gcc/ada/a-cfdlli.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT LIBRARY COMPONENTS                          --
   4 --                                                                          --
   5 --                 ADA.CONTAINERS.FORMAL_DOUBLY_LINKED_LISTS                --
   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 Ada.Containers.Bounded_Doubly_Linked_Lists 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: Next, Previous, Query_Element, Has_Element,
  42 --    Iterate, Reverse_Iterate, Element. This change is motivated by the need
  43 --    to have cursors which are valid on different containers (typically a
  44 --    container C and its previous version C'Old) for expressing properties,
  45 --    which is not possible if cursors encapsulate an access to the underlying
  46 --    container.
  47
  48 --    There are three new functions:
  49
  50 --      function Strict_Equal (Left, Right : List) return Boolean;
  51 --      function First_To_Previous  (Container : List; Current : Cursor)
  52 --         return List;
  53 --      function Current_To_Last (Container : List; Current : Cursor)
  54 --         return List;
  55
  56 --    See subprogram specifications that follow for details
  57
  58 generic
  59    type Element_Type is private;
  60
  61    with function "=" (Left, Right : Element_Type)
  62                       return Boolean is <>;
  63
  64 package Ada.Containers.Formal_Doubly_Linked_Lists is
  65    pragma Annotate (GNATprove, External_Axiomatization);
  66    pragma Pure;
  67
  68    type List (Capacity : Count_Type) is private with
  69      Iterable => (First       => First,
  70                   Next        => Next,
  71                   Has_Element => Has_Element,
  72                   Element     => Element),
  73      Default_Initial_Condition;
  74    pragma Preelaborable_Initialization (List);
  75
  76    type Cursor is private;
  77    pragma Preelaborable_Initialization (Cursor);
  78
  79    Empty_List : constant List;
  80
  81    No_Element : constant Cursor;
  82
  83    function "=" (Left, Right : List) return Boolean with
  84      Global => null;
  85
  86    function Length (Container : List) return Count_Type with
  87      Global => null;
  88
  89    function Is_Empty (Container : List) return Boolean with
  90      Global => null;
  91
  92    procedure Clear (Container : in out List) with
  93      Global => null;
  94
  95    procedure Assign (Target : in out List; Source : List) with
  96      Global => null,
  97      Pre    => Target.Capacity >= Length (Source);
  98
  99    function Copy (Source : List; Capacity : Count_Type := 0) return List with
 100      Global => null,
 101      Pre    => Capacity = 0 or else Capacity >= Source.Capacity;
 102
 103    function Element
 104      (Container : List;
 105       Position : Cursor) return Element_Type
 106    with
 107      Global => null,
 108      Pre    => Has_Element (Container, Position);
 109
 110    procedure Replace_Element
 111      (Container : in out List;
 112       Position  : Cursor;
 113       New_Item  : Element_Type)
 114    with
 115      Global => null,
 116      Pre    => Has_Element (Container, Position);
 117
 118    procedure Move (Target : in out List; Source : in out List) with
 119      Global => null,
 120      Pre    => Target.Capacity >= Length (Source);
 121
 122    procedure Insert
 123      (Container : in out List;
 124       Before    : Cursor;
 125       New_Item  : Element_Type;
 126       Count     : Count_Type := 1)
 127    with
 128      Global => null,
 129      Pre    => Length (Container) + Count <= Container.Capacity
 130                  and then (Has_Element (Container, Before)
 131                             or else Before = No_Element);
 132
 133    procedure Insert
 134      (Container : in out List;
 135       Before    : Cursor;
 136       New_Item  : Element_Type;
 137       Position  : out Cursor;
 138       Count     : Count_Type := 1)
 139    with
 140      Global => null,
 141      Pre    => Length (Container) + Count <= Container.Capacity
 142                  and then (Has_Element (Container, Before)
 143                             or else Before = No_Element);
 144
 145    procedure Insert
 146      (Container : in out List;
 147       Before    : Cursor;
 148       Position  : out Cursor;
 149       Count     : Count_Type := 1)
 150    with
 151      Global => null,
 152      Pre    => Length (Container) + Count <= Container.Capacity
 153                  and then (Has_Element (Container, Before)
 154                             or else Before = No_Element);
 155
 156    procedure Prepend
 157      (Container : in out List;
 158       New_Item  : Element_Type;
 159       Count     : Count_Type := 1)
 160    with
 161      Global => null,
 162      Pre    => Length (Container) + Count <= Container.Capacity;
 163
 164    procedure Append
 165      (Container : in out List;
 166       New_Item  : Element_Type;
 167       Count     : Count_Type := 1)
 168    with
 169      Global => null,
 170      Pre    => Length (Container) + Count <= Container.Capacity;
 171
 172    procedure Delete
 173      (Container : in out List;
 174       Position  : in out Cursor;
 175       Count     : Count_Type := 1)
 176    with
 177      Global => null,
 178      Pre    => Has_Element (Container, Position);
 179
 180    procedure Delete_First
 181      (Container : in out List;
 182       Count     : Count_Type := 1)
 183    with
 184      Global => null;
 185
 186    procedure Delete_Last
 187      (Container : in out List;
 188       Count     : Count_Type := 1)
 189    with
 190      Global => null;
 191
 192    procedure Reverse_Elements (Container : in out List) with
 193      Global => null;
 194
 195    procedure Swap
 196      (Container : in out List;
 197       I, J      : Cursor)
 198    with
 199      Global => null,
 200      Pre    => Has_Element (Container, I) and then Has_Element (Container, J);
 201
 202    procedure Swap_Links
 203      (Container : in out List;
 204       I, J      : Cursor)
 205    with
 206      Global => null,
 207      Pre    => Has_Element (Container, I) and then Has_Element (Container, J);
 208
 209    procedure Splice
 210      (Target : in out List;
 211       Before : Cursor;
 212       Source : in out List)
 213    with
 214      Global => null,
 215      Pre    => Length (Source) + Length (Target) <= Target.Capacity
 216                  and then (Has_Element (Target, Before)
 217                             or else Before = No_Element);
 218
 219    procedure Splice
 220      (Target   : in out List;
 221       Before   : Cursor;
 222       Source   : in out List;
 223       Position : in out Cursor)
 224    with
 225      Global => null,
 226      Pre    => Length (Source) + Length (Target) <= Target.Capacity
 227                  and then (Has_Element (Target, Before)
 228                             or else Before = No_Element)
 229                  and then Has_Element (Source, Position);
 230
 231    procedure Splice
 232      (Container : in out List;
 233       Before    : Cursor;
 234       Position  : Cursor)
 235    with
 236      Global => null,
 237      Pre    => 2 * Length (Container) <= Container.Capacity
 238                  and then (Has_Element (Container, Before)
 239                             or else Before = No_Element)
 240                  and then Has_Element (Container, Position);
 241
 242    function First (Container : List) return Cursor with
 243      Global => null;
 244
 245    function First_Element (Container : List) return Element_Type with
 246      Global => null,
 247      Pre    => not Is_Empty (Container);
 248
 249    function Last (Container : List) return Cursor with
 250      Global => null;
 251
 252    function Last_Element (Container : List) return Element_Type with
 253      Global => null,
 254      Pre    => not Is_Empty (Container);
 255
 256    function Next (Container : List; Position : Cursor) return Cursor with
 257      Global => null,
 258      Pre    => Has_Element (Container, Position) or else Position = No_Element;
 259
 260    procedure Next (Container : List; Position : in out Cursor) with
 261      Global => null,
 262      Pre    => Has_Element (Container, Position) or else Position = No_Element;
 263
 264    function Previous (Container : List; Position : Cursor) return Cursor with
 265      Global => null,
 266      Pre    => Has_Element (Container, Position) or else Position = No_Element;
 267
 268    procedure Previous (Container : List; Position : in out Cursor) with
 269      Global => null,
 270      Pre    => Has_Element (Container, Position) or else Position = No_Element;
 271
 272    function Find
 273      (Container : List;
 274       Item      : Element_Type;
 275       Position  : Cursor := No_Element) return Cursor
 276    with
 277      Global => null,
 278      Pre    => Has_Element (Container, Position) or else Position = No_Element;
 279
 280    function Reverse_Find
 281      (Container : List;
 282       Item      : Element_Type;
 283       Position  : Cursor := No_Element) return Cursor
 284    with
 285      Global => null,
 286      Pre    => Has_Element (Container, Position) or else Position = No_Element;
 287
 288    function Contains
 289      (Container : List;
 290       Item      : Element_Type) return Boolean
 291    with
 292      Global => null;
 293
 294    function Has_Element (Container : List; Position : Cursor) return Boolean
 295    with
 296      Global => null;
 297
 298    generic
 299       with function "<" (Left, Right : Element_Type) return Boolean is <>;
 300    package Generic_Sorting is
 301
 302       function Is_Sorted (Container : List) return Boolean with
 303         Global => null;
 304
 305       procedure Sort (Container : in out List) with
 306         Global => null;
 307
 308       procedure Merge (Target, Source : in out List) with
 309         Global => null;
 310
 311    end Generic_Sorting;
 312
 313    function Strict_Equal (Left, Right : List) return Boolean with
 314      Global => null;
 315    --  Strict_Equal returns True if the containers are physically equal, i.e.
 316    --  they are structurally equal (function "=" returns True) and that they
 317    --  have the same set of cursors.
 318
 319    function First_To_Previous (Container : List; Current : Cursor) return List
 320    with
 321      Global => null,
 322      Pre    => Has_Element (Container, Current) or else Current = No_Element;
 323    function Current_To_Last (Container : List; Current : Cursor) return List
 324    with
 325      Global => null,
 326      Pre    => Has_Element (Container, Current) or else Current = No_Element;
 327    --  First_To_Previous returns a container containing all elements preceding
 328    --  Current (excluded) in Container. Current_To_Last returns a container
 329    --  containing all elements following Current (included) in Container.
 330    --  These two new functions can be used to express invariant properties in
 331    --  loops which iterate over containers. First_To_Previous returns the part
 332    --  of the container already scanned and Current_To_Last the part not
 333    --  scanned yet.
 334
 335 private
 336
 337    type Node_Type is record
 338       Prev    : Count_Type'Base := -1;
 339       Next    : Count_Type;
 340       Element : Element_Type;
 341    end record;
 342
 343    function "=" (L, R : Node_Type) return Boolean is abstract;
 344
 345    type Node_Array is array (Count_Type range <>) of Node_Type;
 346    function "=" (L, R : Node_Array) return Boolean is abstract;
 347
 348    type List (Capacity : Count_Type) is tagged record
 349       Nodes  : Node_Array (1 .. Capacity) := (others => <>);
 350       Free   : Count_Type'Base := -1;
 351       Length : Count_Type := 0;
 352       First  : Count_Type := 0;
 353       Last   : Count_Type := 0;
 354    end record;
 355
 356    type Cursor is record
 357       Node : Count_Type := 0;
 358    end record;
 359
 360    Empty_List : constant List := (0, others => <>);
 361
 362    No_Element : constant Cursor := (Node => 0);
 363
 364 end Ada.Containers.Formal_Doubly_Linked_Lists;