+"' expected to be int") return def } func luaDateNew(L *lua.LState) int { v := L.Get(1) if s, ok := v.(lua.LString); ok { date, err := time.Parse(timeFormat, s.String()) if err != nil { L.ArgError(1, "error parsing date string: "+err.Error()) return 0 } L.Push(TimeToLua(L, &date)) return 1 } var year, month, day int if t, ok := v.(*lua.LTable); ok { year = luaWeakCheckTableFieldInt(L, t, 1, "year", 0) month = luaWeakCheckTableFieldInt(L, t, 1, "month", 1) day = luaWeakCheckTableFieldInt(L, t, 1, "day", 1) } else { year = L.CheckInt(1) month = L.CheckInt(2) day = L.CheckInt(3) } date := time.Date(year, time.Month(month), day, 0, 0, 0, 0, time.Local) L.Push(TimeToLua(L, &date)) return 1 } func luaDateNow(L *lua.LState) int { now := time.Now() date := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, time.Local) L.Push(TimeToLua(L, &date)) return 1 } func luaDate__index(L *lua.LState) int { d := luaCheckTime(L, 1) field := L.CheckString(2) switch field { case "Year", "year": L.Push(lua.LNumber(d.Year())) case "Month", "month": L.Push(lua.LNumber(float64(d.Month()))) case "Day", "day": L.Push(lua.LNumber(float64(d.Day()))) default: L.ArgError(2, "unexpected date attribute: "+field) } return 1 } func luaDate__tostring(L *lua.LState) int { a := luaCheckTime(L, 1) L.Push(lua.LString(a.Format(timeFormat))) return 1 } func luaDate__eq(L *lua.LState) int { a := luaCheckTime(L, 1) b := luaCheckTime(L, 2) L.Push(lua.LBool(a.Equal(*b))) return 1 } func luaDate__lt(L *lua.LState) int { a := luaCheckTime(L, 1) b := luaCheckTime(L, 2) L.Push(lua.LBool(a.Before(*b))) return 1 } func luaDate__le(L *lua.LState) int { a := luaCheckTime(L, 1) b := luaCheckTime(L, 2) L.Push(lua.LBool(a.Equal(*b) || a.Before(*b))) return 1 } func luaDate__add(L *lua.LState) int { a := luaCheckTime(L, 1) b := luaCheckTime(L, 2) date := a.AddDate(b.Year(), int(b.Month()), b.Day()) L.Push(TimeToLua(L, &date)) return 1 } func luaDate__sub(L *lua.LState) int { a := luaCheckTime(L, 1) b := luaCheckTime(L, 2) date := a.AddDate(-b.Year(), -int(b.Month()), -b.Day()) L.Push(TimeToLua(L, &date)) return 1 }