1 // Copyright 2015 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 bio implements common I/O abstractions used within the Go toolchain. 6 package bio 7 8 import ( 9 "bufio" 10 "log" 11 "os" 12 ) 13 14 // Reader implements a seekable buffered io.Reader. 15 type Reader struct { 16 f *os.File 17 *bufio.Reader 18 } 19 20 // Writer implements a seekable buffered io.Writer. 21 type Writer struct { 22 f *os.File 23 *bufio.Writer 24 } 25 26 // Create creates the file named name and returns a Writer 27 // for that file. 28 func Create(name string) (*Writer, error) { 29 f, err := os.Create(name) 30 if err != nil { 31 return nil, err 32 } 33 return &Writer{f: f, Writer: bufio.NewWriter(f)}, nil 34 } 35 36 // Open returns a Reader for the file named name. 37 func Open(name string) (*Reader, error) { 38 f, err := os.Open(name) 39 if err != nil { 40 return nil, err 41 } 42 return &Reader{f: f, Reader: bufio.NewReader(f)}, nil 43 } 44 45 func (r *Reader) Seek(offset int64, whence int) int64 { 46 if whence == 1 { 47 offset -= int64(r.Buffered()) 48 } 49 off, err := r.f.Seek(offset, whence) 50 if err != nil { 51 log.Fatalf("seeking in output: %v", err) 52 } 53 r.Reset(r.f) 54 return off 55 } 56 57 func (w *Writer) Seek(offset int64, whence int) int64 { 58 if err := w.Flush(); err != nil { 59 log.Fatalf("writing output: %v", err) 60 } 61 off, err := w.f.Seek(offset, whence) 62 if err != nil { 63 log.Fatalf("seeking in output: %v", err) 64 } 65 return off 66 } 67 68 func (r *Reader) Offset() int64 { 69 off, err := r.f.Seek(0, 1) 70 if err != nil { 71 log.Fatalf("seeking in output [0, 1]: %v", err) 72 } 73 off -= int64(r.Buffered()) 74 return off 75 } 76 77 func (w *Writer) Offset() int64 { 78 if err := w.Flush(); err != nil { 79 log.Fatalf("writing output: %v", err) 80 } 81 off, err := w.f.Seek(0, 1) 82 if err != nil { 83 log.Fatalf("seeking in output [0, 1]: %v", err) 84 } 85 return off 86 } 87 88 func (r *Reader) Close() error { 89 return r.f.Close() 90 } 91 92 func (w *Writer) Close() error { 93 err := w.Flush() 94 err1 := w.f.Close() 95 if err == nil { 96 err = err1 97 } 98 return err 99 } 100
