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Scala circular buffer set

Just chat with circular buffers. Is this a smart implementation, or is there a faster / more reliable way to trick this cat?

class CircularBuffer[T](size: Int)(implicit mf: Manifest[T]) {

    private val arr = new scala.collection.mutable.ArrayBuffer[T]()

    private var cursor = 0

    val monitor = new ReentrantReadWriteLock()

    def push(value: T) {
      monitor.writeLock().lock()
      try {
        arr(cursor) = value
        cursor += 1
        cursor %= size
      } finally {
        monitor.writeLock().unlock()
      }
    }

    def getAll: Array[T] = {
      monitor.readLock().lock()
      try {
        val copy = new Array[T](size)
        arr.copyToArray(copy)
        copy
      } finally {
        monitor.readLock().unlock()
      }
    }
  }
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1 answer

Creature

A type declaration for an existing scala collection class and appender function is easier to implement than "collapse your own." As noted in the comments, this implementation probably won't be as productive as the “real” circular buffer, but it does its job with very little code:

import scala.collection.immutable

type CircularBuffer[T] = immutable.Vector[T]

def emptyCircularBuffer[T] : CircularBuffer[T] = immutable.Vector.empty[T]

def addToCircularBuffer[T](maxSize : Int)(buffer : CircularBuffer[T], item : T) : CircularBuffer[T]  =
  (buffer :+ item) takeRight maxSize

, "CircularBuffer" Vector, Vector (filter, map, flatMap ..) :

var intCircularBuffer = emptyCircularBuffer[Int]

//Vector(41)
intCircularBuffer = addToCircularBuffer(2)(intCircularBuffer, 41)

//Vector(41, 42)
intCircularBuffer = addToCircularBuffer(2)(intCircularBuffer, 42)

//Vector(42, 43)
intCircularBuffer = addToCircularBuffer(2)(intCircularBuffer, 43)

//Vector(42)
val evens : CircularBuffer[Int] = intCircularBuffer filter ( _ % 2 == 0)

:

def circularIndex[T](buffer : CircularBuffer[T])(index : Int) : T = 
  buffer(index % buffer.size)
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