--- a/solution/cw5/fun_tokens.sc Fri Oct 28 09:08:13 2022 +0100
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,280 +0,0 @@
-// A tokeniser for the Fun language
-//==================================
-//
-// call with
-//
-// amm fun_tokens.sc fact.fun
-//
-// amm fun_tokens.sc defs.fun
-//
-
-
-
-import scala.language.implicitConversions
-import scala.language.reflectiveCalls
-
-abstract class Rexp
-case object ZERO extends Rexp
-case object ONE 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 RECD(x: String, r: Rexp) extends Rexp
-
-abstract class Val
-case object Empty extends Val
-case class Chr(c: Char) extends Val
-case class Sequ(v1: Val, v2: Val) extends Val
-case class Left(v: Val) extends Val
-case class Right(v: Val) extends Val
-case class Stars(vs: List[Val]) extends Val
-case class Rec(x: String, v: Val) extends Val
-
-// some convenience for typing in regular expressions
-def charlist2rexp(s : List[Char]): Rexp = s match {
- case Nil => ONE
- 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 ~ (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 ~ (r: Rexp) = SEQ(s, r)
- def ~ (r: String) = SEQ(s, r)
- def $ (r: Rexp) = RECD(s, r)
-}
-
-def nullable (r: Rexp) : Boolean = r match {
- case ZERO => false
- case ONE => true
- case CHAR(_) => false
- case ALT(r1, r2) => nullable(r1) || nullable(r2)
- case SEQ(r1, r2) => nullable(r1) && nullable(r2)
- case STAR(_) => true
- case RECD(_, r1) => nullable(r1)
-}
-
-def der (c: Char, r: Rexp) : Rexp = r match {
- case ZERO => ZERO
- case ONE => ZERO
- case CHAR(d) => if (c == d) ONE else ZERO
- 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 RECD(_, r1) => der(c, r1)
-}
-
-
-// extracts a string from value
-def flatten(v: Val) : String = v match {
- case Empty => ""
- case Chr(c) => c.toString
- case Left(v) => flatten(v)
- case Right(v) => flatten(v)
- case Sequ(v1, v2) => flatten(v1) + flatten(v2)
- case Stars(vs) => vs.map(flatten).mkString
- case Rec(_, v) => flatten(v)
-}
-
-// extracts an environment from a value;
-// used for tokenise a string
-def env(v: Val) : List[(String, String)] = v match {
- case Empty => Nil
- case Chr(c) => Nil
- case Left(v) => env(v)
- case Right(v) => env(v)
- case Sequ(v1, v2) => env(v1) ::: env(v2)
- case Stars(vs) => vs.flatMap(env)
- case Rec(x, v) => (x, flatten(v))::env(v)
-}
-
-// The Injection Part of the lexer
-
-def mkeps(r: Rexp) : Val = r match {
- case ONE => Empty
- case ALT(r1, r2) =>
- if (nullable(r1)) Left(mkeps(r1)) else Right(mkeps(r2))
- case SEQ(r1, r2) => Sequ(mkeps(r1), mkeps(r2))
- case STAR(r) => Stars(Nil)
- case RECD(x, r) => Rec(x, mkeps(r))
-}
-
-def inj(r: Rexp, c: Char, v: Val) : Val = (r, v) match {
- case (STAR(r), Sequ(v1, Stars(vs))) => Stars(inj(r, c, v1)::vs)
- case (SEQ(r1, r2), Sequ(v1, v2)) => Sequ(inj(r1, c, v1), v2)
- case (SEQ(r1, r2), Left(Sequ(v1, v2))) => Sequ(inj(r1, c, v1), v2)
- case (SEQ(r1, r2), Right(v2)) => Sequ(mkeps(r1), inj(r2, c, v2))
- case (ALT(r1, r2), Left(v1)) => Left(inj(r1, c, v1))
- case (ALT(r1, r2), Right(v2)) => Right(inj(r2, c, v2))
- case (CHAR(d), Empty) => Chr(c)
- case (RECD(x, r1), _) => Rec(x, inj(r1, c, v))
- case _ => { println ("Injection error") ; sys.exit(-1) }
-}
-
-// some "rectification" functions for simplification
-def F_ID(v: Val): Val = v
-def F_RIGHT(f: Val => Val) = (v:Val) => Right(f(v))
-def F_LEFT(f: Val => Val) = (v:Val) => Left(f(v))
-def F_ALT(f1: Val => Val, f2: Val => Val) = (v:Val) => v match {
- case Right(v) => Right(f2(v))
- case Left(v) => Left(f1(v))
-}
-def F_SEQ(f1: Val => Val, f2: Val => Val) = (v:Val) => v match {
- case Sequ(v1, v2) => Sequ(f1(v1), f2(v2))
-}
-def F_SEQ_Empty1(f1: Val => Val, f2: Val => Val) =
- (v:Val) => Sequ(f1(Empty), f2(v))
-def F_SEQ_Empty2(f1: Val => Val, f2: Val => Val) =
- (v:Val) => Sequ(f1(v), f2(Empty))
-def F_RECD(f: Val => Val) = (v:Val) => v match {
- case Rec(x, v) => Rec(x, f(v))
-}
-def F_ERROR(v: Val): Val = throw new Exception("error")
-
-def simp(r: Rexp): (Rexp, Val => Val) = r match {
- case ALT(r1, r2) => {
- val (r1s, f1s) = simp(r1)
- val (r2s, f2s) = simp(r2)
- (r1s, r2s) match {
- case (ZERO, _) => (r2s, F_RIGHT(f2s))
- case (_, ZERO) => (r1s, F_LEFT(f1s))
- case _ => if (r1s == r2s) (r1s, F_LEFT(f1s))
- else (ALT (r1s, r2s), F_ALT(f1s, f2s))
- }
- }
- case SEQ(r1, r2) => {
- val (r1s, f1s) = simp(r1)
- val (r2s, f2s) = simp(r2)
- (r1s, r2s) match {
- case (ZERO, _) => (ZERO, F_ERROR)
- case (_, ZERO) => (ZERO, F_ERROR)
- case (ONE, _) => (r2s, F_SEQ_Empty1(f1s, f2s))
- case (_, ONE) => (r1s, F_SEQ_Empty2(f1s, f2s))
- case _ => (SEQ(r1s,r2s), F_SEQ(f1s, f2s))
- }
- }
- case RECD(x, r1) => {
- val (r1s, f1s) = simp(r1)
- (RECD(x, r1s), F_RECD(f1s))
- }
- case r => (r, F_ID)
-}
-
-// lexing functions including simplification
-def lex_simp(r: Rexp, s: List[Char]) : Val = s match {
- case Nil => if (nullable(r)) mkeps(r) else { println ("Lexing Error") ; sys.exit(-1) }
- case c::cs => {
- val (r_simp, f_simp) = simp(der(c, r))
- inj(r, c, f_simp(lex_simp(r_simp, cs)))
- }
-}
-
-def lexing_simp(r: Rexp, s: String) = env(lex_simp(r, s.toList))
-
-
-// The Lexing Rules for the Fun Language
-
-def PLUS(r: Rexp) = r ~ r.%
-def OPT(r: Rexp) = r | ONE
-
-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" | "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" | "_" | ":"
-val DIGIT = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
-val ID = SYM ~ (SYM | DIGIT).%
-val NUM = PLUS(DIGIT)
-val FNUM = OPT("-") ~ NUM ~ "." ~ NUM
-val KEYWORD : Rexp = "if" | "then" | "else" | "def" | "val"
-val TYPE : Rexp = "Void" | "Int" | "Double"
-val SEMI: Rexp = ";"
-val COLON: Rexp = ":"
-val COMMA: Rexp = ","
-val OP: Rexp = "=" | "==" | "-" | "+" | "*" | "!=" | "<" | ">" | "<=" | ">=" | "%" | "/"
-val WHITESPACE = PLUS(" " | "\n" | "\t" | "\r")
-val RPAREN: Rexp = ")" | "}"
-val LPAREN: Rexp = "(" | "{"
-val ALL = SYM | DIGIT | OP | " " | ":" | ";" | "-" | "." | "\"" | "=" | "," | "(" | ")" | "{" | "}"
-val ALL2 = ALL | "\n"
-val COMMENT = ("/*" ~ ALL2.% ~ "*/") | ("//" ~ ALL.% ~ "\n")
-
-val CHR :Rexp = "'" ~ (ALL | "\\n") ~ "'"
-
-
-val FUN_REGS = (("k" $ KEYWORD) |
- ("t" $ TYPE) |
- ("i" $ ID) |
- ("ch" $ CHR) |
- ("o" $ OP) |
- ("n" $ NUM) |
- ("f" $ FNUM) |
- ("s" $ SEMI) |
- ("co" $ COLON) |
- ("c" $ COMMA) |
- ("pl" $ LPAREN) |
- ("pr" $ RPAREN) |
- ("w" $ (WHITESPACE | COMMENT))).%
-
-
-
-// The tokens for the Fun language
-
-abstract class Token extends Serializable
-case object T_SEMI extends Token
-case object T_COMMA extends Token
-case object T_COLON extends Token
-case object T_LPAREN extends Token
-case object T_RPAREN extends Token
-case class T_ID(s: String) extends Token
-case class T_FID(s: String) extends Token
-case class T_OP(s: String) extends Token
-case class T_NUM(n: Int) extends Token
-case class T_FNUM(x: Double) extends Token
-case class T_KWD(s: String) extends Token
-case class T_TY(s: String) extends Token
-case class T_CHR(i: Int) extends Token
-
-val token : PartialFunction[(String, String), Token] = {
- case ("k", s) => T_KWD(s)
- case ("t", s) => T_TY(s)
- case ("i", s) => T_ID(s)
- case ("o", s) => T_OP(s)
- case ("n", s) => T_NUM(s.toInt)
- case ("ch", s) => if (s == "'\\n'") T_CHR(10) else T_CHR(s(1).toInt)
- case ("f", s) => T_FNUM(s.toDouble)
- case ("s", _) => T_SEMI
- case ("c", _) => T_COMMA
- case ("co", _) => T_COLON
- case ("pl", _) => T_LPAREN
- case ("pr", _) => T_RPAREN
-}
-
-
-def tokenise(s: String) : List[Token] = {
- val tks = lexing_simp(FUN_REGS, s).collect(token)
- if (tks.length != 0) tks
- else { println (s"Tokenise Error") ; sys.exit(-1) }
-}
-
-//import ammonite.ops._
-
-//@doc("Tokenising a file.")
-@main
-def main(fname: String) = {
- println(tokenise(os.read(os.pwd / fname)))
-}