parser

type Scanner interface {
	// Scan will scan the next token.
	Scan() (pos token.Pos, tok token.Token, lit string)

	// ScanWithRegex will scan the next token and include any regex literals.
	ScanWithRegex() (pos token.Pos, tok token.Token, lit string)

	// File returns the file being processed by the Scanner.
	File() *token.File

	// Unread will unread back to the previous location within the Scanner.
	// This can only be called once so the maximum lookahead is one.
	Unread()
}