progs/re4.scala
changeset 477 b78664a24f5d
parent 467 b5ec11e89768
child 546 6589afc6789b
equal deleted inserted replaced
476:d922cc83b70c 477:b78664a24f5d
     1     
     1 // Version which attempts to move whole strings, not
       
     2 // just characters, under derivatives whenever possible
       
     3    
     2 abstract class Rexp
     4 abstract class Rexp
     3 case object ZERO extends Rexp
     5 case object ZERO extends Rexp
     4 case object ONE extends Rexp
     6 case object ONE extends Rexp
     5 case class CHAR(c: Char) extends Rexp
     7 case class CHAR(c: Char) extends Rexp
     6 case class ALT(r1: Rexp, r2: Rexp) extends Rexp 
     8 case class ALT(r1: Rexp, r2: Rexp) extends Rexp 
    48     case (r1s, r2s) => SEQ(r1s, r2s)
    50     case (r1s, r2s) => SEQ(r1s, r2s)
    49   }
    51   }
    50   case r => r
    52   case r => r
    51 }
    53 }
    52 
    54 
       
    55 // *new*
    53 // derivative w.r.t. a string (iterates der)
    56 // derivative w.r.t. a string (iterates der)
    54 def ders2(s: List[Char], r: Rexp) : Rexp = (s, r) match {
    57 def ders2(s: List[Char], r: Rexp) : Rexp = (s, r) match {
    55   case (Nil, r) => r
    58   case (Nil, r) => r
    56   case (s, ZERO) => ZERO
    59   case (s, ZERO) => ZERO
    57   case (s, ONE) => if (s == Nil) ONE else ZERO
    60   case (s, ONE) => if (s == Nil) ONE else ZERO
    66 
    69 
    67 
    70 
    68 //one or zero
    71 //one or zero
    69 def OPT(r: Rexp) = ALT(r, ONE)
    72 def OPT(r: Rexp) = ALT(r, ONE)
    70 
    73 
       
    74 
       
    75 // Test Cases
       
    76 
    71 def EVIL1(n: Int) = SEQ(NTIMES(OPT(CHAR('a')), n), NTIMES(CHAR('a'), n))
    77 def EVIL1(n: Int) = SEQ(NTIMES(OPT(CHAR('a')), n), NTIMES(CHAR('a'), n))
    72 val EVIL2 = SEQ(STAR(STAR(CHAR('a'))), CHAR('b'))
    78 val EVIL2 = SEQ(STAR(STAR(CHAR('a'))), CHAR('b'))
    73 
    79 
    74 
    80 
    75 def time_needed[T](i: Int, code: => T) = {
    81 def time_needed[T](i: Int, code: => T) = {
    77   for (j <- 1 to i) code
    83   for (j <- 1 to i) code
    78   val end = System.nanoTime()
    84   val end = System.nanoTime()
    79   (end - start)/(i * 1.0e9)
    85   (end - start)/(i * 1.0e9)
    80 }
    86 }
    81 
    87 
    82 // warmup
       
    83 //test: (a?{n}) (a{n})
    88 //test: (a?{n}) (a{n})
    84 for (i <- 1 to 7000001 by 500000) {
    89 for (i <- 1 to 7000001 by 500000) {
    85   println(i + " " + "%.5f".format(time_needed(2, matcher(EVIL1(i), "a" * i))))
    90   println(i + " " + "%.5f".format(time_needed(2, matcher(EVIL1(i), "a" * i))))
    86 }
    91 }
    87 
    92