diff options
Diffstat (limited to 'docs/examples/expressions/expressions-current.scala')
-rw-r--r-- | docs/examples/expressions/expressions-current.scala | 53 |
1 files changed, 26 insertions, 27 deletions
diff --git a/docs/examples/expressions/expressions-current.scala b/docs/examples/expressions/expressions-current.scala index 91e5df02ae..5eeb439430 100644 --- a/docs/examples/expressions/expressions-current.scala +++ b/docs/examples/expressions/expressions-current.scala @@ -1,67 +1,66 @@ -package examples.expressions; +package examples.expressions abstract class Lang { trait Visitor { - def caseNum(n: int): unit; + def caseNum(n: int): unit } abstract class Exp { - def visit(v: visitor): unit; + def visit(v: visitor): unit } - type visitor <: Visitor; + type visitor <: Visitor class Num(n: int) extends Exp { - def visit(v: visitor): unit = v.caseNum(n); + def visit(v: visitor): unit = v.caseNum(n) } - class Eval(result: Ref[int]): visitor extends Visitor { - def caseNum(n: int) = result.elem = n; + class Eval(result: Ref[int]) requires visitor extends Visitor { + def caseNum(n: int) = result.elem = n } } abstract class Lang2 extends Lang { abstract class Visitor2 extends Visitor { - def casePlus(left: Exp, right: Exp): unit; + def casePlus(left: Exp, right: Exp): unit } - type visitor <: Visitor2; + type visitor <: Visitor2 class Plus(l: Exp, r: Exp) extends Exp { - def visit(v: visitor): unit = v.casePlus(l, r); + def visit(v: visitor): unit = v.casePlus(l, r) } - class Eval2(result: Ref[int]): visitor extends Eval(result) with Visitor2 { + // class Eval2(result: Ref[int]): visitor extends Eval(result) with Visitor2 { + class Eval2(result: Ref[int]) requires visitor extends Visitor2 { def casePlus(l: Exp, r: Exp) = result.elem = { l.visit(this); result.elem } + { r.visit(this); result.elem } } - class Show2(result: Ref[String]): visitor extends Visitor2 { - def caseNum(n: int) = result.elem = n.toString(); + class Show2(result: Ref[String]) requires visitor extends Visitor2 { + def caseNum(n: int) = result.elem = n.toString() def casePlus(l: Exp, r: Exp) = result.elem = - "(" + { l.visit(this); result.elem } + - "+" + { r.visit(this); result.elem } + ")"; + "(" + { l.visit(this); result.elem } + + "+" + { r.visit(this); result.elem } + ")" } } object Main { - - def main(args: Array[String]) = { + def main(args: Array[String]): unit = { //val l1 = new Lang { type visitor = Visitor } // not yet implemented object l1 extends Lang { type visitor = Visitor } // workaround - val e1: l1.Exp = new l1.Num(42); - val iref = new Ref(0); - Console.println("eval: " + { e1.visit(new l1.Eval(iref)); iref.elem }); + val e1: l1.Exp = new l1.Num(42) + val iref = new Ref(0) + Console.println("eval: " + { e1.visit(new l1.Eval(iref)); iref.elem }) //val l2 = new Lang2 { type visitor = Visitor2 } // not yet implemented object l2 extends Lang2 { type visitor = Visitor2 } // workaround - val e2: l2.Exp = new l2.Plus(new l2.Num(5), new l2.Num(37)); - val sref = new Ref(""); - Console.println("eval: " + { e2.visit(new l2.Eval2(iref)); iref.elem }); - Console.println("show: " + { e2.visit(new l2.Show2(sref)); sref.elem }); - e1.visit(new l1.Eval(iref)); - e2.visit(new l2.Show2(sref)); + val e2: l2.Exp = new l2.Plus(new l2.Num(5), new l2.Num(37)) + val sref = new Ref("") + Console.println("eval: " + { e2.visit(new l2.Eval2(iref)); iref.elem }) + Console.println("show: " + { e2.visit(new l2.Show2(sref)); sref.elem }) + e1.visit(new l1.Eval(iref)) + e2.visit(new l2.Show2(sref)) } } - |