bytes, strings: add (*Reader).WriteTo
Fixes #4031.
R=golang-dev, bradfitz, remyoudompheng, r, dave
CC=golang-dev
https://golang.org/cl/6632046
diff --git a/src/pkg/strings/reader.go b/src/pkg/strings/reader.go
index 8569805..98325ce 100644
--- a/src/pkg/strings/reader.go
+++ b/src/pkg/strings/reader.go
@@ -10,7 +10,7 @@
"unicode/utf8"
)
-// A Reader implements the io.Reader, io.ReaderAt, io.Seeker,
+// A Reader implements the io.Reader, io.ReaderAt, io.Seeker, io.WriterTo,
// io.ByteScanner, and io.RuneScanner interfaces by reading
// from a string.
type Reader struct {
@@ -120,6 +120,25 @@
return abs, nil
}
+// WriteTo implements the io.WriterTo interface.
+func (r *Reader) WriteTo(w io.Writer) (n int64, err error) {
+ r.prevRune = -1
+ if r.i >= len(r.s) {
+ return 0, io.EOF
+ }
+ s := r.s[r.i:]
+ m, err := io.WriteString(w, s)
+ if m > len(s) {
+ panic("strings.Reader.WriteTo: invalid WriteString count")
+ }
+ r.i += m
+ n = int64(m)
+ if m != len(s) && err == nil {
+ err = io.ErrShortWrite
+ }
+ return
+}
+
// NewReader returns a new Reader reading from s.
// It is similar to bytes.NewBufferString but more efficient and read-only.
func NewReader(s string) *Reader { return &Reader{s, 0, -1} }
