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) 2004-2015, 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 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 with
  65   Pure,
  66   SPARK_Mode
  67 is
  68    pragma Annotate (GNATprove, External_Axiomatization);
  69    pragma Annotate (CodePeer, Skip_Analysis);
  70
  71    type List (Capacity : Count_Type) is private with
  72      Iterable => (First       => First,
  73                   Next        => Next,
  74                   Has_Element => Has_Element,
  75                   Element     => Element),
  76      Default_Initial_Condition => Is_Empty (List);
  77    pragma Preelaborable_Initialization (List);
  78
  79    type Cursor is private;
  80    pragma Preelaborable_Initialization (Cursor);
  81
  82    Empty_List : constant List;
  83
  84    No_Element : constant Cursor;
  85
  86    function "=" (Left, Right : List) return Boolean with
  87      Global => null;
  88
  89    function Length (Container : List) return Count_Type with
  90      Global => null;
  91
  92    function Is_Empty (Container : List) return Boolean with
  93      Global => null;
  94
  95    procedure Clear (Container : in out List) with
  96      Global => null;
  97
  98    procedure Assign (Target : in out List; Source : List) with
  99      Global => null,
 100      Pre    => Target.Capacity >= Length (Source);
 101
 102    function Copy (Source : List; Capacity : Count_Type := 0) return List with
 103      Global => null,
 104      Pre    => Capacity = 0 or else Capacity >= Source.Capacity;
 105
 106    function Element
 107      (Container : List;
 108       Position : Cursor) return Element_Type
 109    with
 110      Global => null,
 111      Pre    => Has_Element (Container, Position);
 112
 113    procedure Replace_Element
 114      (Container : in out List;
 115       Position  : Cursor;
 116       New_Item  : Element_Type)
 117    with
 118      Global => null,
 119      Pre    => Has_Element (Container, Position);
 120
 121    procedure Move (Target : in out List; Source : in out List) with
 122      Global => null,
 123      Pre    => Target.Capacity >= Length (Source);
 124
 125    procedure Insert
 126      (Container : in out List;
 127       Before    : Cursor;
 128       New_Item  : Element_Type;
 129       Count     : Count_Type := 1)
 130    with
 131      Global => null,
 132      Pre    => Length (Container) + Count <= Container.Capacity
 133                  and then (Has_Element (Container, Before)
 134                             or else Before = No_Element);
 135
 136    procedure Insert
 137      (Container : in out List;
 138       Before    : Cursor;
 139       New_Item  : Element_Type;
 140       Position  : out Cursor;
 141       Count     : Count_Type := 1)
 142    with
 143      Global => null,
 144      Pre    => Length (Container) + Count <= Container.Capacity
 145                  and then (Has_Element (Container, Before)
 146                             or else Before = No_Element);
 147
 148    procedure Insert
 149      (Container : in out List;
 150       Before    : Cursor;
 151       Position  : out Cursor;
 152       Count     : Count_Type := 1)
 153    with
 154      Global => null,
 155      Pre    => Length (Container) + Count <= Container.Capacity
 156                  and then (Has_Element (Container, Before)
 157                             or else Before = No_Element);
 158
 159    procedure Prepend
 160      (Container : in out List;
 161       New_Item  : Element_Type;
 162       Count     : Count_Type := 1)
 163    with
 164      Global => null,
 165      Pre    => Length (Container) + Count <= Container.Capacity;
 166
 167    procedure Append
 168      (Container : in out List;
 169       New_Item  : Element_Type;
 170       Count     : Count_Type := 1)
 171    with
 172      Global => null,
 173      Pre    => Length (Container) + Count <= Container.Capacity;
 174
 175    procedure Delete
 176      (Container : in out List;
 177       Position  : in out Cursor;
 178       Count     : Count_Type := 1)
 179    with
 180      Global => null,
 181      Pre    => Has_Element (Container, Position);
 182
 183    procedure Delete_First
 184      (Container : in out List;
 185       Count     : Count_Type := 1)
 186    with
 187      Global => null;
 188
 189    procedure Delete_Last
 190      (Container : in out List;
 191       Count     : Count_Type := 1)
 192    with
 193      Global => null;
 194
 195    procedure Reverse_Elements (Container : in out List) with
 196      Global => null;
 197
 198    procedure Swap
 199      (Container : in out List;
 200       I, J      : Cursor)
 201    with
 202      Global => null,
 203      Pre    => Has_Element (Container, I) and then Has_Element (Container, J);
 204
 205    procedure Swap_Links
 206      (Container : in out List;
 207       I, J      : Cursor)
 208    with
 209      Global => null,
 210      Pre    => Has_Element (Container, I) and then Has_Element (Container, J);
 211
 212    procedure Splice
 213      (Target : in out List;
 214       Before : Cursor;
 215       Source : in out List)
 216    with
 217      Global => null,
 218      Pre    => Length (Source) + Length (Target) <= Target.Capacity
 219                  and then (Has_Element (Target, Before)
 220                             or else Before = No_Element);
 221
 222    procedure Splice
 223      (Target   : in out List;
 224       Before   : Cursor;
 225       Source   : in out List;
 226       Position : in out Cursor)
 227    with
 228      Global => null,
 229      Pre    => Length (Source) + Length (Target) <= Target.Capacity
 230                  and then (Has_Element (Target, Before)
 231                             or else Before = No_Element)
 232                  and then Has_Element (Source, Position);
 233
 234    procedure Splice
 235      (Container : in out List;
 236       Before    : Cursor;
 237       Position  : Cursor)
 238    with
 239      Global => null,
 240      Pre    => 2 * Length (Container) <= Container.Capacity
 241                  and then (Has_Element (Container, Before)
 242                             or else Before = No_Element)
 243                  and then Has_Element (Container, Position);
 244
 245    function First (Container : List) return Cursor with
 246      Global => null;
 247
 248    function First_Element (Container : List) return Element_Type with
 249      Global => null,
 250      Pre    => not Is_Empty (Container);
 251
 252    function Last (Container : List) return Cursor with
 253      Global => null;
 254
 255    function Last_Element (Container : List) return Element_Type with
 256      Global => null,
 257      Pre    => not Is_Empty (Container);
 258
 259    function Next (Container : List; Position : Cursor) return Cursor with
 260      Global => null,
 261      Pre    => Has_Element (Container, Position) or else Position = No_Element;
 262
 263    procedure Next (Container : List; Position : in out Cursor) with
 264      Global => null,
 265      Pre    => Has_Element (Container, Position) or else Position = No_Element;
 266
 267    function Previous (Container : List; Position : Cursor) return Cursor with
 268      Global => null,
 269      Pre    => Has_Element (Container, Position) or else Position = No_Element;
 270
 271    procedure Previous (Container : List; Position : in out Cursor) with
 272      Global => null,
 273      Pre    => Has_Element (Container, Position) or else Position = No_Element;
 274
 275    function Find
 276      (Container : List;
 277       Item      : Element_Type;
 278       Position  : Cursor := No_Element) return Cursor
 279    with
 280      Global => null,
 281      Pre    => Has_Element (Container, Position) or else Position = No_Element;
 282
 283    function Reverse_Find
 284      (Container : List;
 285       Item      : Element_Type;
 286       Position  : Cursor := No_Element) return Cursor
 287    with
 288      Global => null,
 289      Pre    => Has_Element (Container, Position) or else Position = No_Element;
 290
 291    function Contains
 292      (Container : List;
 293       Item      : Element_Type) return Boolean
 294    with
 295      Global => null;
 296
 297    function Has_Element (Container : List; Position : Cursor) return Boolean
 298    with
 299      Global => null;
 300
 301    generic
 302       with function "<" (Left, Right : Element_Type) return Boolean is <>;
 303    package Generic_Sorting with SPARK_Mode is
 304
 305       function Is_Sorted (Container : List) return Boolean with
 306         Global => null;
 307
 308       procedure Sort (Container : in out List) with
 309         Global => null;
 310
 311       procedure Merge (Target, Source : in out List) with
 312         Global => null;
 313
 314    end Generic_Sorting;
 315
 316    function Strict_Equal (Left, Right : List) return Boolean with
 317      Ghost,
 318      Global => null;
 319    --  Strict_Equal returns True if the containers are physically equal, i.e.
 320    --  they are structurally equal (function "=" returns True) and that they
 321    --  have the same set of cursors.
 322
 323    function First_To_Previous (Container : List; Current : Cursor) return List
 324    with
 325      Ghost,
 326      Global => null,
 327      Pre    => Has_Element (Container, Current) or else Current = No_Element;
 328
 329    function Current_To_Last (Container : List; Current : Cursor) return List
 330    with
 331      Ghost,
 332      Global => null,
 333      Pre    => Has_Element (Container, Current) or else Current = No_Element;
 334    --  First_To_Previous returns a container containing all elements preceding
 335    --  Current (excluded) in Container. Current_To_Last returns a container
 336    --  containing all elements following Current (included) in Container.
 337    --  These two new functions can be used to express invariant properties in
 338    --  loops which iterate over containers. First_To_Previous returns the part
 339    --  of the container already scanned and Current_To_Last the part not
 340    --  scanned yet.
 341
 342 private
 343    pragma SPARK_Mode (Off);
 344
 345    type Node_Type is record
 346       Prev    : Count_Type'Base := -1;
 347       Next    : Count_Type;
 348       Element : Element_Type;
 349    end record;
 350
 351    function "=" (L, R : Node_Type) return Boolean is abstract;
 352
 353    type Node_Array is array (Count_Type range <>) of Node_Type;
 354    function "=" (L, R : Node_Array) return Boolean is abstract;
 355
 356    type List (Capacity : Count_Type) is record
 357       Free   : Count_Type'Base := -1;
 358       Length : Count_Type := 0;
 359       First  : Count_Type := 0;
 360       Last   : Count_Type := 0;
 361       Nodes  : Node_Array (1 .. Capacity) := (others => <>);
 362    end record;
 363
 364    type Cursor is record
 365       Node : Count_Type := 0;
 366    end record;
 367
 368    Empty_List : constant List := (0, others => <>);
 369
 370    No_Element : constant Cursor := (Node => 0);
 371
 372 end Ada.Containers.Formal_Doubly_Linked_Lists;