Refactor overflowError to be pretty-printable

decode.go

@@ -524,19 +524,6 @@ func (d *Decoder) convertValue(v reflect.Value, typ reflect.Type, src ast.Node)
 	return v.Convert(typ), nil
 }
 
-type overflowError struct {
-	dstType reflect.Type
-	srcNum  string
-}
-
-func (e *overflowError) Error() string {
-	return fmt.Sprintf("cannot unmarshal %s into Go value of type %s ( overflow )", e.srcNum, e.dstType)
-}
-
-func errOverflow(dstType reflect.Type, num string) *overflowError {
-	return &overflowError{dstType: dstType, srcNum: num}
-}
-
 func errTypeMismatch(dstType, srcType reflect.Type, token *token.Token) *errors.TypeError {
 	return &errors.TypeError{DstType: dstType, SrcType: srcType, Token: token}
 }
@@ -904,7 +891,7 @@ func (d *Decoder) decodeValue(ctx context.Context, dst reflect.Value, src ast.No
 		default:
 			return errTypeMismatch(valueType, reflect.TypeOf(v), src.GetToken())
 		}
-		return errOverflow(valueType, fmt.Sprint(v))
+		return errors.ErrOverflow(valueType, fmt.Sprint(v), src.GetToken())
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
 		v := d.nodeToValue(src)
 		switch vv := v.(type) {
@@ -936,7 +923,7 @@ func (d *Decoder) decodeValue(ctx context.Context, dst reflect.Value, src ast.No
 		default:
 			return errTypeMismatch(valueType, reflect.TypeOf(v), src.GetToken())
 		}
-		return errOverflow(valueType, fmt.Sprint(v))
+		return errors.ErrOverflow(valueType, fmt.Sprint(v), src.GetToken())
 	}
 	v := reflect.ValueOf(d.nodeToValue(src))
 	if v.IsValid() {

internal/errors/error.go

@@ -39,6 +39,11 @@ func ErrSyntax(msg string, tk *token.Token) *syntaxError {
 	}
 }
 
+// ErrOverflow creates an overflow error instance with message and a token.
+func ErrOverflow(dstType reflect.Type, num string, tk *token.Token) *overflowError {
+	return &overflowError{dstType: dstType, srcNum: num, token: tk}
+}
+
 type baseError struct {
 	state fmt.State
 	verb  rune
@@ -164,6 +169,39 @@ func (e *wrapError) Error() string {
 	return buf.String()
 }
 
+type overflowError struct {
+	dstType reflect.Type
+	srcNum  string
+	token   *token.Token
+}
+
+func (e *overflowError) Error() string {
+	return fmt.Sprintf("cannot unmarshal %s into Go value of type %s ( overflow )", e.srcNum, e.dstType)
+}
+
+func (e *overflowError) PrettyPrint(p xerrors.Printer, colored, inclSource bool) error {
+	return e.FormatError(&FormatErrorPrinter{Printer: p, Colored: colored, InclSource: inclSource})
+}
+
+func (e *overflowError) FormatError(p xerrors.Printer) error {
+	var pp printer.Printer
+
+	var colored, inclSource bool
+	if fep, ok := p.(*FormatErrorPrinter); ok {
+		colored = fep.Colored
+		inclSource = fep.InclSource
+	}
+
+	pos := fmt.Sprintf("[%d:%d] ", e.token.Position.Line, e.token.Position.Column)
+	msg := pp.PrintErrorMessage(fmt.Sprintf("%s%s", pos, e.Error()), colored)
+	if inclSource {
+		msg += "\n" + pp.PrintErrorToken(e.token, colored)
+	}
+	p.Print(msg)
+
+	return nil
+}
+
 type syntaxError struct {
 	*baseError
 	msg   string