A.18.31 The Generic Package Containers.Bounded_Priority_Queues
Static Semantics
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{
AI05-0159-1}
The language-defined generic package Containers.Bounded_Priority_Queues
provides type Queue, which implements the interface type Containers.Synchronized_Queue_Interfaces.Queue.
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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);
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package Implementation is
... -- not specified by the language
end Implementation;
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protected type Queue
(Capacity : Count_Type := Default_Capacity;
Ceiling : System.Any_Priority := Default_Ceiling)
with Priority => Ceiling
is
new Queue_Interfaces.Queue
with
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overriding
entry Enqueue (New_Item :
in Queue_Interfaces.Element_Type);
overriding
entry Dequeue (Element :
out Queue_Interfaces.Element_Type);
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{
AI05-0159-1}
{
AI05-0251-1}
not overriding
procedure Dequeue_Only_High_Priority
(At_Least :
in Queue_Priority;
Element :
in out Queue_Interfaces.Element_Type;
Success :
out Boolean);
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overriding
function Current_Use
return Count_Type;
overriding
function Peak_Use
return Count_Type;
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private
... -- not specified by the language
end Queue;
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private
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... -- not specified by the language
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end Ada.Containers.Bounded_Priority_Queues;
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{
AI05-0159-1}
The semantics are the same as for Unbounded_Priority_Queues, except:
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The capacity for instances of type Queue is bounded
and specified by the discriminant Capacity.
13.a/3
Ramification: Since this type has a bounded
capacity, Enqueue might block if the queue is full.
Implementation Advice
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{
AI05-0159-1}
Bounded priority queue objects should be implemented without implicit
pointers or dynamic allocation.
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Implementation Advice: Bounded priority
queue objects should be implemented without implicit pointers or dynamic
allocation.
Extensions to Ada 2005
14.a/3
Ada 2005 and 2012 Editions sponsored in part by Ada-Europe