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------------------------------------------------------------------------------
-- --
-- GNAT LIBRARY COMPONENTS --
-- --
-- A D A . C O N T A I N E R S . I N D E F I N I T E _ V E C T O R S --
-- --
-- B o d y --
-- --
-- Copyright (C) 2004-2021, Free Software Foundation, Inc. --
-- --
-- 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 --
-- <http://www.gnu.org/licenses/>. --
-- --
-- This unit was originally developed by Matthew J Heaney. --
------------------------------------------------------------------------------
with Ada.Containers.Generic_Array_Sort;
with Ada.Unchecked_Deallocation;
with System; use type System.Address;
with System.Put_Images;
package body Ada.Containers.Indefinite_Vectors with
SPARK_Mode => Off
is
pragma Warnings (Off, "variable ""Busy*"" is not referenced");
pragma Warnings (Off, "variable ""Lock*"" is not referenced");
-- See comment in Ada.Containers.Helpers
procedure Free is
new Ada.Unchecked_Deallocation (Elements_Type, Elements_Access);
procedure Free is
new Ada.Unchecked_Deallocation (Element_Type, Element_Access);
procedure Append_Slow_Path
(Container : in out Vector;
New_Item : Element_Type;
Count : Count_Type);
-- This is the slow path for Append. This is split out to minimize the size
-- of Append, because we have Inline (Append).
---------
-- "&" --
---------
-- We decide that the capacity of the result of "&" is the minimum needed
-- -- the sum of the lengths of the vector parameters. We could decide to
-- make it larger, but we have no basis for knowing how much larger, so we
-- just allocate the minimum amount of storage.
function "&" (Left, Right : Vector) return Vector is
begin
return Result : Vector do
Reserve_Capacity (Result, Length (Left) + Length (Right));
Append_Vector (Result, Left);
Append_Vector (Result, Right);
end return;
end "&";
function "&" (Left : Vector; Right : Element_Type) return Vector is
begin
return Result : Vector do
Reserve_Capacity (Result, Length (Left) + 1);
Append_Vector (Result, Left);
Append (Result, Right);
end return;
end "&";
function "&" (Left : Element_Type; Right : Vector) return Vector is
begin
return Result : Vector do
Reserve_Capacity (Result, 1 + Length (Right));
Append (Result, Left);
Append_Vector (Result, Right);
end return;
end "&";
function "&" (Left, Right : Element_Type) return Vector is
begin
return Result : Vector do
Reserve_Capacity (Result, 1 + 1);
Append (Result, Left);
Append (Result, Right);
end return;
end "&";
---------
-- "=" --
---------
overriding function "=" (Left, Right : Vector) return Boolean is
begin
if Left.Last /= Right.Last then
return False;
end if;
if Left.Length = 0 then
return True;
end if;
declare
-- Per AI05-0022, the container implementation is required to detect
-- element tampering by a generic actual subprogram.
Lock_Left : With_Lock (Left.TC'Unrestricted_Access);
Lock_Right : With_Lock (Right.TC'Unrestricted_Access);
begin
for J in Index_Type range Index_Type'First .. Left.Last loop
if Left.Elements.EA (J) = null then
if Right.Elements.EA (J) /= null then
return False;
end if;
elsif Right.Elements.EA (J) = null then
return False;
elsif Left.Elements.EA (J).all /= Right.Elements.EA (J).all then
return False;
end if;
end loop;
end;
return True;
end "=";
------------
-- Adjust --
------------
procedure Adjust (Container : in out Vector) is
begin
-- If the counts are nonzero, execution is technically erroneous, but
-- it seems friendly to allow things like concurrent "=" on shared
-- constants.
Zero_Counts (Container.TC);
if Container.Last = No_Index then
Container.Elements := null;
return;
end if;
declare
L : constant Index_Type := Container.Last;
E : Elements_Array renames
Container.Elements.EA (Index_Type'First .. L);
begin
Container.Elements := null;
Container.Last := No_Index;
Container.Elements := new Elements_Type (L);
for J in E'Range loop
if E (J) /= null then
Container.Elements.EA (J) := new Element_Type'(E (J).all);
end if;
Container.Last := J;
end loop;
end;
end Adjust;
-------------------
-- Append_Vector --
-------------------
procedure Append_Vector (Container : in out Vector; New_Item : Vector) is
begin
if Is_Empty (New_Item) then
return;
elsif Checks and then Container.Last = Index_Type'Last then
raise Constraint_Error with "vector is already at its maximum length";
else
Insert_Vector (Container, Container.Last + 1, New_Item);
end if;
end Append_Vector;
procedure Append
(Container : in out Vector;
New_Item : Element_Type;
Count : Count_Type)
is
begin
-- In the general case, we pass the buck to Insert, but for efficiency,
-- we check for the usual case where Count = 1 and the vector has enough
-- room for at least one more element.
if Count = 1
and then Container.Elements /= null
and then Container.Last /= Container.Elements.Last
then
TC_Check (Container.TC);
-- Increment Container.Last after assigning the New_Item, so we
-- leave the Container unmodified in case Finalize/Adjust raises
-- an exception.
declare
New_Last : constant Index_Type := Container.Last + 1;
-- The element allocator may need an accessibility check in the
-- case actual type is class-wide or has access discriminants
-- (see RM 4.8(10.1) and AI12-0035).
pragma Unsuppress (Accessibility_Check);
begin
Container.Elements.EA (New_Last) := new Element_Type'(New_Item);
Container.Last := New_Last;
end;
else
Append_Slow_Path (Container, New_Item, Count);
end if;
end Append;
------------
-- Append --
------------
procedure Append (Container : in out Vector;
New_Item : Element_Type)
is
begin
Insert (Container, Last_Index (Container) + 1, New_Item, 1);
end Append;
----------------------
-- Append_Slow_Path --
----------------------
procedure Append_Slow_Path
(Container : in out Vector;
New_Item : Element_Type;
Count : Count_Type)
is
begin
if Count = 0 then
return;
elsif Checks and then Container.Last = Index_Type'Last then
raise Constraint_Error with "vector is already at its maximum length";
else
Insert (Container, Container.Last + 1, New_Item, Count);
end if;
end Append_Slow_Path;
------------
-- Assign --
------------
procedure Assign (Target : in out Vector; Source : Vector) is
begin
if Target'Address = Source'Address then
return;
else
Target.Clear;
Target.Append_Vector (Source);
end if;
end Assign;
--------------
-- Capacity --
--------------
function Capacity (Container : Vector) return Count_Type is
begin
if Container.Elements = null then
return 0;
else
return Container.Elements.EA'Length;
end if;
end Capacity;
-----------
-- Clear --
-----------
procedure Clear (Container : in out Vector) is
begin
TC_Check (Container.TC);
while Container.Last >= Index_Type'First loop
declare
X : Element_Access := Container.Elements.EA (Container.Last);
begin
Container.Elements.EA (Container.Last) := null;
Container.Last := Container.Last - 1;
Free (X);
end;
end loop;
end Clear;
------------------------
-- Constant_Reference --
------------------------
function Constant_Reference
(Container : aliased Vector;
Position : Cursor) return Constant_Reference_Type
is
begin
if Checks then
if Position.Container = null then
raise Constraint_Error with "Position cursor has no element";
end if;
if Position.Container /= Container'Unrestricted_Access then
raise Program_Error with "Position cursor denotes wrong container";
end if;
if Position.Index > Position.Container.Last then
raise Constraint_Error with "Position cursor is out of range";
end if;
end if;
declare
TC : constant Tamper_Counts_Access :=
Container.TC'Unrestricted_Access;
begin
-- The following will raise Constraint_Error if Element is null
return R : constant Constant_Reference_Type :=
(Element => Container.Elements.EA (Position.Index),
Control => (Controlled with TC))
do
Busy (TC.all);
end return;
end;
end Constant_Reference;
function Constant_Reference
(Container : aliased Vector;
Index : Index_Type) return Constant_Reference_Type
is
begin
if Checks and then Index > Container.Last then
raise Constraint_Error with "Index is out of range";
end if;
declare
TC : constant Tamper_Counts_Access :=
Container.TC'Unrestricted_Access;
begin
-- The following will raise Constraint_Error if Element is null
return R : constant Constant_Reference_Type :=
(Element => Container.Elements.EA (Index),
Control => (Controlled with TC))
do
Busy (TC.all);
end return;
end;
end Constant_Reference;
--------------
-- Contains --
--------------
function Contains
(Container : Vector;
Item : Element_Type) return Boolean
is
begin
return Find_Index (Container, Item) /= No_Index;
end Contains;
----------
-- Copy --
----------
function Copy
(Source : Vector;
Capacity : Count_Type := 0) return Vector
is
C : Count_Type;
begin
if Capacity < Source.Length then
if Checks and then Capacity /= 0 then
raise Capacity_Error
with "Requested capacity is less than Source length";
end if;
C := Source.Length;
else
C := Capacity;
end if;
return Target : Vector do
Target.Reserve_Capacity (C);
Target.Assign (Source);
end return;
end Copy;
------------
-- Delete --
------------
procedure Delete
(Container : in out Vector;
Index : Extended_Index;
Count : Count_Type := 1)
is
Old_Last : constant Index_Type'Base := Container.Last;
New_Last : Index_Type'Base;
Count2 : Count_Type'Base; -- count of items from Index to Old_Last
J : Index_Type'Base; -- first index of items that slide down
begin
-- The tampering bits exist to prevent an item from being deleted (or
-- otherwise harmfully manipulated) while it is being visited. Query,
-- Update, and Iterate increment the busy count on entry, and decrement
-- the count on exit. Delete checks the count to determine whether it is
-- being called while the associated callback procedure is executing.
TC_Check (Container.TC);
-- Delete removes items from the vector, the number of which is the
-- minimum of the specified Count and the items (if any) that exist from
-- Index to Container.Last. There are no constraints on the specified
-- value of Count (it can be larger than what's available at this
-- position in the vector, for example), but there are constraints on
-- the allowed values of the Index.
-- As a precondition on the generic actual Index_Type, the base type
-- must include Index_Type'Pred (Index_Type'First); this is the value
-- that Container.Last assumes when the vector is empty. However, we do
-- not allow that as the value for Index when specifying which items
-- should be deleted, so we must manually check. (That the user is
-- allowed to specify the value at all here is a consequence of the
-- declaration of the Extended_Index subtype, which includes the values
-- in the base range that immediately precede and immediately follow the
-- values in the Index_Type.)
if Checks and then Index < Index_Type'First then
raise Constraint_Error with "Index is out of range (too small)";
end if;
-- We do allow a value greater than Container.Last to be specified as
-- the Index, but only if it's immediately greater. This allows the
-- corner case of deleting no items from the back end of the vector to
-- be treated as a no-op. (It is assumed that specifying an index value
-- greater than Last + 1 indicates some deeper flaw in the caller's
-- algorithm, so that case is treated as a proper error.)
if Index > Old_Last then
if Checks and then Index > Old_Last + 1 then
raise Constraint_Error with "Index is out of range (too large)";
else
return;
end if;
end if;
-- Here and elsewhere we treat deleting 0 items from the container as a
-- no-op, even when the container is busy, so we simply return.
if Count = 0 then
return;
end if;
-- The internal elements array isn't guaranteed to exist unless we have
-- elements, so we handle that case here in order to avoid having to
-- check it later. (Note that an empty vector can never be busy, so
-- there's no semantic harm in returning early.)
if Container.Is_Empty then
return;
end if;
-- We first calculate what's available for deletion starting at
-- Index. Here and elsewhere we use the wider of Index_Type'Base and
-- Count_Type'Base as the type for intermediate values. (See function
-- Length for more information.)
if Count_Type'Base'Last >= Index_Type'Pos (Index_Type'Base'Last) then
Count2 := Count_Type'Base (Old_Last) - Count_Type'Base (Index) + 1;
else
Count2 := Count_Type'Base (Old_Last - Index + 1);
end if;
-- If the number of elements requested (Count) for deletion is equal to
-- (or greater than) the number of elements available (Count2) for
-- deletion beginning at Index, then everything from Index to
-- Container.Last is deleted (this is equivalent to Delete_Last).
if Count >= Count2 then
-- Elements in an indefinite vector are allocated, so we must iterate
-- over the loop and deallocate elements one-at-a-time. We work from
-- back to front, deleting the last element during each pass, in
-- order to gracefully handle deallocation failures.
declare
EA : Elements_Array renames Container.Elements.EA;
begin
while Container.Last >= Index loop
declare
K : constant Index_Type := Container.Last;
X : Element_Access := EA (K);
begin
-- We first isolate the element we're deleting, removing it
-- from the vector before we attempt to deallocate it, in
-- case the deallocation fails.
EA (K) := null;
Container.Last := K - 1;
-- Container invariants have been restored, so it is now
-- safe to attempt to deallocate the element.
Free (X);
end;
end loop;
end;
return;
end if;
-- There are some elements that aren't being deleted (the requested
-- count was less than the available count), so we must slide them down
-- to Index. We first calculate the index values of the respective array
-- slices, using the wider of Index_Type'Base and Count_Type'Base as the
-- type for intermediate calculations. For the elements that slide down,
-- index value New_Last is the last index value of their new home, and
-- index value J is the first index of their old home.
if Index_Type'Base'Last >= Count_Type_Last then
New_Last := Old_Last - Index_Type'Base (Count);
J := Index + Index_Type'Base (Count);
else
New_Last := Index_Type'Base (Count_Type'Base (Old_Last) - Count);
J := Index_Type'Base (Count_Type'Base (Index) + Count);
end if;
-- The internal elements array isn't guaranteed to exist unless we have
-- elements, but we have that guarantee here because we know we have
-- elements to slide. The array index values for each slice have
-- already been determined, so what remains to be done is to first
-- deallocate the elements that are being deleted, and then slide down
-- to Index the elements that aren't being deleted.
declare
EA : Elements_Array renames Container.Elements.EA;
begin
-- Before we can slide down the elements that aren't being deleted,
-- we need to deallocate the elements that are being deleted.
for K in Index .. J - 1 loop
declare
X : Element_Access := EA (K);
begin
-- First we remove the element we're about to deallocate from
-- the vector, in case the deallocation fails, in order to
-- preserve representation invariants.
EA (K) := null;
-- The element has been removed from the vector, so it is now
-- safe to attempt to deallocate it.
Free (X);
end;
end loop;
EA (Index .. New_Last) := EA (J .. Old_Last);
Container.Last := New_Last;
end;
end Delete;
procedure Delete
(Container : in out Vector;
Position : in out Cursor;
Count : Count_Type := 1)
is
begin
if Checks then
if Position.Container = null then
raise Constraint_Error with "Position cursor has no element";
elsif Position.Container /= Container'Unrestricted_Access then
raise Program_Error with "Position cursor denotes wrong container";
elsif Position.Index > Container.Last then
raise Program_Error with "Position index is out of range";
end if;
end if;
Delete (Container, Position.Index, Count);
Position := No_Element;
end Delete;
------------------
-- Delete_First --
------------------
procedure Delete_First
(Container : in out Vector;
Count : Count_Type := 1)
is
begin
if Count = 0 then
return;
elsif Count >= Length (Container) then
Clear (Container);
return;
else
Delete (Container, Index_Type'First, Count);
end if;
end Delete_First;
-----------------
-- Delete_Last --
-----------------
procedure Delete_Last
(Container : in out Vector;
Count : Count_Type := 1)
is
begin
-- It is not permitted to delete items while the container is busy (for
-- example, we're in the middle of a passive iteration). However, we
-- always treat deleting 0 items as a no-op, even when we're busy, so we
-- simply return without checking.
if Count = 0 then
return;
end if;
-- We cannot simply subsume the empty case into the loop below (the loop
-- would iterate 0 times), because we rename the internal array object
-- (which is allocated), but an empty vector isn't guaranteed to have
-- actually allocated an array. (Note that an empty vector can never be
-- busy, so there's no semantic harm in returning early here.)
if Container.Is_Empty then
return;
end if;
-- The tampering bits exist to prevent an item from being deleted (or
-- otherwise harmfully manipulated) while it is being visited. Query,
-- Update, and Iterate increment the busy count on entry, and decrement
-- the count on exit. Delete_Last checks the count to determine whether
-- it is being called while the associated callback procedure is
-- executing.
TC_Check (Container.TC);
-- Elements in an indefinite vector are allocated, so we must iterate
-- over the loop and deallocate elements one-at-a-time. We work from
-- back to front, deleting the last element during each pass, in order
-- to gracefully handle deallocation failures.
declare
E : Elements_Array renames Container.Elements.EA;
begin
for Indx in 1 .. Count_Type'Min (Count, Container.Length) loop
declare
J : constant Index_Type := Container.Last;
X : Element_Access := E (J);
begin
-- Note that we first isolate the element we're deleting,
-- removing it from the vector, before we actually deallocate
-- it, in order to preserve representation invariants even if
-- the deallocation fails.
E (J) := null;
Container.Last := J - 1;
-- Container invariants have been restored, so it is now safe
-- to deallocate the element.
Free (X);
end;
end loop;
end;
end Delete_Last;
-------------
-- Element --
-------------
function Element
(Container : Vector;
Index : Index_Type) return Element_Type
is
begin
if Checks and then Index > Container.Last then
raise Constraint_Error with "Index is out of range";
end if;
declare
EA : constant Element_Access := Container.Elements.EA (Index);
begin
if Checks and then EA = null then
raise Constraint_Error with "element is empty";
else
return EA.all;
end if;
end;
end Element;
function Element (Position : Cursor) return Element_Type is
begin
if Checks then
if Position.Container = null then
raise Constraint_Error with "Position cursor has no element";
end if;
if Position.Index > Position.Container.Last then
raise Constraint_Error with "Position cursor is out of range";
end if;
end if;
declare
EA : constant Element_Access :=
Position.Container.Elements.EA (Position.Index);
begin
if Checks and then EA = null then
raise Constraint_Error with "element is empty";
else
return EA.all;
end if;
end;
end Element;
-----------
-- Empty --
-----------
function Empty (Capacity : Count_Type := 10) return Vector is
begin
return Result : Vector do
Reserve_Capacity (Result, Capacity);
end return;
end Empty;
--------------
-- Finalize --
--------------
procedure Finalize (Container : in out Vector) is
begin
Clear (Container); -- Checks busy-bit
declare
X : Elements_Access := Container.Elements;
begin
Container.Elements := null;
Free (X);
end;
end Finalize;
procedure Finalize (Object : in out Iterator) is
begin
Unbusy (Object.Container.TC);
end Finalize;
----------
-- Find --
----------
function Find
(Container : Vector;
Item : Element_Type;
Position : Cursor := No_Element) return Cursor
is
begin
if Checks and then Position.Container /= null then
if Position.Container /= Container'Unrestricted_Access then
raise Program_Error with "Position cursor denotes wrong container";
end if;
if Position.Index > Container.Last then
raise Program_Error with "Position index is out of range";
end if;
end if;
-- Per AI05-0022, the container implementation is required to detect
-- element tampering by a generic actual subprogram.
declare
Lock : With_Lock (Container.TC'Unrestricted_Access);
begin
for J in Position.Index .. Container.Last loop
if Container.Elements.EA (J).all = Item then
return Cursor'(Container'Unrestricted_Access, J);
end if;
end loop;
return No_Element;
end;
end Find;
----------------
-- Find_Index --
----------------
function Find_Index
(Container : Vector;
Item : Element_Type;
Index : Index_Type := Index_Type'First) return Extended_Index
is
-- Per AI05-0022, the container implementation is required to detect
-- element tampering by a generic actual subprogram.
Lock : With_Lock (Container.TC'Unrestricted_Access);
begin
for Indx in Index .. Container.Last loop
if Container.Elements.EA (Indx).all = Item then
return Indx;
end if;
end loop;
return No_Index;
end Find_Index;
-----------
-- First --
-----------
function First (Container : Vector) return Cursor is
begin
if Is_Empty (Container) then
return No_Element;
end if;
return (Container'Unrestricted_Access, Index_Type'First);
end First;
function First (Object : Iterator) return Cursor is
begin
-- The value of the iterator object's Index component influences the
-- behavior of the First (and Last) selector function.
-- When the Index component is No_Index, this means the iterator
-- object was constructed without a start expression, in which case the
-- (forward) iteration starts from the (logical) beginning of the entire
-- sequence of items (corresponding to Container.First, for a forward
-- iterator).
-- Otherwise, this is iteration over a partial sequence of items.
-- When the Index component isn't No_Index, the iterator object was
-- constructed with a start expression, that specifies the position
-- from which the (forward) partial iteration begins.
if Object.Index = No_Index then
return First (Object.Container.all);
else
return Cursor'(Object.Container, Object.Index);
end if;
end First;
-------------------
-- First_Element --
-------------------
function First_Element (Container : Vector) return Element_Type is
begin
if Checks and then Container.Last = No_Index then
raise Constraint_Error with "Container is empty";
end if;
declare
EA : constant Element_Access :=
Container.Elements.EA (Index_Type'First);
begin
if Checks and then EA = null then
raise Constraint_Error with "first element is empty";
else
return EA.all;
end if;
end;
end First_Element;
-----------------
-- New_Vector --
-----------------
function New_Vector (First, Last : Index_Type) return Vector
is
begin
return (To_Vector (Count_Type (Last - First + 1)));
end New_Vector;
-----------------
-- First_Index --
-----------------
function First_Index (Container : Vector) return Index_Type is
pragma Unreferenced (Container);
begin
return Index_Type'First;
end First_Index;
---------------------
-- Generic_Sorting --
---------------------
package body Generic_Sorting is
-----------------------
-- Local Subprograms --
-----------------------
function Is_Less (L, R : Element_Access) return Boolean;
pragma Inline (Is_Less);
-------------
-- Is_Less --
-------------
function Is_Less (L, R : Element_Access) return Boolean is
begin
if L = null then
return R /= null;
elsif R = null then
return False;
else
return L.all < R.all;
end if;
end Is_Less;
---------------
-- Is_Sorted --
---------------
function Is_Sorted (Container : Vector) return Boolean is
begin
if Container.Last <= Index_Type'First then
return True;
end if;
-- Per AI05-0022, the container implementation is required to detect
-- element tampering by a generic actual subprogram.
declare
Lock : With_Lock (Container.TC'Unrestricted_Access);
E : Elements_Array renames Container.Elements.EA;
begin
for J in Index_Type'First .. Container.Last - 1 loop
if Is_Less (E (J + 1), E (J)) then
return False;
end if;
end loop;
return True;
end;
end Is_Sorted;
-----------
-- Merge --
-----------
procedure Merge (Target, Source : in out Vector) is
I, J : Index_Type'Base;
begin
TC_Check (Source.TC);
-- The semantics of Merge changed slightly per AI05-0021. It was
-- originally the case that if Target and Source denoted the same
-- container object, then the GNAT implementation of Merge did
-- nothing. However, it was argued that RM05 did not precisely
-- specify the semantics for this corner case. The decision of the
-- ARG was that if Target and Source denote the same non-empty
-- container object, then Program_Error is raised.
if Source.Last < Index_Type'First then -- Source is empty
return;
end if;
if Checks and then Target'Address = Source'Address then
raise Program_Error with
"Target and Source denote same non-empty container";
end if;
if Target.Last < Index_Type'First then -- Target is empty
Move (Target => Target, Source => Source);
return;
end if;
I := Target.Last; -- original value (before Set_Length)
Target.Set_Length (Length (Target) + Length (Source));
-- Per AI05-0022, the container implementation is required to detect
-- element tampering by a generic actual subprogram.
declare
TA : Elements_Array renames Target.Elements.EA;
SA : Elements_Array renames Source.Elements.EA;
Lock_Target : With_Lock (Target.TC'Unchecked_Access);
Lock_Source : With_Lock (Source.TC'Unchecked_Access);
begin
J := Target.Last; -- new value (after Set_Length)
while Source.Last >= Index_Type'First loop
pragma Assert
(Source.Last <= Index_Type'First
or else not (Is_Less (SA (Source.Last),
SA (Source.Last - 1))));
if I < Index_Type'First then
declare
Src : Elements_Array renames
SA (Index_Type'First .. Source.Last);
begin
TA (Index_Type'First .. J) := Src;
Src := (others => null);
end;
Source.Last := No_Index;
exit;
end if;
pragma Assert
(I <= Index_Type'First
or else not (Is_Less (TA (I), TA (I - 1))));
declare
Src : Element_Access renames SA (Source.Last);
Tgt : Element_Access renames TA (I);
begin
if Is_Less (Src, Tgt) then
Target.Elements.EA (J) := Tgt;
Tgt := null;
I := I - 1;
else
Target.Elements.EA (J) := Src;
Src := null;
Source.Last := Source.Last - 1;
end if;
end;
J := J - 1;
end loop;
end;
end Merge;
----------
-- Sort --
----------
procedure Sort (Container : in out Vector) is
procedure Sort is new Generic_Array_Sort
(Index_Type => Index_Type,
Element_Type => Element_Access,
Array_Type => Elements_Array,
"<" => Is_Less);
-- Start of processing for Sort
begin
if Container.Last <= Index_Type'First then
return;
end if;
-- The exception behavior for the vector container must match that
-- for the list container, so we check for cursor tampering here
-- (which will catch more things) instead of for element tampering
-- (which will catch fewer things). It's true that the elements of
-- this vector container could be safely moved around while (say) an
-- iteration is taking place (iteration only increments the busy
-- counter), and so technically all we would need here is a test for
-- element tampering (indicated by the lock counter), that's simply
-- an artifact of our array-based implementation. Logically Sort
-- requires a check for cursor tampering.
TC_Check (Container.TC);
-- Per AI05-0022, the container implementation is required to detect
-- element tampering by a generic actual subprogram.
declare
Lock : With_Lock (Container.TC'Unchecked_Access);
begin
Sort (Container.Elements.EA (Index_Type'First .. Container.Last));
end;
end Sort;
end Generic_Sorting;
------------------------
-- Get_Element_Access --
------------------------
function Get_Element_Access
(Position : Cursor) return not null Element_Access
is
Ptr : constant Element_Access :=
Position.Container.Elements.EA (Position.Index);
begin
-- An indefinite vector may contain spaces that hold no elements.
-- Any iteration over an indefinite vector with spaces will raise
-- Constraint_Error.
if Ptr = null then
raise Constraint_Error;
else
return Ptr;
end if;
end Get_Element_Access;
-----------------
-- Has_Element --
-----------------
function Has_Element (Position : Cursor) return Boolean is
begin
if Position.Container = null then
return False;
else
return Position.Index <= Position.Container.Last;
end if;
end Has_Element;
------------
-- Insert --
------------
procedure Insert
(Container : in out Vector;
Before : Extended_Index;
New_Item : Element_Type;
Count : Count_Type := 1)
is
Old_Length : constant Count_Type := Container.Length;
Max_Length : Count_Type'Base; -- determined from range of Index_Type
New_Length : Count_Type'Base; -- sum of current length and Count
New_Last : Index_Type'Base; -- last index of vector after insertion
Index : Index_Type'Base; -- scratch for intermediate values
J : Count_Type'Base; -- scratch
New_Capacity : Count_Type'Base; -- length of new, expanded array
Dst_Last : Index_Type'Base; -- last index of new, expanded array
Dst : Elements_Access; -- new, expanded internal array
begin
-- The tampering bits exist to prevent an item from being harmfully
-- manipulated while it is being visited. Query, Update, and Iterate
-- increment the busy count on entry, and decrement the count on
-- exit. Insert checks the count to determine whether it is being called
-- while the associated callback procedure is executing.
TC_Check (Container.TC);
if Checks then
-- As a precondition on the generic actual Index_Type, the base type
-- must include Index_Type'Pred (Index_Type'First); this is the value
-- that Container.Last assumes when the vector is empty. However, we
-- do not allow that as the value for Index when specifying where the
-- new items should be inserted, so we must manually check. (That the
-- user is allowed to specify the value at all here is a consequence
-- of the declaration of the Extended_Index subtype, which includes
-- the values in the base range that immediately precede and
-- immediately follow the values in the Index_Type.)
if Before < Index_Type'First then
raise Constraint_Error with
"Before index is out of range (too small)";
end if;
-- We do allow a value greater than Container.Last to be specified as
-- the Index, but only if it's immediately greater. This allows for
-- the case of appending items to the back end of the vector. (It is
-- assumed that specifying an index value greater than Last + 1
-- indicates some deeper flaw in the caller's algorithm, so that case
-- is treated as a proper error.)
if Before > Container.Last + 1 then
raise Constraint_Error with
"Before index is out of range (too large)";
end if;
end if;
-- We treat inserting 0 items into the container as a no-op, even when
-- the container is busy, so we simply return.
if Count = 0 then
return;
end if;
-- There are two constraints we need to satisfy. The first constraint is
-- that a container cannot have more than Count_Type'Last elements, so
-- we must check the sum of the current length and the insertion count.
-- Note: we cannot simply add these values, because of the possibility
-- of overflow.
if Checks and then Old_Length > Count_Type'Last - Count then
raise Constraint_Error with "Count is out of range";
end if;
-- It is now safe compute the length of the new vector, without fear of
-- overflow.
New_Length := Old_Length + Count;
-- The second constraint is that the new Last index value cannot exceed
-- Index_Type'Last. In each branch below, we calculate the maximum
-- length (computed from the range of values in Index_Type), and then
-- compare the new length to the maximum length. If the new length is
-- acceptable, then we compute the new last index from that.
if Index_Type'Base'Last >= Count_Type_Last then
-- We have to handle the case when there might be more values in the
-- range of Index_Type than in the range of Count_Type.
if Index_Type'First <= 0 then
-- We know that No_Index (the same as Index_Type'First - 1) is
-- less than 0, so it is safe to compute the following sum without
-- fear of overflow.
Index := No_Index + Index_Type'Base (Count_Type'Last);
if Index <= Index_Type'Last then
-- We have determined that range of Index_Type has at least as
-- many values as in Count_Type, so Count_Type'Last is the
-- maximum number of items that are allowed.
Max_Length := Count_Type'Last;
else
-- The range of Index_Type has fewer values than in Count_Type,
-- so the maximum number of items is computed from the range of
-- the Index_Type.
Max_Length := Count_Type'Base (Index_Type'Last - No_Index);
end if;
else
-- No_Index is equal or greater than 0, so we can safely compute
-- the difference without fear of overflow (which we would have to
-- worry about if No_Index were less than 0, but that case is
-- handled above).
if Index_Type'Last - No_Index >= Count_Type_Last then
-- We have determined that range of Index_Type has at least as
-- many values as in Count_Type, so Count_Type'Last is the
-- maximum number of items that are allowed.
Max_Length := Count_Type'Last;
else
-- The range of Index_Type has fewer values than in Count_Type,
-- so the maximum number of items is computed from the range of
-- the Index_Type.
Max_Length := Count_Type'Base (Index_Type'Last - No_Index);
end if;
end if;
elsif Index_Type'First <= 0 then
-- We know that No_Index (the same as Index_Type'First - 1) is less
-- than 0, so it is safe to compute the following sum without fear of
-- overflow.
J := Count_Type'Base (No_Index) + Count_Type'Last;
if J <= Count_Type'Base (Index_Type'Last) then
-- We have determined that range of Index_Type has at least as
-- many values as in Count_Type, so Count_Type'Last is the maximum
-- number of items that are allowed.
Max_Length := Count_Type'Last;
else
-- The range of Index_Type has fewer values than Count_Type does,
-- so the maximum number of items is computed from the range of
-- the Index_Type.
Max_Length :=
Count_Type'Base (Index_Type'Last) - Count_Type'Base (No_Index);
end if;
else
-- No_Index is equal or greater than 0, so we can safely compute the
-- difference without fear of overflow (which we would have to worry
-- about if No_Index were less than 0, but that case is handled
-- above).
Max_Length :=
Count_Type'Base (Index_Type'Last) - Count_Type'Base (No_Index);
end if;
-- We have just computed the maximum length (number of items). We must
-- now compare the requested length to the maximum length, as we do not
-- allow a vector expand beyond the maximum (because that would create
-- an internal array with a last index value greater than
-- Index_Type'Last, with no way to index those elements).
if Checks and then New_Length > Max_Length then
raise Constraint_Error with "Count is out of range";
end if;
-- New_Last is the last index value of the items in the container after
-- insertion. Use the wider of Index_Type'Base and Count_Type'Base to
-- compute its value from the New_Length.
if Index_Type'Base'Last >= Count_Type_Last then
New_Last := No_Index + Index_Type'Base (New_Length);
else
New_Last := Index_Type'Base (Count_Type'Base (No_Index) + New_Length);
end if;
if Container.Elements = null then
pragma Assert (Container.Last = No_Index);
-- This is the simplest case, with which we must always begin: we're
-- inserting items into an empty vector that hasn't allocated an
-- internal array yet. Note that we don't need to check the busy bit
-- here, because an empty container cannot be busy.
-- In an indefinite vector, elements are allocated individually, and
-- stored as access values on the internal array (the length of which
-- represents the vector "capacity"), which is separately allocated.
Container.Elements := new Elements_Type (New_Last);
-- The element backbone has been successfully allocated, so now we
-- allocate the elements.
for Idx in Container.Elements.EA'Range loop
-- In order to preserve container invariants, we always attempt
-- the element allocation first, before setting the Last index
-- value, in case the allocation fails (either because there is no
-- storage available, or because element initialization fails).
declare
-- The element allocator may need an accessibility check in the
-- case actual type is class-wide or has access discriminants
-- (see RM 4.8(10.1) and AI12-0035).
pragma Unsuppress (Accessibility_Check);
begin
Container.Elements.EA (Idx) := new Element_Type'(New_Item);
end;
-- The allocation of the element succeeded, so it is now safe to
-- update the Last index, restoring container invariants.
Container.Last := Idx;
end loop;
return;
end if;
if New_Length <= Container.Elements.EA'Length then
-- In this case, we're inserting elements into a vector that has
-- already allocated an internal array, and the existing array has
-- enough unused storage for the new items.
declare
E : Elements_Array renames Container.Elements.EA;
K : Index_Type'Base;
begin
if Before > Container.Last then
-- The new items are being appended to the vector, so no
-- sliding of existing elements is required.
for Idx in Before .. New_Last loop
-- In order to preserve container invariants, we always
-- attempt the element allocation first, before setting the
-- Last index value, in case the allocation fails (either
-- because there is no storage available, or because element
-- initialization fails).
declare
-- The element allocator may need an accessibility check
-- in case the actual type is class-wide or has access
-- discriminants (see RM 4.8(10.1) and AI12-0035).
pragma Unsuppress (Accessibility_Check);
begin
E (Idx) := new Element_Type'(New_Item);
end;
-- The allocation of the element succeeded, so it is now
-- safe to update the Last index, restoring container
-- invariants.
Container.Last := Idx;
end loop;
else
-- The new items are being inserted before some existing
-- elements, so we must slide the existing elements up to their
-- new home. We use the wider of Index_Type'Base and
-- Count_Type'Base as the type for intermediate index values.
if Index_Type'Base'Last >= Count_Type_Last then
Index := Before + Index_Type'Base (Count);
else
Index := Index_Type'Base (Count_Type'Base (Before) + Count);
end if;
-- The new items are being inserted in the middle of the array,
-- in the range [Before, Index). Copy the existing elements to
-- the end of the array, to make room for the new items.
E (Index .. New_Last) := E (Before .. Container.Last);
Container.Last := New_Last;
-- We have copied the existing items up to the end of the
-- array, to make room for the new items in the middle of
-- the array. Now we actually allocate the new items.
-- Note: initialize K outside loop to make it clear that
-- K always has a value if the exception handler triggers.
K := Before;
declare
-- The element allocator may need an accessibility check in
-- the case the actual type is class-wide or has access
-- discriminants (see RM 4.8(10.1) and AI12-0035).
pragma Unsuppress (Accessibility_Check);
begin
while K < Index loop
E (K) := new Element_Type'(New_Item);
K := K + 1;
end loop;
exception
when others =>
-- Values in the range [Before, K) were successfully
-- allocated, but values in the range [K, Index) are
-- stale (these array positions contain copies of the
-- old items, that did not get assigned a new item,
-- because the allocation failed). We must finish what
-- we started by clearing out all of the stale values,
-- leaving a "hole" in the middle of the array.
E (K .. Index - 1) := (others => null);
raise;
end;
end if;
end;
return;
end if;
-- In this case, we're inserting elements into a vector that has already
-- allocated an internal array, but the existing array does not have
-- enough storage, so we must allocate a new, longer array. In order to
-- guarantee that the amortized insertion cost is O(1), we always
-- allocate an array whose length is some power-of-two factor of the
-- current array length. (The new array cannot have a length less than
-- the New_Length of the container, but its last index value cannot be
-- greater than Index_Type'Last.)
New_Capacity := Count_Type'Max (1, Container.Elements.EA'Length);
while New_Capacity < New_Length loop
if New_Capacity > Count_Type'Last / 2 then
New_Capacity := Count_Type'Last;
exit;
end if;
New_Capacity := 2 * New_Capacity;
end loop;
if New_Capacity > Max_Length then
-- We have reached the limit of capacity, so no further expansion
-- will occur. (This is not a problem, as there is never a need to
-- have more capacity than the maximum container length.)
New_Capacity := Max_Length;
end if;
-- We have computed the length of the new internal array (and this is
-- what "vector capacity" means), so use that to compute its last index.
if Index_Type'Base'Last >= Count_Type_Last then
Dst_Last := No_Index + Index_Type'Base (New_Capacity);
else
Dst_Last :=
Index_Type'Base (Count_Type'Base (No_Index) + New_Capacity);
end if;
-- Now we allocate the new, longer internal array. If the allocation
-- fails, we have not changed any container state, so no side-effect
-- will occur as a result of propagating the exception.
Dst := new Elements_Type (Dst_Last);
-- We have our new internal array. All that needs to be done now is to
-- copy the existing items (if any) from the old array (the "source"
-- array) to the new array (the "destination" array), and then
-- deallocate the old array.
declare
Src : Elements_Access := Container.Elements;
begin
Dst.EA (Index_Type'First .. Before - 1) :=
Src.EA (Index_Type'First .. Before - 1);
if Before > Container.Last then
-- The new items are being appended to the vector, so no
-- sliding of existing elements is required.
-- We have copied the elements from to the old source array to the
-- new destination array, so we can now deallocate the old array.
Container.Elements := Dst;
Free (Src);
-- Now we append the new items.
for Idx in Before .. New_Last loop
-- In order to preserve container invariants, we always attempt
-- the element allocation first, before setting the Last index
-- value, in case the allocation fails (either because there
-- is no storage available, or because element initialization
-- fails).
declare
-- The element allocator may need an accessibility check in
-- the case the actual type is class-wide or has access
-- discriminants (see RM 4.8(10.1) and AI12-0035).
pragma Unsuppress (Accessibility_Check);
begin
Dst.EA (Idx) := new Element_Type'(New_Item);
end;
-- The allocation of the element succeeded, so it is now safe
-- to update the Last index, restoring container invariants.
Container.Last := Idx;
end loop;
else
-- The new items are being inserted before some existing elements,
-- so we must slide the existing elements up to their new home.
if Index_Type'Base'Last >= Count_Type_Last then
Index := Before + Index_Type'Base (Count);
else
Index := Index_Type'Base (Count_Type'Base (Before) + Count);
end if;
Dst.EA (Index .. New_Last) := Src.EA (Before .. Container.Last);
-- We have copied the elements from to the old source array to the
-- new destination array, so we can now deallocate the old array.
Container.Elements := Dst;
Container.Last := New_Last;
Free (Src);
-- The new array has a range in the middle containing null access
-- values. Fill in that partition of the array with the new items.
for Idx in Before .. Index - 1 loop
-- Note that container invariants have already been satisfied
-- (in particular, the Last index value of the vector has
-- already been updated), so if this allocation fails we simply
-- let it propagate.
declare
-- The element allocator may need an accessibility check in
-- the case the actual type is class-wide or has access
-- discriminants (see RM 4.8(10.1) and AI12-0035).
pragma Unsuppress (Accessibility_Check);
begin
Dst.EA (Idx) := new Element_Type'(New_Item);
end;
end loop;
end if;
end;
end Insert;
procedure Insert_Vector
(Container : in out Vector;
Before : Extended_Index;
New_Item : Vector)
is
N : constant Count_Type := Length (New_Item);
J : Index_Type'Base;
begin
-- Use Insert_Space to create the "hole" (the destination slice) into
-- which we copy the source items.
Insert_Space (Container, Before, Count => N);
if N = 0 then
-- There's nothing else to do here (vetting of parameters was
-- performed already in Insert_Space), so we simply return.
return;
end if;
if Container'Address /= New_Item'Address then
-- This is the simple case. New_Item denotes an object different
-- from Container, so there's nothing special we need to do to copy
-- the source items to their destination, because all of the source
-- items are contiguous.
declare
subtype Src_Index_Subtype is Index_Type'Base range
Index_Type'First .. New_Item.Last;
Src : Elements_Array renames
New_Item.Elements.EA (Src_Index_Subtype);
Dst : Elements_Array renames Container.Elements.EA;
Dst_Index : Index_Type'Base;
begin
Dst_Index := Before - 1;
for Src_Index in Src'Range loop
Dst_Index := Dst_Index + 1;
if Src (Src_Index) /= null then
Dst (Dst_Index) := new Element_Type'(Src (Src_Index).all);
end if;
end loop;
end;
return;
end if;
-- New_Item denotes the same object as Container, so an insertion has
-- potentially split the source items. The first source slice is
-- [Index_Type'First, Before), and the second source slice is
-- [J, Container.Last], where index value J is the first index of the
-- second slice. (J gets computed below, but only after we have
-- determined that the second source slice is non-empty.) The
-- destination slice is always the range [Before, J). We perform the
-- copy in two steps, using each of the two slices of the source items.
declare
L : constant Index_Type'Base := Before - 1;
subtype Src_Index_Subtype is Index_Type'Base range
Index_Type'First .. L;
Src : Elements_Array renames
Container.Elements.EA (Src_Index_Subtype);
Dst : Elements_Array renames Container.Elements.EA;
Dst_Index : Index_Type'Base;
begin
-- We first copy the source items that precede the space we
-- inserted. (If Before equals Index_Type'First, then this first
-- source slice will be empty, which is harmless.)
Dst_Index := Before - 1;
for Src_Index in Src'Range loop
Dst_Index := Dst_Index + 1;
if Src (Src_Index) /= null then
Dst (Dst_Index) := new Element_Type'(Src (Src_Index).all);
end if;
end loop;
if Src'Length = N then
-- The new items were effectively appended to the container, so we
-- have already copied all of the items that need to be copied.
-- We return early here, even though the source slice below is
-- empty (so the assignment would be harmless), because we want to
-- avoid computing J, which will overflow if J is greater than
-- Index_Type'Base'Last.
return;
end if;
end;
-- Index value J is the first index of the second source slice. (It is
-- also 1 greater than the last index of the destination slice.) Note:
-- avoid computing J if J is greater than Index_Type'Base'Last, in order
-- to avoid overflow. Prevent that by returning early above, immediately
-- after copying the first slice of the source, and determining that
-- this second slice of the source is empty.
if Index_Type'Base'Last >= Count_Type_Last then
J := Before + Index_Type'Base (N);
else
J := Index_Type'Base (Count_Type'Base (Before) + N);
end if;
declare
subtype Src_Index_Subtype is Index_Type'Base range
J .. Container.Last;
Src : Elements_Array renames
Container.Elements.EA (Src_Index_Subtype);
Dst : Elements_Array renames Container.Elements.EA;
Dst_Index : Index_Type'Base;
begin
-- We next copy the source items that follow the space we inserted.
-- Index value Dst_Index is the first index of that portion of the
-- destination that receives this slice of the source. (For the
-- reasons given above, this slice is guaranteed to be non-empty.)
if Index_Type'Base'Last >= Count_Type_Last then
Dst_Index := J - Index_Type'Base (Src'Length);
else
Dst_Index := Index_Type'Base (Count_Type'Base (J) - Src'Length);
end if;
for Src_Index in Src'Range loop
if Src (Src_Index) /= null then
Dst (Dst_Index) := new Element_Type'(Src (Src_Index).all);
end if;
Dst_Index := Dst_Index + 1;
end loop;
end;
end Insert_Vector;
procedure Insert_Vector
(Container : in out Vector;
Before : Cursor;
New_Item : Vector)
is
Index : Index_Type'Base;
begin
if Checks and then Before.Container /= null
and then Before.Container /= Container'Unrestricted_Access
then
raise Program_Error with "Before cursor denotes wrong container";
end if;
if Is_Empty (New_Item) then
return;
end if;
if Before.Container = null or else Before.Index > Container.Last then
if Checks and then Container.Last = Index_Type'Last then
raise Constraint_Error with
"vector is already at its maximum length";
end if;
Index := Container.Last + 1;
else
Index := Before.Index;
end if;
Insert_Vector (Container, Index, New_Item);
end Insert_Vector;
procedure Insert_Vector
(Container : in out Vector;
Before : Cursor;
New_Item : Vector;
Position : out Cursor)
is
Index : Index_Type'Base;
begin
if Checks and then Before.Container /= null
and then Before.Container /= Container'Unrestricted_Access
then
raise Program_Error with "Before cursor denotes wrong container";
end if;
if Is_Empty (New_Item) then
if Before.Container = null or else Before.Index > Container.Last then
Position := No_Element;
else
Position := (Container'Unrestricted_Access, Before.Index);
end if;
return;
end if;
if Before.Container = null or else Before.Index > Container.Last then
if Checks and then Container.Last = Index_Type'Last then
raise Constraint_Error with
"vector is already at its maximum length";
end if;
Index := Container.Last + 1;
else
Index := Before.Index;
end if;
Insert_Vector (Container, Index, New_Item);
Position := (Container'Unrestricted_Access, Index);
end Insert_Vector;
procedure Insert
(Container : in out Vector;
Before : Cursor;
New_Item : Element_Type;
Count : Count_Type := 1)
is
Index : Index_Type'Base;
begin
if Checks and then Before.Container /= null
and then Before.Container /= Container'Unrestricted_Access
then
raise Program_Error with "Before cursor denotes wrong container";
end if;
if Count = 0 then
return;
end if;
if Before.Container = null or else Before.Index > Container.Last then
if Checks and then Container.Last = Index_Type'Last then
raise Constraint_Error with
"vector is already at its maximum length";
end if;
Index := Container.Last + 1;
else
Index := Before.Index;
end if;
Insert (Container, Index, New_Item, Count);
end Insert;
procedure Insert
(Container : in out Vector;
Before : Cursor;
New_Item : Element_Type;
Position : out Cursor;
Count : Count_Type := 1)
is
Index : Index_Type'Base;
begin
if Checks and then Before.Container /= null
and then Before.Container /= Container'Unrestricted_Access
then
raise Program_Error with "Before cursor denotes wrong container";
end if;
if Count = 0 then
if Before.Container = null or else Before.Index > Container.Last then
Position := No_Element;
else
Position := (Container'Unrestricted_Access, Before.Index);
end if;
return;
end if;
if Before.Container = null or else Before.Index > Container.Last then
if Checks and then Container.Last = Index_Type'Last then
raise Constraint_Error with
"vector is already at its maximum length";
end if;
Index := Container.Last + 1;
else
Index := Before.Index;
end if;
Insert (Container, Index, New_Item, Count);
Position := (Container'Unrestricted_Access, Index);
end Insert;
------------------
-- Insert_Space --
------------------
procedure Insert_Space
(Container : in out Vector;
Before : Extended_Index;
Count : Count_Type := 1)
is
Old_Length : constant Count_Type := Container.Length;
Max_Length : Count_Type'Base; -- determined from range of Index_Type
New_Length : Count_Type'Base; -- sum of current length and Count
New_Last : Index_Type'Base; -- last index of vector after insertion
Index : Index_Type'Base; -- scratch for intermediate values
J : Count_Type'Base; -- scratch
New_Capacity : Count_Type'Base; -- length of new, expanded array
Dst_Last : Index_Type'Base; -- last index of new, expanded array
Dst : Elements_Access; -- new, expanded internal array
begin
-- The tampering bits exist to prevent an item from being harmfully
-- manipulated while it is being visited. Query, Update, and Iterate
-- increment the busy count on entry, and decrement the count on exit.
-- Insert checks the count to determine whether it is being called while
-- the associated callback procedure is executing.
TC_Check (Container.TC);
if Checks then
-- As a precondition on the generic actual Index_Type, the base type
-- must include Index_Type'Pred (Index_Type'First); this is the value
-- that Container.Last assumes when the vector is empty. However, we
-- do not allow that as the value for Index when specifying where the
-- new items should be inserted, so we must manually check. (That the
-- user is allowed to specify the value at all here is a consequence
-- of the declaration of the Extended_Index subtype, which includes
-- the values in the base range that immediately precede and
-- immediately follow the values in the Index_Type.)
if Before < Index_Type'First then
raise Constraint_Error with
"Before index is out of range (too small)";
end if;
-- We do allow a value greater than Container.Last to be specified as
-- the Index, but only if it's immediately greater. This allows for
-- the case of appending items to the back end of the vector. (It is
-- assumed that specifying an index value greater than Last + 1
-- indicates some deeper flaw in the caller's algorithm, so that case
-- is treated as a proper error.)
if Before > Container.Last + 1 then
raise Constraint_Error with
"Before index is out of range (too large)";
end if;
end if;
-- We treat inserting 0 items into the container as a no-op, even when
-- the container is busy, so we simply return.
if Count = 0 then
return;
end if;
-- There are two constraints we need to satisfy. The first constraint is
-- that a container cannot have more than Count_Type'Last elements, so
-- we must check the sum of the current length and the insertion count.
-- Note: we cannot simply add these values, because of the possibility
-- of overflow.
if Checks and then Old_Length > Count_Type'Last - Count then
raise Constraint_Error with "Count is out of range";
end if;
-- It is now safe compute the length of the new vector, without fear of
-- overflow.
New_Length := Old_Length + Count;
-- The second constraint is that the new Last index value cannot exceed
-- Index_Type'Last. In each branch below, we calculate the maximum
-- length (computed from the range of values in Index_Type), and then
-- compare the new length to the maximum length. If the new length is
-- acceptable, then we compute the new last index from that.
if Index_Type'Base'Last >= Count_Type_Last then
-- We have to handle the case when there might be more values in the
-- range of Index_Type than in the range of Count_Type.
if Index_Type'First <= 0 then
-- We know that No_Index (the same as Index_Type'First - 1) is
-- less than 0, so it is safe to compute the following sum without
-- fear of overflow.
Index := No_Index + Index_Type'Base (Count_Type'Last);
if Index <= Index_Type'Last then
-- We have determined that range of Index_Type has at least as
-- many values as in Count_Type, so Count_Type'Last is the
-- maximum number of items that are allowed.
Max_Length := Count_Type'Last;
else
-- The range of Index_Type has fewer values than in Count_Type,
-- so the maximum number of items is computed from the range of
-- the Index_Type.
Max_Length := Count_Type'Base (Index_Type'Last - No_Index);
end if;
else
-- No_Index is equal or greater than 0, so we can safely compute
-- the difference without fear of overflow (which we would have to
-- worry about if No_Index were less than 0, but that case is
-- handled above).
if Index_Type'Last - No_Index >= Count_Type_Last then
-- We have determined that range of Index_Type has at least as
-- many values as in Count_Type, so Count_Type'Last is the
-- maximum number of items that are allowed.
Max_Length := Count_Type'Last;
else
-- The range of Index_Type has fewer values than in Count_Type,
-- so the maximum number of items is computed from the range of
-- the Index_Type.
Max_Length := Count_Type'Base (Index_Type'Last - No_Index);
end if;
end if;
elsif Index_Type'First <= 0 then
-- We know that No_Index (the same as Index_Type'First - 1) is less
-- than 0, so it is safe to compute the following sum without fear of
-- overflow.
J := Count_Type'Base (No_Index) + Count_Type'Last;
if J <= Count_Type'Base (Index_Type'Last) then
-- We have determined that range of Index_Type has at least as
-- many values as in Count_Type, so Count_Type'Last is the maximum
-- number of items that are allowed.
Max_Length := Count_Type'Last;
else
-- The range of Index_Type has fewer values than Count_Type does,
-- so the maximum number of items is computed from the range of
-- the Index_Type.
Max_Length :=
Count_Type'Base (Index_Type'Last) - Count_Type'Base (No_Index);
end if;
else
-- No_Index is equal or greater than 0, so we can safely compute the
-- difference without fear of overflow (which we would have to worry
-- about if No_Index were less than 0, but that case is handled
-- above).
Max_Length :=
Count_Type'Base (Index_Type'Last) - Count_Type'Base (No_Index);
end if;
-- We have just computed the maximum length (number of items). We must
-- now compare the requested length to the maximum length, as we do not
-- allow a vector expand beyond the maximum (because that would create
-- an internal array with a last index value greater than
-- Index_Type'Last, with no way to index those elements).
if Checks and then New_Length > Max_Length then
raise Constraint_Error with "Count is out of range";
end if;
-- New_Last is the last index value of the items in the container after
-- insertion. Use the wider of Index_Type'Base and Count_Type'Base to
-- compute its value from the New_Length.
if Index_Type'Base'Last >= Count_Type_Last then
New_Last := No_Index + Index_Type'Base (New_Length);
else
New_Last := Index_Type'Base (Count_Type'Base (No_Index) + New_Length);
end if;
if Container.Elements = null then
pragma Assert (Container.Last = No_Index);
-- This is the simplest case, with which we must always begin: we're
-- inserting items into an empty vector that hasn't allocated an
-- internal array yet. Note that we don't need to check the busy bit
-- here, because an empty container cannot be busy.
-- In an indefinite vector, elements are allocated individually, and
-- stored as access values on the internal array (the length of which
-- represents the vector "capacity"), which is separately allocated.
-- We have no elements here (because we're inserting "space"), so all
-- we need to do is allocate the backbone.
Container.Elements := new Elements_Type (New_Last);
Container.Last := New_Last;
return;
end if;
if New_Length <= Container.Elements.EA'Length then
-- In this case, we are inserting elements into a vector that has
-- already allocated an internal array, and the existing array has
-- enough unused storage for the new items.
declare
E : Elements_Array renames Container.Elements.EA;
begin
if Before <= Container.Last then
-- The new space is being inserted before some existing
-- elements, so we must slide the existing elements up to
-- their new home. We use the wider of Index_Type'Base and
-- Count_Type'Base as the type for intermediate index values.
if Index_Type'Base'Last >= Count_Type_Last then
Index := Before + Index_Type'Base (Count);
else
Index := Index_Type'Base (Count_Type'Base (Before) + Count);
end if;
E (Index .. New_Last) := E (Before .. Container.Last);
E (Before .. Index - 1) := (others => null);
end if;
end;
Container.Last := New_Last;
return;
end if;
-- In this case, we're inserting elements into a vector that has already
-- allocated an internal array, but the existing array does not have
-- enough storage, so we must allocate a new, longer array. In order to
-- guarantee that the amortized insertion cost is O(1), we always
-- allocate an array whose length is some power-of-two factor of the
-- current array length. (The new array cannot have a length less than
-- the New_Length of the container, but its last index value cannot be
-- greater than Index_Type'Last.)
New_Capacity := Count_Type'Max (1, Container.Elements.EA'Length);
while New_Capacity < New_Length loop
if New_Capacity > Count_Type'Last / 2 then
New_Capacity := Count_Type'Last;
exit;
end if;
New_Capacity := 2 * New_Capacity;
end loop;
if New_Capacity > Max_Length then
-- We have reached the limit of capacity, so no further expansion
-- will occur. (This is not a problem, as there is never a need to
-- have more capacity than the maximum container length.)
New_Capacity := Max_Length;
end if;
-- We have computed the length of the new internal array (and this is
-- what "vector capacity" means), so use that to compute its last index.
if Index_Type'Base'Last >= Count_Type_Last then
Dst_Last := No_Index + Index_Type'Base (New_Capacity);
else
Dst_Last :=
Index_Type'Base (Count_Type'Base (No_Index) + New_Capacity);
end if;
-- Now we allocate the new, longer internal array. If the allocation
-- fails, we have not changed any container state, so no side-effect
-- will occur as a result of propagating the exception.
Dst := new Elements_Type (Dst_Last);
-- We have our new internal array. All that needs to be done now is to
-- copy the existing items (if any) from the old array (the "source"
-- array) to the new array (the "destination" array), and then
-- deallocate the old array.
declare
Src : Elements_Access := Container.Elements;
begin
Dst.EA (Index_Type'First .. Before - 1) :=
Src.EA (Index_Type'First .. Before - 1);
if Before <= Container.Last then
-- The new items are being inserted before some existing elements,
-- so we must slide the existing elements up to their new home.
if Index_Type'Base'Last >= Count_Type_Last then
Index := Before + Index_Type'Base (Count);
else
Index := Index_Type'Base (Count_Type'Base (Before) + Count);
end if;
Dst.EA (Index .. New_Last) := Src.EA (Before .. Container.Last);
end if;
-- We have copied the elements from to the old, source array to the
-- new, destination array, so we can now restore invariants, and
-- deallocate the old array.
Container.Elements := Dst;
Container.Last := New_Last;
Free (Src);
end;
end Insert_Space;
procedure Insert_Space
(Container : in out Vector;
Before : Cursor;
Position : out Cursor;
Count : Count_Type := 1)
is
Index : Index_Type'Base;
begin
if Checks and then Before.Container /= null
and then Before.Container /= Container'Unrestricted_Access
then
raise Program_Error with "Before cursor denotes wrong container";
end if;
if Count = 0 then
if Before.Container = null or else Before.Index > Container.Last then
Position := No_Element;
else
Position := (Container'Unrestricted_Access, Before.Index);
end if;
return;
end if;
if Before.Container = null or else Before.Index > Container.Last then
if Checks and then Container.Last = Index_Type'Last then
raise Constraint_Error with
"vector is already at its maximum length";
end if;
Index := Container.Last + 1;
else
Index := Before.Index;
end if;
Insert_Space (Container, Index, Count);
Position := (Container'Unrestricted_Access, Index);
end Insert_Space;
--------------
-- Is_Empty --
--------------
function Is_Empty (Container : Vector) return Boolean is
begin
return Container.Last < Index_Type'First;
end Is_Empty;
-------------
-- Iterate --
-------------
procedure Iterate
(Container : Vector;
Process : not null access procedure (Position : Cursor))
is
Busy : With_Busy (Container.TC'Unrestricted_Access);
begin
for Indx in Index_Type'First .. Container.Last loop
Process (Cursor'(Container'Unrestricted_Access, Indx));
end loop;
end Iterate;
function Iterate
(Container : Vector)
return Vector_Iterator_Interfaces.Reversible_Iterator'Class
is
V : constant Vector_Access := Container'Unrestricted_Access;
begin
-- The value of its Index component influences the behavior of the First
-- and Last selector functions of the iterator object. When the Index
-- component is No_Index (as is the case here), this means the iterator
-- object was constructed without a start expression. This is a complete
-- iterator, meaning that the iteration starts from the (logical)
-- beginning of the sequence of items.
-- Note: For a forward iterator, Container.First is the beginning, and
-- for a reverse iterator, Container.Last is the beginning.
return It : constant Iterator :=
(Limited_Controlled with
Container => V,
Index => No_Index)
do
Busy (Container.TC'Unrestricted_Access.all);
end return;
end Iterate;
function Iterate
(Container : Vector;
Start : Cursor)
return Vector_Iterator_Interfaces.Reversible_Iterator'Class
is
V : constant Vector_Access := Container'Unrestricted_Access;
begin
-- It was formerly the case that when Start = No_Element, the partial
-- iterator was defined to behave the same as for a complete iterator,
-- and iterate over the entire sequence of items. However, those
-- semantics were unintuitive and arguably error-prone (it is too easy
-- to accidentally create an endless loop), and so they were changed,
-- per the ARG meeting in Denver on 2011/11. However, there was no
-- consensus about what positive meaning this corner case should have,
-- and so it was decided to simply raise an exception. This does imply,
-- however, that it is not possible to use a partial iterator to specify
-- an empty sequence of items.
if Checks then
if Start.Container = null then
raise Constraint_Error with
"Start position for iterator equals No_Element";
end if;
if Start.Container /= V then
raise Program_Error with
"Start cursor of Iterate designates wrong vector";
end if;
if Start.Index > V.Last then
raise Constraint_Error with
"Start position for iterator equals No_Element";
end if;
end if;
-- The value of its Index component influences the behavior of the First
-- and Last selector functions of the iterator object. When the Index
-- component is not No_Index (as is the case here), it means that this
-- is a partial iteration, over a subset of the complete sequence of
-- items. The iterator object was constructed with a start expression,
-- indicating the position from which the iteration begins. Note that
-- the start position has the same value irrespective of whether this
-- is a forward or reverse iteration.
return It : constant Iterator :=
(Limited_Controlled with
Container => V,
Index => Start.Index)
do
Busy (Container.TC'Unrestricted_Access.all);
end return;
end Iterate;
----------
-- Last --
----------
function Last (Container : Vector) return Cursor is
begin
if Is_Empty (Container) then
return No_Element;
end if;
return (Container'Unrestricted_Access, Container.Last);
end Last;
function Last (Object : Iterator) return Cursor is
begin
-- The value of the iterator object's Index component influences the
-- behavior of the Last (and First) selector function.
-- When the Index component is No_Index, this means the iterator
-- object was constructed without a start expression, in which case the
-- (reverse) iteration starts from the (logical) beginning of the entire
-- sequence (corresponding to Container.Last, for a reverse iterator).
-- Otherwise, this is iteration over a partial sequence of items.
-- When the Index component is not No_Index, the iterator object was
-- constructed with a start expression, that specifies the position
-- from which the (reverse) partial iteration begins.
if Object.Index = No_Index then
return Last (Object.Container.all);
else
return Cursor'(Object.Container, Object.Index);
end if;
end Last;
------------------
-- Last_Element --
------------------
function Last_Element (Container : Vector) return Element_Type is
begin
if Checks and then Container.Last = No_Index then
raise Constraint_Error with "Container is empty";
end if;
declare
EA : constant Element_Access :=
Container.Elements.EA (Container.Last);
begin
if Checks and then EA = null then
raise Constraint_Error with "last element is empty";
else
return EA.all;
end if;
end;
end Last_Element;
----------------
-- Last_Index --
----------------
function Last_Index (Container : Vector) return Extended_Index is
begin
return Container.Last;
end Last_Index;
------------
-- Length --
------------
function Length (Container : Vector) return Count_Type is
L : constant Index_Type'Base := Container.Last;
F : constant Index_Type := Index_Type'First;
begin
-- The base range of the index type (Index_Type'Base) might not include
-- all values for length (Count_Type). Contrariwise, the index type
-- might include values outside the range of length. Hence we use
-- whatever type is wider for intermediate values when calculating
-- length. Note that no matter what the index type is, the maximum
-- length to which a vector is allowed to grow is always the minimum
-- of Count_Type'Last and (IT'Last - IT'First + 1).
-- For example, an Index_Type with range -127 .. 127 is only guaranteed
-- to have a base range of -128 .. 127, but the corresponding vector
-- would have lengths in the range 0 .. 255. In this case we would need
-- to use Count_Type'Base for intermediate values.
-- Another case would be the index range -2**63 + 1 .. -2**63 + 10. The
-- vector would have a maximum length of 10, but the index values lie
-- outside the range of Count_Type (which is only 32 bits). In this
-- case we would need to use Index_Type'Base for intermediate values.
if Count_Type'Base'Last >= Index_Type'Pos (Index_Type'Base'Last) then
return Count_Type'Base (L) - Count_Type'Base (F) + 1;
else
return Count_Type (L - F + 1);
end if;
end Length;
----------
-- Move --
----------
procedure Move
(Target : in out Vector;
Source : in out Vector)
is
begin
if Target'Address = Source'Address then
return;
end if;
TC_Check (Source.TC);
Clear (Target); -- Checks busy-bit
declare
Target_Elements : constant Elements_Access := Target.Elements;
begin
Target.Elements := Source.Elements;
Source.Elements := Target_Elements;
end;
Target.Last := Source.Last;
Source.Last := No_Index;
end Move;
----------
-- Next --
----------
function Next (Position : Cursor) return Cursor is
begin
if Position.Container = null then
return No_Element;
elsif Position.Index < Position.Container.Last then
return (Position.Container, Position.Index + 1);
else
return No_Element;
end if;
end Next;
function Next (Object : Iterator; Position : Cursor) return Cursor is
begin
if Position.Container = null then
return No_Element;
elsif Checks and then Position.Container /= Object.Container then
raise Program_Error with
"Position cursor of Next designates wrong vector";
else
return Next (Position);
end if;
end Next;
procedure Next (Position : in out Cursor) is
begin
if Position.Container = null then
return;
elsif Position.Index < Position.Container.Last then
Position.Index := Position.Index + 1;
else
Position := No_Element;
end if;
end Next;
-------------
-- Prepend --
-------------
procedure Prepend
(Container : in out Vector;
New_Item : Element_Type;
Count : Count_Type := 1)
is
begin
Insert (Container, Index_Type'First, New_Item, Count);
end Prepend;
-------------
-- Prepend_Vector --
-------------
procedure Prepend_Vector (Container : in out Vector; New_Item : Vector) is
begin
Insert_Vector (Container, Index_Type'First, New_Item);
end Prepend_Vector;
--------------
-- Previous --
--------------
function Previous (Position : Cursor) return Cursor is
begin
if Position.Container = null then
return No_Element;
elsif Position.Index > Index_Type'First then
return (Position.Container, Position.Index - 1);
else
return No_Element;
end if;
end Previous;
function Previous (Object : Iterator; Position : Cursor) return Cursor is
begin
if Position.Container = null then
return No_Element;
elsif Checks and then Position.Container /= Object.Container then
raise Program_Error with
"Position cursor of Previous designates wrong vector";
else
return Previous (Position);
end if;
end Previous;
procedure Previous (Position : in out Cursor) is
begin
if Position.Container = null then
return;
elsif Position.Index > Index_Type'First then
Position.Index := Position.Index - 1;
else
Position := No_Element;
end if;
end Previous;
----------------------
-- Pseudo_Reference --
----------------------
function Pseudo_Reference
(Container : aliased Vector'Class) return Reference_Control_Type
is
TC : constant Tamper_Counts_Access := Container.TC'Unrestricted_Access;
begin
return R : constant Reference_Control_Type := (Controlled with TC) do
Busy (TC.all);
end return;
end Pseudo_Reference;
-------------------
-- Query_Element --
-------------------
procedure Query_Element
(Container : Vector;
Index : Index_Type;
Process : not null access procedure (Element : Element_Type))
is
Lock : With_Lock (Container.TC'Unrestricted_Access);
V : Vector renames Container'Unrestricted_Access.all;
begin
if Checks and then Index > Container.Last then
raise Constraint_Error with "Index is out of range";
end if;
if Checks and then V.Elements.EA (Index) = null then
raise Constraint_Error with "element is null";
end if;
Process (V.Elements.EA (Index).all);
end Query_Element;
procedure Query_Element
(Position : Cursor;
Process : not null access procedure (Element : Element_Type))
is
begin
if Checks and then Position.Container = null then
raise Constraint_Error with "Position cursor has no element";
else
Query_Element (Position.Container.all, Position.Index, Process);
end if;
end Query_Element;
---------------
-- Put_Image --
---------------
procedure Put_Image
(S : in out Ada.Strings.Text_Buffers.Root_Buffer_Type'Class; V : Vector)
is
First_Time : Boolean := True;
use System.Put_Images;
procedure Put_Elem (Position : Cursor);
procedure Put_Elem (Position : Cursor) is
begin
if First_Time then
First_Time := False;
else
Simple_Array_Between (S);
end if;
Element_Type'Put_Image (S, Element (Position));
end Put_Elem;
begin
Array_Before (S);
Iterate (V, Put_Elem'Access);
Array_After (S);
end Put_Image;
----------
-- Read --
----------
procedure Read
(Stream : not null access Root_Stream_Type'Class;
Container : out Vector)
is
Length : Count_Type'Base;
Last : Index_Type'Base := Index_Type'Pred (Index_Type'First);
B : Boolean;
begin
Clear (Container);
Count_Type'Base'Read (Stream, Length);
if Length > Capacity (Container) then
Reserve_Capacity (Container, Capacity => Length);
end if;
for J in Count_Type range 1 .. Length loop
Last := Last + 1;
Boolean'Read (Stream, B);
if B then
Container.Elements.EA (Last) :=
new Element_Type'(Element_Type'Input (Stream));
end if;
Container.Last := Last;
end loop;
end Read;
procedure Read
(Stream : not null access Root_Stream_Type'Class;
Position : out Cursor)
is
begin
raise Program_Error with "attempt to stream vector cursor";
end Read;
procedure Read
(Stream : not null access Root_Stream_Type'Class;
Item : out Reference_Type)
is
begin
raise Program_Error with "attempt to stream reference";
end Read;
procedure Read
(Stream : not null access Root_Stream_Type'Class;
Item : out Constant_Reference_Type)
is
begin
raise Program_Error with "attempt to stream reference";
end Read;
---------------
-- Reference --
---------------
function Reference
(Container : aliased in out Vector;
Position : Cursor) return Reference_Type
is
begin
if Checks then
if Position.Container = null then
raise Constraint_Error with "Position cursor has no element";
end if;
if Position.Container /= Container'Unrestricted_Access then
raise Program_Error with "Position cursor denotes wrong container";
end if;
if Position.Index > Position.Container.Last then
raise Constraint_Error with "Position cursor is out of range";
end if;
end if;
declare
TC : constant Tamper_Counts_Access :=
Container.TC'Unrestricted_Access;
begin
-- The following will raise Constraint_Error if Element is null
return R : constant Reference_Type :=
(Element => Container.Elements.EA (Position.Index),
Control => (Controlled with TC))
do
Busy (TC.all);
end return;
end;
end Reference;
function Reference
(Container : aliased in out Vector;
Index : Index_Type) return Reference_Type
is
begin
if Checks and then Index > Container.Last then
raise Constraint_Error with "Index is out of range";
end if;
declare
TC : constant Tamper_Counts_Access :=
Container.TC'Unrestricted_Access;
begin
-- The following will raise Constraint_Error if Element is null
return R : constant Reference_Type :=
(Element => Container.Elements.EA (Index),
Control => (Controlled with TC))
do
Busy (TC.all);
end return;
end;
end Reference;
---------------------
-- Replace_Element --
---------------------
procedure Replace_Element
(Container : in out Vector;
Index : Index_Type;
New_Item : Element_Type)
is
begin
TE_Check (Container.TC);
if Checks and then Index > Container.Last then
raise Constraint_Error with "Index is out of range";
end if;
declare
X : Element_Access := Container.Elements.EA (Index);
-- The element allocator may need an accessibility check in the case
-- where the actual type is class-wide or has access discriminants
-- (see RM 4.8(10.1) and AI12-0035).
pragma Unsuppress (Accessibility_Check);
begin
Container.Elements.EA (Index) := new Element_Type'(New_Item);
Free (X);
end;
end Replace_Element;
procedure Replace_Element
(Container : in out Vector;
Position : Cursor;
New_Item : Element_Type)
is
begin
TE_Check (Container.TC);
if Checks then
if Position.Container = null then
raise Constraint_Error with "Position cursor has no element";
end if;
if Position.Container /= Container'Unrestricted_Access then
raise Program_Error with "Position cursor denotes wrong container";
end if;
if Position.Index > Container.Last then
raise Constraint_Error with "Position cursor is out of range";
end if;
end if;
declare
X : Element_Access := Container.Elements.EA (Position.Index);
-- The element allocator may need an accessibility check in the case
-- where the actual type is class-wide or has access discriminants
-- (see RM 4.8(10.1) and AI12-0035).
pragma Unsuppress (Accessibility_Check);
begin
Container.Elements.EA (Position.Index) := new Element_Type'(New_Item);
Free (X);
end;
end Replace_Element;
----------------------
-- Reserve_Capacity --
----------------------
procedure Reserve_Capacity
(Container : in out Vector;
Capacity : Count_Type)
is
N : constant Count_Type := Length (Container);
Index : Count_Type'Base;
Last : Index_Type'Base;
begin
-- Reserve_Capacity can be used to either expand the storage available
-- for elements (this would be its typical use, in anticipation of
-- future insertion), or to trim back storage. In the latter case,
-- storage can only be trimmed back to the limit of the container
-- length. Note that Reserve_Capacity neither deletes (active) elements
-- nor inserts elements; it only affects container capacity, never
-- container length.
if Capacity = 0 then
-- This is a request to trim back storage, to the minimum amount
-- possible given the current state of the container.
if N = 0 then
-- The container is empty, so in this unique case we can
-- deallocate the entire internal array. Note that an empty
-- container can never be busy, so there's no need to check the
-- tampering bits.
declare
X : Elements_Access := Container.Elements;
begin
-- First we remove the internal array from the container, to
-- handle the case when the deallocation raises an exception
-- (although that's unlikely, since this is simply an array of
-- access values, all of which are null).
Container.Elements := null;
-- Container invariants have been restored, so it is now safe
-- to attempt to deallocate the internal array.
Free (X);
end;
elsif N < Container.Elements.EA'Length then
-- The container is not empty, and the current length is less than
-- the current capacity, so there's storage available to trim. In
-- this case, we allocate a new internal array having a length
-- that exactly matches the number of items in the
-- container. (Reserve_Capacity does not delete active elements,
-- so this is the best we can do with respect to minimizing
-- storage).
TC_Check (Container.TC);
declare
subtype Array_Index_Subtype is Index_Type'Base range
Index_Type'First .. Container.Last;
Src : Elements_Array renames
Container.Elements.EA (Array_Index_Subtype);
X : Elements_Access := Container.Elements;
begin
-- Although we have isolated the old internal array that we're
-- going to deallocate, we don't deallocate it until we have
-- successfully allocated a new one. If there is an exception
-- during allocation (because there is not enough storage), we
-- let it propagate without causing any side-effect.
Container.Elements := new Elements_Type'(Container.Last, Src);
-- We have successfully allocated a new internal array (with a
-- smaller length than the old one, and containing a copy