/* NAME bytescanner.go AUTHOR Dan Kortschak <dan@ausocean.org> LICENSE This is Copyright (C) 2017 the Australian Ocean Lab (AusOcean) It is free software: you can redistribute it and/or modify them under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. It is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License in gpl.txt. If not, see http://www.gnu.org/licenses. */ // Package bytescan implements a byte-level scanner. package codecutil import "io" // ByteScanner is a byte scanner. type ByteScanner struct { buf []byte off int // r is the source of data for the scanner. r io.Reader } // NewByteScanner returns a scanner initialised with an io.Reader and a read buffer. func NewByteScanner(r io.Reader, buf []byte) *ByteScanner { return &ByteScanner{r: r, buf: buf[:0]} } // ScanUntil scans the scanner's underlying io.Reader until a delim byte // has been read, appending all read bytes to dst. The resulting appended data, // the last read byte and whether the last read byte was the delimiter. func (c *ByteScanner) ScanUntil(dst []byte, delim byte) (res []byte, b byte, err error) { outer: for { var i int for i, b = range c.buf[c.off:] { if b != delim { continue } dst = append(dst, c.buf[c.off:c.off+i+1]...) c.off += i + 1 break outer } dst = append(dst, c.buf[c.off:]...) err = c.reload() if err != nil { break } } return dst, b, err } // ReadByte is an unexported ReadByte. func (c *ByteScanner) ReadByte() (byte, error) { if c.off >= len(c.buf) { err := c.reload() if err != nil { return 0, err } } b := c.buf[c.off] c.off++ return b, nil } // reload re-fills the scanner's buffer. func (c *ByteScanner) reload() error { n, err := c.r.Read(c.buf[:cap(c.buf)]) c.buf = c.buf[:n] if err != nil { if err != io.EOF { return err } if n == 0 { return io.EOF } } c.off = 0 return nil }