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 A.4.7 Wide_String Handling

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{AI95-00302-03} Facilities for handling strings of Wide_Character elements are found in the packages Strings.Wide_Maps, Strings.Wide_Fixed, Strings.Wide_Bounded, Strings.Wide_Unbounded, and Strings.Wide_Maps.Wide_Constants, and in the functions Strings.Wide_Hash, Strings.Wide_Fixed.Wide_Hash, Strings.Wide_Bounded.Wide_Hash, and Strings.Wide_Unbounded.Wide_Hash. They provide the same string-handling operations as the corresponding packages and functions for strings of Character elements.

Static Semantics

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The package Strings.Wide_Maps has the following declaration.
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package Ada.Strings.Wide_Maps is
   pragma Preelaborate(Wide_Maps);
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{AI95-00161-01}    -- Representation for a set of Wide_Character values:
   type Wide_Character_Set is private;
   pragma Preelaborable_Initialization(Wide_Character_Set);
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   Null_Set : constant Wide_Character_Set;
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   type Wide_Character_Range is
     record
         Low  : Wide_Character;
         High : Wide_Character;
     end record;
   -- Represents Wide_Character range Low..High
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   type Wide_Character_Ranges is array (Positive range <>)
      of Wide_Character_Range;
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   function To_Set    (Ranges : in Wide_Character_Ranges)
      return Wide_Character_Set;
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   function To_Set    (Span   : in Wide_Character_Range)
      return Wide_Character_Set;
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   function To_Ranges (Set    : in Wide_Character_Set)
      return Wide_Character_Ranges;
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   function "="   (Left, Right : in Wide_Character_Set) return Boolean;
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   function "not" (Right : in Wide_Character_Set)
      return Wide_Character_Set;
   function "and" (Left, Right : in Wide_Character_Set)
      return Wide_Character_Set;
   function "or"  (Left, Right : in Wide_Character_Set)
      return Wide_Character_Set;
   function "xor" (Left, Right : in Wide_Character_Set)
      return Wide_Character_Set;
   function "-"   (Left, Right : in Wide_Character_Set)
      return Wide_Character_Set;
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   function Is_In (Element : in Wide_Character;
                   Set     : in Wide_Character_Set)
      return Boolean;
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   function Is_Subset (Elements : in Wide_Character_Set;
                       Set      : in Wide_Character_Set)
      return Boolean;
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   function "<=" (Left  : in Wide_Character_Set;
                  Right : in Wide_Character_Set)
      return Boolean renames Is_Subset;
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   -- Alternative representation for a set of Wide_Character values:
   subtype Wide_Character_Sequence is Wide_String;
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   function To_Set (Sequence  : in Wide_Character_Sequence)
      return Wide_Character_Set;
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   function To_Set (Singleton : in Wide_Character)
      return Wide_Character_Set;
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   function To_Sequence (Set  : in Wide_Character_Set)
      return Wide_Character_Sequence;
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{AI95-00161-01}    -- Representation for a Wide_Character to Wide_Character mapping:
   type Wide_Character_Mapping is private;
   pragma Preelaborable_Initialization(Wide_Character_Mapping);
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   function Value (Map     : in Wide_Character_Mapping;
                   Element : in Wide_Character)
      return Wide_Character;
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   Identity : constant Wide_Character_Mapping;
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   function To_Mapping (From, To : in Wide_Character_Sequence)
      return Wide_Character_Mapping;
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   function To_Domain (Map : in Wide_Character_Mapping)
      return Wide_Character_Sequence;
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   function To_Range  (Map : in Wide_Character_Mapping)
      return Wide_Character_Sequence;
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   type Wide_Character_Mapping_Function is
      access function (From : in Wide_Character) return Wide_Character;
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private
   ... -- not specified by the language
end Ada.Strings.Wide_Maps;
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The context clause for each of the packages Strings.Wide_Fixed, Strings.Wide_Bounded, and Strings.Wide_Unbounded identifies Strings.Wide_Maps instead of Strings.Maps.
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 {AI95-00302-03} For each of the packages Strings.Fixed, Strings.Bounded, Strings.Unbounded, and Strings.Maps.Constants, and for functions Strings.Hash, Strings.Fixed.Hash, Strings.Bounded.Hash, and Strings.Unbounded.Hash, the corresponding wide string package has the same contents except that
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The following additional declaration is present in Strings.Wide_Maps.Wide_Constants: 
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{AI95-00285-01} {AI95-00395-01} Character_Set : constant Wide_Maps.Wide_Character_Set;
--Contains each Wide_Character value WC such that
--
 Characters.Conversions. Is_Character(WC) is True
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   {AI95-00395-01} Each Wide_Character_Set constant in the package Strings.Wide_Maps.Wide_Constants contains no values outside the Character portion of Wide_Character. Similarly, each Wide_Character_Mapping constant in this package is the identity mapping when applied to any element outside the Character portion of Wide_Character.
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   {AI95-00362-01} Pragma Pure is replaced by pragma Preelaborate in Strings.Wide_Maps.Wide_Constants.
NOTES
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12  {Constraint_Error (raised by failure of run-time check)} If a null Wide_Character_Mapping_Function is passed to any of the Wide_String handling subprograms, Constraint_Error is propagated.
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This paragraph was deleted.13  {AI95-00395-01} Each Wide_Character_Set constant in the package Strings.Wide_Maps.Wide_Constants contains no values outside the Character portion of Wide_Character. Similarly, each Wide_Character_Mapping constant in this package is the identity mapping when applied to any element outside the Character portion of Wide_Character. 

Incompatibilities With Ada 95

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{AI95-00301-01} {incompatibilities with Ada 95} Various new operations are added to Strings.Wide_Fixed, Strings.Wide_Bounded, and Strings.Wide_Unbounded. If one of these packages is referenced in a use_clause, and an entity E with the same defining_identifier as a new entity is defined in a package that is also referenced in a use_clause, the entity E may no longer be use-visible, resulting in errors. This should be rare and is easily fixed if it does occur. 

Extensions to Ada 95

48.b/2
{AI95-00161-01} {extensions to Ada 95} Amendment Correction: Added pragma Preelaborable_Initialization to types Wide_Character_Set and Wide_Character_Mapping, so that they can be used to declare default-initialized objects in preelaborated units.

Wording Changes from Ada 95

48.c/2
{AI95-00285-01} Corrected the description of Character_Set.
48.d/2
{AI95-00302-03} Added wide versions of Strings.Hash and Strings.Unbounded.Hash.
48.e/2
{AI95-00362-01} Added wording so that Strings.Wide_Maps.Wide_Constants does not change to Pure.
48.f/2
{AI95-00395-01} The second Note is now normative text, since there is no way to derive it from the other rules. It's a little weird given the use of Unicode character classifications in Ada 2005; but changing it would be inconsistent with Ada 95 and a one-to-one mapping isn't necessarily correct anyway. 

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