80 // some convenience for typing in regular expressions

    81 import scala.language.implicitConversions    

    82 import scala.language.reflectiveCalls 

    83 def charlist2rexp(s : List[Char]) : Rexp = s match {

    84   case Nil => EMPTY

    85   case c::Nil => CHAR(c)

    86   case c::s => SEQ(CHAR(c), charlist2rexp(s))

    87 }

    88 implicit def string2rexp(s : String) : Rexp = charlist2rexp(s.toList)

    89 

    90 implicit def RexpOps (r: Rexp) = new {

    91   def | (s: Rexp) = ALT(r, s)

    92   def % = STAR(r)

    93   def ~ (s: Rexp) = SEQ(r, s)

    94 }

    95 

    96 implicit def stringOps (s: String) = new {

    97   def | (r: Rexp) = ALT(s, r)

    98   def | (r: String) = ALT(s, r)

    99   def % = STAR(s)

   100   def ~ (r: Rexp) = SEQ(s, r)

   101   def ~ (r: String) = SEQ(s, r)

   102 }

   103 

   104 

   105 

   106 def PLUS(r: Rexp) = SEQ(r, STAR(r))

   107 def RANGE(s: List[Char]) : Rexp = s match {

   108   case Nil => NULL

   109   case c::s => ALT(CHAR(c), RANGE(s))

   110 } 

   111 

   112 println("EVILS:")

   113 val EVIL1 = PLUS(PLUS("a" ~ "a" ~ "a"))

   114 val EVIL2 = PLUS(PLUS("aaaaaaaaaaaaaaaaaaa" ~ OPT("a")))  // 19 as ~ a?

   115 

   116 

   117 //40 * aaa matches

   118 //43 * aaa + aa does not

   119 //45 * aaa + a

   120 

   121 println("EVIL1:")

   122 println(matches(EVIL1, "aaa" * 40))

   123 println(matches(EVIL1, "aaa" * 43 + "aa"))

   124 println(matches(EVIL1, "aaa" * 45 + "a"))

   125 println("EVIL2:")

   126 println(matches(EVIL2, "aaa" * 40))

   127 println(matches(EVIL2, "aaa" * 43 + "aa"))

   128 println(matches(EVIL2, "aaa" * 45 + "a"))

   129 

   130 

   131 

   132 

   133 println("EMAIL:")

   134 val LOWERCASE = "abcdefghijklmnopqrstuvwxyz"

   135 val DIGITS = "0123456789"

   136 val EMAIL = PLUS(RANGE((LOWERCASE + DIGITS + "_" + "." + "-").toList)) ~ "@" ~ 

   137             PLUS(RANGE((LOWERCASE + DIGITS + "." + "-").toList)) ~ "." ~

   138             NMTIMES(RANGE((LOWERCASE + ".").toList), 2, 6)

   139 

   140 val my_email = "christian.urban@kcl.ac.uk"