Merge pull request #71 from ilopX/add-conceptual-builder-pattern

Add conceptual builder pattern

Author: ilopX

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 0.33.0
+- Add conceptual builder pattern.
+
 ## 0.32.0
 - Add conceptual interpreter pattern.
 

README.md

@@ -5,7 +5,7 @@ It contains **Dart** examples for all classic **GoF** design patterns.
 # Implementation checklist:
 - [ ] **Creation**
     - [x] **Abstract Factory** [[Conceptual Gui Factory](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/abstract_factory/conceptual_gui_factory)] [[![16x16](https://user-images.githubusercontent.com/8049534/171852337-57db0faf-1f5e-489a-a79a-22ed4f47b4ed.png) Tool Panel Factory](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/abstract_factory/tool_panel_factory)]
-    - [x] **Builder** - [[Color Text Format](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/builder/color_text_format)]
+    - [x] **Builder** - [[Conceptual](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/builder/conceptual)] [[Color Text Format](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/builder/color_text_format)]
     - [x] **Factory Method** [[Conceptual Platform Dialog](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/factory_method/conceptual_platform_dialog)]
     - [x] **Prototype** - [[Shapes](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/prototype/shapes)] 
     - [ ] **Singleton**

patterns/builder/conceptual/README.md

@@ -0,0 +1,36 @@
+# Builder Pattern
+Builder is a creational design pattern that lets you construct complex objects step by step. The
+pattern allows you to produce different types and representations of an object using the same
+construction code.
+
+## Diagram:
+
+![image](https://user-images.githubusercontent.com/8049534/182850365-52969fc7-d743-430b-acc7-da400eae26aa.png)
+
+## Client code:
+
+```dart
+void main() {
+  final director = Director();
+
+  final product1 = director.construct(ConcreteBuilder1());
+  print(product1);
+
+  final product2 = director.construct(ConcreteBuilder2());
+  print(product2);
+}
+```
+
+### Output:
+
+```
+ConcreteBuilder1
+001: one
+002: two
+003: three
+
+ConcreteBuilder2
+1️⃣: first
+2️⃣: second
+3️⃣: third
+```

patterns/builder/conceptual/concrete_builder/concrete_builder_1.dart

@@ -0,0 +1,25 @@
+import '../pattern/builder.dart';
+import '../pattern/product.dart';
+import '../product/concrete_product_1.dart';
+
+class ConcreteBuilder1 implements Builder {
+  @override
+  void buildPart1() {
+    _product.addLine('one');
+  }
+
+  @override
+  void buildPart2() {
+    _product.addLine('two');
+  }
+
+  @override
+  void buildPart3() {
+    _product.addLine('three');
+  }
+
+  @override
+  Product get result => _product;
+
+  final _product = ConcreteProduct1('ConcreteBuilder1');
+}

patterns/builder/conceptual/concrete_builder/concrete_builder_2.dart

@@ -0,0 +1,25 @@
+import '../pattern/builder.dart';
+import '../pattern/product.dart';
+import '../product/concrete_product_2.dart';
+
+class ConcreteBuilder2 implements Builder {
+  @override
+  void buildPart1() {
+    _product.addLine('first');
+  }
+
+  @override
+  void buildPart2() {
+    _product.addLine('second');
+  }
+
+  @override
+  void buildPart3() {
+    _product.addLine('third');
+  }
+
+  @override
+  Product get result => _product;
+
+  final _product = ConcreteProduct2('ConcreteBuilder2');
+}

patterns/builder/conceptual/main.dart

@@ -0,0 +1,13 @@
+import 'concrete_builder/concrete_builder_1.dart';
+import 'concrete_builder/concrete_builder_2.dart';
+import 'pattern/director.dart';
+
+void main() {
+  final director = Director();
+
+  final product1 = director.construct(ConcreteBuilder1());
+  print(product1);
+
+  final product2 = director.construct(ConcreteBuilder2());
+  print(product2);
+}

patterns/builder/conceptual/pattern/builder.dart

@@ -0,0 +1,9 @@
+import 'product.dart';
+
+abstract class Builder {
+  void buildPart1();
+  void buildPart2();
+  void buildPart3();
+
+  Product get result;
+}

patterns/builder/conceptual/pattern/director.dart

@@ -0,0 +1,12 @@
+import 'builder.dart';
+import 'product.dart';
+
+class Director {
+  Product construct(Builder builder) {
+    builder.buildPart1();
+    builder.buildPart2();
+    builder.buildPart3();
+
+    return builder.result;
+  }
+}

patterns/builder/conceptual/pattern/product.dart

@@ -0,0 +1 @@
+abstract class Product {}

patterns/builder/conceptual/product/concrete_product_1.dart

@@ -0,0 +1,19 @@
+import '../pattern/product.dart';
+
+class ConcreteProduct1 implements Product {
+  ConcreteProduct1(String name) {
+    _buff.add(name);
+  }
+
+  void addLine(String name) {
+    final index = _buff.length.toString().padLeft(3, '0');
+    _buff.add('$index: $name');
+  }
+
+  @override
+  String toString() {
+    return '${_buff.join('\n')}\n';
+  }
+
+  final _buff = <String>[];
+}