diff -r 898c25a4e399 -r 373cf55a3ca5 while1.scala --- a/while1.scala Fri Nov 23 21:21:27 2012 +0000 +++ b/while1.scala Sat Nov 24 07:08:51 2012 +0000 @@ -8,7 +8,7 @@ val DIGIT = RANGE("0123456789") val ID = SEQ(SYM, STAR(ALT(SYM, DIGIT))) val NUM = PLUS(DIGIT) -val KEYWORD = ALTS("skip", "while", "do", "if", "then", "else", "true", "false", "print") +val KEYWORD = ALTS("skip", "while", "do", "if", "then", "else", "true", "false", "write") val SEMI: Rexp = ";" val OP: Rexp = ALTS(":=", "=", "-", "+", "*", "!", "<", ">") val WHITESPACE = PLUS(RANGE(" \n")) @@ -57,7 +57,7 @@ case class If(a: BExp, bl1: Block, bl2: Block) extends Stmt case class While(b: BExp, bl: Block) extends Stmt case class Assign(s: String, a: AExp) extends Stmt -case class Print(s: String) extends Stmt +case class Write(s: String) extends Stmt case class Var(s: String) extends AExp case class Num(i: Int) extends AExp @@ -104,12 +104,13 @@ // boolean expressions lazy val BExp: Parser[List[Token], BExp] = + (T_KWD("true") ==> ((_) => True: BExp)) || + (T_KWD("false") ==> ((_) => False: BExp)) || + (T_LPAREN ~> BExp <~ T_RPAREN) || (AExp ~ T_OP("=") ~ AExp) ==> { case ((x, y), z) => Bop("=", x, z): BExp } || (AExp ~ T_OP("!=") ~ AExp) ==> { case ((x, y), z) => Bop("!=", x, z): BExp } || (AExp ~ T_OP("<") ~ AExp) ==> { case ((x, y), z) => Bop("<", x, z): BExp } || - (AExp ~ T_OP(">") ~ AExp) ==> { case ((x, y), z) => Bop(">", x, z): BExp } || - (T_KWD("true") ==> ((_) => True)) || - (T_KWD("false") ==> ((_) => False: BExp)) + (AExp ~ T_OP(">") ~ AExp) ==> { case ((x, y), z) => Bop("<", z, x): BExp } lazy val Stmt: Parser[List[Token], Stmt] = (T_KWD("skip") ==> ((_) => Skip: Stmt)) || @@ -117,7 +118,7 @@ (T_KWD("if") ~ BExp ~ T_KWD("then") ~ Block ~ T_KWD("else") ~ Block) ==> { case (((((x,y),z),u),v),w) => If(y, u, w): Stmt } || (T_KWD("while") ~ BExp ~ T_KWD("do") ~ Block) ==> { case (((x, y), z), w) => While(y, w) } || - (T_KWD("print") ~ IdParser) ==> { case (x, y) => Print(y) } + (T_KWD("write") ~ IdParser) ==> { case (x, y) => Write(y) } lazy val Stmts: Parser[List[Token], Block] = (Stmt ~ T_SEMI ~ Stmts) ==> { case ((x, y), z) => x :: z : Block } || @@ -135,8 +136,9 @@ case False => false case Bop("=", a1, a2) => eval_aexp(a1, env) == eval_aexp(a2, env) case Bop("!=", a1, a2) => !(eval_aexp(a1, env) == eval_aexp(a2, env)) - case Bop(">", a1, a2) => eval_aexp(a1, env) > eval_aexp(a2, env) case Bop("<", a1, a2) => eval_aexp(a1, env) < eval_aexp(a2, env) + case Bop("&&", a1, a2) => eval_aexp(a1, env) > eval_aexp(a2, env) + case Bop("||", a1, a2) => eval_aexp(a1, env) < eval_aexp(a2, env) } def eval_aexp(a: AExp, env : Env) : Int = a match { @@ -154,7 +156,7 @@ case While(b, bl) => if (eval_bexp(b, env)) eval_stmt(While(b, bl), eval_bl(bl, env)) else env - case Print(x) => { println(env(x)); env } + case Write(x) => { println(env(x)); env } } def eval_bl(bl: Block, env: Env) : Env = bl match { @@ -164,11 +166,21 @@ def eval_prog(name: String) : Env = { val tks = Tok.fromFile(name) - val ast = Stmts.parse_all(tks).head + val ast = Stmts.parse_single(tks) eval_bl(ast, Map.empty) } //examples -eval_prog("fib.while") +eval_prog("loops.while") +//eval_prog("fib.while") + + + + + + + + +