A.18.31 The Generic Package Containers.Bounded_Priority_Queues
Static Semantics
The language-defined generic package Containers.Bounded_Priority_Queues
provides type Queue, which implements the interface type Containers.Synchronized_Queue_Interfaces.Queue.
with System;
with Ada.Containers.Synchronized_Queue_Interfaces;
generic
with package Queue_Interfaces
is new Ada.Containers.Synchronized_Queue_Interfaces (<>);
type Queue_Priority
is private;
with function Get_Priority
(Element : Queue_Interfaces.Element_Type)
return Queue_Priority
is <>;
with function Before
(Left, Right : Queue_Priority)
return Boolean
is <>;
Default_Capacity : Count_Type;
Default_Ceiling : System.Any_Priority := System.Priority'Last;
package Ada.Containers.Bounded_Priority_Queues
is
pragma Preelaborate(Bounded_Priority_Queues);
package Implementation is
... -- not specified by the language
end Implementation;
protected type Queue
(Capacity : Count_Type := Default_Capacity;
Ceiling : System.Any_Priority := Default_Ceiling)
with Priority => Ceiling
is
new Queue_Interfaces.Queue
with
overriding
entry Enqueue (New_Item :
in Queue_Interfaces.Element_Type);
overriding
entry Dequeue (Element :
out Queue_Interfaces.Element_Type);
not overriding
procedure Dequeue_Only_High_Priority
(At_Least :
in Queue_Priority;
Element :
in out Queue_Interfaces.Element_Type;
Success :
out Boolean);
overriding
function Current_Use
return Count_Type;
overriding
function Peak_Use
return Count_Type;
private
... -- not specified by the language
end Queue;
private
... -- not specified by the language
end Ada.Containers.Bounded_Priority_Queues;
The semantics are
the same as for Unbounded_Priority_Queues, except:
The capacity for instances of type Queue is bounded
and specified by the discriminant Capacity.
Implementation Advice
Bounded priority queue objects should be implemented
without implicit pointers or dynamic allocation.
Ada 2005 and 2012 Editions sponsored in part by Ada-Europe