1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                     G N A T . A R R A Y _ S P L I T                      --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 2002-2019, Free Software Foundation, Inc.         --
10--                                                                          --
11-- GNAT is free software;  you can  redistribute it  and/or modify it under --
12-- terms of the  GNU General Public License as published  by the Free Soft- --
13-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
14-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
15-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
16-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
17--                                                                          --
18-- As a special exception under Section 7 of GPL version 3, you are granted --
19-- additional permissions described in the GCC Runtime Library Exception,   --
20-- version 3.1, as published by the Free Software Foundation.               --
21--                                                                          --
22-- You should have received a copy of the GNU General Public License and    --
23-- a copy of the GCC Runtime Library Exception along with this program;     --
24-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
25-- <http://www.gnu.org/licenses/>.                                          --
26--                                                                          --
27-- GNAT was originally developed  by the GNAT team at  New York University. --
28-- Extensive contributions were provided by Ada Core Technologies Inc.      --
29--                                                                          --
30------------------------------------------------------------------------------
31
32--  Useful array-manipulation routines: given a set of separators, split
33--  an array wherever the separators appear, and provide direct access
34--  to the resulting slices.
35
36with Ada.Finalization;
37
38generic
39   type Element is (<>);
40   --  Element of the array, this must be a discrete type
41
42   type Element_Sequence is array (Positive range <>) of Element;
43   --  The array which is a sequence of element
44
45   type Element_Set is private;
46   --  This type represent a set of elements. This set does not define a
47   --  specific order of the elements. The conversion of a sequence to a
48   --  set and membership tests in the set is performed using the routines
49   --  To_Set and Is_In defined below.
50
51   with function To_Set (Sequence : Element_Sequence) return Element_Set;
52   --  Returns an Element_Set given an Element_Sequence. Duplicate elements
53   --  can be ignored during this conversion.
54
55   with function Is_In (Item : Element; Set : Element_Set) return Boolean;
56   --  Returns True if Item is found in Set, False otherwise
57
58package GNAT.Array_Split is
59   pragma Preelaborate;
60
61   Index_Error : exception;
62   --  Raised by all operations below if Index > Field_Count (S)
63
64   type Separator_Mode is
65     (Single,
66      --  In this mode the array is cut at each element in the separator
67      --  set. If two separators are contiguous the result at that position
68      --  is an empty slice.
69
70      Multiple
71      --  In this mode contiguous separators are handled as a single
72      --  separator and no empty slice is created.
73     );
74
75   type Slice_Set is private;
76   --  This type uses by-reference semantics. This is a set of slices as
77   --  returned by Create or Set routines below. The abstraction represents
78   --  a set of items. Each item is a part of the original array named a
79   --  Slice. It is possible to access individual slices by using the Slice
80   --  routine below. The first slice in the Set is at the position/index
81   --  1. The total number of slices in the set is returned by Slice_Count.
82
83   procedure Create
84     (S          : out Slice_Set;
85      From       : Element_Sequence;
86      Separators : Element_Sequence;
87      Mode       : Separator_Mode := Single);
88   --  Create a cut array object. From is the source array, and Separators
89   --  is a sequence of Element along which to split the array. The source
90   --  array is sliced at separator boundaries. The separators are not
91   --  included as part of the resulting slices.
92   --
93   --  Note that if From is terminated by a separator an extra empty element
94   --  is added to the slice set. If From only contains a separator the slice
95   --  set contains two empty elements.
96
97   procedure Create
98     (S          : out Slice_Set;
99      From       : Element_Sequence;
100      Separators : Element_Set;
101      Mode       : Separator_Mode := Single);
102   --  Same as above but using a Element_Set
103
104   procedure Set
105     (S          : in out Slice_Set;
106      Separators : Element_Sequence;
107      Mode       : Separator_Mode := Single);
108   --  Change the set of separators. The source array will be split according
109   --  to this new set of separators.
110
111   procedure Set
112     (S          : in out Slice_Set;
113      Separators : Element_Set;
114      Mode       : Separator_Mode := Single);
115   --  Same as above but using a Element_Set
116
117   type Slice_Number is new Natural;
118   --  Type used to count number of slices
119
120   function Slice_Count (S : Slice_Set) return Slice_Number;
121   pragma Inline (Slice_Count);
122   --  Returns the number of slices (fields) in S
123
124   function Slice
125     (S     : Slice_Set;
126      Index : Slice_Number) return Element_Sequence;
127   pragma Inline (Slice);
128   --  Returns the slice at position Index. First slice is 1. If Index is 0
129   --  the whole array is returned including the separators (this is the
130   --  original source array).
131
132   type Position is (Before, After);
133   --  Used to designate position of separator
134
135   type Slice_Separators is array (Position) of Element;
136   --  Separators found before and after the slice
137
138   Array_End : constant Element;
139   --  This is the separator returned for the start or the end of the array
140
141   function Separators
142     (S     : Slice_Set;
143      Index : Slice_Number) return Slice_Separators;
144   --  Returns the separators used to slice (front and back) the slice at
145   --  position Index. For slices at start and end of the original array, the
146   --  Array_End value is returned for the corresponding outer bound. In
147   --  Multiple mode only the element closest to the slice is returned.
148   --  if Index = 0, returns (Array_End, Array_End).
149
150   type Separators_Indexes is array (Positive range <>) of Positive;
151
152   function Separators (S : Slice_Set) return Separators_Indexes;
153   --  Returns indexes of all separators used to slice original source array S
154
155private
156
157   Array_End : constant Element := Element'First;
158
159   type Element_Access is access Element_Sequence;
160
161   type Indexes_Access is access Separators_Indexes;
162
163   type Slice_Info is record
164      Start : Positive;
165      Stop  : Natural;
166   end record;
167   --  Starting/Ending position of a slice. This does not include separators
168
169   type Slices_Indexes is array (Slice_Number range <>) of Slice_Info;
170   type Slices_Access is access Slices_Indexes;
171   --  All indexes for fast access to slices. In the Slice_Set we keep only
172   --  the original array and the indexes where each slice start and stop.
173
174   type Data is record
175      Ref_Counter : Natural;            -- Reference counter, by-address sem
176      Source      : Element_Access;
177      N_Slice     : Slice_Number := 0;  -- Number of slices found
178      Indexes     : Indexes_Access;
179      Slices      : Slices_Access;
180   end record;
181   type Data_Access is access all Data;
182
183   type Slice_Set is new Ada.Finalization.Controlled with record
184      D : Data_Access;
185   end record;
186
187   procedure Initialize (S : in out Slice_Set);
188   procedure Adjust     (S : in out Slice_Set);
189   procedure Finalize   (S : in out Slice_Set);
190
191end GNAT.Array_Split;
192