package buf import ( "io" "v2ray.com/core/common/bytespool" ) const ( // Size of a regular buffer. Size = 2048 ) // Supplier is a writer that writes contents into the given buffer. type Supplier func([]byte) (int, error) // 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 } pool.Put(b.v) b.v = nil b.Clear() } // Clear clears the content of the buffer, results an empty buffer with // Len() = 0. func (b *Buffer) Clear() { b.start = 0 b.end = 0 } // AppendSupplier appends the content of a BytesWriter to the buffer. func (b *Buffer) AppendSupplier(writer Supplier) error { nBytes, err := writer(b.v[b.end:]) b.end += int32(nBytes) return err } // 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] } // Reset resets the content of the Buffer with a supplier. func (b *Buffer) Reset(writer Supplier) error { nBytes, err := writer(b.v) b.start = 0 b.end = int32(nBytes) if b.end > int32(len(b.v)) { b.end = int32(len(b.v)) } return err } // 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.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 } // WriteBytes appends one or more bytes to the end of the buffer. func (b *Buffer) WriteBytes(bytes ...byte) (int, error) { return b.Write(bytes) } // 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 } // 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), } }