envconf/datatype.go

package envconf
import ("fmt"
        "errors"
        "time"
        "strconv")

type DataType int
const (
    TypeNone DataType = iota
    TypeInt DataType = iota
    TypeDuration DataType = iota
    TypeString DataType = iota
    TypeBool DataType = iota
)

func (dtype DataType) String()(string) {
    types := make(map[DataType]string)
    types[TypeNone] = "none"
    types[TypeInt] = "int"
    types[TypeDuration] = "duration"
    types[TypeString] = "string"
    types[TypeBool] = "bool"
    str, ok := types[dtype]
    if ok {
        return str
    }
    return "invalid"
}

type cValue struct {
    intval int64
    durval time.Duration
    boolval bool
    strval string
    err error
}

func (dtype DataType) parse(key string, str string)(ret cValue) {
    parsers := make(map[DataType](func(string,string)(cValue)))
    parsers[TypeInt] = parseInt
    parsers[TypeDuration] = parseDuration
    parsers[TypeString] = parseString
    parsers[TypeBool] = parseBool
    parser, ok := parsers[dtype]
    if ok {
        return parser(key, str)
    }
    return
}

func parseInt(key string, str string)(ret cValue) {
    val, err := strconv.ParseInt(str, 10, 64)
    if err == nil {
        ret.intval = val
    } else {
        ret.err = errors.New(fmt.Sprintf(`Environment variable "%s" is not of type int.`, key))
    }
    return
}

func parseDuration(key string, str string)(ret cValue) {
    val, err := time.ParseDuration(str)
    if err == nil {
        ret.durval = val
    } else {
        ret.err = errors.New(fmt.Sprintf(`Environment variable "%s" is not of type duration.`, key))
    }
    return
}

func parseBool(key string, str string)(ret cValue) {
    val, err := strconv.ParseBool(str)
    if err == nil {
        ret.boolval = val
    } else {
        ret.err = errors.New(fmt.Sprintf(`Environment variable "%s" is not of type bool.`, key))
    }
    return
}

func parseString(_ string, str string)(ret cValue) {
    ret.strval = str
    return
}