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