1 // Copyright 2010 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
7 type eofReader
struct{}
9 func (eofReader
) Read([]byte) (int, error
) {
13 type multiReader
struct {
17 func (mr
*multiReader
) Read(p
[]byte) (n
int, err error
) {
18 for len(mr
.readers
) > 0 {
19 // Optimization to flatten nested multiReaders (Issue 13558).
20 if len(mr
.readers
) == 1 {
21 if r
, ok
:= mr
.readers
[0].(*multiReader
); ok
{
22 mr
.readers
= r
.readers
26 n
, err
= mr
.readers
[0].Read(p
)
28 // Use eofReader instead of nil to avoid nil panic
29 // after performing flatten (Issue 18232).
30 mr
.readers
[0] = eofReader
{} // permit earlier GC
31 mr
.readers
= mr
.readers
[1:]
33 if n
> 0 || err
!= EOF
{
34 if err
== EOF
&& len(mr
.readers
) > 0 {
35 // Don't return EOF yet. More readers remain.
44 // MultiReader returns a Reader that's the logical concatenation of
45 // the provided input readers. They're read sequentially. Once all
46 // inputs have returned EOF, Read will return EOF. If any of the readers
47 // return a non-nil, non-EOF error, Read will return that error.
48 func MultiReader(readers
...Reader
) Reader
{
49 r
:= make([]Reader
, len(readers
))
51 return &multiReader
{r
}
54 type multiWriter
struct {
58 func (t
*multiWriter
) Write(p
[]byte) (n
int, err error
) {
59 for _
, w
:= range t
.writers
{
72 var _ stringWriter
= (*multiWriter
)(nil)
74 func (t
*multiWriter
) WriteString(s
string) (n
int, err error
) {
75 var p
[]byte // lazily initialized if/when needed
76 for _
, w
:= range t
.writers
{
77 if sw
, ok
:= w
.(stringWriter
); ok
{
78 n
, err
= sw
.WriteString(s
)
96 // MultiWriter creates a writer that duplicates its writes to all the
97 // provided writers, similar to the Unix tee(1) command.
98 func MultiWriter(writers
...Writer
) Writer
{
99 w
:= make([]Writer
, len(writers
))
101 return &multiWriter
{w
}