Impl conceptual visitor pattern project.

Author: ilopX

patterns/visitor/conceptual/after/elements/one.dart

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+import '../pattern/element.dart';
+import '../pattern/visitor.dart';
+
+class One implements Element {
+  final String param1 = '1';
+
+  @override
+  void accept(Visitor visitor) {
+    visitor.visitOne(this);
+  }
+}

patterns/visitor/conceptual/after/elements/three.dart

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+import '../pattern/element.dart';
+import '../pattern/visitor.dart';
+
+class Three implements Element {
+  final String param3 = '3';
+
+  @override
+  void accept(Visitor visitor) {
+    visitor.visitThree(this);
+  }
+}

patterns/visitor/conceptual/after/elements/two.dart

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+import '../pattern/element.dart';
+import '../pattern/visitor.dart';
+
+class Two implements Element {
+  final String param2 = '2';
+
+  @override
+  void accept(Visitor visitor) {
+    visitor.visitTwo(this);
+  }
+}

patterns/visitor/conceptual/after/main.dart

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+import 'elements/one.dart';
+import 'elements/three.dart';
+import 'elements/two.dart';
+import 'operations/concrete_visitor1.dart';
+import 'operations/concrete_visitor2.dart';
+import 'pattern/element.dart';
+import 'pattern/visitor.dart';
+
+void main() {
+  final list = createElements();
+  operation(list, ConcreteVisitor1());
+  operation(list, ConcreteVisitor2());
+}
+
+Iterable<Element> createElements() {
+  return [
+    One(),
+    Two(),
+    Three(),
+  ];
+}
+
+void operation(Iterable<Element> elements, Visitor visitor) {
+  for (final e in elements) {
+    e.accept(visitor);
+  }
+}

patterns/visitor/conceptual/after/operations/concrete_visitor1.dart

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+import '../elements/one.dart';
+import '../elements/three.dart';
+import '../elements/two.dart';
+import '../pattern/visitor.dart';
+
+class ConcreteVisitor1 implements Visitor {
+  @override
+  void visitOne(One one) {
+    print('operation1: one (param1 = ${one.param1})');
+  }
+
+  @override
+  void visitTwo(Two two) {
+    print('operation1: two (param2 = ${two.param2})');
+  }
+
+  @override
+  void visitThree(Three three) {
+    print('operation1: three (param3 = ${three.param3})');
+  }
+}

patterns/visitor/conceptual/after/operations/concrete_visitor2.dart

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+import '../elements/one.dart';
+import '../elements/three.dart';
+import '../elements/two.dart';
+import '../pattern/visitor.dart';
+
+class ConcreteVisitor2 implements Visitor {
+  @override
+  void visitOne(One one) {
+    print('operation2: one (param1 = ${one.param1})');
+  }
+
+  @override
+  void visitTwo(Two two) {
+    print('operation2: two (param2 = ${two.param2})');
+  }
+
+  @override
+  void visitThree(Three three) {
+    print('operation2: three (param3 = ${three.param3})');
+  }
+}

patterns/visitor/conceptual/after/pattern/element.dart

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+import 'visitor.dart';
+
+abstract class Element {
+  void accept(Visitor visitor);
+}

patterns/visitor/conceptual/after/pattern/visitor.dart

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+import '../elements/one.dart';
+import '../elements/three.dart';
+import '../elements/two.dart';
+
+abstract class Visitor {
+  void visitOne(One one);
+
+  void visitTwo(Two two);
+
+  void visitThree(Three three);
+}

patterns/visitor/conceptual/before/elements/elements.dart

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+class One {
+  final String param1 = '1';
+}
+
+class Two {
+  final String param2 = '2';
+}
+
+class Three {
+  final String param3 = '3';
+}

patterns/visitor/conceptual/before/main.dart

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+import 'elements/elements.dart';
+
+void main() {
+  final list = createElements();
+
+  list.forEach(operation1);
+  list.forEach(operation2);
+}
+
+Iterable<Object> createElements() {
+  return [
+    One(),
+    Two(),
+    Three(),
+  ];
+}
+
+void operation1(Object obj) {
+  if (obj is One) {
+    print('operation1: one (param1 = ${obj.param1})');
+  } else if (obj is Two) {
+    print('operation1: two (param2 = ${obj.param2})');
+  } else if (obj is Three) {
+    print('operation1: two (param3 = ${obj.param3})');
+  }
+}
+
+void operation2(Object obj) {
+  if (obj is One) {
+    print('operation2: one (param1 = ${obj.param1})');
+  } else if (obj is Two) {
+    print('operation2: two (param2 = ${obj.param2})');
+  } else if (obj is Three) {
+    print('operation2: two (param3 = ${obj.param3})');
+  }
+}