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)