progs/enfa.scala
changeset 487 a697421eaa04
parent 485 bd6d999ab7b6
child 488 598741d39d21
equal deleted inserted replaced
486:8178fcf377dc 487:a697421eaa04
     1 // epsilon NFAs...immediately translated into NFAs
     1 // epsilon NFAs...immediately translated into NFAs
     2 // (needs nfa.scala)
     2 // (needs :load nfa.scala in REPL)
     3 
     3 
     4 // fixpoint construction
     4 // fixpoint construction
     5 import scala.annotation.tailrec
     5 import scala.annotation.tailrec
     6 @tailrec
     6 @tailrec
     7 def fixpT[A](f: A => A, x: A): A = {
     7 def fixpT[A](f: A => A, x: A): A = {
    35   // result NFA
    35   // result NFA
    36   NFA(ecl(starts), 
    36   NFA(ecl(starts), 
    37       { case (q, c) => nexts(Set(q), c) }, 
    37       { case (q, c) => nexts(Set(q), c) }, 
    38       q => ecl(Set(q)) exists fins)
    38       q => ecl(Set(q)) exists fins)
    39 }
    39 }
       
    40 
       
    41 
       
    42 // eNFA examples
       
    43 val enfa_trans1 : (State, Option[Char]) :=> Set[State] =
       
    44   { case (Q0, Some('a')) => Set(Q0)
       
    45     case (Q0, None) => Set(Q1, Q2)
       
    46     case (Q1, Some('a')) => Set(Q1)
       
    47     case (Q2, Some('b')) => Set(Q2) 
       
    48   }
       
    49 
       
    50 val enfa1 = eNFA(Set[State](Q0), enfa_trans1, Set[State](Q2))
       
    51 
       
    52 
       
    53 //
       
    54 case object R1 extends State
       
    55 case object R2 extends State
       
    56 case object R3 extends State
       
    57 
       
    58 val enfa_trans2 : (State, Option[Char]) :=> Set[State] =
       
    59   { case (R1, Some('b')) => Set(R3)
       
    60     case (R1, None) => Set(R2)
       
    61     case (R2, Some('a')) => Set(R1, R3) 
       
    62   }
       
    63 
       
    64 
       
    65 val enfa2 = eNFA(Set[State](R1), enfa_trans1, Set[State](R3))