func (re *Regexp) doMatch(r io.RuneReader, b []byte, s string) bool {
	return re.doExecute(r, b, s, 0, 0, nil) != nil
}

// doExecute finds the leftmost match in the input, appends the position
// of its subexpressions to dstCap and returns dstCap.
//
// nil is returned if no matches are found and non-nil if matches are found.

//
// There is also a subset of the methods that can be applied to text read
// from a RuneReader:
//
//	MatchReader, FindReaderIndex, FindReaderSubmatchIndex
//
// This set may grow. Note that regular expression matches may need to
// examine text beyond the text returned by a match, so the methods that
// match text from a RuneReader may read arbitrarily far into the input
// before returning.
//

type ByteWriter interface {
	WriteByte(c byte) error
}

// RuneReader is the interface that wraps the ReadRune method.
//
// ReadRune reads a single encoded Unicode character
// and returns the rune and its size in bytes. If no character is
// available, err will be set.
type RuneReader interface {
	ReadRune() (r rune, size int, err error)
}