Impl conceptual builder pattern.

Author: ilopX

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>[];
+}

patterns/builder/conceptual/product/concrete_product_2.dart

@@ -0,0 +1,19 @@
+import '../pattern/product.dart';
+
+class ConcreteProduct2 implements Product {
+  ConcreteProduct2(String name) {
+    _buff.add(name);
+  }
+
+  void addLine(String name) {
+    final num = ['1️⃣', '2️⃣', '3️⃣'][_buff.length - 1];
+    _buff.add('$num: $name');
+  }
+
+  @override
+  String toString() {
+    return '${_buff.join('\n')}\n';
+  }
+
+  final _buff = <String>[];
+}