# A.18.19 The Generic Package Containers.Bounded_Vectors

The language-defined generic package Containers.Bounded_Vectors
provides a private type Vector and a set of operations. It provides the
same operations as the package Containers.Vectors (see

A.18.2),
with the difference that the maximum storage is bounded.

#### Static Semantics

The declaration of
the generic library package Containers.Bounded_Vectors has the same contents
and semantics as Containers.Vectors except:

The type Vector is
declared with a discriminant that specifies the capacity:

**type** Vector (Capacity : Count_Type) **is tagged private**;

The type Vector needs finalization if and only
if type Element_Type needs finalization.

In function Copy, if the Capacity parameter is
equal to or greater than the length of Source, the vector capacity exactly
equals the value of the Capacity parameter.

The description of
Reserve_Capacity is replaced with:

If the specified Capacity is larger than the capacity
of Container, then Reserve_Capacity propagates Capacity_Error. Otherwise,
the operation has no effect.

#### Bounded (Run-Time) Errors

It is a bounded error to assign
from a bounded vector 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 vector object

*V* is finalized,
if tampering with cursors is prohibited for

*V* other than due to
an assignment from another vector, then execution is erroneous.

#### Implementation Requirements

For each instance
of Containers.Vectors and each instance of Containers.Bounded_Vectors,
if the two instances meet the following conditions, then the output generated
by the Vector'Output or Vector'Write subprograms of either instance shall
be readable by the Vector'Input or Vector'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); and

the preceding two conditions also hold for the
Index_Type parameters of the instances.

#### Implementation Advice

Bounded vector 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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