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83 lines
1.6 KiB
83 lines
1.6 KiB
package buffer
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import (
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"bytes"
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"encoding/gob"
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"fmt"
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"io"
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"github.com/djherbis/buffer/limio"
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)
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type memory struct {
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N int64
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*bytes.Buffer
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}
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// New returns a new in memory BufferAt with max size N.
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// It's backed by a bytes.Buffer.
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func New(n int64) BufferAt {
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return &memory{
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N: n,
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Buffer: bytes.NewBuffer(nil),
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}
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}
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func (buf *memory) Cap() int64 {
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return buf.N
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}
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func (buf *memory) Len() int64 {
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return int64(buf.Buffer.Len())
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}
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func (buf *memory) Write(p []byte) (n int, err error) {
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return limio.LimitWriter(buf.Buffer, Gap(buf)).Write(p)
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}
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func (buf *memory) WriteAt(p []byte, off int64) (n int, err error) {
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if off > buf.Len() {
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return 0, io.ErrShortWrite
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} else if len64(p)+off <= buf.Len() {
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d := buf.Bytes()[off:]
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return copy(d, p), nil
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} else {
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d := buf.Bytes()[off:]
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n = copy(d, p)
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m, err := buf.Write(p[n:])
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return n + m, err
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}
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}
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func (buf *memory) ReadAt(p []byte, off int64) (n int, err error) {
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return bytes.NewReader(buf.Bytes()).ReadAt(p, off)
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}
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func (buf *memory) Read(p []byte) (n int, err error) {
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return io.LimitReader(buf.Buffer, buf.Len()).Read(p)
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}
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func (buf *memory) ReadFrom(r io.Reader) (n int64, err error) {
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return buf.Buffer.ReadFrom(io.LimitReader(r, Gap(buf)))
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}
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func init() {
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gob.Register(&memory{})
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}
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func (buf *memory) MarshalBinary() ([]byte, error) {
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var b bytes.Buffer
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fmt.Fprintln(&b, buf.N)
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b.Write(buf.Bytes())
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return b.Bytes(), nil
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}
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func (buf *memory) UnmarshalBinary(bindata []byte) error {
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data := make([]byte, len(bindata))
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copy(data, bindata)
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b := bytes.NewBuffer(data)
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_, err := fmt.Fscanln(b, &buf.N)
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buf.Buffer = bytes.NewBuffer(b.Bytes())
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return err
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}
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