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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT RUN-TIME COMPONENTS                         --

--                                                                          --

--                 A D A . S T R I N G S . U N B O U N D E D                --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 1992-2011, Free Software Foundation, Inc.         --

--                                                                          --

-- This specification is derived from the Ada Reference Manual for use with --

-- GNAT. The copyright notice above, and the license provisions that follow --

-- apply solely to the  contents of the part following the private keyword. --

--                                                                          --

-- GNAT is free software;  you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --

--                                                                          --

-- As a special exception under Section 7 of GPL version 3, you are granted --

-- additional permissions described in the GCC Runtime Library Exception,   --

-- version 3.1, as published by the Free Software Foundation.               --

--                                                                          --

-- You should have received a copy of the GNU General Public License and    --

-- a copy of the GCC Runtime Library Exception along with this program;     --

-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --

-- <http://www.gnu.org/licenses/>.                                          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

------------------------------------------------------------------------------

--  This package provides an implementation of Ada.Strings.Unbounded that uses

--  reference counts to implement copy on modification (rather than copy on

--  assignment). This is significantly more efficient on many targets.

--  This version is supported on:

--    - all Alpha platforms

--    - all ia64 platforms

--    - all PowerPC platforms

--    - all SPARC V9 platforms

--    - all x86 platforms

--    - all x86_64 platforms

   --  This package uses several techniques to increase speed:

   --   - Implicit sharing or copy-on-write. An Unbounded_String contains only

   --     the reference to the data which is shared between several instances.

   --     The shared data is reallocated only when its value is changed and

   --     the object mutation can't be used or it is inefficient to use it.

   --   - Object mutation. Shared data object can be reused without memory

   --     reallocation when all of the following requirements are met:

   --      - the shared data object is no longer used by anyone else;

   --      - the size is sufficient to store the new value;

   --      - the gap after reuse is less then a defined threshold.

   --   - Memory preallocation. Most of used memory allocation algorithms

   --     align allocated segments on the some boundary, thus some amount of

   --     additional memory can be preallocated without any impact. Such

   --     preallocated memory can used later by Append/Insert operations

   --     without reallocation.

   --  Reference counting uses GCC builtin atomic operations, which allows to

   --  safely share internal data between Ada tasks. Nevertheless, this doesn't

   --  make objects of Unbounded_String thread-safe: each instance can't be

   --  accessed by several tasks simultaneously.

with Ada.Strings.Maps;

private with Ada.Finalization;

private with System.Atomic_Counters;

package Ada.Strings.Unbounded is

   pragma Preelaborate;

   type Unbounded_String is private;

   pragma Preelaborable_Initialization (Unbounded_String);

   Null_Unbounded_String : constant Unbounded_String;

   function Length (Source : Unbounded_String) return Natural;

   type String_Access is access all String;

   procedure Free (X : in out String_Access);

   --------------------------------------------------------

   -- Conversion, Concatenation, and Selection Functions --

   --------------------------------------------------------

   function To_Unbounded_String

     (Source : String)  return Unbounded_String;

   function To_Unbounded_String

     (Length : Natural) return Unbounded_String;

   function To_String (Source : Unbounded_String) return String;

   procedure Set_Unbounded_String

     (Target : out Unbounded_String;

      Source : String);

   pragma Ada_05 (Set_Unbounded_String);

   procedure Append

     (Source   : in out Unbounded_String;

      New_Item : Unbounded_String);

   procedure Append

     (Source   : in out Unbounded_String;

      New_Item : String);

   procedure Append

     (Source   : in out Unbounded_String;

      New_Item : Character);

   function "&"

     (Left  : Unbounded_String;

      Right : Unbounded_String) return Unbounded_String;

   function "&"

     (Left  : Unbounded_String;

      Right : String) return Unbounded_String;

   function "&"

     (Left  : String;

      Right : Unbounded_String) return Unbounded_String;

   function "&"

     (Left  : Unbounded_String;

      Right : Character) return Unbounded_String;

   function "&"

     (Left  : Character;

      Right : Unbounded_String) return Unbounded_String;

   function Element

     (Source : Unbounded_String;

      Index  : Positive) return Character;

   procedure Replace_Element

     (Source : in out Unbounded_String;

      Index  : Positive;

      By     : Character);

   function Slice

     (Source : Unbounded_String;

      Low    : Positive;

      High   : Natural) return String;

   function Unbounded_Slice

     (Source : Unbounded_String;

      Low    : Positive;

      High   : Natural) return Unbounded_String;

   pragma Ada_05 (Unbounded_Slice);

   procedure Unbounded_Slice

     (Source : Unbounded_String;

      Target : out Unbounded_String;

      Low    : Positive;

      High   : Natural);

   pragma Ada_05 (Unbounded_Slice);

   function "="

     (Left  : Unbounded_String;

      Right : Unbounded_String) return Boolean;

   function "="

     (Left  : Unbounded_String;

      Right : String) return Boolean;

   function "="

     (Left  : String;

      Right : Unbounded_String) return Boolean;

   function "<"

     (Left  : Unbounded_String;

      Right : Unbounded_String) return Boolean;

   function "<"

     (Left  : Unbounded_String;

      Right : String) return Boolean;

   function "<"

     (Left  : String;

      Right : Unbounded_String) return Boolean;

   function "<="

     (Left  : Unbounded_String;

      Right : Unbounded_String) return Boolean;

   function "<="

     (Left  : Unbounded_String;

      Right : String) return Boolean;

   function "<="

     (Left  : String;

      Right : Unbounded_String) return Boolean;

   function ">"

     (Left  : Unbounded_String;

      Right : Unbounded_String) return Boolean;

   function ">"

     (Left  : Unbounded_String;

      Right : String) return Boolean;

   function ">"

     (Left  : String;

      Right : Unbounded_String) return Boolean;

   function ">="

     (Left  : Unbounded_String;

      Right : Unbounded_String) return Boolean;

   function ">="

     (Left  : Unbounded_String;

      Right : String) return Boolean;

   function ">="

     (Left  : String;

      Right : Unbounded_String) return Boolean;

   ------------------------

   -- Search Subprograms --

   ------------------------

   function Index

     (Source  : Unbounded_String;

      Pattern : String;

      Going   : Direction := Forward;

      Mapping : Maps.Character_Mapping := Maps.Identity) return Natural;

   function Index

     (Source  : Unbounded_String;

      Pattern : String;

      Going   : Direction := Forward;

      Mapping : Maps.Character_Mapping_Function) return Natural;

   function Index

     (Source : Unbounded_String;

      Set    : Maps.Character_Set;

      Test   : Membership := Inside;

      Going  : Direction  := Forward) return Natural;

   function Index

     (Source  : Unbounded_String;

      Pattern : String;

      From    : Positive;

      Going   : Direction := Forward;

      Mapping : Maps.Character_Mapping := Maps.Identity) return Natural;

   pragma Ada_05 (Index);

   function Index

     (Source  : Unbounded_String;

      Pattern : String;

      From    : Positive;

      Going   : Direction := Forward;

      Mapping : Maps.Character_Mapping_Function) return Natural;

   pragma Ada_05 (Index);

   function Index

     (Source  : Unbounded_String;

      Set     : Maps.Character_Set;

      From    : Positive;

      Test    : Membership := Inside;

      Going   : Direction := Forward) return Natural;

   pragma Ada_05 (Index);

   function Index_Non_Blank

     (Source : Unbounded_String;

      Going  : Direction := Forward) return Natural;

   function Index_Non_Blank

     (Source : Unbounded_String;

      From   : Positive;

      Going  : Direction := Forward) return Natural;

   pragma Ada_05 (Index_Non_Blank);

   function Count

     (Source  : Unbounded_String;

      Pattern : String;

      Mapping : Maps.Character_Mapping := Maps.Identity) return Natural;

   function Count

     (Source  : Unbounded_String;

      Pattern : String;

      Mapping : Maps.Character_Mapping_Function) return Natural;

   function Count

     (Source : Unbounded_String;

      Set    : Maps.Character_Set) return Natural;

   procedure Find_Token

     (Source : Unbounded_String;

      Set    : Maps.Character_Set;

      From   : Positive;

      Test   : Membership;

      First  : out Positive;

      Last   : out Natural);

   pragma Ada_2012 (Find_Token);

   procedure Find_Token

     (Source : Unbounded_String;

      Set    : Maps.Character_Set;

      Test   : Membership;

      First  : out Positive;

      Last   : out Natural);

   ------------------------------------

   -- String Translation Subprograms --

   ------------------------------------

   function Translate

     (Source  : Unbounded_String;

      Mapping : Maps.Character_Mapping) return Unbounded_String;

   procedure Translate

     (Source  : in out Unbounded_String;

      Mapping : Maps.Character_Mapping);

   function Translate

     (Source  : Unbounded_String;

      Mapping : Maps.Character_Mapping_Function) return Unbounded_String;

   procedure Translate

     (Source  : in out Unbounded_String;

      Mapping : Maps.Character_Mapping_Function);

   ---------------------------------------

   -- String Transformation Subprograms --

   ---------------------------------------

   function Replace_Slice

     (Source : Unbounded_String;

      Low    : Positive;

      High   : Natural;

      By     : String) return Unbounded_String;

   procedure Replace_Slice

     (Source : in out Unbounded_String;

      Low    : Positive;

      High   : Natural;

      By     : String);

   function Insert

     (Source   : Unbounded_String;

      Before   : Positive;

      New_Item : String) return Unbounded_String;

   procedure Insert

     (Source   : in out Unbounded_String;

      Before   : Positive;

      New_Item : String);

   function Overwrite

     (Source   : Unbounded_String;

      Position : Positive;

      New_Item : String) return Unbounded_String;

   procedure Overwrite

     (Source   : in out Unbounded_String;

      Position : Positive;

      New_Item : String);

   function Delete

     (Source  : Unbounded_String;

      From    : Positive;

      Through : Natural) return Unbounded_String;

   procedure Delete

     (Source  : in out Unbounded_String;

      From    : Positive;

      Through : Natural);

   function Trim

     (Source : Unbounded_String;

      Side   : Trim_End) return Unbounded_String;

   procedure Trim

     (Source : in out Unbounded_String;

      Side   : Trim_End);

   function Trim

     (Source : Unbounded_String;

      Left   : Maps.Character_Set;

      Right  : Maps.Character_Set) return Unbounded_String;

   procedure Trim

     (Source : in out Unbounded_String;

      Left   : Maps.Character_Set;

      Right  : Maps.Character_Set);

   function Head

     (Source : Unbounded_String;

      Count  : Natural;

      Pad    : Character := Space) return Unbounded_String;

   procedure Head

     (Source : in out Unbounded_String;

      Count  : Natural;

      Pad    : Character := Space);

   function Tail

     (Source : Unbounded_String;

      Count  : Natural;

      Pad    : Character := Space) return Unbounded_String;

   procedure Tail

     (Source : in out Unbounded_String;

      Count  : Natural;

      Pad    : Character := Space);

   function "*"

     (Left  : Natural;

      Right : Character) return Unbounded_String;

   function "*"

     (Left  : Natural;

      Right : String) return Unbounded_String;

   function "*"

     (Left  : Natural;

      Right : Unbounded_String) return Unbounded_String;

private

   pragma Inline (Length);

   package AF renames Ada.Finalization;

   type Shared_String (Max_Length : Natural) is limited record

      Counter : System.Atomic_Counters.Atomic_Counter;

      --  Reference counter

      Last : Natural := 0;

      Data : String (1 .. Max_Length);

      --  Last is the index of last significant element of the Data. All

      --  elements with larger indexes are currently insignificant.

   end record;

   type Shared_String_Access is access all Shared_String;

   procedure Reference (Item : not null Shared_String_Access);

   --  Increment reference counter

   procedure Unreference (Item : not null Shared_String_Access);

   --  Decrement reference counter, deallocate Item when counter goes to zero

   function Can_Be_Reused

     (Item   : Shared_String_Access;

      Length : Natural) return Boolean;

   --  Returns True if Shared_String can be reused. There are two criteria when

   --  Shared_String can be reused: its reference counter must be one (thus

   --  Shared_String is owned exclusively) and its size is sufficient to

   --  store string with specified length effectively.

   function Allocate (Max_Length : Natural) return Shared_String_Access;

   --  Allocates new Shared_String with at least specified maximum length.

   --  Actual maximum length of the allocated Shared_String can be slightly

   --  greater. Returns reference to Empty_Shared_String when requested length

   --  is zero.

   Empty_Shared_String : aliased Shared_String (0);

   function To_Unbounded (S : String) return Unbounded_String

     renames To_Unbounded_String;

   --  This renames are here only to be used in the pragma Stream_Convert

   type Unbounded_String is new AF.Controlled with record

      Reference : Shared_String_Access := Empty_Shared_String'Access;

   end record;

   pragma Stream_Convert (Unbounded_String, To_Unbounded, To_String);

   --  Provide stream routines without dragging in Ada.Streams

   pragma Finalize_Storage_Only (Unbounded_String);

   --  Finalization is required only for freeing storage

   overriding procedure Initialize (Object : in out Unbounded_String);

   overriding procedure Adjust     (Object : in out Unbounded_String);

   overriding procedure Finalize   (Object : in out Unbounded_String);

   Null_Unbounded_String : constant Unbounded_String :=

                             (AF.Controlled with

                                Reference => Empty_Shared_String'Access);

end Ada.Strings.Unbounded;