buffer_bytes.go

package anet

import (
	"errors"
)

func NewBytesBuffer(cap int) ReadWriter {
	return &bytesBuffer{
		buffer: make([]byte, 0, cap),
		start:  0,
		end:    0,
		cap:    cap,
	}
}

type bytesBuffer struct {
	buffer []byte
	start  int
	end    int
	cap    int
}

var _ Reader = &bytesBuffer{}
var _ Writer = &bytesBuffer{}
var _ ReadWriter = &bytesBuffer{}

func (b *bytesBuffer) Seek(n int) ([]byte, error) {
	if b.Len() < n {
		return nil, errors.New("not enough data in buffer")
	}
	data := b.buffer[b.start : b.start+n]
	return data, nil
}

func (b *bytesBuffer) SeekAck(n int) error {
	if b.Len() < n {
		return errors.New("not enough data in buffer")
	}
	b.start += n
	return nil
}

func (b *bytesBuffer) SeekAll() ([]byte, error) {
	data := b.buffer[b.start:b.end]
	return data, nil
}

func (b *bytesBuffer) ReadAll() ([]byte, error) {
	data := b.buffer[b.start:b.end]
	b.start = 0
	b.end = 0
	return data, nil
}

func (b *bytesBuffer) ReadUtil(delim byte) ([]byte, error) {
	panic("unreachable code")
}

func (b *bytesBuffer) ReadBytes(n int) ([]byte, error) {
	if b.Len() < n {
		return nil, errors.New("not enough data in buffer")
	}
	data := b.buffer[b.start : b.start+n]
	b.start += n
	return data, nil
}

func (b *bytesBuffer) ReadString(n int) (string, error) {
	if b.Len() < n {
		return "", errors.New("not enough data in buffer")
	}
	data := b.buffer[b.start : b.start+n]
	b.start += n
	return string(data), nil
}

func (b *bytesBuffer) Len() int {
	return b.end - b.start
}

func (b *bytesBuffer) Release() {
	if b.start == b.end {
		b.start = 0
		b.end = 0
		return
	}
	if b.start > 0 {
		copy(b.buffer, b.buffer[b.start:b.end])
		b.end -= b.start
		b.start = 0
	}
}

func (b *bytesBuffer) Book(n int) []byte {
	if b.remain() < n {
		b.increase(n)
	}
	return b.buffer[b.end : b.end+n]
}

func (b *bytesBuffer) BookAck(n int) error {
	if b.remain() < n {
		return errors.New("not enough space in buffer")
	}
	b.end += n
	return nil
}

func (b *bytesBuffer) WriteBytes(data []byte, n int) error {
	if b.remain() < n {
		b.increase(n)
	}
	copy(b.buffer[b.end:b.end+n], data)
	b.end += n
	return nil
}

func (b *bytesBuffer) WriteString(data string, n int) error {
	if b.remain() < n {
		b.increase(n)
	}
	copy(b.buffer[b.end:b.end+n], []byte(data))
	b.end += n
	return nil
}

func (b *bytesBuffer) Flush() error {
	panic("unreachable code")
}

func (b *bytesBuffer) increase(n int) {
	if b.cap < n {
		b.cap = n * 2
	} else {
		b.cap = b.cap * 2
	}
	newBuffer := make([]byte, b.end, b.cap)
	copy(newBuffer, b.buffer[b.start:b.end])
	b.buffer = newBuffer
	b.end -= b.start
	b.start = 0
}

func (b *bytesBuffer) remain() int {
	return b.cap - b.end
}