Return errors rather than doing panics.

This makes it simpler to handle errors in code importing this package.

encode.go

@@ -8,6 +8,14 @@ import (
 	"reflect"
 )
 
+type TypeError struct {
+	typ string
+}
+
+func (te *TypeError) Error() string {
+	return fmt.Sprintf("no support for type '%s'", te.typ)
+}
+
 // An Encoder encodes Go data structures into pickle byte stream
 type Encoder struct {
 	w io.Writer
@@ -79,7 +87,7 @@ func (e *Encoder) encode(rv reflect.Value) error {
 		e.w.Write([]byte{opNone})
 
 	default:
-		panic(fmt.Sprintf("no support for type '%s'", rk.String()))
+		return &TypeError{typ: rk.String()}
 	}
 
 	return nil

ogórek.go

@@ -80,6 +80,7 @@ const (
 
 var errNotImplemented = errors.New("unimplemented opcode")
 var ErrInvalidPickleVersion = errors.New("invalid pickle version")
+var ErrNoMarker = errors.New("no marker in stack")
 
 type OpcodeError struct {
 	Key byte
@@ -243,15 +244,15 @@ func (d *Decoder) mark() {
 }
 
 // Return the position of the topmost marker
-func (d *Decoder) marker() int {
+func (d *Decoder) marker() (int, error) {
 	m := mark{}
 	var k int
 	for k = len(d.stack) - 1; d.stack[k] != m && k > 0; k-- {
 	}
 	if k >= 0 {
-		return k
+		return k, nil
 	}
-	panic("no marker in stack")
+	return 0, ErrNoMarker
 }
 
 // Append a new value
@@ -553,7 +554,11 @@ func (d *Decoder) global() error {
 }
 
 func (d *Decoder) loadDict() error {
-	k := d.marker()
+	k, err := d.marker()
+	if err != nil {
+		return err
+	}
+
 	m := make(map[interface{}]interface{}, 0)
 	items := d.stack[k+1:]
 	for i := 0; i < len(items); i += 2 {
@@ -570,7 +575,11 @@ func (d *Decoder) loadEmptyDict() error {
 }
 
 func (d *Decoder) loadAppends() error {
-	k := d.marker()
+	k, err := d.marker()
+	if err != nil {
+		return err
+	}
+
 	l := d.stack[k-1]
 	switch l.(type) {
 	case []interface{}:
@@ -621,14 +630,22 @@ func (d *Decoder) loadBool(b bool) error {
 }
 
 func (d *Decoder) loadList() error {
-	k := d.marker()
+	k, err := d.marker()
+	if err != nil {
+		return err
+	}
+
 	v := append([]interface{}{}, d.stack[k+1:]...)
 	d.stack = append(d.stack[:k], v)
 	return nil
 }
 
 func (d *Decoder) loadTuple() error {
-	k := d.marker()
+	k, err := d.marker()
+	if err != nil {
+		return err
+	}
+
 	v := append([]interface{}{}, d.stack[k+1:]...)
 	d.stack = append(d.stack[:k], v)
 	return nil
@@ -700,7 +717,11 @@ func (d *Decoder) loadSetItem() error {
 }
 
 func (d *Decoder) loadSetItems() error {
-	k := d.marker()
+	k, err := d.marker()
+	if err != nil {
+		return err
+	}
+
 	l := d.stack[k-1]
 	switch m := l.(type) {
 	case map[interface{}]interface{}:

ogórek_test.go

@@ -18,7 +18,11 @@ func TestMarker(t *testing.T) {
 	buf := bytes.Buffer{}
 	dec := NewDecoder(&buf)
 	dec.mark()
-	if dec.marker() != 0 {
+	k, err := dec.marker()
+	if err != nil {
+		t.Error(err)
+	}
+	if k != 0 {
 		t.Error("no marker found")
 	}
 }
@@ -50,7 +54,7 @@ func TestDecode(t *testing.T) {
 		{"unicode", "V\\u65e5\\u672c\\u8a9e\np0\n.", string("日本語")},
 		{"empty dict", "(dp0\n.", make(map[interface{}]interface{})},
 		{"dict with strings", "(dp0\nS'a'\np1\nS'1'\np2\nsS'b'\np3\nS'2'\np4\ns.", map[interface{}]interface{}{"a": "1", "b": "2"}},
-		{"GLOBAL and REDUCE opcodes", "cfoo\nbar\nS'bing'\n\x85R.", Call{Callable: Class{Module: "foo", Name: "bar"}, Args: []interface{} {"bing"}}},
+		{"GLOBAL and REDUCE opcodes", "cfoo\nbar\nS'bing'\n\x85R.", Call{Callable: Class{Module: "foo", Name: "bar"}, Args: []interface{}{"bing"}}},
 		{"LONG_BINPUT opcode", "(lr0000I17\na.", []interface{}{int64(17)}},
 		{"graphite message1", string(graphitePickle1), []interface{}{map[interface{}]interface{}{"values": []interface{}{float64(473), float64(497), float64(540), float64(1497), float64(1808), float64(1890), float64(2013), float64(1821), float64(1847), float64(2176), float64(2156), float64(1250), float64(2055), float64(1570), None{}, None{}}, "start": int64(1383782400), "step": int64(86400), "end": int64(1385164800), "name": "ZZZZ.UUUUUUUU.CCCCCCCC.MMMMMMMM.XXXXXXXXX.TTT"}}},
 		{"graphite message2", string(graphitePickle2), []interface{}{map[interface{}]interface{}{"values": []interface{}{float64(473), float64(497), float64(540), float64(1497), float64(1808), float64(1890), float64(2013), float64(1821), float64(1847), float64(2176), float64(2156), float64(1250), float64(2055), float64(1570), None{}, None{}}, "start": int64(1383782400), "step": int64(86400), "end": int64(1385164800), "name": "user.login.area.machine.metric.minute"}}},