Scala编程之螺旋

一、概述

今天在《Scala In Programming》中学习了关于Scala的组合与继承，下面通过一个实例作为知识的巩固。

二、实例展示

1、实例名称：

根据给定的边界值，画出一个螺旋。

2、实例描述：

a、首先给出四个类：Element、ArrayElement、UniformElement、LineElemnt，其中Element为抽象的超类，其余三个类分别继承于Element。

import scalaDemo.Element._

/**
  * Created by user on 2016/1/18.
  */
abstract class Element {
   def contents: Array[String]
   def height: Int = contents.length
   def width: Int = contents(0).length

   def above(that: Element): Element = {
      val thisParam = this widen that.width
      val thatParam = that widen this.width
      elem(thisParam.contents ++ thatParam.contents)
   }

   def beside(that: Element): Element = {
      val thisParam = this highten that.height
      val thatParam = that highten this.height
      elem(
        for((line1,line2) <- thisParam.contents zip thatParam.contents)
        yield line1 + line2
      )
   }

   def widen(w: Int): Element = {
      if(w <= width) this else{
         val left = elem(' ',(w - width)/2,height)
         val right = elem(' ', w - width - left.width, height)
         left beside this beside right
      }
   }

   def highten(h: Int): Element = {
      if(h <= height){
         this
      }else{
         val top = elem(' ', width, (h - height)/2)
         val bot = elem(' ', width, h - height - top.height)
         top above this above bot
      }
   }

   override def toString = contents.mkString("\n")
}

/**
  * Created by user on 2016/1/18.
  */
class ArrayElement(contentsParam: Array[String]) extends Element{
  override def contents: Array[String] = {
      contentsParam
  }
}

/**
  * Created by user on 2016/1/18.
  */
class UniformElement(char: Char, width: Int, height: Int) extends Element{
    private val line = char.toString * width
    override def contents: Array[String] = {
        Array.apply(line + ": " + height)
    }
}

/**
  * Created by user on 2016/1/18.
  */
class LineElement(line: String) extends Element{
   override def contents: Array[String] = {
       Array.apply(line)
   }
}

b、定义一个object：Element

import scalaDemo.classes.{ArrayElement, LineElement, UniformElement, Element}

/**
  * Created by user on 2016/1/18.
  */
object Element {
  def elem(contents: Array[String]): Element = {
      new ArrayElement(contents)
  }

  def elem(char: Char, width: Int, height: Int): Element = {
      new UniformElement(char,width,height)
  }

  def elem(line: String): Element = {
      new LineElement(line)
  }
}

c、测试实例

import scalaDemo.Element.elem
import scalaDemo.classes.Element

/**
  * Created by user on 2016/1/18.
  */
object Spiral{
   val space = elem(" ")
   val corner = elem("+")

   def spiral(edges: Int, direction: Int): Element = {
       if(edges == 1){
          elem("+")
       }else{
          val sp = spiral(edges - 1, (direction + 3) % 4)
          def verticalBar = elem('|',1,sp.height)
          def horizontalBar = elem('-',sp.width,1)
          if(direction == 0){
             (corner beside horizontalBar) above (sp beside space)
          }else if(direction == 1){
             (sp above space) beside (corner above verticalBar)
          }else if(direction == 2){
             (space beside sp) above (horizontalBar beside corner)
          }else{
             (verticalBar above corner) beside (space above sp)
          }
       }
   }

   def main (args: Array[String]) {
      val constents = new Array[String](3)
      constents(0) = "AAAAAAA" + ","
      constents(1) = "BBBBBBB" + ","
      constents(2) = "CCCCCCC"
      println(spiral(constents.length,3))
   }
}

三、测试结果

请查看附件中的图片

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