diff options
Diffstat (limited to 'test/pos/abstract-data.scala')
-rw-r--r-- | test/pos/abstract-data.scala | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/test/pos/abstract-data.scala b/test/pos/abstract-data.scala new file mode 100644 index 0000000000..f3d4a966bb --- /dev/null +++ b/test/pos/abstract-data.scala @@ -0,0 +1,55 @@ +package expAbstractData; + +/** A base class consisting of + * - a root trait (i.e. abstract class) `Exp' with an `eval' function + * - an abstract type `exp' bounded by `Exp' + * - a concrete instance class `Num' of `Exp' for numeric literals + */ +trait Base { + type exp <: Exp; + + trait Exp { + def eval: int + } + class Num(v: int): exp extends Exp { + val value = v; + def eval = value + } +} + +object testBase extends Base with Executable { + type exp = Exp; + val term = new Num(2); + System.out.println(term.eval); +} + +/** Data extension: An extension of `Base' with `Plus' expressions + */ +trait BasePlus extends Base { + class Plus(l: exp, r: exp): exp extends Exp { + val left = l; + val right = r; + def eval = left.eval + right.eval + } +} + +/** Operation extension: An extension of `Base' with 'show' methods. + */ +trait Show extends Base { + type exp <: Exp1; + + trait Exp1 extends Exp { + def show: String; + } + class Num1(v: int): exp extends Num(v) with Exp1 { + def show = value.toString(); + } +} + +/** Operation extension: An extension of `BasePlus' with 'show' methods. + */ +trait ShowPlus extends BasePlus with Show { + class Plus1(l: exp, r: exp): exp extends Plus(l, r) with Exp1 { + def show = left.show + " + " + right.show + } +}
\ No newline at end of file |