file.coffee

StringScanner = null
( ->
  setState = (target, matches, values) ->
    target.head     = values?.head ? target.head
    target.last     = values?.last ? target.last
    target.captures = matches.slice 1
    target.match    = matches[0]

  class StringScanner
    constructor: (source) ->
      @source = source.toString()
      @reset()
  
    scan: (regexp) ->
      if (matches = regexp.exec @getRemainder()) and matches.index is 0
        setState @, matches,
          head: @head + matches[0].length
          last: @head
      else
        setState @, []
)()