1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT LIBRARY COMPONENTS                          --
4--                                                                          --
5--    A D A . C O N T A I N E R S . F O R M A L _ H A S H E D _ M A P S     --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 2004-2015, Free Software Foundation, Inc.         --
10--                                                                          --
11-- This specification is derived from the Ada Reference Manual for use with --
12-- GNAT. The copyright notice above, and the license provisions that follow --
13-- apply solely to the  contents of the part following the private keyword. --
14--                                                                          --
15-- GNAT is free software;  you can  redistribute it  and/or modify it under --
16-- terms of the  GNU General Public License as published  by the Free Soft- --
17-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
18-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
19-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
20-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
21--                                                                          --
22-- As a special exception under Section 7 of GPL version 3, you are granted --
23-- additional permissions described in the GCC Runtime Library Exception,   --
24-- version 3.1, as published by the Free Software Foundation.               --
25--                                                                          --
26-- You should have received a copy of the GNU General Public License and    --
27-- a copy of the GCC Runtime Library Exception along with this program;     --
28-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
29-- <http://www.gnu.org/licenses/>.                                          --
30------------------------------------------------------------------------------
31
32--  This spec is derived from package Ada.Containers.Bounded_Hashed_Maps in the
33--  Ada 2012 RM. The modifications are meant to facilitate formal proofs by
34--  making it easier to express properties, and by making the specification of
35--  this unit compatible with SPARK 2014. Note that the API of this unit may be
36--  subject to incompatible changes as SPARK 2014 evolves.
37
38--  The modifications are:
39
40--    A parameter for the container is added to every function reading the
41--    contents of a container: Key, Element, Next, Query_Element, Has_Element,
42--    Iterate, Equivalent_Keys. This change is motivated by the need to have
43--    cursors which are valid on different containers (typically a container C
44--    and its previous version C'Old) for expressing properties, which is not
45--    possible if cursors encapsulate an access to the underlying container.
46
47--    There are four new functions:
48
49--      function Strict_Equal (Left, Right : Map) return Boolean;
50--      function Overlap (Left, Right : Map) return Boolean;
51--      function First_To_Previous (Container : Map; Current : Cursor)
52--         return Map;
53--      function Current_To_Last (Container : Map; Current : Cursor)
54--         return Map;
55
56--    See detailed specifications for these subprograms
57
58private with Ada.Containers.Hash_Tables;
59
60generic
61   type Key_Type is private;
62   type Element_Type is private;
63
64   with function Hash (Key : Key_Type) return Hash_Type;
65   with function Equivalent_Keys (Left, Right : Key_Type) return Boolean;
66   with function "=" (Left, Right : Element_Type) return Boolean is <>;
67
68package Ada.Containers.Formal_Hashed_Maps with
69  Pure,
70  SPARK_Mode
71is
72   pragma Annotate (GNATprove, External_Axiomatization);
73   pragma Annotate (CodePeer, Skip_Analysis);
74
75   type Map (Capacity : Count_Type; Modulus : Hash_Type) is private with
76     Iterable => (First       => First,
77                  Next        => Next,
78                  Has_Element => Has_Element,
79                  Element     => Element),
80     Default_Initial_Condition => Is_Empty (Map);
81   pragma Preelaborable_Initialization (Map);
82
83   type Cursor is private;
84   pragma Preelaborable_Initialization (Cursor);
85
86   Empty_Map : constant Map;
87
88   No_Element : constant Cursor;
89
90   function "=" (Left, Right : Map) return Boolean with
91     Global => null;
92
93   function Capacity (Container : Map) return Count_Type with
94     Global => null;
95
96   procedure Reserve_Capacity
97     (Container : in out Map;
98      Capacity  : Count_Type)
99   with
100     Global => null,
101     Pre    => Capacity <= Container.Capacity;
102
103   function Length (Container : Map) return Count_Type with
104     Global => null;
105
106   function Is_Empty (Container : Map) return Boolean with
107     Global => null;
108
109   procedure Clear (Container : in out Map) with
110     Global => null;
111
112   procedure Assign (Target : in out Map; Source : Map) with
113     Global => null,
114     Pre    => Target.Capacity >= Length (Source);
115
116   function Copy
117     (Source   : Map;
118      Capacity : Count_Type := 0) return Map
119   with
120     Global => null,
121     Pre    => Capacity = 0 or else Capacity >= Source.Capacity;
122   --  Copy returns a container stricty equal to Source. It must have
123   --  the same cursors associated with each element. Therefore:
124   --  - capacity=0 means use container.capacity as capacity of target
125   --  - the modulus cannot be changed.
126
127   function Key (Container : Map; Position : Cursor) return Key_Type with
128     Global => null,
129     Pre    => Has_Element (Container, Position);
130
131   function Element
132     (Container : Map;
133      Position  : Cursor) return Element_Type
134   with
135     Global => null,
136     Pre    => Has_Element (Container, Position);
137
138   procedure Replace_Element
139     (Container : in out Map;
140      Position  : Cursor;
141      New_Item  : Element_Type)
142   with
143     Global => null,
144     Pre    => Has_Element (Container, Position);
145
146   procedure Move (Target : in out Map; Source : in out Map) with
147     Global => null,
148     Pre    => Target.Capacity >= Length (Source);
149
150   procedure Insert
151     (Container : in out Map;
152      Key       : Key_Type;
153      New_Item  : Element_Type;
154      Position  : out Cursor;
155      Inserted  : out Boolean)
156   with
157     Global => null,
158     Pre    => Length (Container) < Container.Capacity;
159
160   procedure Insert
161     (Container : in out Map;
162      Key       : Key_Type;
163      New_Item  : Element_Type)
164   with
165     Global => null,
166     Pre    => Length (Container) < Container.Capacity
167                 and then (not Contains (Container, Key));
168
169   procedure Include
170     (Container : in out Map;
171      Key       : Key_Type;
172      New_Item  : Element_Type)
173   with
174     Global => null,
175     Pre    => Length (Container) < Container.Capacity;
176
177   procedure Replace
178     (Container : in out Map;
179      Key       : Key_Type;
180      New_Item  : Element_Type)
181   with
182     Global => null,
183     Pre    => Contains (Container, Key);
184
185   procedure Exclude (Container : in out Map; Key : Key_Type) with
186     Global => null;
187
188   procedure Delete (Container : in out Map; Key : Key_Type) with
189     Global => null,
190     Pre    => Contains (Container, Key);
191
192   procedure Delete (Container : in out Map; Position : in out Cursor) with
193     Global => null,
194     Pre    => Has_Element (Container, Position);
195
196   function First (Container : Map) return Cursor with
197     Global => null;
198
199   function Next (Container : Map; Position : Cursor) return Cursor with
200     Global => null,
201     Pre    => Has_Element (Container, Position) or else Position = No_Element;
202
203   procedure Next (Container : Map; Position : in out Cursor) with
204     Global => null,
205     Pre    => Has_Element (Container, Position) or else Position = No_Element;
206
207   function Find (Container : Map; Key : Key_Type) return Cursor with
208     Global => null;
209
210   function Contains (Container : Map; Key : Key_Type) return Boolean with
211     Global => null;
212
213   function Element (Container : Map; Key : Key_Type) return Element_Type with
214     Global => null,
215     Pre    => Contains (Container, Key);
216
217   function Has_Element (Container : Map; Position : Cursor) return Boolean
218   with
219     Global => null;
220
221   function Equivalent_Keys
222     (Left   : Map;
223      CLeft  : Cursor;
224      Right  : Map;
225      CRight : Cursor) return Boolean
226   with
227     Global => null;
228
229   function Equivalent_Keys
230     (Left  : Map;
231      CLeft : Cursor;
232      Right : Key_Type) return Boolean
233   with
234     Global => null;
235
236   function Equivalent_Keys
237     (Left   : Key_Type;
238      Right  : Map;
239      CRight : Cursor) return Boolean
240   with
241     Global => null;
242
243   function Default_Modulus (Capacity : Count_Type) return Hash_Type with
244     Global => null;
245
246   function Strict_Equal (Left, Right : Map) return Boolean with
247     Ghost,
248     Global => null;
249   --  Strict_Equal returns True if the containers are physically equal, i.e.
250   --  they are structurally equal (function "=" returns True) and that they
251   --  have the same set of cursors.
252
253   function First_To_Previous (Container : Map; Current : Cursor) return Map
254   with
255     Ghost,
256     Global => null,
257     Pre    => Has_Element (Container, Current) or else Current = No_Element;
258
259   function Current_To_Last (Container : Map; Current : Cursor) return Map
260   with
261     Ghost,
262     Global => null,
263     Pre    => Has_Element (Container, Current) or else Current = No_Element;
264   --  First_To_Previous returns a container containing all elements preceding
265   --  Current (excluded) in Container. Current_To_Last returns a container
266   --  containing all elements following Current (included) in Container.
267   --  These two new functions can be used to express invariant properties in
268   --  loops which iterate over containers. First_To_Previous returns the part
269   --  of the container already scanned and Current_To_Last the part not
270   --  scanned yet.
271
272   function Overlap (Left, Right : Map) return Boolean with
273     Global => null;
274   --  Overlap returns True if the containers have common keys
275
276private
277   pragma SPARK_Mode (Off);
278
279   pragma Inline (Length);
280   pragma Inline (Is_Empty);
281   pragma Inline (Clear);
282   pragma Inline (Key);
283   pragma Inline (Element);
284   pragma Inline (Contains);
285   pragma Inline (Capacity);
286   pragma Inline (Has_Element);
287   pragma Inline (Equivalent_Keys);
288   pragma Inline (Next);
289
290   type Node_Type is record
291      Key         : Key_Type;
292      Element     : Element_Type;
293      Next        : Count_Type;
294      Has_Element : Boolean := False;
295   end record;
296
297   package HT_Types is new
298     Ada.Containers.Hash_Tables.Generic_Bounded_Hash_Table_Types (Node_Type);
299
300   type Map (Capacity : Count_Type; Modulus : Hash_Type) is
301     new HT_Types.Hash_Table_Type (Capacity, Modulus) with null record;
302
303   use HT_Types;
304
305   type Cursor is record
306      Node : Count_Type;
307   end record;
308
309   Empty_Map : constant Map := (Capacity => 0, Modulus => 0, others => <>);
310
311   No_Element : constant Cursor := (Node => 0);
312
313end Ada.Containers.Formal_Hashed_Maps;
314