unmarshal: support encoding.TextUnmarshaler

marshal.go

@@ -71,6 +71,7 @@ const (
 var timeType = reflect.TypeOf(time.Time{})
 var marshalerType = reflect.TypeOf(new(Marshaler)).Elem()
 var textMarshalerType = reflect.TypeOf(new(encoding.TextMarshaler)).Elem()
+var textUnmarshalerType = reflect.TypeOf(new(encoding.TextUnmarshaler)).Elem()
 var localDateType = reflect.TypeOf(LocalDate{})
 var localTimeType = reflect.TypeOf(LocalTime{})
 var localDateTimeType = reflect.TypeOf(LocalDateTime{})
@@ -155,6 +156,14 @@ func callTextMarshaler(mval reflect.Value) ([]byte, error) {
 	return mval.Interface().(encoding.TextMarshaler).MarshalText()
 }
 
+func isTextUnmarshaler(mtype reflect.Type) bool {
+	return mtype.Implements(textUnmarshalerType)
+}
+
+func callTextUnmarshaler(mval reflect.Value, text []byte) error {
+	return mval.Interface().(encoding.TextUnmarshaler).UnmarshalText(text)
+}
+
 // Marshaler is the interface implemented by types that
 // can marshal themselves into valid TOML.
 type Marshaler interface {
@@ -866,6 +875,14 @@ func (d *Decoder) valueFromToml(mtype reflect.Type, tval interface{}, mval1 *ref
 		return reflect.ValueOf(nil), fmt.Errorf("Can't convert %v(%T) to a slice", tval, tval)
 	default:
 		d.visitor.visit()
+		// Check if pointer to value implements the encoding.TextUnmarshaler.
+		if mvalPtr := reflect.New(mtype); isTextUnmarshaler(mvalPtr.Type()) && !isTimeType(mtype) {
+			if err := d.unmarshalText(tval, mvalPtr); err != nil {
+				return reflect.ValueOf(nil), fmt.Errorf("unmarshal text: %v", err)
+			}
+			return mvalPtr.Elem(), nil
+		}
+
 		switch mtype.Kind() {
 		case reflect.Bool, reflect.Struct:
 			val := reflect.ValueOf(tval)
@@ -983,6 +1000,12 @@ func (d *Decoder) unwrapPointer(mtype reflect.Type, tval interface{}, mval1 *ref
 	return mval, nil
 }
 
+func (d *Decoder) unmarshalText(tval interface{}, mval reflect.Value) error {
+	var buf bytes.Buffer
+	fmt.Fprint(&buf, tval)
+	return callTextUnmarshaler(mval, buf.Bytes())
+}
+
 func tomlOptions(vf reflect.StructField, an annotation) tomlOpts {
 	tag := vf.Tag.Get(an.tag)
 	parse := strings.Split(tag, ",")

marshal_test.go

@@ -7,6 +7,7 @@ import (
 	"io/ioutil"
 	"os"
 	"reflect"
+	"strconv"
 	"strings"
 	"testing"
 	"time"
@@ -3226,3 +3227,74 @@ func TestDecoderStrictValid(t *testing.T) {
 		t.Fatal("unexpected error:", err)
 	}
 }
+
+type intWrapper struct {
+	Value int
+}
+
+func (w *intWrapper) UnmarshalText(text []byte) error {
+	var err error
+	if w.Value, err = strconv.Atoi(string(text)); err == nil {
+		return nil
+	}
+	if b, err := strconv.ParseBool(string(text)); err == nil {
+		if b {
+			w.Value = 1
+		}
+		return nil
+	}
+	if f, err := strconv.ParseFloat(string(text), 32); err == nil {
+		w.Value = int(f)
+		return nil
+	}
+	return fmt.Errorf("unsupported: %s", text)
+}
+
+func TestTextUnmarshal(t *testing.T) {
+	var doc struct {
+		UnixTime intWrapper
+		Version  *intWrapper
+
+		Bool  intWrapper
+		Int   intWrapper
+		Float intWrapper
+	}
+
+	input := `
+UnixTime = "12"
+Version = "42"
+Bool = true
+Int = 21
+Float = 2.0
+`
+
+	if err := Unmarshal([]byte(input), &doc); err != nil {
+		t.Fatalf("unexpected err: %s", err.Error())
+	}
+	if doc.UnixTime.Value != 12 {
+		t.Fatalf("expected UnixTime: 12 got: %d", doc.UnixTime.Value)
+	}
+	if doc.Version.Value != 42 {
+		t.Fatalf("expected Version: 42 got: %d", doc.Version.Value)
+	}
+	if doc.Bool.Value != 1 {
+		t.Fatalf("expected Bool: 1 got: %d", doc.Bool.Value)
+	}
+	if doc.Int.Value != 21 {
+		t.Fatalf("expected Int: 21 got: %d", doc.Int.Value)
+	}
+	if doc.Float.Value != 2 {
+		t.Fatalf("expected Float: 2 got: %d", doc.Float.Value)
+	}
+}
+
+func TestTextUnmarshalError(t *testing.T) {
+	var doc struct {
+		Failer intWrapper
+	}
+
+	input := `Failer = "hello"`
+	if err := Unmarshal([]byte(input), &doc); err == nil {
+		t.Fatalf("expected err, got none")
+	}
+}