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// 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.
// @dart = 2.9
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}');
}