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

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                     G N A T . A R R A Y _ S P L I T                      --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 2002-2009, Free Software Foundation, Inc.         --

--                                                                          --

-- 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.      --

--                                                                          --

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

--  Useful array-manipulation routines: given a set of separators, split

--  an array wherever the separators appear, and provide direct access

--  to the resulting slices.

with Ada.Finalization;

generic

   type Element is (<>);

   --  Element of the array, this must be a discrete type

   type Element_Sequence is array (Positive range <>) of Element;

   --  The array which is a sequence of element

   type Element_Set is private;

   --  This type represent a set of elements. This set does not defined a

   --  specific order of the elements. The conversion of a sequence to a

   --  set and membership tests in the set is performed using the routines

   --  To_Set and Is_In defined below.

   with function To_Set (Sequence : Element_Sequence) return Element_Set;

   --  Returns an Element_Set given an Element_Sequence. Duplicate elements

   --  can be ignored during this conversion.

   with function Is_In (Item : Element; Set : Element_Set) return Boolean;

   --  Returns True if Item is found in Set, False otherwise

package GNAT.Array_Split is

   Index_Error : exception;

   --  Raised by all operations below if Index > Field_Count (S)

   type Separator_Mode is

     (Single,

      --  In this mode the array is cut at each element in the separator

      --  set. If two separators are contiguous the result at that position

      --  is an empty slice.

      Multiple

      --  In this mode contiguous separators are handled as a single

      --  separator and no empty slice is created.

     );

   type Slice_Set is private;

   --  This type uses by-reference semantics. This is a set of slices as

   --  returned by Create or Set routines below. The abstraction represents

   --  a set of items. Each item is a part of the original string named a

   --  Slice. It is possible to access individual slices by using the Slice

   --  routine below. The first slice in the Set is at the position/index

   --  1. The total number of slices in the set is returned by Slice_Count.

   procedure Create

     (S          : out Slice_Set;

      From       : Element_Sequence;

      Separators : Element_Sequence;

      Mode       : Separator_Mode := Single);

   --  Create a cut array object. From is the source array, and Separators

   --  is a sequence of Element along which to split the array. The source

   --  array is sliced at separator boundaries. The separators are not

   --  included as part of the resulting slices.

   --

   --  Note that if From is terminated by a separator an extra empty element

   --  is added to the slice set. If From only contains a separator the slice

   --  set contains two empty elements.

   procedure Create

     (S          : out Slice_Set;

      From       : Element_Sequence;

      Separators : Element_Set;

      Mode       : Separator_Mode := Single);

   --  Same as above but using a Element_Set

   procedure Set

     (S          : in out Slice_Set;

      Separators : Element_Sequence;

      Mode       : Separator_Mode := Single);

   --  Change the set of separators. The source array will be split according

   --  to this new set of separators.

   procedure Set

     (S          : in out Slice_Set;

      Separators : Element_Set;

      Mode       : Separator_Mode := Single);

   --  Same as above but using a Element_Set

   type Slice_Number is new Natural;

   --  Type used to count number of slices

   function Slice_Count (S : Slice_Set) return Slice_Number;

   pragma Inline (Slice_Count);

   --  Returns the number of slices (fields) in S

   function Slice

     (S     : Slice_Set;

      Index : Slice_Number) return Element_Sequence;

   pragma Inline (Slice);

   --  Returns the slice at position Index. First slice is 1. If Index is 0

   --  the whole array is returned including the separators (this is the

   --  original source array).

   type Position is (Before, After);

   --  Used to designate position of separator

   type Slice_Separators is array (Position) of Element;

   --  Separators found before and after the slice

   Array_End : constant Element;

   --  This is the separator returned for the start or the end of the array

   function Separators

     (S     : Slice_Set;

      Index : Slice_Number) return Slice_Separators;

   --  Returns the separators used to slice (front and back) the slice at

   --  position Index. For slices at start and end of the original array, the

   --  Array_End value is returned for the corresponding outer bound. In

   --  Multiple mode only the element closest to the slice is returned.

   --  if Index = 0, returns (Array_End, Array_End).

   type Separators_Indexes is array (Positive range <>) of Positive;

   function Separators (S : Slice_Set) return Separators_Indexes;

   --  Returns indexes of all separators used to slice original source array S

private

   Array_End : constant Element := Element'First;

   type Element_Access is access Element_Sequence;

   type Counter is access Natural;

   type Indexes_Access is access Separators_Indexes;

   type Slice_Info is record

      Start : Positive;

      Stop  : Natural;

   end record;

   --  Starting/Ending position of a slice. This does not include separators

   type Slices_Indexes is array (Slice_Number range <>) of Slice_Info;

   type Slices_Access is access Slices_Indexes;

   --  All indexes for fast access to slices. In the Slice_Set we keep only

   --  the original array and the indexes where each slice start and stop.

   type Slice_Set is new Ada.Finalization.Controlled with record

      Ref_Counter : Counter;            -- Reference counter, by-address sem

      Source      : Element_Access;

      N_Slice     : Slice_Number := 0;  -- Number of slices found

      Indexes     : Indexes_Access;

      Slices      : Slices_Access;

   end record;

   procedure Initialize (S : in out Slice_Set);

   procedure Adjust     (S : in out Slice_Set);

   procedure Finalize   (S : in out Slice_Set);

end GNAT.Array_Split;