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 _ V E C T O R 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_Vectors in the Ada
33--  2012 RM. The modifications are meant to facilitate formal proofs by making
34--  it easier to express properties, and by making the specification of this
35--  unit compatible with SPARK 2014. Note that the API of this unit may be
36--  subject to incompatible changes as SPARK 2014 evolves.
37
38generic
39   type Index_Type is range <>;
40   type Element_Type is private;
41
42   with function "=" (Left, Right : Element_Type) return Boolean is <>;
43
44   Bounded : Boolean := True;
45   --  If True, the containers are bounded; the initial capacity is the maximum
46   --  size, and heap allocation will be avoided. If False, the containers can
47   --  grow via heap allocation.
48
49package Ada.Containers.Formal_Vectors with
50  SPARK_Mode
51is
52   pragma Annotate (GNATprove, External_Axiomatization);
53
54   subtype Extended_Index is Index_Type'Base
55   range Index_Type'First - 1 ..
56     Index_Type'Min (Index_Type'Base'Last - 1, Index_Type'Last) + 1;
57
58   No_Index : constant Extended_Index := Extended_Index'First;
59
60   subtype Capacity_Range is
61     Count_Type range 0 .. Count_Type (Index_Type'Last - Index_Type'First + 1);
62
63   type Vector (Capacity : Capacity_Range) is limited private with
64     Default_Initial_Condition => Is_Empty (Vector);
65   --  In the bounded case, Capacity is the capacity of the container, which
66   --  never changes. In the unbounded case, Capacity is the initial capacity
67   --  of the container, and operations such as Reserve_Capacity and Append can
68   --  increase the capacity. The capacity never shrinks, except in the case of
69   --  Clear.
70   --
71   --  Note that all objects of type Vector are constrained, including in the
72   --  unbounded case; you can't assign from one object to another if the
73   --  Capacity is different.
74
75   function Empty_Vector return Vector;
76
77   function "=" (Left, Right : Vector) return Boolean with
78     Global => null;
79
80   function To_Vector
81     (New_Item : Element_Type;
82      Length   : Capacity_Range) return Vector
83   with
84     Global => null;
85
86   function Capacity (Container : Vector) return Capacity_Range with
87     Global => null,
88     Post => Capacity'Result >= Container.Capacity;
89
90   procedure Reserve_Capacity
91     (Container : in out Vector;
92      Capacity  : Capacity_Range)
93   with
94     Global => null,
95     Pre    => (if Bounded then Capacity <= Container.Capacity);
96
97   function Length (Container : Vector) return Capacity_Range with
98     Global => null;
99
100   function Is_Empty (Container : Vector) return Boolean with
101     Global => null;
102
103   procedure Clear (Container : in out Vector) with
104     Global => null;
105   --  Note that this reclaims storage in the unbounded case. You need to call
106   --  this before a container goes out of scope in order to avoid storage
107   --  leaks. In addition, "X := ..." can leak unless you Clear(X) first.
108
109   procedure Assign (Target : in out Vector; Source : Vector) with
110     Global => null,
111     Pre    => (if Bounded then Length (Source) <= Target.Capacity);
112
113   function Copy
114     (Source   : Vector;
115      Capacity : Capacity_Range := 0) return Vector
116   with
117     Global => null,
118     Pre    => (if Bounded then (Capacity = 0 or Length (Source) <= Capacity));
119
120   function Element
121     (Container : Vector;
122      Index     : Index_Type) return Element_Type
123   with
124     Global => null,
125     Pre    => Index in First_Index (Container) .. Last_Index (Container);
126
127   procedure Replace_Element
128     (Container : in out Vector;
129      Index     : Index_Type;
130      New_Item  : Element_Type)
131   with
132     Global => null,
133     Pre    => Index in First_Index (Container) .. Last_Index (Container);
134
135   procedure Append
136     (Container : in out Vector;
137      New_Item  : Vector)
138   with
139     Global => null,
140     Pre    => (if Bounded then
141                 Length (Container) + Length (New_Item) <= Container.Capacity);
142
143   procedure Append
144     (Container : in out Vector;
145      New_Item  : Element_Type)
146   with
147     Global => null,
148     Pre    => (if Bounded then
149                  Length (Container) < Container.Capacity);
150
151   procedure Delete_Last
152     (Container : in out Vector)
153   with
154     Global => null;
155
156   procedure Reverse_Elements (Container : in out Vector) with
157     Global => null;
158
159   procedure Swap (Container : in out Vector; I, J : Index_Type) with
160     Global => null,
161     Pre    => I in First_Index (Container) .. Last_Index (Container)
162      and then J in First_Index (Container) .. Last_Index (Container);
163
164   function First_Index (Container : Vector) return Index_Type with
165     Global => null;
166
167   function First_Element (Container : Vector) return Element_Type with
168     Global => null,
169     Pre    => not Is_Empty (Container);
170
171   function Last_Index (Container : Vector) return Extended_Index with
172     Global => null;
173
174   function Last_Element (Container : Vector) return Element_Type with
175     Global => null,
176     Pre    => not Is_Empty (Container);
177
178   function Find_Index
179     (Container : Vector;
180      Item      : Element_Type;
181      Index     : Index_Type := Index_Type'First) return Extended_Index
182   with
183     Global => null;
184
185   function Reverse_Find_Index
186     (Container : Vector;
187      Item      : Element_Type;
188      Index     : Index_Type := Index_Type'Last) return Extended_Index
189   with
190     Global => null;
191
192   function Contains
193     (Container : Vector;
194      Item      : Element_Type) return Boolean
195   with
196     Global => null;
197
198   function Has_Element
199     (Container : Vector;
200      Position  : Extended_Index) return Boolean
201   with
202     Global => null;
203
204   generic
205      with function "<" (Left, Right : Element_Type) return Boolean is <>;
206   package Generic_Sorting is
207
208      function Is_Sorted (Container : Vector) return Boolean with
209        Global => null;
210
211      procedure Sort (Container : in out Vector) with
212        Global => null;
213
214   end Generic_Sorting;
215
216   function First_To_Previous
217     (Container : Vector;
218      Current   : Index_Type) return Vector
219   with
220     Ghost,
221     Global => null,
222     Pre    => Current in First_Index (Container) .. Last_Index (Container);
223
224   function Current_To_Last
225     (Container : Vector;
226      Current   : Index_Type) return Vector
227   with
228     Ghost,
229     Global => null,
230     Pre    => Current in First_Index (Container) .. Last_Index (Container);
231   --  First_To_Previous returns a container containing all elements preceding
232   --  Current (excluded) in Container. Current_To_Last returns a container
233   --  containing all elements following Current (included) in Container.
234   --  These two new functions can be used to express invariant properties in
235   --  loops which iterate over containers. First_To_Previous returns the part
236   --  of the container already scanned and Current_To_Last the part not
237   --  scanned yet.
238
239private
240   pragma SPARK_Mode (Off);
241
242   pragma Inline (First_Index);
243   pragma Inline (Last_Index);
244   pragma Inline (Element);
245   pragma Inline (First_Element);
246   pragma Inline (Last_Element);
247   pragma Inline (Replace_Element);
248   pragma Inline (Contains);
249
250   subtype Array_Index is Capacity_Range range 1 .. Capacity_Range'Last;
251   type Elements_Array is array (Array_Index range <>) of Element_Type;
252   function "=" (L, R : Elements_Array) return Boolean is abstract;
253
254   type Elements_Array_Ptr is access all Elements_Array;
255
256   type Vector (Capacity : Capacity_Range) is limited record
257      --  In the bounded case, the elements are stored in Elements. In the
258      --  unbounded case, the elements are initially stored in Elements, until
259      --  we run out of room, then we switch to Elements_Ptr.
260      Last         : Extended_Index := No_Index;
261      Elements_Ptr : Elements_Array_Ptr := null;
262      Elements     : aliased Elements_Array (1 .. Capacity);
263   end record;
264
265   --  The primary reason Vector is limited is that in the unbounded case, once
266   --  Elements_Ptr is in use, assignment statements won't work. "X := Y;" will
267   --  cause X and Y to share state; that is, X.Elements_Ptr = Y.Elements_Ptr,
268   --  so for example "Append (X, ...);" will modify BOTH X and Y. That would
269   --  allow SPARK to "prove" things that are false. We could fix that by
270   --  making Vector a controlled type, and override Adjust to make a deep
271   --  copy, but finalization is not allowed in SPARK.
272   --
273   --  Note that (unfortunately) this means that 'Old and 'Loop_Entry are not
274   --  allowed on Vectors.
275
276   function Empty_Vector return Vector is
277     ((Capacity => 0, others => <>));
278
279end Ada.Containers.Formal_Vectors;
280