NAME

       UMap - maintains a mapping between two sets of pointers

SYNOPSIS

       #include <Unidraw/umap.h>

DESCRIPTION

       UMap  is  an abstract class for objects that store an arbitrary number of pointer pairs and can search to
       find either member of a pair given the other.  A UMapElem object stores each pointer pair  in  the  UMap.
       UMapElem  is an abstract class that defines virtuals for returning either member of the pair, referred to
       as the id and the tag.  Subclasses of UMapElem redefine these virtuals to return  either  member  of  the
       pair they store.

UMAPELEM PUBLIC OPERATIONS

       UMapElem()
              The base class constructor does nothing by default.

       virtual void* id()
       virtual void* tag()
              Return  the  id  or  the  tag  that  the  UMapElem stores.  Subclasses typically define two member
              variables that store pair's values and redefine these operations to return them.

UMAP PUBLIC OPERATIONS

       virtual ~UMap()
              The destructor deletes all UMapElem objects in the UMap.

       int Count()
              Return the number of mappings in the UMap, corresponding to the number of UMapElems that have been
              registered.

       void Clear()
              Delete all the UMapElem mappings in the UMap without destroying the UMap.

UMAP PROTECTED OPERATIONS

       UMap() The base class constructor does nothing by default.

       void Register(UMapElem*)
       void Unregister(UMapElem*)
              Register or remove a UMapElem from the UMap.

       int Index(UMapElem*)
       UMapElem* Elem(int index)
              A UMap stores its UMapElem in its _elems UArray protected member variable.  The  Index  operations
              returns  the  index  of  the  given  UMapElem  in the UArray, while Elem returns the UMapElem at a
              specified index.  These operations simply perform the corresponding operations on the UArray.

       virtual UMapElem* FindId(void* id)
       virtual UMapElem* FindTag(void* tag)
              FindId searches the UMap for the UMapElem element containing the given id, while FindTag  searches
              for  the  one  with the given tag.  These operations perform linear searches by default, comparing
              their arguments against the values  that  the  UMapElems'  id  and  tag  operations  return.   The
              comparison  is  based on the pointer values; subclasses can redefine these operations to make more
              sophisticated comparisons based on the id or tags actual type.  For example, if either the id is a
              string, then FindId might do a string comparison to detect a match.

SEE ALSO

       UArray(3U)

Unidraw                                          4 October 1990                                         UMap(3U)