more oop

// More OOP

// - dynamic polymorphism
// - inheritance
// - subtyping

// - encapsulation

// trait aka abstract class
trait Iterator[A] {
  def hasNext: Boolean
  def next(): A
}

// those are called stubs, you can have them in abstract class or trait but not in a class
// they just sorta hold shit for when you define them in subclasses

class ListIterator[A](list: List[A]) extends Iterator[A] {
  private var cur = list
  def hasNext: Boolean = cur.nonEmpty
  def next(): A = {
    val item = cur.head
    cur = cur.tail
    item
  }
}

class ArrayIterator[A](arr: Array[A]) extends Iterator[A] {
  private var i = 0
  def hasNext: Boolean = i < arr.length
  def next(): A = {
    val item = arr(i)
    i += 1
    item
  }
}

val iter = ...
while(iter.hasNext) print(iter.next())

// Algorithms              Data Structures
// ----------              ---------------
// printall                arrays
// reverse                 lists
// map/filter              BSTs
// adding                  files
// findFirst               strings