Composite

• 用树形结构分层
• 通过统一对待来简化操作

interface Component {
  operation: Function;
}
abstract class Leaf implements Component {
  operation() {}
}
abstract class Composite implements Component {
  protected childs: Component[] = [];
  operation() {
    this.childs.forEach(child => {
      child.operation();
    });
  }
  add(component: Component) {
    this.childs.push(component);
  }
  remove(component: Component) {
    this.childs.splice(this.childs.indexOf(component), 1);
  }
  getChild() {
    return this.childs;
  }
}
class Duck extends Composite {
  constructor(childs: Component[]) {
    super();
    this.childs = childs;
  }
}
class DuckVoice extends Leaf {
  operation() {
    console.log('Quack.');
  }
}
class DuckFly extends Composite {
  operation() {
    console.log('It flies.');
    super.operation();
  }
  add(component: Component) {
    super.add(component);
    return this;
  }
}
class Wing extends Leaf {
  operation() {
    console.log('Flap-flap-flap');
  }
}
const wings = [new Wing(), new Wing()];
const flyAbility = new DuckFly().add(wings[0]).add(wings[1]);
const voiceAbility = new DuckVoice();
const duck = new Duck([flyAbility, voiceAbility]);
duck.operation();

参考资料

1. 24 | 组合模式：如何用树形结构处理对象之间的复杂关系？
2. 组合模式
3. The Composite Pattern for TypeScript Developers