package buf import ( "io" "v2ray.com/core/common/bytespool" ) const ( // Size of a regular buffer. Size = 2048 ) // Buffer is a recyclable allocation of a byte array. Buffer.Release() recycles // the buffer into an internal buffer pool, in order to recreate a buffer more // quickly. type Buffer struct { v []byte start int32 end int32 } // Release recycles the buffer into an internal buffer pool. func (b *Buffer) Release() { if b == nil || b.v == nil { return } p := b.v b.v = nil b.Clear() pool.Put(p) } // Clear clears the content of the buffer, results an empty buffer with // Len() = 0. func (b *Buffer) Clear() { b.start = 0 b.end = 0 } // Byte returns the bytes at index. func (b *Buffer) Byte(index int32) byte { return b.v[b.start+index] } // SetByte sets the byte value at index. func (b *Buffer) SetByte(index int32, value byte) { b.v[b.start+index] = value } // Bytes returns the content bytes of this Buffer. func (b *Buffer) Bytes() []byte { return b.v[b.start:b.end] } // Extend increases the buffer size by n bytes, and returns the extended part. // It panics if result size is larger than buf.Size. func (b *Buffer) Extend(n int32) []byte { end := b.end + n if end > int32(len(b.v)) { panic("extending out of bound") } ext := b.v[b.end:end] b.end = end return ext } // BytesRange returns a slice of this buffer with given from and to boundary. func (b *Buffer) BytesRange(from, to int32) []byte { if from < 0 { from += b.Len() } if to < 0 { to += b.Len() } return b.v[b.start+from : b.start+to] } // BytesFrom returns a slice of this Buffer starting from the given position. func (b *Buffer) BytesFrom(from int32) []byte { if from < 0 { from += b.Len() } return b.v[b.start+from : b.end] } // BytesTo returns a slice of this Buffer from start to the given position. func (b *Buffer) BytesTo(to int32) []byte { if to < 0 { to += b.Len() } return b.v[b.start : b.start+to] } // Resize cuts the buffer at the given position. func (b *Buffer) Resize(from, to int32) { if from < 0 { from += b.Len() } if to < 0 { to += b.Len() } if to < from { panic("Invalid slice") } b.end = b.start + to b.start += from } // Advance cuts the buffer at the given position. func (b *Buffer) Advance(from int32) { if from < 0 { from += b.Len() } b.start += from } // Len returns the length of the buffer content. func (b *Buffer) Len() int32 { if b == nil { return 0 } return b.end - b.start } // IsEmpty returns true if the buffer is empty. func (b *Buffer) IsEmpty() bool { return b.Len() == 0 } // IsFull returns true if the buffer has no more room to grow. func (b *Buffer) IsFull() bool { return b != nil && b.end == int32(len(b.v)) } // Write implements Write method in io.Writer. func (b *Buffer) Write(data []byte) (int, error) { nBytes := copy(b.v[b.end:], data) b.end += int32(nBytes) return nBytes, nil } // WriteByte writes a single byte into the buffer. func (b *Buffer) WriteByte(v byte) error { if b.IsFull() { return newError("buffer full") } b.v[b.end] = v b.end++ return nil } // WriteString implements io.StringWriter. func (b *Buffer) WriteString(s string) (int, error) { return b.Write([]byte(s)) } // Read implements io.Reader.Read(). func (b *Buffer) Read(data []byte) (int, error) { if b.Len() == 0 { return 0, io.EOF } nBytes := copy(data, b.v[b.start:b.end]) if int32(nBytes) == b.Len() { b.Clear() } else { b.start += int32(nBytes) } return nBytes, nil } // ReadFrom implements io.ReaderFrom. func (b *Buffer) ReadFrom(reader io.Reader) (int64, error) { n, err := reader.Read(b.v[b.end:]) b.end += int32(n) return int64(n), err } // ReadFullFrom reads exact size of bytes from given reader, or until error occurs. func (b *Buffer) ReadFullFrom(reader io.Reader, size int32) (int64, error) { end := b.end + size if end > int32(len(b.v)) { v := end return 0, newError("out of bound: ", v) } n, err := io.ReadFull(reader, b.v[b.end:end]) b.end += int32(n) return int64(n), err } // String returns the string form of this Buffer. func (b *Buffer) String() string { return string(b.Bytes()) } var pool = bytespool.GetPool(Size) // New creates a Buffer with 0 length and 2K capacity. func New() *Buffer { return &Buffer{ v: pool.Get().([]byte), } } // StackNew creates a new Buffer object on stack. // This method is for buffers that is released in the same function. func StackNew() Buffer { return Buffer{ v: pool.Get().([]byte), } }