Source file src/pkg/io/multi.go
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 are drained, Read will return EOF. 30 func MultiReader(readers ...Reader) Reader { 31 return &multiReader{readers} 32 } 33 34 type multiWriter struct { 35 writers []Writer 36 } 37 38 func (t *multiWriter) Write(p []byte) (n int, err error) { 39 for _, w := range t.writers { 40 n, err = w.Write(p) 41 if err != nil { 42 return 43 } 44 if n != len(p) { 45 err = ErrShortWrite 46 return 47 } 48 } 49 return len(p), nil 50 } 51 52 // MultiWriter creates a writer that duplicates its writes to all the 53 // provided writers, similar to the Unix tee(1) command. 54 func MultiWriter(writers ...Writer) Writer { 55 return &multiWriter{writers} 56 }