------------------------------------------------------------------------------ -- -- -- GNAT LIBRARY COMPONENTS -- -- -- -- ADA.CONTAINERS.FORMAL_INDEFINITE_VECTORS -- -- -- -- S p e c -- -- -- -- Copyright (C) 2014-2019, Free Software Foundation, Inc. -- -- -- -- This specification is derived from the Ada Reference Manual for use with -- -- GNAT. The copyright notice above, and the license provisions that follow -- -- apply solely to the contents of the part following the private keyword. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 3, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. -- -- -- -- As a special exception under Section 7 of GPL version 3, you are granted -- -- additional permissions described in the GCC Runtime Library Exception, -- -- version 3.1, as published by the Free Software Foundation. -- -- -- -- You should have received a copy of the GNU General Public License and -- -- a copy of the GCC Runtime Library Exception along with this program; -- -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- -- . -- ------------------------------------------------------------------------------ -- Similar to Ada.Containers.Formal_Vectors. The main difference is that -- Element_Type may be indefinite (but not an unconstrained array). with Ada.Containers.Bounded_Holders; with Ada.Containers.Functional_Vectors; generic type Index_Type is range <>; type Element_Type (<>) is private; with function "=" (Left, Right : Element_Type) return Boolean is <>; Max_Size_In_Storage_Elements : Natural; -- Maximum size of Vector elements in bytes. This has the same meaning as -- in Ada.Containers.Bounded_Holders, with the same restrictions. Note that -- setting this too small can lead to erroneous execution; see comments in -- Ada.Containers.Bounded_Holders. If Element_Type is class-wide, it is the -- responsibility of clients to calculate the maximum size of all types in -- the class. Bounded : Boolean := True; -- If True, the containers are bounded; the initial capacity is the maximum -- size, and heap allocation will be avoided. If False, the containers can -- grow via heap allocation. package Ada.Containers.Formal_Indefinite_Vectors with SPARK_Mode => On is pragma Annotate (CodePeer, Skip_Analysis); subtype Extended_Index is Index_Type'Base range Index_Type'First - 1 .. Index_Type'Min (Index_Type'Base'Last - 1, Index_Type'Last) + 1; No_Index : constant Extended_Index := Extended_Index'First; Last_Count : constant Count_Type := (if Index_Type'Last < Index_Type'First then 0 elsif Index_Type'Last < -1 or else Index_Type'Pos (Index_Type'First) > Index_Type'Pos (Index_Type'Last) - Count_Type'Last then Index_Type'Pos (Index_Type'Last) - Index_Type'Pos (Index_Type'First) + 1 else Count_Type'Last); -- Maximal capacity of any vector. It is the minimum of the size of the -- index range and the last possible Count_Type. subtype Capacity_Range is Count_Type range 0 .. Last_Count; type Vector (Capacity : Capacity_Range) is limited private with Default_Initial_Condition => Is_Empty (Vector); -- In the bounded case, Capacity is the capacity of the container, which -- never changes. In the unbounded case, Capacity is the initial capacity -- of the container, and operations such as Reserve_Capacity and Append can -- increase the capacity. The capacity never shrinks, except in the case of -- Clear. -- -- Note that all objects of type Vector are constrained, including in the -- unbounded case; you can't assign from one object to another if the -- Capacity is different. function Length (Container : Vector) return Capacity_Range with Global => null, Post => Length'Result <= Capacity (Container); pragma Unevaluated_Use_Of_Old (Allow); package Formal_Model with Ghost is package M is new Ada.Containers.Functional_Vectors (Index_Type => Index_Type, Element_Type => Element_Type); function "=" (Left : M.Sequence; Right : M.Sequence) return Boolean renames M."="; function "<" (Left : M.Sequence; Right : M.Sequence) return Boolean renames M."<"; function "<=" (Left : M.Sequence; Right : M.Sequence) return Boolean renames M."<="; function M_Elements_In_Union (Container : M.Sequence; Left : M.Sequence; Right : M.Sequence) return Boolean -- The elements of Container are contained in either Left or Right with Global => null, Post => M_Elements_In_Union'Result = (for all I in Index_Type'First .. M.Last (Container) => (for some J in Index_Type'First .. M.Last (Left) => Element (Container, I) = Element (Left, J)) or (for some J in Index_Type'First .. M.Last (Right) => Element (Container, I) = Element (Right, J))); pragma Annotate (GNATprove, Inline_For_Proof, M_Elements_In_Union); function M_Elements_Included (Left : M.Sequence; L_Fst : Index_Type := Index_Type'First; L_Lst : Extended_Index; Right : M.Sequence; R_Fst : Index_Type := Index_Type'First; R_Lst : Extended_Index) return Boolean -- The elements of the slice from L_Fst to L_Lst in Left are contained -- in the slide from R_Fst to R_Lst in Right. with Global => null, Pre => L_Lst <= M.Last (Left) and R_Lst <= M.Last (Right), Post => M_Elements_Included'Result = (for all I in L_Fst .. L_Lst => (for some J in R_Fst .. R_Lst => Element (Left, I) = Element (Right, J))); pragma Annotate (GNATprove, Inline_For_Proof, M_Elements_Included); function M_Elements_Reversed (Left : M.Sequence; Right : M.Sequence) return Boolean -- Right is Left in reverse order with Global => null, Post => M_Elements_Reversed'Result = (M.Length (Left) = M.Length (Right) and (for all I in Index_Type'First .. M.Last (Left) => Element (Left, I) = Element (Right, M.Last (Left) - I + 1)) and (for all I in Index_Type'First .. M.Last (Right) => Element (Right, I) = Element (Left, M.Last (Left) - I + 1))); pragma Annotate (GNATprove, Inline_For_Proof, M_Elements_Reversed); function M_Elements_Swapped (Left : M.Sequence; Right : M.Sequence; X : Index_Type; Y : Index_Type) return Boolean -- Elements stored at X and Y are reversed in Left and Right with Global => null, Pre => X <= M.Last (Left) and Y <= M.Last (Left), Post => M_Elements_Swapped'Result = (M.Length (Left) = M.Length (Right) and Element (Left, X) = Element (Right, Y) and Element (Left, Y) = Element (Right, X) and M.Equal_Except (Left, Right, X, Y)); pragma Annotate (GNATprove, Inline_For_Proof, M_Elements_Swapped); function Model (Container : Vector) return M.Sequence with -- The high-level model of a vector is a sequence of elements. The -- sequence really is similar to the vector itself. However, it is not -- limited which allows usage of 'Old and 'Loop_Entry attributes. Ghost, Global => null, Post => M.Length (Model'Result) = Length (Container); function Element (S : M.Sequence; I : Index_Type) return Element_Type renames M.Get; -- To improve readability of contracts, we rename the function used to -- access an element in the model to Element. end Formal_Model; use Formal_Model; function Empty_Vector return Vector with Global => null, Post => Length (Empty_Vector'Result) = 0; function "=" (Left, Right : Vector) return Boolean with Global => null, Post => "="'Result = (Model (Left) = Model (Right)); function To_Vector (New_Item : Element_Type; Length : Capacity_Range) return Vector with Global => null, Post => Formal_Indefinite_Vectors.Length (To_Vector'Result) = Length and M.Constant_Range (Container => Model (To_Vector'Result), Fst => Index_Type'First, Lst => Last_Index (To_Vector'Result), Item => New_Item); function Capacity (Container : Vector) return Capacity_Range with Global => null, Post => Capacity'Result = (if Bounded then Container.Capacity else Capacity_Range'Last); pragma Annotate (GNATprove, Inline_For_Proof, Capacity); procedure Reserve_Capacity (Container : in out Vector; Capacity : Capacity_Range) with Global => null, Pre => (if Bounded then Capacity <= Container.Capacity), Post => Model (Container) = Model (Container)'Old; function Is_Empty (Container : Vector) return Boolean with Global => null, Post => Is_Empty'Result = (Length (Container) = 0); procedure Clear (Container : in out Vector) with Global => null, Post => Length (Container) = 0; -- Note that this reclaims storage in the unbounded case. You need to call -- this before a container goes out of scope in order to avoid storage -- leaks. In addition, "X := ..." can leak unless you Clear(X) first. procedure Assign (Target : in out Vector; Source : Vector) with Global => null, Pre => (if Bounded then Length (Source) <= Target.Capacity), Post => Model (Target) = Model (Source); function Copy (Source : Vector; Capacity : Capacity_Range := 0) return Vector with Global => null, Pre => (if Bounded then (Capacity = 0 or Length (Source) <= Capacity)), Post => Model (Copy'Result) = Model (Source) and (if Capacity = 0 then Copy'Result.Capacity = Length (Source) else Copy'Result.Capacity = Capacity); procedure Move (Target : in out Vector; Source : in out Vector) with Global => null, Pre => (if Bounded then Length (Source) <= Capacity (Target)), Post => Model (Target) = Model (Source)'Old and Length (Source) = 0; function Element (Container : Vector; Index : Index_Type) return Element_Type with Global => null, Pre => Index in First_Index (Container) .. Last_Index (Container), Post => Element'Result = Element (Model (Container), Index); pragma Annotate (GNATprove, Inline_For_Proof, Element); procedure Replace_Element (Container : in out Vector; Index : Index_Type; New_Item : Element_Type) with Global => null, Pre => Index in First_Index (Container) .. Last_Index (Container), Post => Length (Container) = Length (Container)'Old -- Container now has New_Item at index Index and Element (Model (Container), Index) = New_Item -- All other elements are preserved and M.Equal_Except (Left => Model (Container)'Old, Right => Model (Container), Position => Index); procedure Insert (Container : in out Vector; Before : Extended_Index; New_Item : Vector) with Global => null, Pre => Length (Container) <= Capacity (Container) - Length (New_Item) and (Before in Index_Type'First .. Last_Index (Container) or (Before /= No_Index and then Before - 1 = Last_Index (Container))), Post => Length (Container) = Length (Container)'Old + Length (New_Item) -- Elements located before Before in Container are preserved and M.Range_Equal (Left => Model (Container)'Old, Right => Model (Container), Fst => Index_Type'First, Lst => Before - 1) -- Elements of New_Item are inserted at position Before and (if Length (New_Item) > 0 then M.Range_Shifted (Left => Model (New_Item), Right => Model (Container), Fst => Index_Type'First, Lst => Last_Index (New_Item), Offset => Count_Type (Before - Index_Type'First))) -- Elements located after Before in Container are shifted and M.Range_Shifted (Left => Model (Container)'Old, Right => Model (Container), Fst => Before, Lst => Last_Index (Container)'Old, Offset => Length (New_Item)); procedure Insert (Container : in out Vector; Before : Extended_Index; New_Item : Element_Type) with Global => null, Pre => Length (Container) < Capacity (Container) and then (Before in Index_Type'First .. Last_Index (Container) + 1), Post => Length (Container) = Length (Container)'Old + 1 -- Elements located before Before in Container are preserved and M.Range_Equal (Left => Model (Container)'Old, Right => Model (Container), Fst => Index_Type'First, Lst => Before - 1) -- Container now has New_Item at index Before and Element (Model (Container), Before) = New_Item -- Elements located after Before in Container are shifted by 1 and M.Range_Shifted (Left => Model (Container)'Old, Right => Model (Container), Fst => Before, Lst => Last_Index (Container)'Old, Offset => 1); procedure Insert (Container : in out Vector; Before : Extended_Index; New_Item : Element_Type; Count : Count_Type) with Global => null, Pre => Length (Container) <= Capacity (Container) - Count and (Before in Index_Type'First .. Last_Index (Container) or (Before /= No_Index and then Before - 1 = Last_Index (Container))), Post => Length (Container) = Length (Container)'Old + Count -- Elements located before Before in Container are preserved and M.Range_Equal (Left => Model (Container)'Old, Right => Model (Container), Fst => Index_Type'First, Lst => Before - 1) -- New_Item is inserted Count times at position Before and (if Count > 0 then M.Constant_Range (Container => Model (Container), Fst => Before, Lst => Before + Index_Type'Base (Count - 1), Item => New_Item)) -- Elements located after Before in Container are shifted and M.Range_Shifted (Left => Model (Container)'Old, Right => Model (Container), Fst => Before, Lst => Last_Index (Container)'Old, Offset => Count); procedure Prepend (Container : in out Vector; New_Item : Vector) with Global => null, Pre => Length (Container) <= Capacity (Container) - Length (New_Item), Post => Length (Container) = Length (Container)'Old + Length (New_Item) -- Elements of New_Item are inserted at the beginning of Container and M.Range_Equal (Left => Model (New_Item), Right => Model (Container), Fst => Index_Type'First, Lst => Last_Index (New_Item)) -- Elements of Container are shifted and M.Range_Shifted (Left => Model (Container)'Old, Right => Model (Container), Fst => Index_Type'First, Lst => Last_Index (Container)'Old, Offset => Length (New_Item)); procedure Prepend (Container : in out Vector; New_Item : Element_Type) with Global => null, Pre => Length (Container) < Capacity (Container), Post => Length (Container) = Length (Container)'Old + 1 -- Container now has New_Item at Index_Type'First and Element (Model (Container), Index_Type'First) = New_Item -- Elements of Container are shifted by 1 and M.Range_Shifted (Left => Model (Container)'Old, Right => Model (Container), Fst => Index_Type'First, Lst => Last_Index (Container)'Old, Offset => 1); procedure Prepend (Container : in out Vector; New_Item : Element_Type; Count : Count_Type) with Global => null, Pre => Length (Container) <= Capacity (Container) - Count, Post => Length (Container) = Length (Container)'Old + Count -- New_Item is inserted Count times at the beginning of Container and M.Constant_Range (Container => Model (Container), Fst => Index_Type'First, Lst => Index_Type'First + Index_Type'Base (Count - 1), Item => New_Item) -- Elements of Container are shifted and M.Range_Shifted (Left => Model (Container)'Old, Right => Model (Container), Fst => Index_Type'First, Lst => Last_Index (Container)'Old, Offset => Count); procedure Append (Container : in out Vector; New_Item : Vector) with Global => null, Pre => Length (Container) <= Capacity (Container) - Length (New_Item), Post => Length (Container) = Length (Container)'Old + Length (New_Item) -- The elements of Container are preserved and Model (Container)'Old <= Model (Container) -- Elements of New_Item are inserted at the end of Container and (if Length (New_Item) > 0 then M.Range_Shifted (Left => Model (New_Item), Right => Model (Container), Fst => Index_Type'First, Lst => Last_Index (New_Item), Offset => Count_Type (Last_Index (Container)'Old - Index_Type'First + 1))); procedure Append (Container : in out Vector; New_Item : Element_Type) with Global => null, Pre => Length (Container) < Capacity (Container), Post => Length (Container) = Length (Container)'Old + 1 -- Elements of Container are preserved and Model (Container)'Old < Model (Container) -- Container now has New_Item at the end of Container and Element (Model (Container), Last_Index (Container)'Old + 1) = New_Item; procedure Append (Container : in out Vector; New_Item : Element_Type; Count : Count_Type) with Global => null, Pre => Length (Container) <= Capacity (Container) - Count, Post => Length (Container) = Length (Container)'Old + Count -- Elements of Container are preserved and Model (Container)'Old <= Model (Container) -- New_Item is inserted Count times at the end of Container and (if Count > 0 then M.Constant_Range (Container => Model (Container), Fst => Last_Index (Container)'Old + 1, Lst => Last_Index (Container)'Old + Index_Type'Base (Count), Item => New_Item)); procedure Delete (Container : in out Vector; Index : Extended_Index) with Global => null, Pre => Index in First_Index (Container) .. Last_Index (Container), Post => Length (Container) = Length (Container)'Old - 1 -- Elements located before Index in Container are preserved and M.Range_Equal (Left => Model (Container)'Old, Right => Model (Container), Fst => Index_Type'First, Lst => Index - 1) -- Elements located after Index in Container are shifted by 1 and M.Range_Shifted (Left => Model (Container), Right => Model (Container)'Old, Fst => Index, Lst => Last_Index (Container), Offset => 1); procedure Delete (Container : in out Vector; Index : Extended_Index; Count : Count_Type) with Global => null, Pre => Index in First_Index (Container) .. Last_Index (Container), Post => Length (Container) in Length (Container)'Old - Count .. Length (Container)'Old -- The elements of Container located before Index are preserved. and M.Range_Equal (Left => Model (Container)'Old, Right => Model (Container), Fst => Index_Type'First, Lst => Index - 1), Contract_Cases => -- All the elements after Position have been erased (Length (Container) - Count <= Count_Type (Index - Index_Type'First) => Length (Container) = Count_Type (Index - Index_Type'First), others => Length (Container) = Length (Container)'Old - Count -- Other elements are shifted by Count and M.Range_Shifted (Left => Model (Container), Right => Model (Container)'Old, Fst => Index, Lst => Last_Index (Container), Offset => Count)); procedure Delete_First (Container : in out Vector) with Global => null, Pre => Length (Container) > 0, Post => Length (Container) = Length (Container)'Old - 1 -- Elements of Container are shifted by 1 and M.Range_Shifted (Left => Model (Container), Right => Model (Container)'Old, Fst => Index_Type'First, Lst => Last_Index (Container), Offset => 1); procedure Delete_First (Container : in out Vector; Count : Count_Type) with Global => null, Contract_Cases => -- All the elements of Container have been erased (Length (Container) <= Count => Length (Container) = 0, others => Length (Container) = Length (Container)'Old - Count -- Elements of Container are shifted by Count and M.Range_Shifted (Left => Model (Container), Right => Model (Container)'Old, Fst => Index_Type'First, Lst => Last_Index (Container), Offset => Count)); procedure Delete_Last (Container : in out Vector) with Global => null, Pre => Length (Container) > 0, Post => Length (Container) = Length (Container)'Old - 1 -- Elements of Container are preserved and Model (Container) < Model (Container)'Old; procedure Delete_Last (Container : in out Vector; Count : Count_Type) with Global => null, Contract_Cases => -- All the elements after Position have been erased (Length (Container) <= Count => Length (Container) = 0, others => Length (Container) = Length (Container)'Old - Count -- The elements of Container are preserved and Model (Container) <= Model (Container)'Old); procedure Reverse_Elements (Container : in out Vector) with Global => null, Post => M_Elements_Reversed (Model (Container)'Old, Model (Container)); procedure Swap (Container : in out Vector; I : Index_Type; J : Index_Type) with Global => null, Pre => I in First_Index (Container) .. Last_Index (Container) and then J in First_Index (Container) .. Last_Index (Container), Post => M_Elements_Swapped (Model (Container)'Old, Model (Container), I, J); function First_Index (Container : Vector) return Index_Type with Global => null, Post => First_Index'Result = Index_Type'First; pragma Annotate (GNATprove, Inline_For_Proof, First_Index); function First_Element (Container : Vector) return Element_Type with Global => null, Pre => not Is_Empty (Container), Post => First_Element'Result = Element (Model (Container), Index_Type'First); pragma Annotate (GNATprove, Inline_For_Proof, First_Element); function Last_Index (Container : Vector) return Extended_Index with Global => null, Post => Last_Index'Result = M.Last (Model (Container)); pragma Annotate (GNATprove, Inline_For_Proof, Last_Index); function Last_Element (Container : Vector) return Element_Type with Global => null, Pre => not Is_Empty (Container), Post => Last_Element'Result = Element (Model (Container), Last_Index (Container)); pragma Annotate (GNATprove, Inline_For_Proof, Last_Element); function Find_Index (Container : Vector; Item : Element_Type; Index : Index_Type := Index_Type'First) return Extended_Index with Global => null, Contract_Cases => -- If Item is not contained in Container after Index, Find_Index -- returns No_Index. (Index > Last_Index (Container) or else not M.Contains (Container => Model (Container), Fst => Index, Lst => Last_Index (Container), Item => Item) => Find_Index'Result = No_Index, -- Otherwise, Find_Index returns a valid index greater than Index others => Find_Index'Result in Index .. Last_Index (Container) -- The element at this index in Container is Item and Element (Model (Container), Find_Index'Result) = Item -- It is the first occurrence of Item after Index in Container and not M.Contains (Container => Model (Container), Fst => Index, Lst => Find_Index'Result - 1, Item => Item)); function Reverse_Find_Index (Container : Vector; Item : Element_Type; Index : Index_Type := Index_Type'Last) return Extended_Index with Global => null, Contract_Cases => -- If Item is not contained in Container before Index, -- Reverse_Find_Index returns No_Index. (not M.Contains (Container => Model (Container), Fst => Index_Type'First, Lst => (if Index <= Last_Index (Container) then Index else Last_Index (Container)), Item => Item) => Reverse_Find_Index'Result = No_Index, -- Otherwise, Reverse_Find_Index returns a valid index smaller than -- Index others => Reverse_Find_Index'Result in Index_Type'First .. Index and Reverse_Find_Index'Result <= Last_Index (Container) -- The element at this index in Container is Item and Element (Model (Container), Reverse_Find_Index'Result) = Item -- It is the last occurrence of Item before Index in Container and not M.Contains (Container => Model (Container), Fst => Reverse_Find_Index'Result + 1, Lst => (if Index <= Last_Index (Container) then Index else Last_Index (Container)), Item => Item)); function Contains (Container : Vector; Item : Element_Type) return Boolean with Global => null, Post => Contains'Result = M.Contains (Container => Model (Container), Fst => Index_Type'First, Lst => Last_Index (Container), Item => Item); function Has_Element (Container : Vector; Position : Extended_Index) return Boolean with Global => null, Post => Has_Element'Result = (Position in Index_Type'First .. Last_Index (Container)); pragma Annotate (GNATprove, Inline_For_Proof, Has_Element); generic with function "<" (Left, Right : Element_Type) return Boolean is <>; package Generic_Sorting with SPARK_Mode is package Formal_Model with Ghost is function M_Elements_Sorted (Container : M.Sequence) return Boolean with Global => null, Post => M_Elements_Sorted'Result = (for all I in Index_Type'First .. M.Last (Container) => (for all J in I .. M.Last (Container) => Element (Container, I) = Element (Container, J) or Element (Container, I) < Element (Container, J))); pragma Annotate (GNATprove, Inline_For_Proof, M_Elements_Sorted); end Formal_Model; use Formal_Model; function Is_Sorted (Container : Vector) return Boolean with Global => null, Post => Is_Sorted'Result = M_Elements_Sorted (Model (Container)); procedure Sort (Container : in out Vector) with Global => null, Post => Length (Container) = Length (Container)'Old and M_Elements_Sorted (Model (Container)) and M_Elements_Included (Left => Model (Container)'Old, L_Lst => Last_Index (Container), Right => Model (Container), R_Lst => Last_Index (Container)) and M_Elements_Included (Left => Model (Container), L_Lst => Last_Index (Container), Right => Model (Container)'Old, R_Lst => Last_Index (Container)); procedure Merge (Target : in out Vector; Source : in out Vector) with -- Target and Source should not be aliased Global => null, Pre => Length (Source) <= Capacity (Target) - Length (Target), Post => Length (Target) = Length (Target)'Old + Length (Source)'Old and Length (Source) = 0 and (if M_Elements_Sorted (Model (Target)'Old) and M_Elements_Sorted (Model (Source)'Old) then M_Elements_Sorted (Model (Target))) and M_Elements_Included (Left => Model (Target)'Old, L_Lst => Last_Index (Target)'Old, Right => Model (Target), R_Lst => Last_Index (Target)) and M_Elements_Included (Left => Model (Source)'Old, L_Lst => Last_Index (Source)'Old, Right => Model (Target), R_Lst => Last_Index (Target)) and M_Elements_In_Union (Model (Target), Model (Source)'Old, Model (Target)'Old); end Generic_Sorting; private pragma SPARK_Mode (Off); pragma Inline (First_Index); pragma Inline (Last_Index); pragma Inline (Element); pragma Inline (First_Element); pragma Inline (Last_Element); pragma Inline (Replace_Element); pragma Inline (Contains); -- The implementation method is to instantiate Bounded_Holders to get a -- definite type for Element_Type. package Holders is new Bounded_Holders (Element_Type, Max_Size_In_Storage_Elements, "="); use Holders; subtype Array_Index is Capacity_Range range 1 .. Capacity_Range'Last; type Elements_Array is array (Array_Index range <>) of Holder; function "=" (L, R : Elements_Array) return Boolean is abstract; type Elements_Array_Ptr is access all Elements_Array; type Vector (Capacity : Capacity_Range) is limited record -- In the bounded case, the elements are stored in Elements. In the -- unbounded case, the elements are initially stored in Elements, until -- we run out of room, then we switch to Elements_Ptr. Last : Extended_Index := No_Index; Elements_Ptr : Elements_Array_Ptr := null; Elements : aliased Elements_Array (1 .. Capacity); end record; -- The primary reason Vector is limited is that in the unbounded case, once -- Elements_Ptr is in use, assignment statements won't work. "X := Y;" will -- cause X and Y to share state; that is, X.Elements_Ptr = Y.Elements_Ptr, -- so for example "Append (X, ...);" will modify BOTH X and Y. That would -- allow SPARK to "prove" things that are false. We could fix that by -- making Vector a controlled type, and override Adjust to make a deep -- copy, but finalization is not allowed in SPARK. -- -- Note that (unfortunately) this means that 'Old and 'Loop_Entry are not -- allowed on Vectors. function Empty_Vector return Vector is ((Capacity => 0, others => <>)); end Ada.Containers.Formal_Indefinite_Vectors;