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   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) 2004-2013, 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
  58 private with Ada.Containers.Hash_Tables;
  59
  60 generic
  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
  68 package Ada.Containers.Formal_Hashed_Maps is
  69    pragma Annotate (GNATprove, External_Axiomatization);
  70    pragma Pure;
  71
  72    type Map (Capacity : Count_Type; Modulus : Hash_Type) is private with
  73      Iterable => (First       => First,
  74                   Next        => Next,
  75                   Has_Element => Has_Element,
  76                   Element     => Element);
  77    pragma Preelaborable_Initialization (Map);
  78
  79    type Cursor is private;
  80    pragma Preelaborable_Initialization (Cursor);
  81
  82    Empty_Map : constant Map;
  83
  84    No_Element : constant Cursor;
  85
  86    function "=" (Left, Right : Map) return Boolean with
  87      Global => null;
  88
  89    function Capacity (Container : Map) return Count_Type with
  90      Global => null;
  91
  92    procedure Reserve_Capacity
  93      (Container : in out Map;
  94       Capacity  : Count_Type)
  95    with
  96      Global => null,
  97      Pre    => Capacity <= Container.Capacity;
  98
  99    function Length (Container : Map) return Count_Type with
 100      Global => null;
 101
 102    function Is_Empty (Container : Map) return Boolean with
 103      Global => null;
 104
 105    procedure Clear (Container : in out Map) with
 106      Global => null;
 107
 108    procedure Assign (Target : in out Map; Source : Map) with
 109      Global => null,
 110      Pre    => Target.Capacity >= Length (Source);
 111
 112    function Copy
 113      (Source   : Map;
 114       Capacity : Count_Type := 0) return Map
 115    with
 116      Global => null,
 117      Pre    => Capacity = 0 or else Capacity >= Source.Capacity;
 118    --  Copy returns a container stricty equal to Source. It must have
 119    --  the same cursors associated with each element. Therefore:
 120    --  - capacity=0 means use container.capacity as capacity of target
 121    --  - the modulus cannot be changed.
 122
 123    function Key (Container : Map; Position : Cursor) return Key_Type with
 124      Global => null,
 125      Pre    => Has_Element (Container, Position);
 126
 127    function Element
 128      (Container : Map;
 129       Position  : Cursor) return Element_Type
 130    with
 131      Global => null,
 132      Pre    => Has_Element (Container, Position);
 133
 134    procedure Replace_Element
 135      (Container : in out Map;
 136       Position  : Cursor;
 137       New_Item  : Element_Type)
 138    with
 139      Global => null,
 140      Pre    => Has_Element (Container, Position);
 141
 142    procedure Move (Target : in out Map; Source : in out Map) with
 143      Global => null,
 144      Pre    => Target.Capacity >= Length (Source);
 145
 146    procedure Insert
 147      (Container : in out Map;
 148       Key       : Key_Type;
 149       New_Item  : Element_Type;
 150       Position  : out Cursor;
 151       Inserted  : out Boolean)
 152    with
 153      Global => null,
 154      Pre    => Length (Container) < Container.Capacity;
 155
 156    procedure Insert
 157      (Container : in out Map;
 158       Key       : Key_Type;
 159       New_Item  : Element_Type)
 160    with
 161      Global => null,
 162      Pre    => Length (Container) < Container.Capacity
 163                  and then (not Contains (Container, Key));
 164
 165    procedure Include
 166      (Container : in out Map;
 167       Key       : Key_Type;
 168       New_Item  : Element_Type)
 169    with
 170      Global => null,
 171      Pre    => Length (Container) < Container.Capacity;
 172
 173    procedure Replace
 174      (Container : in out Map;
 175       Key       : Key_Type;
 176       New_Item  : Element_Type)
 177    with
 178      Global => null,
 179      Pre    => Contains (Container, Key);
 180
 181    procedure Exclude (Container : in out Map; Key : Key_Type) with
 182      Global => null;
 183
 184    procedure Delete (Container : in out Map; Key : Key_Type) with
 185      Global => null,
 186      Pre    => Contains (Container, Key);
 187
 188    procedure Delete (Container : in out Map; Position : in out Cursor) with
 189      Global => null,
 190      Pre    => Has_Element (Container, Position);
 191
 192    function First (Container : Map) return Cursor with
 193      Global => null;
 194
 195    function Next (Container : Map; Position : Cursor) return Cursor with
 196      Global => null,
 197      Pre    => Has_Element (Container, Position) or else Position = No_Element;
 198
 199    procedure Next (Container : Map; Position : in out Cursor) with
 200      Global => null,
 201      Pre    => Has_Element (Container, Position) or else Position = No_Element;
 202
 203    function Find (Container : Map; Key : Key_Type) return Cursor with
 204      Global => null;
 205
 206    function Contains (Container : Map; Key : Key_Type) return Boolean with
 207      Global => null;
 208
 209    function Element (Container : Map; Key : Key_Type) return Element_Type with
 210      Global => null,
 211      Pre    => Contains (Container, Key);
 212
 213    function Has_Element (Container : Map; Position : Cursor) return Boolean
 214    with
 215      Global => null;
 216
 217    function Equivalent_Keys
 218      (Left   : Map;
 219       CLeft  : Cursor;
 220       Right  : Map;
 221       CRight : Cursor) return Boolean
 222    with
 223      Global => null;
 224
 225    function Equivalent_Keys
 226      (Left  : Map;
 227       CLeft : Cursor;
 228       Right : Key_Type) return Boolean
 229    with
 230      Global => null;
 231
 232    function Equivalent_Keys
 233      (Left   : Key_Type;
 234       Right  : Map;
 235       CRight : Cursor) return Boolean
 236    with
 237      Global => null;
 238
 239    function Default_Modulus (Capacity : Count_Type) return Hash_Type with
 240      Global => null;
 241
 242    function Strict_Equal (Left, Right : Map) return Boolean with
 243      Global => null;
 244    --  Strict_Equal returns True if the containers are physically equal, i.e.
 245    --  they are structurally equal (function "=" returns True) and that they
 246    --  have the same set of cursors.
 247
 248    function First_To_Previous (Container : Map; Current : Cursor) return Map
 249    with
 250      Global => null,
 251      Pre    => Has_Element (Container, Current) or else Current = No_Element;
 252    function Current_To_Last (Container : Map; Current : Cursor) return Map
 253    with
 254      Global => null,
 255      Pre    => Has_Element (Container, Current) or else Current = No_Element;
 256    --  First_To_Previous returns a container containing all elements preceding
 257    --  Current (excluded) in Container. Current_To_Last returns a container
 258    --  containing all elements following Current (included) in Container.
 259    --  These two new functions can be used to express invariant properties in
 260    --  loops which iterate over containers. First_To_Previous returns the part
 261    --  of the container already scanned and Current_To_Last the part not
 262    --  scanned yet.
 263
 264    function Overlap (Left, Right : Map) return Boolean with
 265      Global => null;
 266    --  Overlap returns True if the containers have common keys
 267
 268 private
 269    pragma Inline (Length);
 270    pragma Inline (Is_Empty);
 271    pragma Inline (Clear);
 272    pragma Inline (Key);
 273    pragma Inline (Element);
 274    pragma Inline (Contains);
 275    pragma Inline (Capacity);
 276    pragma Inline (Has_Element);
 277    pragma Inline (Equivalent_Keys);
 278    pragma Inline (Next);
 279
 280    type Node_Type is record
 281       Key         : Key_Type;
 282       Element     : Element_Type;
 283       Next        : Count_Type;
 284       Has_Element : Boolean := False;
 285    end record;
 286
 287    package HT_Types is new
 288      Ada.Containers.Hash_Tables.Generic_Bounded_Hash_Table_Types
 289        (Node_Type);
 290
 291    type Map (Capacity : Count_Type; Modulus : Hash_Type) is
 292       new HT_Types.Hash_Table_Type (Capacity, Modulus) with null record;
 293
 294    use HT_Types;
 295
 296    type Cursor is record
 297       Node : Count_Type;
 298    end record;
 299
 300    Empty_Map : constant Map := (Capacity => 0, Modulus => 0, others => <>);
 301
 302    No_Element : constant Cursor := (Node => 0);
 303
 304 end Ada.Containers.Formal_Hashed_Maps;