/* __ *\ ** ________ ___ / / ___ Scala API ** ** / __/ __// _ | / / / _ | (c) 2003-2011, LAMP/EPFL ** ** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ ** ** /____/\___/_/ |_/____/_/ | | ** ** |/ ** \* */ package scala.collection package mutable import generic._ import collection.immutable.{List, Nil} import collection.Iterator import annotation.migration /** Factory object for the `mutable.Stack` class. * * $factoryInfo * @define coll mutable stack * @define Coll mutable.Stack */ object Stack extends SeqFactory[Stack] { class StackBuilder[A] extends Builder[A, Stack[A]] { val lbuff = new ListBuffer[A] def +=(elem: A) = { lbuff += elem; this } def clear = lbuff.clear def result = { val lst = lbuff.result new Stack(lst) } } implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Stack[A]] = new GenericCanBuildFrom[A] def newBuilder[A]: Builder[A, Stack[A]] = new StackBuilder[A] val empty: Stack[Nothing] = new Stack(Nil) } /** A stack implements a data structure which allows to store and retrieve * objects in a last-in-first-out (LIFO) fashion. * * @tparam A type of the elements contained in this stack. * * @author Matthias Zenger * @author Martin Odersky * @version 2.8 * @since 1 * @define Coll Stack * @define coll stack * @define orderDependent * @define orderDependentFold * @define mayNotTerminateInf * @define willNotTerminateInf */ @cloneable class Stack[A] private (var elems: List[A]) extends Seq[A] with SeqLike[A, Stack[A]] with GenericTraversableTemplate[A, Stack] with Cloneable[Stack[A]] with Serializable { def this() = this(Nil) override def companion = Stack /** Checks if the stack is empty. * * @return true, iff there is no element on the stack */ override def isEmpty: Boolean = elems.isEmpty /** The number of elements in the stack */ override def length = elems.length /** Retrieve n'th element from stack, where top of stack has index 0. * * This is a linear time operation. * * @param index the index of the element to return * @return the element at the specified index * @throws IndexOutOfBoundsException if the index is out of bounds */ override def apply(index: Int) = elems(index) /** Replace element at index <code>n</code> with the new element * <code>newelem</code>. * * This is a linear time operation. * * @param n the index of the element to replace. * @param newelem the new element. * @throws IndexOutOfBoundsException if the index is not valid */ def update(n: Int, newelem: A) = if(n < 0 || n >= length) throw new IndexOutOfBoundsException(n.toString) else elems = elems.take(n) ++ (newelem :: elems.drop(n+1)) /** Push an element on the stack. * * @param elem the element to push on the stack. * @return the stack with the new element on top. */ def push(elem: A): this.type = { elems = elem :: elems; this } /** Push two or more elements onto the stack. The last element * of the sequence will be on top of the new stack. * * @param elems the element sequence. * @return the stack with the new elements on top. */ def push(elem1: A, elem2: A, elems: A*): this.type = this.push(elem1).push(elem2).pushAll(elems) /** Push all elements in the given traversable object onto * the stack. The last element in the traversable object * will be on top of the new stack. * * @param xs the traversable object. * @return the stack with the new elements on top. */ def pushAll(xs: TraversableOnce[A]): this.type = { xs.seq foreach push ; this } @deprecated("use pushAll", "2.8.0") @migration(2, 8, "Stack ++= now pushes arguments on the stack from left to right.") def ++=(xs: TraversableOnce[A]): this.type = pushAll(xs) /** Returns the top element of the stack. This method will not remove * the element from the stack. An error is signaled if there is no * element on the stack. * * @throws Predef.NoSuchElementException * @return the top element */ def top: A = elems.head /** Removes the top element from the stack. * * @throws Predef.NoSuchElementException * @return the top element */ def pop(): A = { val res = elems.head elems = elems.tail res } /** * Removes all elements from the stack. After this operation completed, * the stack will be empty. */ def clear(): Unit = elems = Nil /** Returns an iterator over all elements on the stack. This iterator * is stable with respect to state changes in the stack object; i.e. * such changes will not be reflected in the iterator. The iterator * issues elements in the reversed order they were inserted into the stack * (LIFO order). * * @return an iterator over all stack elements. */ @migration(2, 8, "Stack iterator and foreach now traverse in FIFO order.") override def iterator: Iterator[A] = elems.iterator /** Creates a list of all stack elements in LIFO order. * * @return the created list. */ @migration(2, 8, "Stack iterator and foreach now traverse in FIFO order.") override def toList: List[A] = elems @migration(2, 8, "Stack iterator and foreach now traverse in FIFO order.") override def foreach[U](f: A => U): Unit = super.foreach(f) /** This method clones the stack. * * @return a stack with the same elements. */ override def clone(): Stack[A] = new Stack[A](elems) }