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A.18.29 The Generic Package Containers.Bounded_Synchronized_Queues

Static Semantics

1/3
{AI05-0159-1} The language-defined generic package Containers.Bounded_Synchronized_Queues provides type Queue, which implements the interface type Containers.Synchronized_Queue_Interfaces.Queue.
2/5
{AI12-0112-1} with System;
with Ada.Containers.Synchronized_Queue_Interfaces;
generic
   with package Queue_Interfaces is new Ada.Containers.Synchronized_Queue_Interfaces (<>);
   Default_Capacity : Count_Type;
   Default_Ceiling  : System.Any_Priority := System.Priority'Last;
package Ada.Containers.Bounded_Synchronized_Queues is
   with Preelaborate,
        Nonblocking, Global => null is

   pragma Preelaborate(Bounded_Synchronized_Queues);
2.a/5
Discussion: {AI12-0112-1} For discussion on the reasons and meaning of the specifications of the Global and Nonblocking aspects of this generic package, see the notes on the specification of the Containers.Vectors package (see A.18.2). 
3/3
   package Implementation is
      ... -- not specified by the language
   end Implementation;
4/3
   protected type Queue
        (Capacity : Count_Type := Default_Capacity;
         Ceiling  : System.Any_Priority := Default_Ceiling)
           with Priority => Ceiling is
        new Queue_Interfaces.Queue with
5/3
      overriding
      entry Enqueue (New_Item : in Queue_Interfaces.Element_Type);
      overriding
      entry Dequeue (Element : out Queue_Interfaces.Element_Type);
6/5
{AI12-0112-1}       overriding
      function Current_Use return Count_Type
         with Nonblocking, Global => (nulluse null)
;
      overriding
      function Peak_Use return Count_Type
         with Nonblocking, Global => (nulluse null)
;
7/3
   private
      ... -- not specified by the language
   end Queue;
8/3
private
9/3
   ... -- not specified by the language
10/3
end Ada.Containers.Bounded_Synchronized_Queues;
11/3
{AI05-0159-1} The semantics are the same as for Unbounded_Synchronized_Queues, except:
12/3
The capacity for instances of type Queue is bounded and specified by the discriminant Capacity. 
12.a/3
Ramification: Since this type has a bounded capacity, Enqueue might block if the queue is full. 

Implementation Advice

13/3
{AI05-0159-1} Bounded queue objects should be implemented without implicit pointers or dynamic allocation. 
13.a.1/3
Implementation Advice: Bounded queue objects should be implemented without implicit pointers or dynamic allocation.

Extensions to Ada 2005

13.a/3
{AI05-0159-1} The generic package Containers.Bounded_Synchronized_Queues is new. 

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