dart-sdk/tests/language/mixin_bound_test.dart

// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import "package:expect/expect.dart";

// library abstract_expressions;

abstract class AbstractExpression {}

abstract class AbstractAddition<E> {
  E operand1, operand2;
  AbstractAddition(this.operand1, this.operand2);
}

abstract class AbstractSubtraction<E> {
  E operand1, operand2;
  AbstractSubtraction(this.operand1, this.operand2);
}

abstract class AbstractNumber {
  int val;
  AbstractNumber(this.val);
}

// library evaluator;

abstract class ExpressionWithEval {
 int get eval;
}

abstract class AdditionWithEval<E extends ExpressionWithEval> {
 E get operand1;
 E get operand2;
 int get eval => operand1.eval + operand2.eval;
}

abstract class SubtractionWithEval<E extends ExpressionWithEval>{
  E get operand1;
  E get operand2;
  int get eval => operand1.eval - operand2.eval;
}

abstract class NumberWithEval {
  int get val;
  int get eval => val;
}

// library multiplication;

abstract class AbstractMultiplication<E> {
  E operand1, operand2;
  AbstractMultiplication(this.operand1, this.operand2);

}

// library multiplicationEvaluator;

// import 'evaluator.dart' show ExpressionWithEval;

abstract class MultiplicationWithEval<E extends ExpressionWithEval> {
  E get operand1;
  E get operand2;
  int get eval => operand1.eval * operand2.eval;
}

// library string_converter;

abstract class ExpressionWithStringConversion {
 String toString();
}

abstract class AdditionWithStringConversion<E extends ExpressionWithStringConversion> {
  E get operand1;
  E get operand2;
  String toString() =>'($operand1 + $operand2))';
}

abstract class SubtractionWithStringConversion<E extends ExpressionWithStringConversion> {
  E get operand1;
  E get operand2;
  String toString() => '($operand1 - $operand2)';
}

abstract class NumberWithStringConversion {
  int get val;
  String toString() => val.toString();
}

abstract class MultiplicationWithStringConversion<E extends ExpressionWithStringConversion> {
  E get operand1;
  E get operand2;
  String toString() => '($operand1 * $operand2)';
}

// library expressions;

// import 'abstractExpressions.dart';
// import 'evaluator.dart';
// import 'multiplication.dart';
// import 'multiplicationEvaluator.dart';
// import 'stringConverter.dart';

abstract class Expression =
  AbstractExpression with ExpressionWithEval, ExpressionWithStringConversion;

class Addition =
  AbstractAddition<Expression> with AdditionWithEval<Expression>,
                                    AdditionWithStringConversion<Expression> implements Expression;

class Subtraction =
  AbstractSubtraction<Expression> with SubtractionWithEval<Expression>,
                                       SubtractionWithStringConversion<Expression> implements Expression;

class Number =
  AbstractNumber with NumberWithEval,
                      NumberWithStringConversion implements Expression;


class Multiplication =
  AbstractMultiplication<Expression> with MultiplicationWithEval<Expression>,
                                          MultiplicationWithStringConversion<Expression> implements Expression;


void main() {
  Expression e = new Multiplication(new Addition(new Number(4), new Number(2)),
                                    new Subtraction(new Number(10), new Number(7)));
  Expect.equals('((4 + 2)) * (10 - 7)) = 18', '$e = ${e.eval}');
}