diff -r 47f86885d481 -r e85600529ca5 re0.scala
--- a/re0.scala	Sun Dec 23 00:38:56 2012 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,113 +0,0 @@
-    
-abstract class Rexp
-
-case object NULL extends Rexp
-case object EMPTY extends Rexp
-case class CHAR(c: Char) extends Rexp
-case class ALT(r1: Rexp, r2: Rexp) extends Rexp 
-case class SEQ(r1: Rexp, r2: Rexp) extends Rexp 
-case class STAR(r: Rexp) extends Rexp 
-case class NOT(r: Rexp) extends Rexp
-case class REP(r: Rexp, n: Int) extends Rexp 
-
-// some convenience for typing in regular expressions
-def charlist2rexp(s : List[Char]) : Rexp = s match {
-  case Nil => EMPTY
-  case c::Nil => CHAR(c)
-  case c::s => SEQ(CHAR(c), charlist2rexp(s))
-}
-implicit def string2rexp(s : String) : Rexp = charlist2rexp(s.toList)
-
-implicit def RexpOps(r: Rexp) = new {
-  def | (s: Rexp) = ALT(r, s)
-  def % = STAR(r)
-  def %(n: Int) = REP(r, n) 
-  def %%(n: Int) = SEQ(REP(r, n), STAR(r)) 
-  def ? = ALT(EMPTY, r)
-  def unary_! = NOT(r)
-  def ~ (s: Rexp) = SEQ(r, s)
-}
-
-implicit def stringOps(s: String) = new {
-  def | (r: Rexp) = ALT(s, r)
-  def | (r: String) = ALT(s, r)
-  def % = STAR(s)
-  def %(n: Int) = REP(s, n)
-  def %%(n: Int) = SEQ(REP(s, n), STAR(s)) 
-  def ? = ALT(EMPTY, s)
-  def unary_! = NOT(s)
-  def ~ (r: Rexp) = SEQ(s, r)
-  def ~ (r: String) = SEQ(s, r)
-}
-
-
-// nullable function: tests whether the regular 
-// expression can recognise the empty string
-def nullable (r: Rexp) : Boolean = r match {
-  case NULL => false
-  case EMPTY => true
-  case CHAR(_) => false
-  case ALT(r1, r2) => nullable(r1) || nullable(r2)
-  case SEQ(r1, r2) => nullable(r1) && nullable(r2)
-  case STAR(_) => true
-  case NOT(r) => !(nullable(r))
-  case REP(r, i) => if (i == 0) true else nullable(r)
-}
-
-// derivative of a regular expression w.r.t. a character
-def der (c: Char, r: Rexp) : Rexp = r match {
-  case NULL => NULL
-  case EMPTY => NULL
-  case CHAR(d) => if (c == d) EMPTY else NULL
-  case ALT(r1, r2) => ALT(der(c, r1), der(c, r2))
-  case SEQ(r1, r2) => 
-    if (nullable(r1)) ALT(SEQ(der(c, r1), r2), der(c, r2))
-    else SEQ(der(c, r1), r2)
-  case STAR(r) => SEQ(der(c, r), STAR(r))
-  case NOT(r) => NOT(der (c, r))
-  case REP(r, i) => 
-    if (i == 0) NULL else SEQ(der(c, r), REP(r, i - 1))
-}
-
-// derivative w.r.t. a string (iterates der)
-def ders (s: List[Char], r: Rexp) : Rexp = s match {
-  case Nil => r
-  case c::s => ders(s, der(c, r))
-}
-
-// main matcher function
-def matcher(r: Rexp, s: String) : Boolean = nullable(ders(s.toList, r))
-
-//examples
-val digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
-val int = ("+" | "-").? ~ digit.%%(1)
-val real = ("+" | "-").? ~ digit.%%(1) ~ ("." ~ digit.%%(1)).? ~ (("e" | "E") ~ ("+" | "-").? ~ digit.%%(1)).?
-
-val ints = List("0", "-4534", "+049", "99")
-val reals = List("0.9", "-12.8", "+91.0", "9e12", "+9.21E-12", "-512E+01")
-val errs = List("", "-", "+", "+-1", "-+2", "2-")
-
-ints.map(s => matcher(int, s))
-reals.map(s => matcher(int, s))
-errs.map(s => matcher(int, s))
-
-ints.map(s => matcher(real, s))
-reals.map(s => matcher(real, s))
-errs.map(s => matcher(real, s))
-
-
-
-def RTEST(n: Int) = ("a".? %(n)) ~ ("a" %(n))
-
-def time_needed[T](i: Int, code: => T) = {
-  val start = System.nanoTime()
-  for (j <- 1 to i) code
-  val end = System.nanoTime()
-  (end - start)/(i * 1.0e9)
-}
-
-for (i <- 1 to 29) {
-  println(i + ": " + "%.5f".format(time_needed(1, matcher(RTEST(i), "a" * i))))
-}
-
-