title: java library to parse regular expressions into a syntax tree
body: <p>I'd like a library that can take the string representation of a regexp and convert that into a syntax tree for easy programmatic manipulation. Something that would transform: </p>
  
  <p>(\s?)bla[a-z] </p>
  
  <p>into something like:</p>
  
  <pre>
  PARENTHESIS
    CHAR:SPACE
      WILD
  WORD:bla
  CHAR:a-z
  </pre>