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A.18.24 The Generic Package Containers.Bounded_Ordered_Sets

The language-defined generic package Containers.Bounded_Ordered_Sets provides a private type Set and a set of operations. It provides the same operations as the package Containers.Ordered_Sets (see A.18.9), with the difference that the maximum storage is bounded.

Static Semantics

The declaration of the generic library package Containers.Bounded_Ordered_Sets has the same contents and semantics as Containers.Ordered_Sets except:
The pragma Preelaborate is replaced with pragma Pure.
The type Set is declared with a discriminant that specifies the capacity (maximum number of elements) as follows: 
  type Set (Capacity : Count_Type) is tagged private;
The type Set needs finalization if and only if type Element_Type needs finalization.
If Insert (or Include) adds an element, a check is made that the capacity is not exceeded, and Capacity_Error is raised if this check fails.
In procedure Assign, if Source length is greater than Target capacity, then Capacity_Error is propagated.
The function Copy is replaced with: 
  function Copy (Source   : Set;
                 Capacity : Count_Type := 0) return Set;
Returns a set whose elements are initialized from the values in Source. If Capacity is 0, then the set capacity is the length of Source; if Capacity is equal to or greater than the length of Source, the set capacity is the specified value; otherwise, the operation propagates Capacity_Error. 

Bounded (Run-Time) Errors

 It is a bounded error to assign from a bounded set 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

 When a bounded set object S is finalized, if tampering with cursors is prohibited for S other than due to an assignment from another set, then execution is erroneous.

Implementation Requirements

 For each instance of Containers.Ordered_Sets and each instance of Containers.Bounded_Ordered_Sets, if the two instances meet the following conditions, then the output generated by the Set'Output or Set'Write subprograms of either instance shall be readable by the Set'Input or Set'Read of the other instance, respectively:
the Element_Type parameters of the two instances are statically matching subtypes of the same type; and
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). 

Implementation Advice

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

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