Limited_Lists

Linked list with some nice features.
• Private implementation: can't mess around with this.
• Small memory footprint: only one extra pointer per item.
• Built-in iterator for simple loops.
• Modify while iterating: insert, remove, update.
• Item direct iteration: unlimited parallel independent iterators.
• Direct access to first and last item: can add items at both ends.
• Cached item count.

		type Content_Type
	Generic type of the items to be stored.

		type List_Access
	Instance of a list, needs to be created before it can be used.

		type Item
	Instance of a list item. Most useful if you need multiple iterators.

List construction

		function Create
	Create a list.
	Param  Type  Description return  List_Access

		procedure Append
	Append a list at the end of another list. This is done by simply linking from the last item to the first item of the tail, not by copying the items of the tail. This means that if you modify the tail list later, the modifications will appear in the appended list as well.
	Param  Type  Description access This  List  Append to this list. access Tail  List  Append these items at the end.

Adding items

		function Push
	Insert an item at the end of the list.
	Param  Type  Description access This  List  Push into this list. return  Item_Access  The newly created item.

		function Unshift
	Insert an item at the beginning of the list.
	Param  Type  Description access This  List  Unshift into this list. return  Item_Access  The newly created item.

Removing items

		function Pop
	Remove an item at the end of the list.
	Param  Type  Description access This  List  Pop out of this list. return  Item_Access  The removed item.

		function Shift
	Remove an item at the beginning of the list.
	Param  Type  Description access This  List  Shift out of this list. return  Item_Access  The removed item.

Item indexing

		function Count
	Count items in this list. This operation is not O(n) but O(1) because the result comes straight from a counter variable.
	Param  Type  Description access This  List  Get information about this list. return  Natural  The number of items in the list.

		function Empty
	Is the list empty? Returns True if and only if there are no items in the list.
	Param  Type  Description access This  List  Get information about this list. return  Boolean  This list empty?

		function Index
	Read the current iteration position as a number, starting with 1 at the first item. An index of 0 means: no current item, so either we're not currently iterating or the iteration has finished.
	Param  Type  Description access This  List  Get information about this list. return  Natural  Iteration index of this list.

First and last item

		function First
	Read the first item in the list.
	Param  Type  Description access This  List  Read from this list. return  Content_Type  The first item.

		function Last
	Read the last item in the list.
	Param  Type  Description access This  List  Read from this list. return  Content_Type  The last item.

Iterating over a list

		procedure Reset
	Reset the iteration index to 0. This starts a new iteration. There must be a call to Next before the first item can be read from the function Current.
	Param  Type  Description access This  List  The list to iterate over.

		procedure Next
	Go to the next item.
	Param  Type  Description access This  List  The list to iterate over.

		function Next
	Go to the next item. Returns False if and only if we reached the end of the list.
	Param  Type  Description access This  List  The list to iterate over. return  Boolean  Successfully moved to next item?

		function Next_Available
	Is the a next item available? Returns False if the current item is the last one in the list.
	Param  Type  Description access This  List  The list to iterate over. return  Boolean  Next item available?

		function Next_Content
	Get the content of the next item.
	Param  Type  Description access This  List  The list to iterate over. return  Content_Type  The content of the next item.

		function End_Of_List
	End of list reached? Returns True if and only if the current item pointer is null. This also occurs after calling Reset but before calling Next.
	Param  Type  Description access This  List  The list to iterate over. return  Boolean  Reached end of list?

		function Current
	Read the item at the current iteration pointer.
	Param  Type  Description access This  List  The list to iterate over. return  Content_Type  Current item.

Manipulating a list while iterating

		procedure Remove_Current
	Remove the item at the current iteration pointer from the list.
	Param  Type  Description access This  List  The list to modify.

		function Insert_Before_Current
	Insert an item directly before the item at the current iteration pointer.
	Param  Type  Description access This  List  The list to modify. return  Item_Access  The newly created item.

		function Insert_After_Current
	Insert an item directly after the item at the current iteration pointer.
	Param  Type  Description access This  List  The list to modify. return  Item_Access  The newly created item.

Item direct iteration

		function First_Item
	Get the first item of the list.
	Param  Type  Description access This  List  Read from this list. return  Item_Access  The first item.

		function Last_Item
	Get the last item of the list.
	Param  Type  Description access This  List  Read from this list. return  Item_Access  The last item.

		function Current_Item
	Get the current iteration item of the list.
	Param  Type  Description access This  List  Read from this list. return  Item_Access  The last item.

		procedure Next_Item
	Go to the next item.
	Param  Type  Description in out This  Item_Access  Advance this item.

		function Next_Item
	Get the next item.
	Param  Type  Description access This  Item  Get this item's successor. return  Item_Access  The successor of the input item.

		function Item_Invalid
	Returns True if and only if the item pointer is null. This happens after the last item in the list.
	Param  Type  Description in This  Item_Access  The iterating list item. return  Boolean  Reached end of list?

		function Item_Equals
	Compare two items (not the contents but the pointers).
	Param  Type  Description in This  Item_Access  Compare this item. in Other  Item_Access  To that other item. return  Boolean  True if the pointers are the same.

		function Item_Content
	Read an item's content.
	Param  Type  Description access This  Item  Read content from this item. return  Content_Type  Content of this item.

		procedure Remove_Item
	Remove an item from the list and advance the item pointer.
	Param  Type  Description in Previous  Item_Access  May be null if removing first. in out This  Item_Access  Remove and advance this item. access Context  List  Remove the item from this list.