peek method
Gets the line that is linesAhead
lines ahead of the current one, or
null
if there is none.
peek(0)
is equivalent to current.
peek(1)
is equivalent to next.
Implementation
String? peek(int linesAhead) {
if (linesAhead < 0) {
throw ArgumentError('Invalid linesAhead: $linesAhead; must be >= 0.');
}
// Don't read past the end.
if (_pos >= lines.length - linesAhead) return null;
return lines[_pos + linesAhead];
}