The parser class is the most 
  fundamental entity in the framework. A parser accepts a scanner comprised of 
  a first-last iterator pair and returns a match object as its result. The iterators 
  delimit the data currently being parsed. The match object evaluates to true 
  if the parse succeeds, in which case the input is advanced accordingly. Each 
  parser can represent a specific pattern or algorithm, or it can be a more complex 
  parser formed as a composition of other parsers.</p>
<p>All parsers in