| // Copyright 2015 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 bio implements common I/O abstractions used within the Go toolchain. |
| package bio |
| |
| import ( |
| "bufio" |
| "log" |
| "os" |
| ) |
| |
| // Reader implements a seekable buffered io.Reader. |
| type Reader struct { |
| f *os.File |
| *bufio.Reader |
| } |
| |
| // Writer implements a seekable buffered io.Writer. |
| type Writer struct { |
| f *os.File |
| *bufio.Writer |
| } |
| |
| // Create creates the file named name and returns a Writer |
| // for that file. |
| func Create(name string) (*Writer, error) { |
| f, err := os.Create(name) |
| if err != nil { |
| return nil, err |
| } |
| return &Writer{f: f, Writer: bufio.NewWriter(f)}, nil |
| } |
| |
| // Open returns a Reader for the file named name. |
| func Open(name string) (*Reader, error) { |
| f, err := os.Open(name) |
| if err != nil { |
| return nil, err |
| } |
| return &Reader{f: f, Reader: bufio.NewReader(f)}, nil |
| } |
| |
| func (r *Reader) Seek(offset int64, whence int) int64 { |
| if whence == 1 { |
| offset -= int64(r.Buffered()) |
| } |
| off, err := r.f.Seek(offset, whence) |
| if err != nil { |
| log.Fatalf("seeking in output: %v", err) |
| } |
| r.Reset(r.f) |
| return off |
| } |
| |
| func (w *Writer) Seek(offset int64, whence int) int64 { |
| if err := w.Flush(); err != nil { |
| log.Fatalf("writing output: %v", err) |
| } |
| off, err := w.f.Seek(offset, whence) |
| if err != nil { |
| log.Fatalf("seeking in output: %v", err) |
| } |
| return off |
| } |
| |
| func (r *Reader) Offset() int64 { |
| off, err := r.f.Seek(0, 1) |
| if err != nil { |
| log.Fatalf("seeking in output [0, 1]: %v", err) |
| } |
| off -= int64(r.Buffered()) |
| return off |
| } |
| |
| func (w *Writer) Offset() int64 { |
| if err := w.Flush(); err != nil { |
| log.Fatalf("writing output: %v", err) |
| } |
| off, err := w.f.Seek(0, 1) |
| if err != nil { |
| log.Fatalf("seeking in output [0, 1]: %v", err) |
| } |
| return off |
| } |
| |
| func (r *Reader) Close() error { |
| return r.f.Close() |
| } |
| |
| func (w *Writer) Close() error { |
| err := w.Flush() |
| err1 := w.f.Close() |
| if err == nil { |
| err = err1 |
| } |
| return err |
| } |