/
slice.go
201 lines (171 loc) · 4.15 KB
/
slice.go
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// Copyright 2015 The Golang Plus 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 bytesp
import (
"errors"
"io"
"strconv"
"unicode/utf8"
)
// Slice is a wrapper type for []byte.
// Its pointer form, *Slice, implements io.Reader, io.Writer, io.ByteReader,
// io.ByteWriter, io.Closer, io.ReaderFrom, io.WriterTo and io.RuneReader
// interfaces.
//
// Benchmark shows *Slice is a better alternative for bytes.Buffer for writings and consumes less resource.
type Slice []byte
var (
// Make sure *Slice implement the interfaces.
_ io.Reader = (*Slice)(nil)
_ io.Writer = (*Slice)(nil)
_ io.ByteReader = (*Slice)(nil)
_ io.ByteWriter = (*Slice)(nil)
_ io.Closer = (*Slice)(nil)
_ io.ReaderFrom = (*Slice)(nil)
_ io.WriterTo = (*Slice)(nil)
_ io.RuneReader = (*Slice)(nil)
)
// NewPSlice returns a *Slice with intialized contents.
func NewPSlice(bytes []byte) *Slice {
return (*Slice)(&bytes)
}
// Read implements the io.Reader interface.
// After some bytes are read, the slice shrinks.
func (s *Slice) Read(p []byte) (n int, err error) {
if len(p) == 0 {
return 0, nil
}
if len(*s) == 0 {
return 0, io.EOF
}
n = copy(p, *s)
if n == len(*s) {
*s = nil
} else {
*s = (*s)[n:]
}
return n, nil
}
// Reset sets the length of the slice to 0.
func (s *Slice) Reset() {
*s = (*s)[:0]
}
// Skip skips n bytes.
func (s *Slice) Skip(n int64) (int64, error) {
if n == 0 {
return 0, nil
}
if len(*s) == 0 {
return 0, io.EOF
}
if n >= int64(len(*s)) {
n = int64(len(*s))
*s = nil
} else {
*s = (*s)[int(n):]
}
return n, nil
}
// Write implements the io.Writer interface.
// Bytes are appended to the tail of the slice.
func (s *Slice) Write(p []byte) (n int, err error) {
*s = append(*s, p...)
return len(p), nil
}
// ReadByte implements the io.ByteReader interface.
func (s *Slice) ReadByte() (c byte, err error) {
if len(*s) < 1 {
return 0, io.EOF
}
c = (*s)[0]
if len(*s) > 1 {
*s = (*s)[1:]
} else {
*s = nil
}
return c, nil
}
// WriteByte implements the io.ByteWriter interface.
func (s *Slice) WriteByte(c byte) error {
*s = append(*s, c)
return nil
}
// Close implements the io.Closer interface.
// It does nothing.
func (s Slice) Close() error {
return nil
}
// ReadFrom implements the io.ReaderFrom interface.
func (s *Slice) ReadFrom(r io.Reader) (n int64, err error) {
const buf_SIZE = 32 * 1024
buf := make([]byte, buf_SIZE)
for {
nRead, err := r.Read(buf)
if nRead == 0 {
if err != io.EOF {
return n, err
}
break
}
n += int64(nRead)
*s = append(*s, buf[:nRead]...)
if err == io.EOF {
break
}
if err != nil {
return n, err
}
}
return n, nil
}
// WriteTo implements the io.WriterTo interface.
func (s Slice) WriteTo(w io.Writer) (n int64, err error) {
nWrite, err := w.Write(s)
return int64(nWrite), err
}
// ReadRune implements the io.RuneReader interface.
func (s *Slice) ReadRune() (r rune, size int, err error) {
if !utf8.FullRune(*s) {
return utf8.RuneError, 0, io.ErrUnexpectedEOF
}
r, size = utf8.DecodeRune(*s)
*s = (*s)[size:]
return r, size, err
}
// error for a invalid rune
var ErrInvalidRune = errors.New("Slice: invalid rune")
var emptySlices = [...][]byte{
nil,
{0},
{0, 0},
{0, 0, 0},
{0, 0, 0, 0},
}
// WriteRune writes a single Unicode code point, returning the number of bytes
// written and any error.
func (s *Slice) WriteRune(r rune) (size int, err error) {
if r < utf8.RuneSelf {
*s = append(*s, byte(r))
return 1, nil
}
l := utf8.RuneLen(r)
if l < 0 {
return 0, ErrInvalidRune
}
*s = append(*s, emptySlices[l]...)
utf8.EncodeRune((*s)[len(*s)-l:], r)
return l, nil
}
// WriteString appends the contents of str to the slice, growing the slice as
// needed. The return value n is the length of str; err is always nil.
func (s *Slice) WriteString(str string) (size int, err error) {
*s = append(*s, str...)
return len(str), nil
}
// WriteItoa converts i into text of the specified base and write to s.
func (s *Slice) WriteItoa(i int64, base int) (size int, err error) {
l := len(*s)
*s = strconv.AppendInt([]byte(*s), i, base)
return len(*s) - l, nil
}