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// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package io
type multiReader struct {
readers []Reader
}
func (mr *multiReader) Read(p []byte) (n int, err error) {
for len(mr.readers) > 0 {
// Optimization to flatten nested multiReaders (Issue 13558)
if len(mr.readers) == 1 {
if r, ok := mr.readers[0].(*multiReader); ok {
mr.readers = r.readers
continue
}
}
n, err = mr.readers[0].Read(p)
if err == EOF {
mr.readers = mr.readers[1:]
}
if n > 0 || err != EOF {
if err == EOF && len(mr.readers) > 0 {
// Don't return EOF yet. More readers remain.
err = nil
}
return
}
}
return 0, EOF
}
// MultiReader returns a Reader that's the logical concatenation of
// the provided input readers. They're read sequentially. Once all
// inputs have returned EOF, Read will return EOF. If any of the readers
// return a non-nil, non-EOF error, Read will return that error.
func MultiReader(readers ...Reader) Reader {
r := make([]Reader, len(readers))
copy(r, readers)
return &multiReader{r}
}
type multiWriter struct {
writers []Writer
}
func (t *multiWriter) Write(p []byte) (n int, err error) {
for _, w := range t.writers {
n, err = w.Write(p)
if err != nil {
return
}
if n != len(p) {
err = ErrShortWrite
return
}
}
return len(p), nil
}
var _ stringWriter = (*multiWriter)(nil)
func (t *multiWriter) WriteString(s string) (n int, err error) {
var p []byte // lazily initialized if/when needed
for _, w := range t.writers {
if sw, ok := w.(stringWriter); ok {
n, err = sw.WriteString(s)
} else {
if p == nil {
p = []byte(s)
}
n, err = w.Write(p)
}
if err != nil {
return
}
if n != len(s) {
err = ErrShortWrite
return
}
}
return len(s), nil
}
// MultiWriter creates a writer that duplicates its writes to all the
// provided writers, similar to the Unix tee(1) command.
func MultiWriter(writers ...Writer) Writer {
w := make([]Writer, len(writers))
copy(w, writers)
return &multiWriter{w}
}
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