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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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//:load matcher.scala
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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//:load parser3.scala
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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3 |
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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// some regular expressions
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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val LETTER = RANGE("abcdefghijklmnopqrstuvwxyz")
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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val ID = PLUS(LETTER)
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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val DIGIT = RANGE("0123456789")
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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val NONZERODIGIT = RANGE("123456789")
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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val NUMBER = ALT(SEQ(NONZERODIGIT, STAR(DIGIT)), "0")
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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val LPAREN = CHAR('(')
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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val RPAREN = CHAR(')')
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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14 |
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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val WHITESPACE = PLUS(RANGE(" \n"))
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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val OPS = RANGE("+-*")
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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17 |
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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// for classifying the strings that have been lexed
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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abstract class Token
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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case object T_WHITESPACE extends Token
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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case class T_NUM(s: String) extends Token
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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case class T_OP(s: String) extends Token
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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case object T_LPAREN extends Token
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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case object T_RPAREN extends Token
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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// lexing rules for arithmetic expressions
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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val lexing_rules: List[Rule[Token]]=
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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List((NUMBER, (s) => T_NUM(s.mkString)),
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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(WHITESPACE, (s) => T_WHITESPACE),
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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(LPAREN, (s) => T_LPAREN),
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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(RPAREN, (s) => T_RPAREN),
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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(OPS, (s) => T_OP(s.mkString)))
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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val Tk = Tokenizer(lexing_rules, List(T_WHITESPACE))
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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case class TokParser(tok: Token) extends Parser[List[Token], Token] {
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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def parse(ts: List[Token]) = ts match {
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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case t::ts if (t == tok) => Set((t, ts))
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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case _ => Set ()
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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implicit def token2tparser(t: Token) = TokParser(t)
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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46 |
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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case object NumParser extends Parser[List[Token], Int] {
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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def parse(ts: List[Token]) = ts match {
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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case T_NUM(s)::ts => Set((s.toInt, ts))
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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case _ => Set ()
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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53 |
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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lazy val E: Parser[List[Token], Int] = (T ~ T_OP("+") ~ E) ==> { case ((x, y), z) => x + z } || T
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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55 |
lazy val T: Parser[List[Token], Int] = (F ~ T_OP("*") ~ T) ==> { case ((x, y), z) => x * z } || F
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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56 |
lazy val F: Parser[List[Token], Int] = (T_LPAREN ~> E <~ T_RPAREN) || NumParser
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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57 |
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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println(E.parse_all(Tk.fromString("1 + 2 + 3")))
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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println(E.parse_all(Tk.fromString("1 + 2 * 3")))
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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println(E.parse_all(Tk.fromString("(1 + 2) * 3")))
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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println(E.parse_all(Tk.fromString("(14 + 2) * (3 + 2)")))
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents:
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62 |
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