UList(3U)						    InterViews Reference Manual 						 UList(3U)

NAME

       UList - circular, doubly-linked list class

SYNOPSIS

       #include <Unidraw/ulist.h>

DESCRIPTION

       UList implements a circular, doubly-linked list.  The sentinel and each entry in the list are instances of the UList class, each containing
       a void pointer to the data they contain as well as pointers to the next and previous UList  instance  in  the  list.   The  sentinel  UList
       instance is considered to represent the list.

PUBLIC OPERATIONS

       UList(void* = nil)
	      Create a new UList instance, optionally supplying the value for the void pointer it stores.

       virtual ~UList()
	      Delete  the  entire list.  Normally the sentinel, which represents the list, is the entry that is deleted explicitly.  Note that the
	      data on the list, stored as void*'s, cannot be deleted in this manner.

       void Append(UList*)
       void Prepend(UList*)
	      When performed on the sentinel, Append appends an element to the end of the list and Prepend prepends it to  the	beginning  of  the
	      list.   When  performed  on  a  UList  instance  other than the sentinel, Append has the effect of inserting its argument before the
	      instance, while Prepend has the effect of inserting it after the instance.

       void Remove(UList*)
	      Unlink the specified UList instance from the list it is in.  The object on which this operation is called is irrelevant.

       void Delete(void*)
	      Find the UList instance in this list containing the given void pointer, remove it from the list it is in, and delete it.

       UList* Find(void*)
	      Return the UList instance in this list containing the given void pointer.

       UList* First()
       UList* Last()
       UList* End()
       UList* Next()
       UList* Prev()
	      Return various UList instance in the list relative to this, i.e., as if it were the sentinel.  End returns the sentinel  (this)  and
	      is useful for detecting the end of an iteration through the list; the other operations are self-explanatory.

       boolean IsEmpty()
	      Return whether or not the list has any elements.

       void* operator()()
	      Return the void pointer that the UList stores.

       UList* operator[](int i)
	      Return the ith UList in the list, where the next element is the first, etc.

Unidraw 							  3 October 1990							 UList(3U)