75   | 
   107   | 
    76 // extracts a string from value  | 
   108 // extracts a string from value  | 
    77 def flatten(v: Val) : String = v match { | 
   109 def flatten(v: Val) : String = v match { | 
    78   case Empty => ""  | 
   110   case Empty => ""  | 
    79   case Chr(c) => c.toString  | 
   111   case Chr(c) => c.toString  | 
    80   case Left(v) => flatten(v)  | 
   112   case Proj(_, v) => flatten(v)  | 
    81   case Right(v) => flatten(v)  | 
         | 
    82   case Sequ(v1, v2) => flatten(v1) ++ flatten(v2)  | 
   113   case Sequ(v1, v2) => flatten(v1) ++ flatten(v2)  | 
    83   case Stars(vs) => vs.map(flatten).mkString  | 
   114   case Stars(vs) => vs.map(flatten).mkString  | 
    84   case Rec(_, v) => flatten(v)  | 
   115 }  | 
    85 }  | 
   116   | 
    86   | 
   117   | 
    87 // extracts an environment from a value  | 
   118 // mkeps  | 
    88 def env[A](v: Val) : List[A] = v match { | 
         | 
    89   case Empty => Nil  | 
         | 
    90   case Chr(c) => Nil  | 
         | 
    91   case Left(v) => env(v)  | 
         | 
    92   case Right(v) => env(v)  | 
         | 
    93   case Sequ(v1, v2) => env(v1) ::: env(v2)  | 
         | 
    94   case Stars(vs) => vs.flatMap(env)  | 
         | 
    95   case Rec(f, v) => ((f:String => A)(flatten(v)))::env(v)  | 
         | 
    96 }  | 
         | 
    97   | 
         | 
    98 // injection part  | 
         | 
    99 def mkeps(r: Rexp) : Val = r match { | 
   119 def mkeps(r: Rexp) : Val = r match { | 
   100   case ONE => Empty  | 
   120   case ONE => Empty  | 
   101   case ALT(r1, r2) =>   | 
   121   case ALTS(r1::rs) =>   | 
   102     if (nullable(r1)) Left(mkeps(r1)) else Right(mkeps(r2))  | 
   122     if (nullable(r1)) Proj(0, mkeps(r1))   | 
         | 
   123     else IncProj(1, mkeps(ALTS(rs)))  | 
   103   case SEQ(r1, r2) => Sequ(mkeps(r1), mkeps(r2))  | 
   124   case SEQ(r1, r2) => Sequ(mkeps(r1), mkeps(r2))  | 
   104   case STAR(r) => Stars(Nil)  | 
   125   case STAR(r) => Stars(Nil)  | 
   105   case RECD(x, r) => Rec(x, mkeps(r))  | 
   126 }  | 
   106 }  | 
   127   | 
   107   | 
   128 // injection   | 
   108   | 
         | 
   109 def inj(r: Rexp, c: Char, v: Val) : Val = (r, v) match { | 
   129 def inj(r: Rexp, c: Char, v: Val) : Val = (r, v) match { | 
   110   case (STAR(r), Sequ(v1, Stars(vs))) => Stars(inj(r, c, v1)::vs)  | 
   130   case (STAR(r), Sequ(v1, Stars(vs))) => Stars(inj(r, c, v1)::vs)  | 
   111   case (SEQ(r1, r2), Sequ(v1, v2)) => Sequ(inj(r1, c, v1), v2)  | 
   131   case (SEQ(r1, r2), Sequ(v1, v2)) => Sequ(inj(r1, c, v1), v2)  | 
   112   case (SEQ(r1, r2), Left(Sequ(v1, v2))) => Sequ(inj(r1, c, v1), v2)  | 
   132   case (SEQ(r1, r2), Proj(0, Sequ(v1, v2))) => Sequ(inj(r1, c, v1), v2)  | 
   113   case (SEQ(r1, r2), Right(v2)) => Sequ(mkeps(r1), inj(r2, c, v2))  | 
   133   case (SEQ(r1, r2), Proj(1, v2)) => Sequ(mkeps(r1), inj(r2, c, v2))  | 
   114   case (ALT(r1, r2), Left(v1)) => Left(inj(r1, c, v1))  | 
   134   case (ALTS(rs), Proj(n, v1)) => Proj(n, inj(rs(n), c, v1))  | 
   115   case (ALT(r1, r2), Right(v2)) => Right(inj(r2, c, v2))  | 
         | 
   116   case (CHAR(d), Empty) => Chr(c)   | 
   135   case (CHAR(d), Empty) => Chr(c)   | 
   117   case (RECD(x, r1), _) => Rec(x, inj(r1, c, v))  | 
         | 
   118 }  | 
   136 }  | 
   119   | 
   137   | 
   120 // main lexing function (produces a value)  | 
   138 // main lexing function (produces a value)  | 
         | 
   139 //  - does  not simplify  | 
   121 def lex(r: Rexp, s: List[Char]) : Val = s match { | 
   140 def lex(r: Rexp, s: List[Char]) : Val = s match { | 
   122   case Nil => if (nullable(r)) mkeps(r)   | 
   141   case Nil => { | 
   123               else throw new Exception("Not matched") | 
   142     //println(s"Size of the last regex: ${size(r)}") | 
         | 
   143     if (nullable(r)) mkeps(r) else throw new Exception("Not matched") | 
         | 
   144   }  | 
   124   case c::cs => inj(r, c, lex(der(c, r), cs))  | 
   145   case c::cs => inj(r, c, lex(der(c, r), cs))  | 
   125 }  | 
   146 }  | 
   126   | 
   147   | 
   127 def lexing(r: Rexp, s: String) : Val = lex(r, s.toList)  | 
   148 def lexing(r: Rexp, s: String) : Val = lex(r, s.toList)  | 
   128   | 
   149   | 
         | 
   150 lexing("a" | ZERO, "a") | 
         | 
   151 lexing(ZERO | "a", "a")  | 
   129   | 
   152   | 
   130 lexing(("ab" | "a") ~ ("b" | ONE), "ab") | 
   153 lexing(("ab" | "a") ~ ("b" | ONE), "ab") | 
         | 
   154   | 
         | 
   155   | 
         | 
   156 // removing duplicate regular expressions  | 
         | 
   157 val unit = (ZERO, F_ERROR(_))  | 
         | 
   158   | 
         | 
   159 def dups2(xs: List[(Rexp, Val => Val)],   | 
         | 
   160 	 acc: List[(Rexp, Val => Val)] = Nil) : List[(Rexp, Val => Val)] = xs match { | 
         | 
   161   case Nil => acc  | 
         | 
   162   case (x, y)::xs =>   | 
         | 
   163 	     if (acc.map(_._1).contains(x)) dups2(xs, acc :+ unit)  | 
         | 
   164 	     else dups2(xs, acc :+ (x, y))  | 
         | 
   165 }  | 
         | 
   166   | 
         | 
   167 def dups(xs: List[(Rexp, Val => Val)]) : List[(Rexp, Val => Val)] = { | 
         | 
   168   val out = dups2(xs)  | 
         | 
   169   //if (out != xs) { | 
         | 
   170   //  println()  | 
         | 
   171   //  println(s"Input ${string(ALTS(xs.map(_._1)))}") | 
         | 
   172   //  println(s"Ouput ${string(ALTS(out.map(_._1)))}") | 
         | 
   173   //}  | 
         | 
   174   out  | 
         | 
   175 }  | 
         | 
   176   | 
   131   | 
   177   | 
   132 // some "rectification" functions for simplification  | 
   178 // some "rectification" functions for simplification  | 
   133 def F_ID(v: Val): Val = v  | 
   179 def F_ID(v: Val): Val = v  | 
   134 def F_RIGHT(f: Val => Val) = (v:Val) => Right(f(v))  | 
         | 
   135 def F_LEFT(f: Val => Val) = (v:Val) => Left(f(v))  | 
         | 
   136 def F_ALT(f1: Val => Val, f2: Val => Val) = (v:Val) => v match { | 
         | 
   137   case Right(v) => Right(f2(v))  | 
         | 
   138   case Left(v) => Left(f1(v))  | 
         | 
   139 }  | 
         | 
   140 def F_SEQ(f1: Val => Val, f2: Val => Val) = (v:Val) => v match { | 
   180 def F_SEQ(f1: Val => Val, f2: Val => Val) = (v:Val) => v match { | 
   141   case Sequ(v1, v2) => Sequ(f1(v1), f2(v2))  | 
   181   case Sequ(v1, v2) => Sequ(f1(v1), f2(v2))  | 
   142 }  | 
   182 }  | 
   143 def F_SEQ_Empty1(f1: Val => Val, f2: Val => Val) =   | 
   183 def F_SEQ_Empty1(f1: Val => Val, f2: Val => Val) =   | 
   144   (v:Val) => Sequ(f1(Empty), f2(v))  | 
   184   (v:Val) => Sequ(f1(Empty), f2(v))  | 
   145 def F_SEQ_Empty2(f1: Val => Val, f2: Val => Val) =   | 
   185 def F_SEQ_Empty2(f1: Val => Val, f2: Val => Val) =   | 
   146   (v:Val) => Sequ(f1(v), f2(Empty))  | 
   186   (v:Val) => Sequ(f1(v), f2(Empty))  | 
   147 def F_RECD(f: Val => Val) = (v:Val) => v match { | 
         | 
   148   case Rec(x, v) => Rec(x, f(v))  | 
         | 
   149 }  | 
         | 
   150 def F_ERROR(v: Val): Val = throw new Exception("error") | 
   187 def F_ERROR(v: Val): Val = throw new Exception("error") | 
         | 
   188 def F_PRINT(v: Val): Val = { | 
         | 
   189   println(s"value is ${v}") | 
         | 
   190   throw new Exception("caught error") | 
         | 
   191 }  | 
         | 
   192   | 
         | 
   193 def flats(rs: List[Rexp], seen: Set[Rexp]) : (List[Rexp], Val => Val) = { | 
         | 
   194   //println(s"I am flats: ${string(ALTS(rs))}") | 
         | 
   195   //println(s"The size of seen is ${seen.size}, ${seen.map(string)}") | 
         | 
   196   rs match { | 
         | 
   197   case Nil => (Nil, F_ERROR)  | 
         | 
   198   case r::rs1 if seen.contains(simp(r)._1) => { | 
         | 
   199     //println(s" I remove ${string(r)}") | 
         | 
   200     val (rs2, f) = flats(rs1, seen)  | 
         | 
   201     (rs2, (v:Val) => IncProj(1, f(v)))  | 
         | 
   202   }  | 
         | 
   203   case ZERO::rs1 => { | 
         | 
   204     val (rs2, f) = flats(rs1, seen)  | 
         | 
   205     (rs2, (v:Val) => IncProj(1, f(v)))  | 
         | 
   206   }  | 
         | 
   207   case ALTS(rs0)::rs1 => { | 
         | 
   208     val (rss, f1) = flats(rs0, seen)  | 
         | 
   209     val (rs2, f2) = flats(rs1, rss.toSet ++ seen)  | 
         | 
   210     (rss:::rs2, (v:Val) => v match { | 
         | 
   211       case Proj(n, vn) =>   | 
         | 
   212      	if (n < rss.length) Proj(0, f1(Proj(n, vn)))  | 
         | 
   213   	else IncProj(1, f2(Proj(n - rss.length, vn)))  | 
         | 
   214     })  | 
         | 
   215   }  | 
         | 
   216   case r1::rs2 => { | 
         | 
   217     val (r1s, f1) = simp(r1)  | 
         | 
   218     val (rs3, f2) = flats(rs2, seen + r1s)  | 
         | 
   219     (r1s::rs3, (v:Val) => v match { | 
         | 
   220       case Proj(0, vn) => Proj(0, f1(vn))  | 
         | 
   221       case Proj(n, vn) => IncProj(1, f2(Proj(n - 1, vn)))  | 
         | 
   222     })  | 
         | 
   223   }  | 
         | 
   224 }}  | 
   151   | 
   225   | 
   152 // simplification of regular expressions returning also an  | 
   226 // simplification of regular expressions returning also an  | 
   153 // rectification function; no simplification under STAR   | 
   227 // rectification function; no simplification under STAR   | 
   154 def simp(r: Rexp): (Rexp, Val => Val) = r match { | 
   228 def simp(r: Rexp): (Rexp, Val => Val) = r match { | 
   155   case ALT(r1, r2) => { | 
   229   case ALTS(rs) => { | 
   156     val (r1s, f1s) = simp(r1)  | 
   230     val (rs_s, fs_s) = flats(rs, Set())  | 
   157     val (r2s, f2s) = simp(r2)  | 
   231     rs_s match { | 
   158     (r1s, r2s) match { | 
   232       case Nil => (ZERO, F_ERROR)   | 
   159       case (ZERO, _) => (r2s, F_RIGHT(f2s))  | 
   233       case r::Nil => (r, (v:Val) => fs_s(Proj(0, v)))  | 
   160       case (_, ZERO) => (r1s, F_LEFT(f1s))  | 
   234       case rs_sd => (ALTS(rs_sd), fs_s)  | 
   161       case _ => if (r1s == r2s) (r1s, F_LEFT(f1s))  | 
         | 
   162                 else (ALT (r1s, r2s), F_ALT(f1s, f2s))   | 
         | 
   163     }  | 
   235     }  | 
   164   }  | 
   236   }  | 
   165   case SEQ(r1, r2) => { | 
   237   case SEQ(r1, r2) => { | 
   166     val (r1s, f1s) = simp(r1)  | 
   238     val (r1s, f1s) = simp(r1)  | 
   167     val (r2s, f2s) = simp(r2)  | 
   239     val (r2s, f2s) = simp(r2)  | 
   168     (r1s, r2s) match { | 
   240     (r1s, r2s) match { | 
   169       case (ZERO, _) => (ZERO, F_ERROR)  | 
   241       case (ZERO, _) => (ZERO, F_ERROR)  | 
   170       case (_, ZERO) => (ZERO, F_ERROR)  | 
   242       case (_, ZERO) => (ZERO, F_ERROR)  | 
   171       case (ONE, _) => (r2s, F_SEQ_Empty1(f1s, f2s))  | 
   243       case (ONE, _) => (r2s, F_SEQ_Empty1(f1s, f2s))  | 
   172       case (_, ONE) => (r1s, F_SEQ_Empty2(f1s, f2s))  | 
   244       case (_, ONE) => (r1s, F_SEQ_Empty2(f1s, f2s))  | 
         | 
   245       case (ALTS(rs), r2s) => (ALTS(rs.map(SEQ(_, r2s))),   | 
         | 
   246 			       (v:Val) => v match { | 
         | 
   247 				 case Proj(n, Sequ(v1, v2)) => Sequ(f1s(Proj(n, v1)), f2s(v2))  | 
         | 
   248 			       }  | 
         | 
   249 			      )  | 
   173       case _ => (SEQ(r1s,r2s), F_SEQ(f1s, f2s))  | 
   250       case _ => (SEQ(r1s,r2s), F_SEQ(f1s, f2s))  | 
   174     }  | 
   251     }  | 
   175   }  | 
   252   }  | 
   176   case RECD(x, r1) => { | 
         | 
   177     val (r1s, f1s) = simp(r1)  | 
         | 
   178     (RECD(x, r1s), F_RECD(f1s))  | 
         | 
   179   }  | 
         | 
   180   case r => (r, F_ID)  | 
   253   case r => (r, F_ID)  | 
   181 }  | 
   254 }  | 
   182   | 
   255   | 
   183 def lex_simp(r: Rexp, s: List[Char]) : Val = s match { | 
   256 def lex_simp(r: Rexp, s: List[Char]) : Val = s match { | 
   184   case Nil => if (nullable(r)) mkeps(r) else throw new Exception("Not matched") | 
   257   case Nil => { | 
         | 
   258     //println(s"Size of the last regex: ${size(r)}") | 
         | 
   259     //println(s"${string(r)}") | 
         | 
   260     if (nullable(r)) mkeps(r) else throw new Exception("Not matched") | 
         | 
   261   }  | 
   185   case c::cs => { | 
   262   case c::cs => { | 
   186     val (r_simp, f_simp) = simp(der(c, r))  | 
   263     val rd = der(c, r)       | 
   187     inj(r, c, f_simp(lex_simp(r_simp, cs)))  | 
   264     val (r_simp, f_simp) = simp(rd)  | 
         | 
   265     //println(s"BEFORE ${string(rd)}") | 
         | 
   266     //println(s"AFTER  ${string(r_simp)}") | 
         | 
   267     val rec = lex_simp(r_simp, cs)  | 
         | 
   268     inj(r, c, f_simp(rec))  | 
   188   }  | 
   269   }  | 
   189 }  | 
   270 }  | 
   190   | 
   271   | 
   191 def lexing_simp(r: Rexp, s: String) : Val = lex_simp(r, s.toList)  | 
   272 def lexing_simp(r: Rexp, s: String) : Val = lex_simp(r, s.toList)  | 
   192   | 
   273   | 
         | 
   274   | 
         | 
   275 lexing_simp("ab" | "aa", "ab") | 
         | 
   276 lexing_simp("ab" | "aa", "aa") | 
         | 
   277   | 
         | 
   278 lexing(STAR("a" | "aa"), "aaaaa") | 
         | 
   279 lexing_simp(STAR("a" | "aa"), "aaaaa") | 
         | 
   280   | 
         | 
   281 lexing(STAR("a" | "aa"), "aaaaaaaaaaa") | 
         | 
   282 lexing_simp(STAR("a" | "aa"), "aaaaaaaaaaa") | 
         | 
   283   | 
         | 
   284 lexing_simp(STAR("a" | "aa"), "a" * 2) | 
         | 
   285 lexing_simp(STAR("a" | "aa"), "a" * 3) | 
         | 
   286 lexing_simp(STAR("a" | "aa"), "a" * 4) | 
         | 
   287   | 
         | 
   288   | 
         | 
   289 lexing_simp(STAR("a" | "aa"), "a" * 20) | 
         | 
   290 lexing_simp(STAR("a" | "aa"), "a" * 2000) | 
         | 
   291   | 
         | 
   292 lexing(ALTS(List("aa", "aa", "aa", "ab", "ab")), "ab") | 
         | 
   293 lexing_simp(ALTS(List("aa", "aa", "aa", "ab", "ab")), "ab") | 
         | 
   294   | 
         | 
   295 lexing(ALTS(List(("aa" | "ab" | "aa"), "aa", "ab", "ab")), "ab") | 
         | 
   296 lexing_simp(ALTS(List(("aa" | "ab" | "aa"), "aa", "ab", "ab")), "ab") | 
         | 
   297   | 
         | 
   298 lexing(ALTS(List(ZERO, ZERO, ONE, "aa", ZERO, "aa", "aa")), "aa")  | 
         | 
   299 lexing_simp(ALTS(List(ZERO, ZERO, ONE, "aa", ZERO, "aa", "aa")), "aa")  | 
         | 
   300   | 
         | 
   301 lexing_simp(ONE | ZERO, "")  | 
         | 
   302 lexing_simp(ZERO | ONE, "")  | 
         | 
   303   | 
         | 
   304 lexing("a" | ZERO, "a") | 
         | 
   305 lexing_simp("a" | ZERO, "a") | 
         | 
   306 lexing(ZERO | "a", "a")  | 
         | 
   307 lexing_simp(ZERO | "a", "a")  | 
         | 
   308   | 
         | 
   309 lexing(ALTS(List(ZERO, ZERO, ONE, "a", ZERO, "a")), "a")  | 
         | 
   310 lexing_simp(ALTS(List(ZERO, ZERO, ONE, "a", ZERO, "a")), "a")  | 
         | 
   311 lexing(ALTS(List("a")), "a") | 
         | 
   312 lexing_simp(ALTS(List("a")), "a") | 
         | 
   313   | 
         | 
   314 lexing_simp(("a" | ZERO) | ZERO, "a") | 
         | 
   315 lexing_simp("a" | (ZERO | ZERO), "a") | 
         | 
   316 lexing_simp(ZERO | ("a" | ZERO), "a") | 
         | 
   317   | 
         | 
   318   | 
         | 
   319 lexing_simp("abc", "abc") | 
         | 
   320   | 
         | 
   321 lexing_simp("abc" | ONE, "abc") | 
         | 
   322   | 
         | 
   323 lexing(("a" | "ab") ~ ("b" | ""), "ab") | 
   193 lexing_simp(("a" | "ab") ~ ("b" | ""), "ab") | 
   324 lexing_simp(("a" | "ab") ~ ("b" | ""), "ab") | 
   194   | 
   325 lexing_simp(("ba" | "c" | "ab"), "ab") | 
   195 // Lexing Rules for a Small While Language  | 
   326   | 
   196   | 
   327 lexing(ALTS(List(ALTS(Nil), "c", "ab")), "ab")  | 
   197 def PLUS(r: Rexp) = r ~ r.%  | 
   328 lexing_simp(ALTS(List(ALTS(Nil), "c", "ab")), "ab")  | 
   198   | 
   329   | 
   199 val SYM = "a" | "b" | "c" | "d" | "e" | "f" | "g" | "h" | "i" | "j" | "k" | "l" | "m" | "n" | "o" | "p" | "q" | "r" | "s" | "t" | "u" | "v" | "w" | "x" | "y" | "z"  | 
   330 lexing(ALTS(List(ALTS("ab"::Nil), "c", "ab")), "ab") | 
   200 val DIGIT = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"  | 
   331 lexing_simp(ALTS(List(ALTS("ab"::Nil), "c", "ab")), "ab") | 
   201 val ID = SYM ~ (SYM | DIGIT).%   | 
   332   | 
   202 val NUM = PLUS(DIGIT)  | 
   333 lexing(ALTS(List(ALTS(List("a","ab")), "c", "ab")), "ab") | 
   203 val KEYWORD : Rexp = "skip" | "while" | "do" | "if" | "then" | "else" | "read" | "write" | "true" | "false"  | 
   334 lexing_simp(ALTS(List(ALTS(List("a","ab")), "c", "ab")), "ab") | 
   204 val SEMI: Rexp = ";"  | 
   335   | 
   205 val OP: Rexp = ":=" | "==" | "-" | "+" | "*" | "!=" | "<" | ">" | "<=" | ">=" | "%" | "/"  | 
   336 lexing(ALTS(List(ALTS(List("ab","a")), "c", "ab")), "ab") | 
   206 val WHITESPACE = PLUS(" " | "\n" | "\t") | 
   337 lexing_simp(ALTS(List(ALTS(List("ab","a")), "c", "ab")), "ab") | 
   207 val RPAREN: Rexp = ")"  | 
   338   | 
   208 val LPAREN: Rexp = "(" | 
   339 lexing(ALTS(List(ALTS(List("ab","a","a")), "c", "ab")), "ab") | 
   209 val BEGIN: Rexp = "{" | 
   340 lexing_simp(ALTS(List(ALTS(List("ab","a","a")), "c", "ab")), "ab") | 
   210 val END: Rexp = "}"  | 
   341   | 
   211 val STRING: Rexp = "\"" ~ SYM.% ~ "\""  | 
   342 lexing(ALTS(List(ALTS(List("a","ab","a")), "c", "ab")), "ab") | 
   212   | 
   343 lexing_simp(ALTS(List(ALTS(List("a","ab","a")), "c", "ab")), "ab") | 
   213   | 
   344   | 
   214 val WHILE_REGS = (((s) => Token $ KEYWORD) |   | 
   345 lexing(ALTS(List(ALTS(List("b","a","ab")), "c", "ab")), "ab") | 
   215                   ("i" $ ID) |  | 
   346 lexing_simp(ALTS(List(ALTS(List("b","a","ab")), "c", "ab")), "ab") | 
   216                   ("o" $ OP) |  | 
   347   | 
   217                   ("n" $ NUM) |  | 
   348   | 
   218                   ("s" $ SEMI) |  | 
   349 lexing_simp(ALTS(List("ba", "c", "ab")), "ab") | 
   219                   ("str" $ STRING) | | 
   350   | 
   220                   ("p" $ (LPAREN | RPAREN)) |  | 
   351 lexing(ALTS(List("a", "ab", "a")), "ab") | 
   221                   ("b" $ (BEGIN | END)) |  | 
   352 lexing_simp(ALTS(List("a", "ab", "a")), "ab") | 
   222                   ("w" $ WHITESPACE)).% | 
   353   | 
   223   | 
   354 lexing(STAR("a" | "aa"), "aa") | 
   224   | 
   355 lexing_simp(STAR("a" | "aa"), "aa") | 
   225   | 
   356   | 
   226   | 
   357   | 
   227 // extracts an environment from a value  | 
   358   | 
   228 def env(v: Val) : List[Token] = v match { | 
   359   | 
   229   case Empty => Nil  | 
   360 def enum(n: Int, s: String) : Set[Rexp] = n match { | 
   230   case Chr(c) => Nil  | 
   361   case 0 => Set(ZERO, ONE) ++ s.toSet.map(CHAR)  | 
   231   case Left(v) => env(v)  | 
   362   case n => { | 
   232   case Right(v) => env(v)  | 
   363     val rs = enum(n - 1, s)  | 
   233   case Sequ(v1, v2) => env(v1) ::: env(v2)  | 
   364     rs ++  | 
   234   case Stars(vs) => vs.flatMap(env)  | 
   365     (for (r1 <- rs; r2 <- rs) yield ALT(r1, r2)) ++  | 
   235   case Rec(f, v) => (f(flatten(v)))::env(v)  | 
   366     (for (r1 <- rs; r2 <- rs) yield SEQ(r1, r2)) ++  | 
   236 }  | 
   367     (for (r1 <- rs) yield STAR(r1))  | 
   237   | 
   368   }  | 
   238 //   Testing  | 
   369 }  | 
   239 //============  | 
   370   | 
   240   | 
   371 def strs(n: Int, cs: String) : Set[String] = { | 
   241 def time[T](code: => T) = { | 
   372   if (n == 0) Set("") | 
   242   val start = System.nanoTime()  | 
   373   else { | 
   243   val result = code  | 
   374     val ss = strs(n - 1, cs)  | 
   244   val end = System.nanoTime()  | 
   375     ss ++  | 
   245   println((end - start)/1.0e9)  | 
   376     (for (s <- ss; c <- cs.toList) yield c + s)  | 
   246   result  | 
   377   }  | 
   247 }  | 
   378 }  | 
   248   | 
   379   | 
   249 val r1 = ("a" | "ab") ~ ("bcd" | "c") | 
   380 import scala.util.Try  | 
   250 println(lexing(r1, "abcd"))  | 
   381   | 
   251   | 
   382 def tests(n: Int, m: Int, s: String) = { | 
   252 val r2 = ("" | "a") ~ ("ab" | "b") | 
   383   val rs = enum(n, s)  | 
   253 println(lexing(r2, "ab"))  | 
   384   val ss = strs(m, s)  | 
   254   | 
   385   println(s"cases generated: ${rs.size} regexes and ${ss.size} strings") | 
   255   | 
   386   for (r1 <- rs.par; s1 <- ss.par) yield { | 
   256 // Two Simple While Tests  | 
   387     val res1 = Try(Some(lexing(r1, s1))).getOrElse(None)  | 
   257 //========================  | 
   388     val res2 = Try(Some(lexing_simp(r1, s1))).getOrElse(None)  | 
   258 println("prog0 test") | 
   389     if (res1 != res2) println(s"Disagree on ${r1} and ${s1}") | 
   259   | 
   390     if (res1 != res2) Some((r1, s1)) else None  | 
   260 val prog0 = """read n"""  | 
   391   }  | 
   261 println(env(lexing_simp(WHILE_REGS, prog0)))  | 
   392 }  | 
   262   | 
   393   | 
   263 println("prog1 test") | 
   394 println("Testing") | 
   264   | 
   395 println(tests(2,7,"abc"))  | 
   265 val prog1 = """read  n; write (n)"""  | 
   396   | 
   266 println(env(lexing_simp(WHILE_REGS, prog1)))  | 
   397   | 
   267   | 
   398   | 
   268   | 
         | 
   269 // Bigger Test  | 
         | 
   270 //=============  | 
         | 
   271   | 
         | 
   272 val prog2 = """  | 
         | 
   273 write "fib";  | 
         | 
   274 read n;  | 
         | 
   275 minus1 := 0;  | 
         | 
   276 minus2 := 1;  | 
         | 
   277 while n > 0 do { | 
         | 
   278   temp := minus2;  | 
         | 
   279   minus2 := minus1 + minus2;  | 
         | 
   280   minus1 := temp;  | 
         | 
   281   n := n - 1  | 
         | 
   282 };  | 
         | 
   283 write "result";  | 
         | 
   284 write minus2  | 
         | 
   285 """  | 
         | 
   286   | 
         | 
   287 println("Tokens") | 
         | 
   288 println(env(lexing_simp(WHILE_REGS, prog2)))  | 
         | 
   289 println(env(lexing_simp(WHILE_REGS, prog2)).filterNot{_._1 == "w"}.mkString("\n")) | 
         | 
   290   | 
         | 
   291 // some more timing tests with  | 
         | 
   292 // i copies of the program  | 
         | 
   293   | 
         | 
   294 for (i <- 1 to 21 by 10) { | 
         | 
   295   print(i.toString + ":  ")  | 
         | 
   296   time(lexing_simp(WHILE_REGS, prog2 * i))  | 
         | 
   297 }  | 
         | 
   298   | 
         | 
   299 abstract class Token  | 
         | 
   300 case class KeyToken(s: String) extends Token  | 
         | 
   301 case class IdToken(s: String) extends Token  | 
         | 
   302   | 
         | 
   303 list[(STRING, STRING)]=> List(TOKEN)  | 
         |