parse method
Parses the input and returns the parse result.
Creates a default parse context on the input starting at start and
calls the internal parsing logic of this parser.
For example, letter().plus().parse('abc') results in an instance of
Success, where Context.position is 3 and Success.value is
[a, b, c].
Similarly, letter().plus().parse('123') results in an instance of
Failure, where Context.position is 0 and Failure.message is
'letter expected'.
Implementation
@nonVirtual
Result<R> parse(String input, {int start = 0}) =>
parseOn(Context(input, start));