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. 4 5 package io 6 7 type multiReader struct { 8 readers []Reader 9 } 10 11 func (mr *multiReader) Read(p []byte) (n int, err error) { 12 for len(mr.readers) > 0 { 13 n, err = mr.readers[0].Read(p) 14 if n > 0 || err != EOF { 15 if err == EOF { 16 // Don't return EOF yet. There may be more bytes 17 // in the remaining readers. 18 err = nil 19 } 20 return 21 } 22 mr.readers = mr.readers[1:] 23 } 24 return 0, EOF 25 } 26 27 // MultiReader returns a Reader that's the logical concatenation of 28 // the provided input readers. They're read sequentially. Once all 29 // inputs have returned EOF, Read will return EOF. If any of the readers 30 // return a non-nil, non-EOF error, Read will return that error. 31 func MultiReader(readers ...Reader) Reader { 32 r := make([]Reader, len(readers)) 33 copy(r, readers) 34 return &multiReader{r} 35 } 36 37 type multiWriter struct { 38 writers []Writer 39 } 40 41 func (t *multiWriter) Write(p []byte) (n int, err error) { 42 for _, w := range t.writers { 43 n, err = w.Write(p) 44 if err != nil { 45 return 46 } 47 if n != len(p) { 48 err = ErrShortWrite 49 return 50 } 51 } 52 return len(p), nil 53 } 54 55 // MultiWriter creates a writer that duplicates its writes to all the 56 // provided writers, similar to the Unix tee(1) command. 57 func MultiWriter(writers ...Writer) Writer { 58 w := make([]Writer, len(writers)) 59 copy(w, writers) 60 return &multiWriter{w} 61 } 62
