79 lines
1.7 KiB
Go
79 lines
1.7 KiB
Go
package arg
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import (
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"encoding"
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"fmt"
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"reflect"
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"strconv"
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"time"
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)
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// set a value from a string
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func setScalar(v reflect.Value, s string) error {
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if !v.CanSet() {
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return fmt.Errorf("field is not exported")
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}
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// If we have a nil pointer then allocate a new object
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if v.Kind() == reflect.Ptr && v.IsNil() {
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v.Set(reflect.New(v.Type().Elem()))
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}
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// Get the object as an interface
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scalar := v.Interface()
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// If it implements encoding.TextUnmarshaler then use that
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if scalar, ok := scalar.(encoding.TextUnmarshaler); ok {
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return scalar.UnmarshalText([]byte(s))
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}
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// If we have a pointer then dereference it
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if v.Kind() == reflect.Ptr {
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v = v.Elem()
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}
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// Switch on concrete type
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switch scalar.(type) {
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case time.Duration:
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x, err := time.ParseDuration(s)
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if err != nil {
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return err
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}
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v.Set(reflect.ValueOf(x))
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return nil
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}
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// Switch on kind so that we can handle derived types
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switch v.Kind() {
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case reflect.String:
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v.SetString(s)
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case reflect.Bool:
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x, err := strconv.ParseBool(s)
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if err != nil {
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return err
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}
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v.SetBool(x)
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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x, err := strconv.ParseInt(s, 10, v.Type().Bits())
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if err != nil {
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return err
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}
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v.SetInt(x)
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
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x, err := strconv.ParseUint(s, 10, v.Type().Bits())
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if err != nil {
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return err
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}
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v.SetUint(x)
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case reflect.Float32, reflect.Float64:
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x, err := strconv.ParseFloat(s, v.Type().Bits())
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if err != nil {
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return err
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}
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v.SetFloat(x)
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default:
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return fmt.Errorf("cannot parse argument into %s", v.Type().String())
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}
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return nil
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}
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