Stack.cs

usingSystem;
usingSystem.Collections.Generic;

namespaceDataStructures.Lists
{
/// <summary>
/// The Stack (LIFO) Data Structure.
/// </summary>
/// <typeparam name="T">Type</typeparam>
publicclassStack<T>:IEnumerable<T>whereT:IComparable<T>
{
/// <summary>
/// Instance variables.
/// _collection: Array-Based List.
/// Count: Public Getter for returning the number of elements.
/// </summary>
privateArrayList<T>_collection{get;set;}
publicintCount{get{return_collection.Count;}}


/// <summary>
/// CONSTRUCTORS
/// </summary>
publicStack()
{
// The internal collection is implemented as an array-based list.
// See the ArrayList.cs for the list implementation.
_collection=newArrayList<T>();
}


publicStack(intinitialCapacity)
{
if(initialCapacity<0)
{
thrownewArgumentOutOfRangeException();
}

// The internal collection is implemented as an array-based list.
// See the ArrayList.cs for the list implementation.
_collection=newArrayList<T>(initialCapacity);
}


/// <summary>
/// Checks whether the stack is empty.
/// </summary>
/// <returns>True if stack is empty, false otherwise.</returns>
publicboolIsEmpty
{
get
{
return_collection.IsEmpty;
}
}


/// <summary>
/// Returns the top element in the stack.
/// </summary>
publicTTop
{
get
{
try
{
return_collection[_collection.Count-1];
}
catch(Exception)
{
thrownewException("Stack is empty.");
}
}
}


/// <summary>
/// Inserts an element at the top of the stack.
/// </summary>
/// <param name="dataItem">Element to be inserted.</param>
publicvoidPush(TdataItem)
{
_collection.Add(dataItem);
}


/// <summary>
/// Removes the top element from stack.
/// </summary>
publicTPop()
{
if(Count>0)
{
vartop=Top;
_collection.RemoveAt(_collection.Count-1);
returntop;
}

thrownewException("Stack is empty.");
}

/// <summary>
/// Returns an array version of this stack.
/// </summary>
/// <returns>System.Array.</returns>
publicT[]ToArray()
{
return_collection.ToArray();
}


/// <summary>
/// Returns a human-readable, multi-line, print-out (string) of this stack.
/// </summary>
/// <returns>String.</returns>
publicstringToHumanReadable()
{
return_collection.ToHumanReadable();
}


/********************************************************************************/


publicIEnumerator<T>GetEnumerator()
{
for(inti=_collection.Count-1;i>=0;--i)
yieldreturn_collection[i];
}

System.Collections.IEnumeratorSystem.Collections.IEnumerable.GetEnumerator()
{
returnthis.GetEnumerator();
}

}

}