Scala de Design Pattern: Composite

Compositeパターン。
割と普通。

abstract class Node(name: String) {

    override def toString = name

    def addChild(node: Node): Unit

    def callRecursively = println(toString)

}
class InnerNode(name: String) extends Node(name: String) {

    var children = List[Node]()

    def addChild(node: Node) = children ::= node

    override def callRecursively = {

        super.callRecursively

        children.foreach(_.callRecursively)

    }

}
class LeafNode(name: String) extends Node(name: String) {

    def addChild(node: Node) = throw new RuntimeException("葉ノードに子ノードは追加できまへん")

}
object Main {

    def main(args: Array[String]) = {

        val rootNode = new InnerNode("根っこ")

        val InnerNodeA = new InnerNode("内部節A")

        val InnerNodeB = new InnerNode("内部節B")

        val LeafNodeA = new LeafNode("葉A")

        val LeafNodeB = new LeafNode("葉B")

        

        rootNode.addChild(InnerNodeA)

        rootNode.addChild(InnerNodeB)

        InnerNodeA.addChild(LeafNodeA)

        InnerNodeA.addChild(LeafNodeB)

        

        rootNode.callRecursively

    }

}
// 【実行結果】

// 根っこ

// 内部節B

// 内部節A

// 葉B

// 葉A