Composite

Composite pattern is a structural design pattern that lets you compose objects into tree structures and then work with these structures as if they were individual objects.

Use the Composite pattern when you have to implement a tree-like object structure. Use the pattern when you want the client code to treat both simple and complex elements uniformly.

Implementation

interface Component {
  operation(): string;
}

class Leaf implements Component {
  operation(): string {
    return "Leaf";
  }
}

class Composite implements Component {
  private children: Component[] = [];

  add(component: Component): void {
    this.children.push(component);
  }

  operation(): string {
    const results = [];
    for (const child of this.children) {
      results.push(child.operation());
    }

    return `Branch(${results.join("+")})`;
  }
}

Composite

Implementation

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