/// <summary>
/// Initializes a new instance of the <see cref="T:HeadTail`1"/> class by unwinding the given <see cref="T:IEnumerator`1"/> instance.
/// </summary>
/// <param name="values">The given <see cref="T:IEnumerator`1"/> instance that provides the values that should be stored
/// in this <see cref="T:HeadTail`1"/> instance.</param>
private HeadTail(IEnumerator <TElement> values)
{
this.head = values.Current;
if (values.MoveNext())
{
this.tail = new HeadTail <TElement> (values);
}
}
/// <summary>
/// Enumerate all elements stored in this <see cref="T:HeadTail`1"/> instance.
/// </summary>
/// <returns>A <see cref="T:IEnumerable`1"/> instance containing all elements stored by this <see cref="T:HeadTail`1"/> instance.</returns>
/// <remarks>
/// <para>The resulting <see cref="T:IEnumerable`1"/> is guaranteed to emit at least one element: the head.</para>
/// <para>The method doesn't use recursion for performance issues.</para>
/// </remarks>
public override IEnumerator <TElement> GetEnumerator()
{
IHeadTail <TElement> current = this;
do
{
yield return(current.Head);
current = current.Tail;
} while(current != null);
}
/// <summary>
/// Initializes a new instance of the <see cref="T:HeadTail`1"/> class that contains all the elements of the given <paramref name="value"/>.
/// </summary>
/// <param name="values">A <see cref="T:IEnumerable`1"/> that contains the list of elements that must be stored in this <see cref="T:HeadTail`1"/> instance.</param>
/// <exception cref="ArgumentNullException">If the given <paramref name="values"/> is not effective.</exception>
/// <exception cref="ArgumentException">If the <see cref="T:IEnumerator`1"/> instance derived from <paramref name="values"/> is not effective.</exception>
/// <exception cref="ArgumentException">If <paramref name="values"/> contains zero elements.</exception>
public HeadTail(IEnumerable <TElement> values)
{
if (values == null)
{
throw new ArgumentNullException("values", "The values must be effective.");
}
IEnumerator <TElement> enumerator = values.GetEnumerator();
if (enumerator == null)
{
throw new ArgumentException("Values produced a noneffective enumerator.", "values");
}
if (!enumerator.MoveNext())
{
throw new ArgumentException("Values must contain at least one element.", "values");
}
this.head = enumerator.Current;
if (enumerator.MoveNext())
{
this.tail = new HeadTail <TElement> (enumerator);
}
}
/// <summary>
/// Determines whether the specified <see cref="object"/> is equal to the current <see cref="T:HeadTail`1"/>.
/// </summary>
/// <param name="obj">The <see cref="System.Object"/> to compare with the current <see cref="T:HeadTail`1"/>.</param>
/// <returns><c>true</c> if the specified <see cref="object"/> is equal to the current <see cref="T:HeadTail`1"/>; otherwise, <c>false</c>.</returns>
/// <remarks>
/// <para>The given <paramref name="obj"/> doesn't need to be a <see cref="T:HeadTail`1"/> instance, an instance
/// derived from <see cref="T:IHeadTail`1"/> with the same list of objects is sufficient.</para>
/// <para>The method checks at every item in the <see cref="T:IHeadTail`1"/> instances if the references are
/// equal to increase performance.</para>
/// </remarks>
public override bool Equals(object obj)
{
if (object.ReferenceEquals(this, obj))
{
return(true);
}
if (obj != null && obj is IHeadTail <TElement> )
{
IHeadTail <TElement> htobj = (IHeadTail <TElement>)obj;
if (!Object.Equals(this.head, htobj.Head))
{
return(false);
}
if (this.tail != null)
{
return(this.tail.Equals(htobj.Tail));
}
else
{
return(htobj.Tail == null);
}
}
return(false);
}
/// <summary>
/// Initializes a new instance of the <see cref="T:HeadTail`1"/> class with a given <paramref name="head"/> and <paramref name="tail"/>.
/// </summary>
/// <param name="head">The given head describing the first element of the new <see cref="T:HeadTail`1"/>.</param>
/// <param name="tail">The given tail describing the rest of the elements in the new <see cref="T:HeadTail`1"/>.</param>
public HeadTail(TElement head, IHeadTail <TElement> tail)
{
this.head = head;
this.tail = tail;
}