diff options
Diffstat (limited to 'rlp')
| -rw-r--r-- | rlp/encode.go | 71 | ||||
| -rw-r--r-- | rlp/encode_test.go | 15 |
2 files changed, 85 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)) diff --git a/rlp/encode_test.go b/rlp/encode_test.go index 18b843737..c283fbd57 100644 --- a/rlp/encode_test.go +++ b/rlp/encode_test.go @@ -40,6 +40,8 @@ func (e *encodableReader) Read(b []byte) (int, error) { panic("called") } +type namedByteType byte + var ( _ = Encoder(&testEncoder{}) _ = Encoder(byteEncoder(0)) @@ -102,6 +104,10 @@ var encTests = []encTest{ // byte slices, strings {val: []byte{}, output: "80"}, {val: []byte{1, 2, 3}, output: "83010203"}, + + {val: []namedByteType{1, 2, 3}, output: "83010203"}, + {val: [...]namedByteType{1, 2, 3}, output: "83010203"}, + {val: "", output: "80"}, {val: "dog", output: "83646F67"}, { @@ -177,6 +183,15 @@ var encTests = []encTest{ {val: &recstruct{5, nil}, output: "C205C0"}, {val: &recstruct{5, &recstruct{4, &recstruct{3, nil}}}, output: "C605C404C203C0"}, + // flat + {val: Flat(uint(1)), error: "rlp.Flat: uint did not encode as list"}, + {val: Flat(simplestruct{A: 3, B: "foo"}), output: "0383666F6F"}, + { + // value generates more list headers after the Flat + val: []interface{}{"foo", []uint{1, 2}, Flat([]uint{3, 4}), []uint{5, 6}, "bar"}, + output: "D083666F6FC201020304C2050683626172", + }, + // nil {val: (*uint)(nil), output: "80"}, {val: (*string)(nil), output: "80"}, |