A.18.11 The Package Containers.Indefinite_Doubly_Linked_Lists
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AI95-00302-03}
The language-defined generic package Containers.Indefinite_Doubly_Linked_Lists
provides private types List and Cursor, and a set of operations for each
type. It provides the same operations as the package Containers.Doubly_Linked_Lists
(see
A.18.3), with the difference that the
generic formal Element_Type is indefinite.
Static Semantics
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AI95-00302-03}
The declaration of the generic library package Containers.Indefinite_Doubly_Linked_Lists
has the same contents as Containers.Doubly_Linked_Lists except:
The generic formal Element_Type is indefinite.
The procedure with
the profile:
procedure Insert (Container : in out List;
Before : in Cursor;
Position : out Cursor;
Count : in Count_Type := 1);
is omitted.
Discussion: This procedure is omitted
because there is no way to create a default-initialized object of an
indefinite type. We considered having this routine insert an empty element
similar to the empty elements of a vector, but rejected this possibility
because the semantics are fairly complex and very different from the
existing case. That would make it more error-prone to convert a container
from a definite type to an indefinite type; by omitting the routine completely,
any problems will be diagnosed by the compiler.
The actual Element parameter of access subprogram
Process of Update_Element may be constrained even if Element_Type is
unconstrained.
Extensions to Ada 95
{
AI95-00302-03}
{
extensions to Ada 95}
The generic package
Containers.Indefinite_Doubly_Linked_Lists is new.
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