--- a/solutions/cw5/fun_tokens.sc Sat Dec 03 21:58:47 2022 +0000
+++ b/solutions/cw5/fun_tokens.sc Fri Dec 09 11:00:05 2022 +0000
@@ -1,27 +1,31 @@
-// A tokeniser for the Fun language
-//==================================
+// Author: Zhuo Ying Jiang Li
+// Starting code by Dr Christian Urban
+
+// lexer
+
//
-// call with
-//
-// amm fun_tokens.sc fact.fun
-//
-// amm fun_tokens.sc defs.fun
+// Use this command to print the list of tokens:
+// amm fun_token.sc <name>.fun
//
-
+type Token = (String, String)
+type Tokens = List[Token]
-import scala.language.implicitConversions
-import scala.language.reflectiveCalls
-
-abstract class Rexp
+// regular expressions including records
+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
-
+case class RANGE(chars: List[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 OPTIONAL(r: Rexp) extends Rexp
+case class PLUS(r: Rexp) extends Rexp
+case class NTIMES(r: Rexp, n: Int) extends Rexp
+case class RECD(x: String, r: Rexp) extends Rexp // records for extracting strings or tokens
+
+// values
abstract class Val
case object Empty extends Val
case class Chr(c: Char) extends Val
@@ -29,20 +33,27 @@
case class Left(v: Val) extends Val
case class Right(v: Val) extends Val
case class Stars(vs: List[Val]) extends Val
+case class Opt(v: Val) extends Val
+case class Pls(vs: List[Val]) extends Val
+case class Nt(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))
+ case c::vs => SEQ(CHAR(c), charlist2rexp(vs))
}
-implicit def string2rexp(s : String) : Rexp =
+
+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 ? = OPTIONAL(r)
+ def + = PLUS(r)
+ def ^ (n: Int) = NTIMES(r, n)
def ~ (s: Rexp) = SEQ(r, s)
}
@@ -50,66 +61,89 @@
def | (r: Rexp) = ALT(s, r)
def | (r: String) = ALT(s, r)
def % = STAR(s)
+ def ? = OPTIONAL(s)
+ def + = PLUS(s)
+ def ^ (n: Int) = NTIMES(s, n)
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 {
+def nullable(r: Rexp) : Boolean = r match {
case ZERO => false
case ONE => true
case CHAR(_) => false
+ case RANGE(_) => false
case ALT(r1, r2) => nullable(r1) || nullable(r2)
case SEQ(r1, r2) => nullable(r1) && nullable(r2)
case STAR(_) => true
+ case OPTIONAL(r1) => true
+ case PLUS(r1) => nullable(r1)
+ case NTIMES(r1, n) => if (n == 0) true else nullable(r1)
case RECD(_, r1) => nullable(r1)
}
-def der (c: Char, r: Rexp) : Rexp = r match {
+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 RANGE(chars) => if (chars.contains(c)) ONE else ZERO
case ALT(r1, r2) => ALT(der(c, r1), der(c, r2))
- case SEQ(r1, 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 OPTIONAL(r) => der(c, r)
+ case PLUS(r) => SEQ(der(c, r), STAR(r))
+ case NTIMES(r1, n) => if (n == 0) ZERO else SEQ(der(c, r1), NTIMES(r1, n - 1))
case RECD(_, r1) => der(c, r1)
}
-
-// extracts a string from value
+// extracts a string from a 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 Sequ(v1, v2) => flatten(v1) ++ flatten(v2)
case Stars(vs) => vs.map(flatten).mkString
+ case Opt(v) => flatten(v)
+ case Pls(vs) => vs.map(flatten).mkString
+ case Nt(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 {
+// used for tokenising a string
+def env(v: Val) : Tokens = 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 Opt(v) => env(v)
+ case Pls(vs) => vs.flatMap(env)
+ case Nt(vs) => vs.flatMap(env)
case Rec(x, v) => (x, flatten(v))::env(v)
}
-// The Injection Part of the lexer
+
+// The injection and mkeps part of the lexer
+//===========================================
def mkeps(r: Rexp) : Val = r match {
case ONE => Empty
- case ALT(r1, r2) =>
+ case RANGE(chars) => throw new Exception("lexing error") // this will never be called but the coursework asks for it so...
+ 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 OPTIONAL(r) => Opt(Empty)
+ case PLUS(r) => Pls(List(mkeps(r))) // scala define a list with one element
+ case NTIMES(r, n) => if (n == 0) Nt(Nil) else Nt(List.fill(n)(mkeps(r))) // wrong
case RECD(x, r) => Rec(x, mkeps(r))
+ case _ => throw new Exception("lexing error")
}
def inj(r: Rexp, c: Char, v: Val) : Val = (r, v) match {
@@ -119,9 +153,12 @@
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 (CHAR(d), Empty) => Chr(c)
+ case (RANGE(chars), Empty) => Chr(c)
+ case (OPTIONAL(r1), v) => Opt(inj(r1, c, v))
+ case (PLUS(r1), Sequ(v1, Stars(vs))) => Pls(inj(r1, c, v1)::vs)
+ case (NTIMES(r1, n), Sequ(v1, Nt(vs))) => Nt(inj(r1, c, v1)::vs)
case (RECD(x, r1), _) => Rec(x, inj(r1, c, v))
- case _ => { println ("Injection error") ; sys.exit(-1) }
}
// some "rectification" functions for simplification
@@ -135,15 +172,14 @@
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) =
+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) =
+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")
+// simplification
def simp(r: Rexp): (Rexp, Val => Val) = r match {
case ALT(r1, r2) => {
val (r1s, f1s) = simp(r1)
@@ -152,7 +188,7 @@
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))
+ else (ALT (r1s, r2s), F_ALT(f1s, f2s))
}
}
case SEQ(r1, r2) => {
@@ -166,115 +202,75 @@
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 Nil => if (nullable(r)) mkeps(r) else
+ { throw new Exception("lexing error") }
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))
+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
+// FUN language lexer
-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 DIGIT = RANGE("0123456789".toList)
+val LOWERCASE = RANGE("abcdefghijklmnopqrstuvwxyz".toList)
+val UPPERCASE = RANGE("ABCDEFGHIJKLMNOPQRSTUVWXYZ".toList)
+val SYM = RANGE("!\"#$%&'()*+,-./:;<>=?`@[]\\^_{}|~".toList) // I referenced the CPP ASCII table https://en.cppreference.com/w/cpp/language/ascii
-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
+val KEYWORD : Rexp = "val" | "if" | "then" | "else" | "def" | "skip" // "skip" is hardcoded because hanoi.fun calls skip() without parentheses
+val TYPE : Rexp = "Int" | "Double" | "Void"
+val GLOBAL_ID : Rexp = UPPERCASE ~ ("_" | LOWERCASE | DIGIT | UPPERCASE).% // start with capital letter and followed by any case
+val ID : Rexp = LOWERCASE ~ ("_" | UPPERCASE | LOWERCASE | DIGIT).% // start with lowercase
+val SEMI : Rexp = ";"
+val COLON : Rexp = ":"
+val OP : Rexp = "=" | "==" | "-" | "+" | "*" | "!=" | "<" | ">" | "<=" | ">=" | "%" | "/" // no && and || operators
+val INT : Rexp = DIGIT.+
+val DOUBLE : Rexp = DIGIT.+ ~ "." ~ DIGIT.+ // negative numbers sign is lexed as operator, but the parser will identify negative numbers
+val COMMA : Rexp = ","
+val WHITESPACES: Rexp = (" " | "\n" | "\t" | "\r").+ // whitespaces are either " " or \n or \t or \r
+val LPAREN : Rexp = RANGE("({".toList)
+val RPAREN : Rexp = RANGE(")}".toList)
+val CH : Rexp = "'" ~ (LOWERCASE | UPPERCASE | DIGIT | SYM | " " | "\\n" | "\\t" | "\\r") ~ "'" // \n, \t and \r should also be tokenized, any character should be, whitespaces too
+val COMMENT : Rexp = ("//" ~ (LOWERCASE | UPPERCASE | SYM | DIGIT | RANGE(" \t\r".toList)).% ~ "\n") | ("/*" ~ (LOWERCASE | UPPERCASE | SYM | DIGIT | RANGE(" \n\t\r".toList)).% ~ "*/")
-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 FUN_REGS = (("keyword" $ KEYWORD) |
+ ("type" $ TYPE) |
+ ("global" $ GLOBAL_ID) |
+ ("id" $ ID) |
+ ("op" $ OP) |
+ ("double" $ DOUBLE) |
+ ("int" $ INT) |
+ ("semi" $ SEMI) |
+ ("colon" $ COLON) |
+ ("comma" $ COMMA) |
+ ("ch" $ CH) |
+ ("par" $ (LPAREN | RPAREN)) |
+ COMMENT | WHITESPACES).%
-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 fun_lex(program: String) : Tokens = {
+ lexing_simp(FUN_REGS, program)
}
-
-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) }
+def tokenise(program: String) : Tokens = {
+ lexing_simp(FUN_REGS, program)
}
-//import ammonite.ops._
+import scala.io.Source._
-//@doc("Tokenising a file.")
@main
-def main(fname: String) = {
- println(tokenise(os.read(os.pwd / fname)))
+def lex(filename: String) = {
+ // read file
+ val fun_code = fromFile(filename).getLines.mkString("\n")
+ // print tokens to screen
+ println(fun_lex(fun_code).mkString("\n"))
}