public void AddHead()
{
_Item head = null;
_Item tail = null;
// build the list
for (var i = 0; i <= 10_000; i++)
{
var item = new _Item {
Value = i
};
tail = tail ?? item;
head.AddHead(ref head, item);
}
// read forward
{
var cur = head;
for (var i = 10_000; i >= 0; i--)
{
Assert.Equal(i, cur.Value);
if (cur.Next.HasValue)
{
cur = cur.Next.Value;
}
else
{
cur = null;
}
}
Assert.Null(cur);
}
// read backwards
{
var cur = tail;
for (var i = 0; i <= 10_000; i++)
{
Assert.Equal(i, cur.Value);
if (cur.Previous.HasValue)
{
cur = cur.Previous.Value;
}
else
{
cur = null;
}
}
Assert.Null(cur);
}
}
public void Remove()
{
_Item head = null;
_Item tail = null;
_Item oneZeroZero = null;
_Item twoZeroZero = null;
_Item threeThreeThree = null;
// build the list
for (var i = 0; i <= 10_000; i++)
{
var item = new _Item {
Value = i
};
if (i == 100)
{
oneZeroZero = item;
}
if (i == 200)
{
twoZeroZero = item;
}
if (i == 333)
{
threeThreeThree = item;
}
tail = tail ?? item;
head.AddHead(ref head, item);
}
// remove 100
{
head.Remove(ref head, oneZeroZero);
Assert.False(oneZeroZero.Previous.HasValue);
Assert.False(oneZeroZero.Next.HasValue);
// read forward
{
var cur = head;
for (var i = 10_000; i >= 0; i--)
{
if (i == 100)
{
continue;
}
Assert.Equal(i, cur.Value);
if (cur.Next.HasValue)
{
cur = cur.Next.Value;
}
else
{
cur = null;
}
}
Assert.Null(cur);
}
// read backwards
{
var cur = tail;
for (var i = 0; i <= 10_000; i++)
{
if (i == 100)
{
continue;
}
Assert.Equal(i, cur.Value);
if (cur.Previous.HasValue)
{
cur = cur.Previous.Value;
}
else
{
cur = null;
}
}
Assert.Null(cur);
}
}
// remove 200
{
head.Remove(ref head, twoZeroZero);
Assert.False(twoZeroZero.Previous.HasValue);
Assert.False(twoZeroZero.Next.HasValue);
// read forward
{
var cur = head;
for (var i = 10_000; i >= 0; i--)
{
if (i == 100)
{
continue;
}
if (i == 200)
{
continue;
}
Assert.Equal(i, cur.Value);
if (cur.Next.HasValue)
{
cur = cur.Next.Value;
}
else
{
cur = null;
}
}
Assert.Null(cur);
}
// read backwards
{
var cur = tail;
for (var i = 0; i <= 10_000; i++)
{
if (i == 100)
{
continue;
}
if (i == 200)
{
continue;
}
Assert.Equal(i, cur.Value);
if (cur.Previous.HasValue)
{
cur = cur.Previous.Value;
}
else
{
cur = null;
}
}
Assert.Null(cur);
}
}
// remove 333
{
head.Remove(ref head, threeThreeThree);
Assert.False(threeThreeThree.Previous.HasValue);
Assert.False(threeThreeThree.Next.HasValue);
// read forward
{
var cur = head;
for (var i = 10_000; i >= 0; i--)
{
if (i == 100)
{
continue;
}
if (i == 200)
{
continue;
}
if (i == 333)
{
continue;
}
Assert.Equal(i, cur.Value);
if (cur.Next.HasValue)
{
cur = cur.Next.Value;
}
else
{
cur = null;
}
}
Assert.Null(cur);
}
// read backwards
{
var cur = tail;
for (var i = 0; i <= 10_000; i++)
{
if (i == 100)
{
continue;
}
if (i == 200)
{
continue;
}
if (i == 333)
{
continue;
}
Assert.Equal(i, cur.Value);
if (cur.Previous.HasValue)
{
cur = cur.Previous.Value;
}
else
{
cur = null;
}
}
Assert.Null(cur);
}
}
// remove head
{
var oldHead = head;
head.Remove(ref head, head);
Assert.False(oldHead.Previous.HasValue);
Assert.False(oldHead.Next.HasValue);
Assert.NotNull(head);
Assert.Equal(9_999, head.Value);
// read forward
{
var cur = head;
for (var i = 10_000; i >= 0; i--)
{
if (i == 10_000)
{
continue;
}
if (i == 100)
{
continue;
}
if (i == 200)
{
continue;
}
if (i == 333)
{
continue;
}
Assert.Equal(i, cur.Value);
if (cur.Next.HasValue)
{
cur = cur.Next.Value;
}
else
{
cur = null;
}
}
Assert.Null(cur);
}
// read backwards
{
var cur = tail;
for (var i = 0; i <= 10_000; i++)
{
if (i == 10_000)
{
continue;
}
if (i == 100)
{
continue;
}
if (i == 200)
{
continue;
}
if (i == 333)
{
continue;
}
Assert.Equal(i, cur.Value);
if (cur.Previous.HasValue)
{
cur = cur.Previous.Value;
}
else
{
cur = null;
}
}
Assert.Null(cur);
}
}
// remove tail
{
var oldTail = tail;
var newTail = tail.Previous.Value;
head.Remove(ref head, tail);
Assert.False(oldTail.Previous.HasValue);
Assert.False(oldTail.Next.HasValue);
tail = newTail;
Assert.Equal(1, tail.Value);
// read forward
{
var cur = head;
for (var i = 10_000; i >= 0; i--)
{
if (i == 10_000)
{
continue;
}
if (i == 0)
{
continue;
}
if (i == 100)
{
continue;
}
if (i == 200)
{
continue;
}
if (i == 333)
{
continue;
}
Assert.Equal(i, cur.Value);
if (cur.Next.HasValue)
{
cur = cur.Next.Value;
}
else
{
cur = null;
}
}
Assert.Null(cur);
}
// read backwards
{
var cur = tail;
for (var i = 0; i <= 10_000; i++)
{
if (i == 10_000)
{
continue;
}
if (i == 0)
{
continue;
}
if (i == 100)
{
continue;
}
if (i == 200)
{
continue;
}
if (i == 333)
{
continue;
}
Assert.Equal(i, cur.Value);
if (cur.Previous.HasValue)
{
cur = cur.Previous.Value;
}
else
{
cur = null;
}
}
Assert.Null(cur);
}
}
// remove everything
{
while (head != null)
{
var oldHead = head;
head.Remove(ref head, head);
Assert.False(oldHead.Previous.HasValue);
Assert.False(oldHead.Next.HasValue);
}
Assert.Null(head);
}
}