goutils/seekbuf/seekbuf.go

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// Package seekbuf implements a read-seekable buffer.
package seekbuf
import "io"
// Buffer is a ReadWriteCloser that supports seeking. It's intended to
// replicate the functionality of bytes.Buffer that I use in my projects.
//
// Note that the seeking is limited to the read marker; all writes are
// append-only.
type Buffer struct {
data []byte
pos int
}
func New(data []byte) *Buffer {
return &Buffer{
data: data,
}
}
func (b *Buffer) Read(p []byte) (int, error) {
if b.pos >= len(b.data) {
return 0, io.EOF
}
n := copy(p, b.data[b.pos:])
b.pos += n
return n, nil
}
func (b *Buffer) Write(p []byte) (int, error) {
b.data = append(b.data, p...)
return len(p), nil
}
// Seek sets the read pointer to pos.
func (b *Buffer) Seek(pos int) {
b.pos = pos
}
// Rewind resets the read pointer to 0.
func (b *Buffer) Rewind() {
b.Seek(0)
}
// Close clears all the data out of the buffer and sets the read position to 0.
func (b *Buffer) Close() error {
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b.data = nil
b.pos = 0
return nil
}
// Len returns the length of data remaining to be read.
func (b *Buffer) Len() int {
return len(b.data[b.pos:])
}