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A.18.22 The Generic Package Containers.Bounded_Ordered_Maps

1/3
The language-defined generic package Containers.Bounded_Ordered_Maps provides a private type Map and a set of operations. It provides the same operations as the package Containers.Ordered_Maps (see A.18.6), with the difference that the maximum storage is bounded. 

Static Semantics

2/3
The declaration of the generic library package Containers.Bounded_Ordered_Maps has the same contents and semantics as Containers.Ordered_Maps except:
3/5
The aspect Preelaborate is replaced with aspect Pure. Aspect Global is deleted.
4/3
The type Map is declared with a discriminant that specifies the capacity (maximum number of elements) as follows: 
5/5
  type Map (Capacity : Count_Type) is tagged private...
5.1/5
The aspect_definition for Preelaborable_Initialization for type Map is changed to: 
5.2/5
  Preelaborable_Initialization =>
     Element_Type'Preelaborable_Initialization
        and
     Key_Type'Preelaborable_Initialization
6/3
The type Map needs finalization if and only if type Key_Type or type Element_Type needs finalization.
6.1/5
The function Empty is replaced by:
6.2/5
   function Empty (Capacity : Count_Type := implementation-defined)
      return Map
      with Post =>
            Empty'Result.Capacity = Capacity and then
            not Tampering_With_Elements_Prohibited (Empty'Result) and then
            not Tampering_With_Cursors_Prohibited (Empty'Result) and then
            Length (Empty'Result) = 0;
7/5
For procedures Insert and Include, the part of the precondition reading:
7.1/5
     (<some length> <= Count_Type'Last - <some other length>
        or else raise Constraint_Error)
7.2/5
is replaced by:
7.3/5
     (<some length> <= Count_Type'Last - <some other length>
         or else raise Constraint_Error) and then
      (<some length> <= Container.Capacity - <some other length>
         or else raise Capacity_Error)
8/5
In procedure Assign, the precondition is altered to:
8.1/5
   Pre => (not Tampering_With_Cursors_Prohibited (Target)
             or else raise Program_Error) and then
          (Length (Source) <= Target.Capacity
             or else raise Capacity_Error),
9/3
The function Copy is replaced with: 
10/5
  function Copy (Source   : Map;
                 Capacity : Count_Type := 0) return Map
     with Pre  => Capacity = 0 or else Capacity >= Length (Source)
                     or else raise Capacity_Error,
          Post => 
             Length (Copy'Result) = Length (Source) and then
             not Tampering_With_Elements_Prohibited (Copy'Result) and then
             not Tampering_With_Cursors_Prohibited (Copy'Result) and then
             Copy'Result.Capacity = (if Capacity = 0 then
                Length (Source) else Capacity);
11/5
Returns a map with key/element pairs initialized from the values in Source. 

Bounded (Run-Time) Errors

12/3
It is a bounded error to assign from a bounded map object while tampering with elements or cursors of that object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target object prohibiting tampering with elements or cursors, or execution proceeds normally.

Erroneous Execution

13/3
When a bounded map object M is finalized, if tampering with cursors is prohibited for M other than due to an assignment from another map, then execution is erroneous.

Implementation Requirements

14/3
For each instance of Containers.Ordered_Maps and each instance of Containers.Bounded_Ordered_Maps, if the two instances meet the following conditions, then the output generated by the Map'Output or Map'Write subprograms of either instance shall be readable by the Map'Input or Map'Read of the other instance, respectively:
15/3
the Element_Type parameters of the two instances are statically matching subtypes of the same type; and
16/3
the output generated by Element_Type'Output or Element_Type'Write is readable by Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the type of the two actual Element_Type parameters); and
17/3
the preceding two conditions also hold for the Key_Type parameters of the instances. 

Implementation Advice

18/3
Bounded ordered map objects should be implemented without implicit pointers or dynamic allocation. 
19/3
The implementation advice for procedure Move to minimize copying does not apply. 

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