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encoding/binary: Add support for slices of arrays of fixed-size values.

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R=rsc
CC=krasin
https://golang.org/cl/167050
This commit is contained in:
Maxim Ushakov 2009-12-11 13:04:03 -08:00 committed by Russ Cox
parent ddde7f6625
commit 349095885e
2 changed files with 52 additions and 6 deletions
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43
src/pkg/encoding/binary/binary.go
View File

@ -113,15 +113,24 @@ func (bigEndian) String() string { return "BigEndian" }
func (bigEndian) GoString() string { return "binary.BigEndian" }
// Read reads structured binary data from r into data.
// Data must be a pointer to a fixed-size value.
// Data must be a pointer to a fixed-size value or a slice
// of fixed-size values.
// A fixed-size value is either a fixed-size integer
// (int8, uint8, int16, uint16, ...) or an array or struct
// containing only fixed-size values. Bytes read from
// r are decoded using the specified byte order and written
// to successive fields of the data.
func Read(r io.Reader, order ByteOrder, data interface{}) os.Error {
v := reflect.NewValue(data).(*reflect.PtrValue).Elem();
size := sizeof(v.Type());
var v reflect.Value;
switch d := reflect.NewValue(data).(type) {
case *reflect.PtrValue:
v = d.Elem()
case *reflect.SliceValue:
v = d
default:
return os.NewError("binary.Read: invalid type " + v.Type().String())
}
size := TotalSize(v);
if size < 0 {
return os.NewError("binary.Read: invalid type " + v.Type().String())
}
@ -143,7 +152,7 @@ func Read(r io.Reader, order ByteOrder, data interface{}) os.Error {
// from successive fields of the data.
func Write(w io.Writer, order ByteOrder, data interface{}) os.Error {
v := reflect.Indirect(reflect.NewValue(data));
size := sizeof(v.Type());
size := TotalSize(v);
if size < 0 {
return os.NewError("binary.Write: invalid type " + v.Type().String())
}
@ -154,8 +163,19 @@ func Write(w io.Writer, order ByteOrder, data interface{}) os.Error {
return err;
}
func sizeof(t reflect.Type) int {
switch t := t.(type) {
func TotalSize(v reflect.Value) int {
if sv, ok := v.(*reflect.SliceValue); ok {
elem := sizeof(v.Type().(*reflect.SliceType).Elem());
if elem < 0 {
return -1
}
return sv.Len() * elem;
}
return sizeof(v.Type());
}
func sizeof(v reflect.Type) int {
switch t := v.(type) {
case *reflect.ArrayType:
n := sizeof(t.Elem());
if n < 0 {
@ -281,6 +301,12 @@ func (d *decoder) value(v reflect.Value) {
d.value(v.Field(i))
}
case *reflect.SliceValue:
l := v.Len();
for i := 0; i < l; i++ {
d.value(v.Elem(i))
}
case *reflect.Uint8Value:
v.Set(d.uint8())
case *reflect.Uint16Value:
@ -316,6 +342,11 @@ func (e *encoder) value(v reflect.Value) {
for i := 0; i < l; i++ {
e.value(v.Field(i))
}
case *reflect.SliceValue:
l := v.Len();
for i := 0; i < l; i++ {
e.value(v.Elem(i))
}
case *reflect.Uint8Value:
e.uint8(v.Get())

15
src/pkg/encoding/binary/binary_test.go
View File

@ -64,6 +64,9 @@ var little = []byte{
39, 40, 41, 42,
}
var src = []byte{1, 2, 3, 4, 5, 6, 7, 8}
var res = []int32{0x01020304, 0x05060708}
func checkResult(t *testing.T, dir string, order, err os.Error, have, want interface{}) {
if err != nil {
t.Errorf("%v %v: %v", dir, order, err);
@ -97,3 +100,15 @@ func TestLittleEndianWrite(t *testing.T) { testWrite(t, LittleEndian, little, s)
func TestBigEndianPtrWrite(t *testing.T) { testWrite(t, BigEndian, big, &s) }
func TestLittleEndianPtrWrite(t *testing.T) { testWrite(t, LittleEndian, little, &s) }
func TestReadSlice(t *testing.T) {
slice := make([]int32, 2);
err := Read(bytes.NewBuffer(src), BigEndian, slice);
checkResult(t, "ReadSlice", BigEndian, err, slice, res);
}
func TestWriteSlice(t *testing.T) {
buf := new(bytes.Buffer);
err := Write(buf, BigEndian, res);
checkResult(t, "WriteSlice", BigEndian, err, buf.Bytes(), src);
}