/* CookieJarArrayBuffer implementation of the CookieJar ADT in Scala
   H. Conrad Cunningham
   Version #1:  15 March 2010
   Version #1a: 22 March 2010 Comment correction

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*/

import scala.collection.mutable._


/* Class CookieJarArrayBuffer implements the CookieJar ADT using
   Scala's ArrayBuffer data structure to implement the jar (mathematical
   bag) of cookies.  The cookies occur in the Arraybuffer the same number of 
   times they do in the cookie jar.

   IMPLEMENTATION INVARIANT: 
     (ForAll c : c IN CookieType ::
                  OCCURRENCES(c,Bag) == jar.filter(_==c).length )
*/

class CookieJarArrayBuffer[CookieType] extends CookieJar[CookieType] {

  // CookieJar's bag model is implemented by ArrayBuffer jar.
  private var jar = new ArrayBuffer[CookieType]
 
  def putIn(cookie: CookieType) { jar += cookie }
 
  def eat(cookie: CookieType) {
    val in = jar.indexOf(cookie) 
    if (in >= 0)
      jar.remove(in)
    else 
      throw new RuntimeException(
        "Attempt to eat cookie \"" + cookie + "\", which is not in the jar.")
  }
       
  def isEmpty: Boolean                 = jar.isEmpty

  def has(cookie: CookieType): Boolean = jar.contains(cookie)

  /* Redefine toString to return form "CookieJar(e1,e2,e3,...,en)" with all 
     elements of bag in arbitrary order. 
  */

  override def toString = "CookieJar(" + jar.mkString(",") + ")"

}