progs/re3.scala
changeset 440 e14cd32ad497
parent 434 8664ff87cd77
child 441 028816884f70
equal deleted inserted replaced
439:7611ace6a93b 440:e14cd32ad497
    27   case CHAR(d) => if (c == d) ONE else ZERO
    27   case CHAR(d) => if (c == d) ONE else ZERO
    28   case ALT(r1, r2) => ALT(der(c, r1), der(c, r2))
    28   case ALT(r1, r2) => ALT(der(c, r1), der(c, r2))
    29   case SEQ(r1, r2) => 
    29   case SEQ(r1, r2) => 
    30     if (nullable(r1)) ALT(SEQ(der(c, r1), r2), der(c, r2))
    30     if (nullable(r1)) ALT(SEQ(der(c, r1), r2), der(c, r2))
    31     else SEQ(der(c, r1), r2)
    31     else SEQ(der(c, r1), r2)
    32   case STAR(r) => SEQ(der(c, r), STAR(r))
    32   case STAR(r1) => SEQ(der(c, r1), STAR(r1))
    33   case NTIMES(r, i) => 
    33   case NTIMES(r, i) => 
    34     if (i == 0) ZERO else SEQ(der(c, r), NTIMES(r, i - 1))
    34     if (i == 0) ZERO else SEQ(der(c, r), NTIMES(r, i - 1))
    35 }
    35 }
    36 
    36 
    37 def simp(r: Rexp) : Rexp = r match {
    37 def simp(r: Rexp) : Rexp = r match {
    66 //one or zero
    66 //one or zero
    67 def OPT(r: Rexp) = ALT(r, ONE)
    67 def OPT(r: Rexp) = ALT(r, ONE)
    68 
    68 
    69 //evil regular expressions
    69 //evil regular expressions
    70 def EVIL1(n: Int) = SEQ(NTIMES(OPT(CHAR('a')), n), NTIMES(CHAR('a'), n))
    70 def EVIL1(n: Int) = SEQ(NTIMES(OPT(CHAR('a')), n), NTIMES(CHAR('a'), n))
    71 val EVIL2 = SEQ(STAR(CHAR('a')), CHAR('b'))
    71 val EVIL2 = SEQ(STAR(STAR(CHAR('a'))), CHAR('b'))
    72 
    72 
    73 
    73 
    74 def time_needed[T](i: Int, code: => T) = {
    74 def time_needed[T](i: Int, code: => T) = {
    75   val start = System.nanoTime()
    75   val start = System.nanoTime()
    76   for (j <- 1 to i) code
    76   for (j <- 1 to i) code