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12.5.3 Formal Array Types

(1)

The class determined for a formal array type is the class of all array types.

Syntax

(2)
       formal_array_type_definition ::= array_type_definition

Legality Rules

(3)

The only form of discrete_subtype_definition that is allowed within the declaration of a generic formal (constrained) array subtype is a subtype_mark.

(4)

For a formal array subtype, the actual subtype shall satisfy the following conditions:

(5)

• The formal array type and the actual array type shall have the same dimensionality; the formal subtype and the actual subtype shall be either both constrained or both unconstrained.

(6)

• For each index position, the index types shall be the same, and the index subtypes (if unconstrained), or the index ranges (if constrained), shall statically match (see 4.9.1).

(7)

• The component subtypes of the formal and actual array types shall statically match.

(8)

• If the formal type has aliased components, then so shall the actual.

Examples

(9)

Example of formal array types:

(10)
       --  given the generic package
(11)
       generic
          type Item   is private;
          type Index  is (<>);
          type Vector is array (Index range <>) of Item;
          type Table  is array (Index) of Item;
       package P is
          ...
       end P;
(12)
       --  and the types
(13)
       type Mix    is array (Color range <>) of Boolean;
       type Option is array (Color) of Boolean;
(14)
       --  then Mix can match Vector and Option can match Table
(15)
       package R is new P(Item   => Boolean, Index => Color,
                          Vector => Mix,     Table => Option);
(16)
       --  Note that Mix cannot match Table and Option cannot match Vector

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