Merge branch 'develop' of https://github.com/ethereum/go-ethereum into develop

1 files changed, 70 insertions, 1 deletions

diff --git a/rlp/encode.go b/rlp/encode.go
index d80b66315..9d11d66bf 100644
--- a/rlp/encode.go
+++ b/rlp/encode.go
@@ -32,6 +32,48 @@ type Encoder interface {
 	EncodeRLP(io.Writer) error
 }
 
+// Flat wraps a value (which must encode as a list) so
+// it encodes as the list's elements.
+//
+// Example: suppose you have defined a type
+//
+//     type foo struct { A, B uint }
+//
+// Under normal encoding rules,
+//
+//     rlp.Encode(foo{1, 2}) --> 0xC20102
+//
+// This function can help you achieve the following encoding:
+//
+//     rlp.Encode(rlp.Flat(foo{1, 2})) --> 0x0102
+func Flat(val interface{}) Encoder {
+	return flatenc{val}
+}
+
+type flatenc struct{ val interface{} }
+
+func (e flatenc) EncodeRLP(out io.Writer) error {
+	// record current output position
+	var (
+		eb          = out.(*encbuf)
+		prevstrsize = len(eb.str)
+		prevnheads  = len(eb.lheads)
+	)
+	if err := eb.encode(e.val); err != nil {
+		return err
+	}
+	// check that a new list header has appeared
+	if len(eb.lheads) == prevnheads || eb.lheads[prevnheads].offset == prevstrsize-1 {
+		return fmt.Errorf("rlp.Flat: %T did not encode as list", e.val)
+	}
+	// remove the new list header
+	newhead := eb.lheads[prevnheads]
+	copy(eb.lheads[prevnheads:], eb.lheads[prevnheads+1:])
+	eb.lheads = eb.lheads[:len(eb.lheads)-1]
+	eb.lhsize -= newhead.tagsize()
+	return nil
+}
+
 // Encode writes the RLP encoding of val to w. Note that Encode may
 // perform many small writes in some cases. Consider making w
 // buffered.
@@ -123,6 +165,13 @@ func (head *listhead) encode(buf []byte) []byte {
 	}
 }
 
+func (head *listhead) tagsize() int {
+	if head.size < 56 {
+		return 1
+	}
+	return 1 + intsize(uint64(head.size))
+}
+
 func newencbuf() *encbuf {
 	return &encbuf{sizebuf: make([]byte, 9)}
 }
@@ -301,8 +350,10 @@ func makeWriter(typ reflect.Type) (writer, error) {
 		return writeUint, nil
 	case kind == reflect.String:
 		return writeString, nil
-	case kind == reflect.Slice && typ.Elem().Kind() == reflect.Uint8 && !typ.Elem().Implements(encoderInterface):
+	case kind == reflect.Slice && isByte(typ.Elem()):
 		return writeBytes, nil
+	case kind == reflect.Array && isByte(typ.Elem()):
+		return writeByteArray, nil
 	case kind == reflect.Slice || kind == reflect.Array:
 		return makeSliceWriter(typ)
 	case kind == reflect.Struct:
@@ -314,6 +365,10 @@ func makeWriter(typ reflect.Type) (writer, error) {
 	}
 }
 
+func isByte(typ reflect.Type) bool {
+	return typ.Kind() == reflect.Uint8 && !typ.Implements(encoderInterface)
+}
+
 func writeUint(val reflect.Value, w *encbuf) error {
 	i := val.Uint()
 	if i == 0 {
@@ -358,6 +413,20 @@ func writeBytes(val reflect.Value, w *encbuf) error {
 	return nil
 }
 
+func writeByteArray(val reflect.Value, w *encbuf) error {
+	if !val.CanAddr() {
+		// Slice requires the value to be addressable.
+		// Make it addressable by copying.
+		copy := reflect.New(val.Type()).Elem()
+		copy.Set(val)
+		val = copy
+	}
+	size := val.Len()
+	slice := val.Slice(0, size).Bytes()
+	w.encodeString(slice)
+	return nil
+}
+
 func writeString(val reflect.Value, w *encbuf) error {
 	s := val.String()
 	w.encodeStringHeader(len(s))