86 lines
2.4 KiB
Dart
86 lines
2.4 KiB
Dart
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class PizzaBuilder {
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late String _crust;
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int _diameter;
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late Set<String> _toppings;
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PizzaBuilder(this._diameter);
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String get crust => _crust;
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set crust(String newCrust) {
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_crust = newCrust;
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}
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int get diameter => _diameter;
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set diameter(int newDiameter) {
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_diameter = newDiameter;
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}
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Set<String> get toppings => _toppings;
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set toppings(Set<String> newToppings) {
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_toppings = newToppings;
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_ensureCheese();
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}
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void _ensureCheese() {
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_toppings.add("cheese");
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}
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Pizza build() {
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return Pizza(this);
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}
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}
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class Pizza {
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late String _crust;
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late int _diameter;
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late Set<String> _toppings;
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Pizza(PizzaBuilder builder) {
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_crust = builder.crust;
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_diameter = builder.diameter;
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_toppings = builder.toppings;
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}
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String get crust => _crust;
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int get diameter => _diameter;
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String get toppings => _stringifiedToppings();
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String _stringifiedToppings() {
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var stringToppings = _toppings.join(", ");
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var lastComma = stringToppings.lastIndexOf(",");
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var replacement = ",".allMatches(stringToppings).length > 1 ? ", and" : " and";
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return stringToppings.replaceRange(lastComma, lastComma + 1, replacement);
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}
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@override
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String toString() {
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return "A delicous $_diameter\" pizza with $_crust crust covered in $toppings";
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}
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}
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void main() {
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// Create a handy PizzaBuilder with an 8" diameter.
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var pizzaBuilder = PizzaBuilder(8);
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// Add some attributes to the builder.
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pizzaBuilder.crust = "deep dish";
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pizzaBuilder.toppings = Set.from(["pepperoni"]);
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// Let's make a pizza!
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var plainPizza = Pizza(pizzaBuilder);
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print("Behold! $plainPizza.");
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assert(plainPizza.toString() == "Behold! A delicous 8\" pizza with deep dish crust covered in pepperoni and cheese.");
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// Now to adjust some things for the next pizza...
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pizzaBuilder.crust = "gold plated";
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pizzaBuilder.diameter = 72;
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pizzaBuilder.toppings = Set.from(["anchovies", "caviar", "diamonds"]);
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// The beauty of the build is you can quickly iterate and produce instances of a class.
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// For example, we have an early employee of the latest unicorn in line. So much disposable income!
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// Also note, we use the .build() function of the builder this time.
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var luxuriousPizza = pizzaBuilder.build();
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print("Wow! $luxuriousPizza? Someone is rich!");
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assert(luxuriousPizza.toString() == "Wow! A delicous 72\" pizza with gold plated crust covered in anchovies, caviar, diamonds, and cheese? Someone is rich!");
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}
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