Fantom-foundation/go-lachesis

package fast

// Buffer is a fixed-sized buffer of byte with Read and Write methods.
type Buffer struct {
    buf    *[]byte
    offset int
}

// NewBuffer wraps bytes with buffer.
func NewBuffer(bb []byte) *Buffer {
    return &Buffer{
        buf:    &bb,
        offset: 0,
    }
}

// WriteByte to the buffer.
func (b *Buffer) WriteByte(v byte) {
    (*b.buf)[b.offset] = v
    b.offset++
}

// Write the byte to the buffer.
func (b *Buffer) Write(v []byte) {
    n := copy((*b.buf)[b.offset:], v)
    b.offset += n

    if n != len(v) {
        panic("buffer overflow")
    }
}

// Read n bytes.
func (b *Buffer) Read(n int) []byte {
    var res []byte
    res = (*b.buf)[b.offset : b.offset+n]
    b.offset += n

    return res
}

// Position of internal cursor.
func (b *Buffer) Position() int {
    return b.offset
}