A.18.31 The Generic Package Containers.Bounded_Priority_Queues
Static Semantics
{
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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);
{
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{
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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;
{
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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.
Ramification: Since
this type has a bounded capacity, Enqueue might block if the queue is
full.
Implementation Advice
{
AI05-0159-1}
Bounded priority queue objects should be implemented
without implicit pointers or dynamic allocation.
Implementation Advice:
Bounded priority queue objects should
be implemented without implicit pointers or dynamic allocation.
Extensions to Ada 2005
Ada 2005 and 2012 Editions sponsored in part by Ada-Europe