-- --
-- B o d y --
-- --
--- Copyright (C) 2004-2009, Free Software Foundation, Inc. --
+-- Copyright (C) 2004-2012, 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- --
package body Ada.Containers.Vectors is
- type Int is range System.Min_Int .. System.Max_Int;
- type UInt is mod System.Max_Binary_Modulus;
-
procedure Free is
new Ada.Unchecked_Deallocation (Elements_Type, Elements_Access);
+ type Iterator is new Limited_Controlled and
+ Vector_Iterator_Interfaces.Reversible_Iterator with
+ record
+ Container : Vector_Access;
+ Index : Index_Type'Base;
+ end record;
+
+ overriding procedure Finalize (Object : in out Iterator);
+
+ overriding function First (Object : Iterator) return Cursor;
+ overriding function Last (Object : Iterator) return Cursor;
+
+ overriding function Next
+ (Object : Iterator;
+ Position : Cursor) return Cursor;
+
+ overriding function Previous
+ (Object : Iterator;
+ Position : Cursor) return Cursor;
+
---------
-- "&" --
---------
function "&" (Left, Right : Vector) return Vector is
- LN : constant Count_Type := Length (Left);
- RN : constant Count_Type := Length (Right);
+ LN : constant Count_Type := Length (Left);
+ RN : constant Count_Type := Length (Right);
+ N : Count_Type'Base; -- length of result
+ J : Count_Type'Base; -- for computing intermediate index values
+ Last : Index_Type'Base; -- Last index of result
begin
+ -- We decide that the capacity of the result is 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.
+
+ -- Here we handle the easy cases first, when one of the vector
+ -- parameters is empty. (We say "easy" because there's nothing to
+ -- compute, that can potentially overflow.)
+
if LN = 0 then
if RN = 0 then
return Empty_Vector;
end if;
- declare
- N : constant Int'Base := Int (LN) + Int (RN);
- Last_As_Int : Int'Base;
+ -- Neither of the vector parameters is empty, so must compute the length
+ -- of the result vector and its last index. (This is the harder case,
+ -- because our computations must avoid overflow.)
- begin
- if Int (No_Index) > Int'Last - N then
+ -- 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 combined lengths. Note that we cannot
+ -- simply add the lengths, because of the possibility of overflow.
+
+ if LN > Count_Type'Last - RN then
+ raise Constraint_Error with "new length is out of range";
+ end if;
+
+ -- It is now safe compute the length of the new vector, without fear of
+ -- overflow.
+
+ N := LN + RN;
+
+ -- The second constraint is that the new Last index value cannot
+ -- exceed Index_Type'Last. We use the wider of Index_Type'Base and
+ -- Count_Type'Base as the type for intermediate values.
+
+ if Index_Type'Base'Last >= Count_Type'Pos (Count_Type'Last) then
+
+ -- We perform a two-part test. First we determine whether the
+ -- computed Last value lies in the base range of the type, and then
+ -- determine whether it lies in the range of the index (sub)type.
+
+ -- Last must satisfy this relation:
+ -- First + Length - 1 <= Last
+ -- We regroup terms:
+ -- First - 1 <= Last - Length
+ -- Which can rewrite as:
+ -- No_Index <= Last - Length
+
+ if Index_Type'Base'Last - Index_Type'Base (N) < No_Index then
raise Constraint_Error with "new length is out of range";
end if;
- Last_As_Int := Int (No_Index) + N;
+ -- We now know that the computed value of Last is within the base
+ -- range of the type, so it is safe to compute its value:
- if Last_As_Int > Int (Index_Type'Last) then
+ Last := No_Index + Index_Type'Base (N);
+
+ -- Finally we test whether the value is within the range of the
+ -- generic actual index subtype:
+
+ if Last > Index_Type'Last then
raise Constraint_Error with "new length is out of range";
end if;
- declare
- Last : constant Index_Type := Index_Type (Last_As_Int);
+ elsif Index_Type'First <= 0 then
- LE : Elements_Array renames
- Left.Elements.EA (Index_Type'First .. Left.Last);
+ -- Here we can compute Last directly, in the normal way. We know that
+ -- No_Index is less than 0, so there is no danger of overflow when
+ -- adding the (positive) value of length.
- RE : Elements_Array renames
- Right.Elements.EA (Index_Type'First .. Right.Last);
+ J := Count_Type'Base (No_Index) + N; -- Last
- Elements : constant Elements_Access :=
- new Elements_Type'(Last, LE & RE);
+ if J > Count_Type'Base (Index_Type'Last) then
+ raise Constraint_Error with "new length is out of range";
+ end if;
- begin
- return (Controlled with Elements, Last, 0, 0);
- end;
+ -- We know that the computed value (having type Count_Type) of Last
+ -- is within the range of the generic actual index subtype, so it is
+ -- safe to convert to Index_Type:
+
+ Last := Index_Type'Base (J);
+
+ else
+ -- Here Index_Type'First (and Index_Type'Last) is positive, so we
+ -- must test the length indirectly (by working backwards from the
+ -- largest possible value of Last), in order to prevent overflow.
+
+ J := Count_Type'Base (Index_Type'Last) - N; -- No_Index
+
+ if J < Count_Type'Base (No_Index) then
+ raise Constraint_Error with "new length is out of range";
+ end if;
+
+ -- We have determined that the result length would not create a Last
+ -- index value outside of the range of Index_Type, so we can now
+ -- safely compute its value.
+
+ Last := Index_Type'Base (Count_Type'Base (No_Index) + N);
+ end if;
+
+ declare
+ LE : Elements_Array renames
+ Left.Elements.EA (Index_Type'First .. Left.Last);
+
+ RE : Elements_Array renames
+ Right.Elements.EA (Index_Type'First .. Right.Last);
+
+ Elements : constant Elements_Access :=
+ new Elements_Type'(Last, LE & RE);
+
+ begin
+ return (Controlled with Elements, Last, 0, 0);
end;
end "&";
function "&" (Left : Vector; Right : Element_Type) return Vector is
- LN : constant Count_Type := Length (Left);
-
begin
- if LN = 0 then
+ -- We decide that the capacity of the result is the sum of the lengths
+ -- of the 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.
+
+ -- Handle easy case first, when the vector parameter (Left) is empty
+
+ if Left.Is_Empty then
declare
Elements : constant Elements_Access :=
new Elements_Type'
end;
end if;
- declare
- Last_As_Int : Int'Base;
-
- begin
- if Int (Index_Type'First) > Int'Last - Int (LN) then
- raise Constraint_Error with "new length is out of range";
- end if;
+ -- The vector parameter is not empty, so we must compute the length of
+ -- the result vector and its last index, but in such a way that overflow
+ -- is avoided. We must satisfy two constraints: the new length cannot
+ -- exceed Count_Type'Last, and the new Last index cannot exceed
+ -- Index_Type'Last.
- Last_As_Int := Int (Index_Type'First) + Int (LN);
+ if Left.Length = Count_Type'Last then
+ raise Constraint_Error with "new length is out of range";
+ end if;
- if Last_As_Int > Int (Index_Type'Last) then
- raise Constraint_Error with "new length is out of range";
- end if;
+ if Left.Last >= Index_Type'Last then
+ raise Constraint_Error with "new length is out of range";
+ end if;
- declare
- Last : constant Index_Type := Index_Type (Last_As_Int);
+ declare
+ Last : constant Index_Type := Left.Last + 1;
- LE : Elements_Array renames
- Left.Elements.EA (Index_Type'First .. Left.Last);
+ LE : Elements_Array renames
+ Left.Elements.EA (Index_Type'First .. Left.Last);
- Elements : constant Elements_Access :=
- new Elements_Type'
- (Last => Last,
- EA => LE & Right);
+ Elements : constant Elements_Access :=
+ new Elements_Type'(Last => Last, EA => LE & Right);
- begin
- return (Controlled with Elements, Last, 0, 0);
- end;
+ begin
+ return (Controlled with Elements, Last, 0, 0);
end;
end "&";
function "&" (Left : Element_Type; Right : Vector) return Vector is
- RN : constant Count_Type := Length (Right);
-
begin
- if RN = 0 then
+ -- We decide that the capacity of the result is the sum of the lengths
+ -- of the 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.
+
+ -- Handle easy case first, when the vector parameter (Right) is empty
+
+ if Right.Is_Empty then
declare
Elements : constant Elements_Access :=
new Elements_Type'
end;
end if;
- declare
- Last_As_Int : Int'Base;
-
- begin
- if Int (Index_Type'First) > Int'Last - Int (RN) then
- raise Constraint_Error with "new length is out of range";
- end if;
+ -- The vector parameter is not empty, so we must compute the length of
+ -- the result vector and its last index, but in such a way that overflow
+ -- is avoided. We must satisfy two constraints: the new length cannot
+ -- exceed Count_Type'Last, and the new Last index cannot exceed
+ -- Index_Type'Last.
- Last_As_Int := Int (Index_Type'First) + Int (RN);
+ if Right.Length = Count_Type'Last then
+ raise Constraint_Error with "new length is out of range";
+ end if;
- if Last_As_Int > Int (Index_Type'Last) then
- raise Constraint_Error with "new length is out of range";
- end if;
+ if Right.Last >= Index_Type'Last then
+ raise Constraint_Error with "new length is out of range";
+ end if;
- declare
- Last : constant Index_Type := Index_Type (Last_As_Int);
+ declare
+ Last : constant Index_Type := Right.Last + 1;
- RE : Elements_Array renames
- Right.Elements.EA (Index_Type'First .. Right.Last);
+ RE : Elements_Array renames
+ Right.Elements.EA (Index_Type'First .. Right.Last);
- Elements : constant Elements_Access :=
- new Elements_Type'
- (Last => Last,
- EA => Left & RE);
+ Elements : constant Elements_Access :=
+ new Elements_Type'
+ (Last => Last,
+ EA => Left & RE);
- begin
- return (Controlled with Elements, Last, 0, 0);
- end;
+ begin
+ return (Controlled with Elements, Last, 0, 0);
end;
end "&";
function "&" (Left, Right : Element_Type) return Vector is
begin
+ -- We decide that the capacity of the result is the sum of the lengths
+ -- of the 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.
+
+ -- We must compute the length of the result vector and its last index,
+ -- but in such a way that overflow is avoided. We must satisfy two
+ -- constraints: the new length cannot exceed Count_Type'Last (here, we
+ -- know that that condition is satisfied), and the new Last index cannot
+ -- exceed Index_Type'Last.
+
if Index_Type'First >= Index_Type'Last then
raise Constraint_Error with "new length is out of range";
end if;
end;
end Adjust;
+ procedure Adjust (Control : in out Reference_Control_Type) is
+ begin
+ if Control.Container /= null then
+ declare
+ C : Vector renames Control.Container.all;
+ B : Natural renames C.Busy;
+ L : Natural renames C.Lock;
+ begin
+ B := B + 1;
+ L := L + 1;
+ end;
+ end if;
+ end Adjust;
+
------------
-- Append --
------------
Count);
end Append;
+ ------------
+ -- Assign --
+ ------------
+
+ procedure Assign (Target : in out Vector; Source : Vector) is
+ begin
+ if Target'Address = Source'Address then
+ return;
+ end if;
+
+ Target.Clear;
+ Target.Append (Source);
+ end Assign;
+
--------------
-- Capacity --
--------------
begin
if Container.Elements = null then
return 0;
+ else
+ return Container.Elements.EA'Length;
end if;
-
- return Container.Elements.EA'Length;
end Capacity;
-----------
begin
if Container.Busy > 0 then
raise Program_Error with
- "attempt to tamper with elements (vector is busy)";
+ "attempt to tamper with cursors (vector is busy)";
+ else
+ Container.Last := No_Index;
end if;
-
- Container.Last := No_Index;
end Clear;
+ ------------------------
+ -- Constant_Reference --
+ ------------------------
+
+ function Constant_Reference
+ (Container : aliased Vector;
+ Position : Cursor) return Constant_Reference_Type
+ is
+ begin
+ 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;
+
+ declare
+ C : Vector renames Position.Container.all;
+ B : Natural renames C.Busy;
+ L : Natural renames C.Lock;
+ begin
+ return R : constant Constant_Reference_Type :=
+ (Element =>
+ Container.Elements.EA (Position.Index)'Access,
+ Control =>
+ (Controlled with Container'Unrestricted_Access))
+ do
+ B := B + 1;
+ L := L + 1;
+ end return;
+ end;
+ end Constant_Reference;
+
+ function Constant_Reference
+ (Container : aliased Vector;
+ Index : Index_Type) return Constant_Reference_Type
+ is
+ begin
+ if Index > Container.Last then
+ raise Constraint_Error with "Index is out of range";
+ else
+ declare
+ C : Vector renames Container'Unrestricted_Access.all;
+ B : Natural renames C.Busy;
+ L : Natural renames C.Lock;
+ begin
+ return R : constant Constant_Reference_Type :=
+ (Element => Container.Elements.EA (Index)'Access,
+ Control =>
+ (Controlled with Container'Unrestricted_Access))
+ do
+ B := B + 1;
+ L := L + 1;
+ end return;
+ end;
+ end if;
+ end Constant_Reference;
+
--------------
-- Contains --
--------------
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 = 0 then
+ C := Source.Length;
+
+ elsif Capacity >= Source.Length then
+ C := Capacity;
+
+ else
+ raise Capacity_Error
+ with "Requested capacity is less than Source length";
+ end if;
+
+ return Target : Vector do
+ Target.Reserve_Capacity (C);
+ Target.Assign (Source);
+ end return;
+ end Copy;
+
------------
-- Delete --
------------
Index : Extended_Index;
Count : Count_Type := 1)
is
- begin
+ 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
+ -- 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 Index < Index_Type'First then
raise Constraint_Error with "Index is out of range (too small)";
end if;
- if Index > Container.Last then
- if Index > Container.Last + 1 then
+ -- 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 Index > Old_Last + 1 then
raise Constraint_Error with "Index is out of range (too large)";
end if;
return;
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 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.
+
if Container.Busy > 0 then
raise Program_Error with
- "attempt to tamper with elements (vector is busy)";
+ "attempt to tamper with cursors (vector is busy)";
end if;
- declare
- I_As_Int : constant Int := Int (Index);
- Old_Last_As_Int : constant Int := Index_Type'Pos (Container.Last);
+ -- 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.)
- Count1 : constant Int'Base := Count_Type'Pos (Count);
- Count2 : constant Int'Base := Old_Last_As_Int - I_As_Int + 1;
- N : constant Int'Base := Int'Min (Count1, Count2);
+ if Count_Type'Base'Last >= Index_Type'Pos (Index_Type'Base'Last) then
+ Count2 := Count_Type'Base (Old_Last) - Count_Type'Base (Index) + 1;
- J_As_Int : constant Int'Base := I_As_Int + N;
+ else
+ Count2 := Count_Type'Base (Old_Last - Index + 1);
+ end if;
- begin
- if J_As_Int > Old_Last_As_Int then
- Container.Last := Index - 1;
+ -- If more elements are requested (Count) for deletion than are
+ -- available (Count2) for deletion beginning at Index, then everything
+ -- from Index is deleted. There are no elements to slide down, and so
+ -- all we need to do is set the value of Container.Last.
- else
- declare
- J : constant Index_Type := Index_Type (J_As_Int);
- EA : Elements_Array renames Container.Elements.EA;
+ if Count >= Count2 then
+ Container.Last := Index - 1;
+ return;
+ end if;
- New_Last_As_Int : constant Int'Base := Old_Last_As_Int - N;
- New_Last : constant Index_Type :=
- Index_Type (New_Last_As_Int);
+ -- There are some elements 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.
- begin
- EA (Index .. New_Last) := EA (J .. Container.Last);
- Container.Last := New_Last;
- end;
- end if;
+ if Index_Type'Base'Last >= Count_Type'Pos (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 we just slide down to Index the elements
+ -- that weren't deleted.
+
+ declare
+ EA : Elements_Array renames Container.Elements.EA;
+
+ begin
+ EA (Index .. New_Last) := EA (J .. Old_Last);
+ Container.Last := New_Last;
end;
end Delete;
(Container : in out Vector;
Count : Count_Type := 1)
is
- Index : Int'Base;
-
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;
+ -- 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.
+
if Container.Busy > 0 then
raise Program_Error with
- "attempt to tamper with elements (vector is busy)";
+ "attempt to tamper with cursors (vector is busy)";
end if;
- Index := Int'Base (Container.Last) - Int'Base (Count);
+ -- There is no restriction on how large Count can be when deleting
+ -- items. If it is equal or greater than the current length, then this
+ -- is equivalent to clearing the vector. (In particular, there's no need
+ -- for us to actually calculate the new value for Last.)
- Container.Last :=
- (if Index < Index_Type'Pos (Index_Type'First)
- then No_Index
- else Index_Type (Index));
+ -- If the requested count is less than the current length, then we must
+ -- calculate the new value for Last. For the type we use the widest of
+ -- Index_Type'Base and Count_Type'Base for the intermediate values of
+ -- our calculation. (See the comments in Length for more information.)
+
+ if Count >= Container.Length then
+ Container.Last := No_Index;
+
+ elsif Index_Type'Base'Last >= Count_Type'Pos (Count_Type'Last) then
+ Container.Last := Container.Last - Index_Type'Base (Count);
+
+ else
+ Container.Last :=
+ Index_Type'Base (Count_Type'Base (Container.Last) - Count);
+ end if;
end Delete_Last;
-------------
begin
if Position.Container = null then
raise Constraint_Error with "Position cursor has no element";
- end if;
-
- if Position.Index > Position.Container.Last then
+ elsif Position.Index > Position.Container.Last then
raise Constraint_Error with "Position cursor is out of range";
+ else
+ return Position.Container.Elements.EA (Position.Index);
end if;
-
- return Position.Container.Elements.EA (Position.Index);
end Element;
--------------
begin
if Container.Busy > 0 then
raise Program_Error with
- "attempt to tamper with elements (vector is busy)";
+ "attempt to tamper with cursors (vector is busy)";
end if;
Container.Elements := null;
Free (X);
end Finalize;
+ procedure Finalize (Object : in out Iterator) is
+ B : Natural renames Object.Container.Busy;
+ begin
+ B := B - 1;
+ end Finalize;
+
+ procedure Finalize (Control : in out Reference_Control_Type) is
+ begin
+ if Control.Container /= null then
+ declare
+ C : Vector renames Control.Container.all;
+ B : Natural renames C.Busy;
+ L : Natural renames C.Lock;
+ begin
+ B := B - 1;
+ L := L - 1;
+ end;
+
+ Control.Container := null;
+ end if;
+ end Finalize;
+
----------
-- Find --
----------
for J in Position.Index .. Container.Last loop
if Container.Elements.EA (J) = Item then
- return (Container'Unchecked_Access, J);
+ return (Container'Unrestricted_Access, J);
end if;
end loop;
begin
if Is_Empty (Container) then
return No_Element;
+ else
+ return (Container'Unrestricted_Access, Index_Type'First);
end if;
+ 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).
- return (Container'Unchecked_Access, Index_Type'First);
+ -- 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;
-------------------
begin
if Container.Last = No_Index then
raise Constraint_Error with "Container is empty";
+ else
+ return Container.Elements.EA (Index_Type'First);
end if;
-
- return Container.Elements.EA (Index_Type'First);
end First_Element;
-----------------
declare
EA : Elements_Array renames Container.Elements.EA;
begin
- for I in Index_Type'First .. Container.Last - 1 loop
- if EA (I + 1) < EA (I) then
+ for J in Index_Type'First .. Container.Last - 1 loop
+ if EA (J + 1) < EA (J) then
return False;
end if;
end loop;
J : Index_Type'Base;
begin
- if Target.Last < Index_Type'First then
- Move (Target => Target, Source => Source);
+ -- 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 Target'Address = Source'Address then
- return;
+ raise Program_Error with
+ "Target and Source denote same non-empty container";
end if;
- if Source.Last < Index_Type'First then
+ if Target.Last < Index_Type'First then -- Target is empty
+ Move (Target => Target, Source => Source);
return;
end if;
if Source.Busy > 0 then
raise Program_Error with
- "attempt to tamper with elements (vector is busy)";
+ "attempt to tamper with cursors (vector is busy)";
end if;
Target.Set_Length (Length (Target) + Length (Source));
-- Sort --
----------
- procedure Sort (Container : in out Vector)
- is
+ procedure Sort (Container : in out Vector) is
procedure Sort is
new Generic_Array_Sort
(Index_Type => Index_Type,
return;
end if;
- if Container.Lock > 0 then
+ -- 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.
+
+ if Container.Busy > 0 then
raise Program_Error with
- "attempt to tamper with cursors (vector is locked)";
+ "attempt to tamper with cursors (vector is busy)";
end if;
Sort (Container.Elements.EA (Index_Type'First .. Container.Last));
function Has_Element (Position : Cursor) return Boolean is
begin
- if Position.Container = null then
- return False;
- end if;
-
- return Position.Index <= Position.Container.Last;
+ return Position /= No_Element;
end Has_Element;
------------
New_Item : Element_Type;
Count : Count_Type := 1)
is
- N : constant Int := Count_Type'Pos (Count);
+ 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
- First : constant Int := Int (Index_Type'First);
- New_Last_As_Int : Int'Base;
- New_Last : Index_Type;
- New_Length : UInt;
- Max_Length : constant UInt := UInt (Count_Type'Last);
+ Index : Index_Type'Base; -- scratch for intermediate values
+ J : Count_Type'Base; -- scratch
- Dst : Elements_Access;
+ 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
+ -- 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
and then Before > Container.Last + 1
then
"Before index is out of range (too large)";
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;
- declare
- Old_Last_As_Int : constant Int := Int (Container.Last);
+ -- 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.
- begin
- if Old_Last_As_Int > Int'Last - N then
- raise Constraint_Error with "new length is out of range";
- end if;
+ if Old_Length > Count_Type'Last - Count then
+ raise Constraint_Error with "Count is out of range";
+ end if;
- New_Last_As_Int := Old_Last_As_Int + N;
+ -- It is now safe compute the length of the new vector, without fear of
+ -- overflow.
- if New_Last_As_Int > Int (Index_Type'Last) then
- raise Constraint_Error with "new length is out of range";
- end if;
+ New_Length := Old_Length + Count;
- New_Length := UInt (New_Last_As_Int - First + Int'(1));
+ -- 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 New_Length > Max_Length then
- raise Constraint_Error with "new length is out of range";
- end if;
+ if Index_Type'Base'Last >= Count_Type'Pos (Count_Type'Last) then
- New_Last := Index_Type (New_Last_As_Int);
- end;
+ -- 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 Container.Busy > 0 then
- raise Program_Error with
- "attempt to tamper with elements (vector is busy)";
+ 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).
+
+ Max_Length := Count_Type'Base (Index_Type'Last - No_Index);
+ 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 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'Pos (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 order to preserve container invariants, we allocate the new
+ -- internal array first, before setting the Last index value, in case
+ -- the allocation fails (which can happen either because there is no
+ -- storage available, or because element initialization fails).
+
Container.Elements := new Elements_Type'
(Last => New_Last,
EA => (others => New_Item));
+
+ -- The allocation of the new, internal array succeeded, so it is now
+ -- safe to update the Last index, restoring container invariants.
+
Container.Last := New_Last;
+
return;
end if;
- if New_Last <= Container.Elements.Last then
+ -- 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.
+
+ if Container.Busy > 0 then
+ raise Program_Error with
+ "attempt to tamper with cursors (vector is busy)";
+ end if;
+
+ -- An internal array has already been allocated, so we must determine
+ -- whether there is enough unused storage for the new items.
+
+ 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
EA : Elements_Array renames Container.Elements.EA;
begin
- if Before <= Container.Last then
- declare
- Index_As_Int : constant Int'Base :=
- Index_Type'Pos (Before) + N;
-
- Index : constant Index_Type := Index_Type (Index_As_Int);
+ if Before > Container.Last then
- begin
- EA (Index .. New_Last) := EA (Before .. Container.Last);
+ -- The new items are being appended to the vector, so no
+ -- sliding of existing elements is required.
- EA (Before .. Index_Type'Pred (Index)) :=
- (others => New_Item);
- end;
+ EA (Before .. New_Last) := (others => New_Item);
else
- EA (Before .. New_Last) := (others => New_Item);
+ -- 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'Pos (Count_Type'Last) then
+ Index := Before + Index_Type'Base (Count);
+
+ else
+ Index := Index_Type'Base (Count_Type'Base (Before) + Count);
+ end if;
+
+ EA (Index .. New_Last) := EA (Before .. Container.Last);
+ EA (Before .. Index - 1) := (others => New_Item);
end if;
end;
return;
end if;
- declare
- C, CC : UInt;
+ -- 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;
- begin
- C := UInt'Max (1, Container.Elements.EA'Length); -- ???
- while C < New_Length loop
- if C > UInt'Last / 2 then
- C := UInt'Last;
- exit;
- end if;
+ New_Capacity := 2 * New_Capacity;
+ end loop;
- C := 2 * C;
- end loop;
+ if New_Capacity > Max_Length then
- if C > Max_Length then
- C := Max_Length;
- end if;
+ -- 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.)
- if Index_Type'First <= 0
- and then Index_Type'Last >= 0
- then
- CC := UInt (Index_Type'Last) + UInt (-Index_Type'First) + 1;
- else
- CC := UInt (Int (Index_Type'Last) - First + 1);
- end if;
+ New_Capacity := Max_Length;
+ end if;
- if C > CC then
- C := CC;
- 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.
- declare
- Dst_Last : constant Index_Type :=
- Index_Type (First + UInt'Pos (C) - 1);
+ if Index_Type'Base'Last >= Count_Type'Pos (Count_Type'Last) then
+ Dst_Last := No_Index + Index_Type'Base (New_Capacity);
- begin
- Dst := new Elements_Type (Dst_Last);
- end;
- end;
+ 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, object SA below) to the new array (the "destination" array,
+ -- object DA below), and then deallocate the old array.
declare
- SA : Elements_Array renames Container.Elements.EA;
- DA : Elements_Array renames Dst.EA;
+ SA : Elements_Array renames Container.Elements.EA; -- source
+ DA : Elements_Array renames Dst.EA; -- destination
begin
- DA (Index_Type'First .. Index_Type'Pred (Before)) :=
- SA (Index_Type'First .. Index_Type'Pred (Before));
+ DA (Index_Type'First .. Before - 1) :=
+ SA (Index_Type'First .. Before - 1);
- if Before <= Container.Last then
- declare
- Index_As_Int : constant Int'Base :=
- Index_Type'Pos (Before) + N;
+ if Before > Container.Last then
+ DA (Before .. New_Last) := (others => New_Item);
- Index : constant Index_Type := Index_Type (Index_As_Int);
+ else
+ -- The new items are being inserted before some existing elements,
+ -- so we must slide the existing elements up to their new home.
- begin
- DA (Before .. Index_Type'Pred (Index)) := (others => New_Item);
- DA (Index .. New_Last) := SA (Before .. Container.Last);
- end;
+ if Index_Type'Base'Last >= Count_Type'Pos (Count_Type'Last) then
+ Index := Before + Index_Type'Base (Count);
- else
- DA (Before .. New_Last) := (others => New_Item);
+ else
+ Index := Index_Type'Base (Count_Type'Base (Before) + Count);
+ end if;
+
+ DA (Before .. Index - 1) := (others => New_Item);
+ DA (Index .. New_Last) := SA (Before .. Container.Last);
end if;
+
exception
when others =>
Free (Dst);
raise;
end;
+ -- We have successfully copied the items onto the new array, so the
+ -- final thing to do is deallocate the old array.
+
declare
X : Elements_Access := Container.Elements;
begin
+ -- We first isolate the old internal array, removing it from the
+ -- container and replacing it with the new internal array, before we
+ -- deallocate the old array (which can fail if finalization of
+ -- elements propagates an exception).
+
Container.Elements := Dst;
Container.Last := New_Last;
+
+ -- The container invariants have been restored, so it is now safe to
+ -- attempt to deallocate the old array.
+
Free (X);
end;
end Insert;
New_Item : Vector)
is
N : constant Count_Type := Length (New_Item);
+ J : Index_Type'Base;
begin
- if Before < Index_Type'First then
- raise Constraint_Error with
- "Before index is out of range (too small)";
+ -- 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 Before > Container.Last
- and then Before > Container.Last + 1
- then
- raise Constraint_Error with
- "Before index is out of range (too large)";
+ -- We calculate the last index value of the destination slice using the
+ -- wider of Index_Type'Base and count_Type'Base.
+
+ if Index_Type'Base'Last >= Count_Type'Pos (Count_Type'Last) then
+ J := (Before - 1) + Index_Type'Base (N);
+
+ else
+ J := Index_Type'Base (Count_Type'Base (Before - 1) + N);
end if;
- if N = 0 then
+ 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.
+
+ Container.Elements.EA (Before .. J) :=
+ New_Item.Elements.EA (Index_Type'First .. New_Item.Last);
+
return;
end if;
- Insert_Space (Container, Before, Count => N);
+ -- New_Item denotes the same object as Container, so an insertion has
+ -- potentially split the source items. The destination is always the
+ -- range [Before, J], but the source is [Index_Type'First, Before) and
+ -- (J, Container.Last]. We perform the copy in two steps, using each of
+ -- the two slices of the source items.
declare
- Dst_Last_As_Int : constant Int'Base :=
- Int'Base (Before) + Int'Base (N) - 1;
+ L : constant Index_Type'Base := Before - 1;
- Dst_Last : constant Index_Type := Index_Type (Dst_Last_As_Int);
+ subtype Src_Index_Subtype is Index_Type'Base range
+ Index_Type'First .. L;
- begin
- if Container'Address /= New_Item'Address then
- Container.Elements.EA (Before .. Dst_Last) :=
- New_Item.Elements.EA (Index_Type'First .. New_Item.Last);
+ Src : Elements_Array renames
+ Container.Elements.EA (Src_Index_Subtype);
- return;
- end if;
+ K : Index_Type'Base;
- declare
- subtype Src_Index_Subtype is Index_Type'Base range
- Index_Type'First .. Before - 1;
+ begin
+ -- We first copy the source items that precede the space we
+ -- inserted. Index value K is the last index of that portion
+ -- destination that receives this slice of the source. (If Before
+ -- equals Index_Type'First, then this first source slice will be
+ -- empty, which is harmless.)
- Src : Elements_Array renames
- Container.Elements.EA (Src_Index_Subtype);
+ if Index_Type'Base'Last >= Count_Type'Pos (Count_Type'Last) then
+ K := L + Index_Type'Base (Src'Length);
- Index_As_Int : constant Int'Base :=
- Int (Before) + Src'Length - 1;
+ else
+ K := Index_Type'Base (Count_Type'Base (L) + Src'Length);
+ end if;
- Index : constant Index_Type'Base :=
- Index_Type'Base (Index_As_Int);
+ Container.Elements.EA (Before .. K) := Src;
- Dst : Elements_Array renames
- Container.Elements.EA (Before .. Index);
+ if Src'Length = N then
- begin
- Dst := Src;
- end;
+ -- 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 + 1, which will overflow if J equals
+ -- Index_Type'Base'Last.
- if Dst_Last = Container.Last then
return;
end if;
+ end;
- declare
- subtype Src_Index_Subtype is Index_Type'Base range
- Dst_Last + 1 .. Container.Last;
+ declare
+ -- Note that we want to avoid computing J + 1 here, in case J equals
+ -- Index_Type'Base'Last. We 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.
- Src : Elements_Array renames
- Container.Elements.EA (Src_Index_Subtype);
+ F : constant Index_Type'Base := J + 1;
- Index_As_Int : constant Int'Base :=
- Dst_Last_As_Int - Src'Length + 1;
+ subtype Src_Index_Subtype is Index_Type'Base range
+ F .. Container.Last;
- Index : constant Index_Type :=
- Index_Type (Index_As_Int);
+ Src : Elements_Array renames
+ Container.Elements.EA (Src_Index_Subtype);
- Dst : Elements_Array renames
- Container.Elements.EA (Index .. Dst_Last);
+ K : Index_Type'Base;
- begin
- Dst := Src;
- end;
+ begin
+ -- We next copy the source items that follow the space we inserted.
+ -- Index value K 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'Pos (Count_Type'Last) then
+ K := F - Index_Type'Base (Src'Length);
+
+ else
+ K := Index_Type'Base (Count_Type'Base (F) - Src'Length);
+ end if;
+
+ Container.Elements.EA (K .. J) := Src;
end;
end Insert;
begin
if Before.Container /= null
- and then Before.Container /= Container'Unchecked_Access
+ and then Before.Container /= Container'Unrestricted_Access
then
raise Program_Error with "Before cursor denotes wrong container";
end if;
begin
if Before.Container /= null
- and then Before.Container /= Container'Unchecked_Access
+ and then Before.Container /= Container'Unrestricted_Access
then
raise Program_Error with "Before cursor denotes wrong container";
end if;
then
Position := No_Element;
else
- Position := (Container'Unchecked_Access, Before.Index);
+ Position := (Container'Unrestricted_Access, Before.Index);
end if;
return;
Insert (Container, Index, New_Item);
- Position := Cursor'(Container'Unchecked_Access, Index);
+ Position := (Container'Unrestricted_Access, Index);
end Insert;
procedure Insert
begin
if Before.Container /= null
- and then Before.Container /= Container'Unchecked_Access
+ and then Before.Container /= Container'Unrestricted_Access
then
raise Program_Error with "Before cursor denotes wrong container";
end if;
if Container.Last = Index_Type'Last then
raise Constraint_Error with
"vector is already at its maximum length";
+ else
+ Index := Container.Last + 1;
end if;
- Index := Container.Last + 1;
-
else
Index := Before.Index;
end if;
begin
if Before.Container /= null
- and then Before.Container /= Container'Unchecked_Access
+ and then Before.Container /= Container'Unrestricted_Access
then
raise Program_Error with "Before cursor denotes wrong container";
end if;
then
Position := No_Element;
else
- Position := (Container'Unchecked_Access, Before.Index);
+ Position := (Container'Unrestricted_Access, Before.Index);
end if;
return;
Insert (Container, Index, New_Item, Count);
- Position := Cursor'(Container'Unchecked_Access, Index);
+ Position := (Container'Unrestricted_Access, Index);
end Insert;
procedure Insert
Before : Extended_Index;
Count : Count_Type := 1)
is
- N : constant Int := Count_Type'Pos (Count);
+ 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
- First : constant Int := Int (Index_Type'First);
- New_Last_As_Int : Int'Base;
- New_Last : Index_Type;
- New_Length : UInt;
- Max_Length : constant UInt := UInt (Count_Type'Last);
+ Index : Index_Type'Base; -- scratch for intermediate values
+ J : Count_Type'Base; -- scratch
- Dst : Elements_Access;
+ 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
+ -- 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
and then Before > Container.Last + 1
then
"Before index is out of range (too large)";
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;
- declare
- Old_Last_As_Int : constant Int := Int (Container.Last);
+ -- 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.
- begin
- if Old_Last_As_Int > Int'Last - N then
- raise Constraint_Error with "new length is out of range";
- end if;
+ if Old_Length > Count_Type'Last - Count then
+ raise Constraint_Error with "Count is out of range";
+ end if;
- New_Last_As_Int := Old_Last_As_Int + N;
+ -- It is now safe compute the length of the new vector, without fear of
+ -- overflow.
- if New_Last_As_Int > Int (Index_Type'Last) then
- raise Constraint_Error with "new length is out of range";
+ 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'Pos (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).
+
+ Max_Length := Count_Type'Base (Index_Type'Last - No_Index);
end if;
- New_Length := UInt (New_Last_As_Int - First + Int'(1));
+ elsif Index_Type'First <= 0 then
- if New_Length > Max_Length then
- raise Constraint_Error with "new length is out of range";
+ -- 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;
- New_Last := Index_Type (New_Last_As_Int);
- end;
+ 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 Container.Busy > 0 then
- raise Program_Error with
- "attempt to tamper with elements (vector is busy)";
+ 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 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'Pos (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 order to preserve container invariants, we allocate the new
+ -- internal array first, before setting the Last index value, in case
+ -- the allocation fails (which can happen either because there is no
+ -- storage available, or because default-valued element
+ -- initialization fails).
+
Container.Elements := new Elements_Type (New_Last);
+
+ -- The allocation of the new, internal array succeeded, so it is now
+ -- safe to update the Last index, restoring container invariants.
+
Container.Last := New_Last;
+
return;
end if;
+ -- 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.
+
+ if Container.Busy > 0 then
+ raise Program_Error with
+ "attempt to tamper with cursors (vector is busy)";
+ end if;
+
+ -- An internal array has already been allocated, so we must determine
+ -- whether there is enough unused storage for the new items.
+
if New_Last <= Container.Elements.Last then
+
+ -- In this case, we're inserting space into a vector that has already
+ -- allocated an internal array, and the existing array has enough
+ -- unused storage for the new items.
+
declare
EA : Elements_Array renames Container.Elements.EA;
+
begin
if Before <= Container.Last then
- declare
- Index_As_Int : constant Int'Base :=
- Index_Type'Pos (Before) + N;
- Index : constant Index_Type := Index_Type (Index_As_Int);
+ -- The 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'Pos (Count_Type'Last) then
+ Index := Before + Index_Type'Base (Count);
+
+ else
+ Index := Index_Type'Base (Count_Type'Base (Before) + Count);
+ end if;
- begin
- EA (Index .. New_Last) := EA (Before .. Container.Last);
- end;
+ EA (Index .. New_Last) := EA (Before .. Container.Last);
end if;
end;
return;
end if;
- declare
- C, CC : UInt;
+ -- In this case, we're inserting space 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;
- begin
- C := UInt'Max (1, Container.Elements.EA'Length); -- ???
- while C < New_Length loop
- if C > UInt'Last / 2 then
- C := UInt'Last;
- exit;
- end if;
+ New_Capacity := 2 * New_Capacity;
+ end loop;
- C := 2 * C;
- end loop;
+ if New_Capacity > Max_Length then
- if C > Max_Length then
- C := Max_Length;
- end if;
+ -- 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.)
- if Index_Type'First <= 0
- and then Index_Type'Last >= 0
- then
- CC := UInt (Index_Type'Last) + UInt (-Index_Type'First) + 1;
- else
- CC := UInt (Int (Index_Type'Last) - First + 1);
- end if;
+ New_Capacity := Max_Length;
+ end if;
- if C > CC then
- C := CC;
- 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.
- declare
- Dst_Last : constant Index_Type :=
- Index_Type (First + UInt'Pos (C) - 1);
+ if Index_Type'Base'Last >= Count_Type'Pos (Count_Type'Last) then
+ Dst_Last := No_Index + Index_Type'Base (New_Capacity);
- begin
- Dst := new Elements_Type (Dst_Last);
- end;
- end;
+ 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, object SA below) to the new array (the "destination" array,
+ -- object DA below), and then deallocate the old array.
declare
- SA : Elements_Array renames Container.Elements.EA;
- DA : Elements_Array renames Dst.EA;
+ SA : Elements_Array renames Container.Elements.EA; -- source
+ DA : Elements_Array renames Dst.EA; -- destination
begin
- DA (Index_Type'First .. Index_Type'Pred (Before)) :=
- SA (Index_Type'First .. Index_Type'Pred (Before));
+ DA (Index_Type'First .. Before - 1) :=
+ SA (Index_Type'First .. Before - 1);
if Before <= Container.Last then
- declare
- Index_As_Int : constant Int'Base :=
- Index_Type'Pos (Before) + N;
- Index : constant Index_Type := Index_Type (Index_As_Int);
+ -- The space is being inserted before some existing elements, so
+ -- we must slide the existing elements up to their new home.
- begin
- DA (Index .. New_Last) := SA (Before .. Container.Last);
- end;
+ if Index_Type'Base'Last >= Count_Type'Pos (Count_Type'Last) then
+ Index := Before + Index_Type'Base (Count);
+
+ else
+ Index := Index_Type'Base (Count_Type'Base (Before) + Count);
+ end if;
+
+ DA (Index .. New_Last) := SA (Before .. Container.Last);
end if;
+
exception
when others =>
Free (Dst);
raise;
end;
+ -- We have successfully copied the items onto the new array, so the
+ -- final thing to do is restore invariants, and deallocate the old
+ -- array.
+
declare
X : Elements_Access := Container.Elements;
+
begin
+ -- We first isolate the old internal array, removing it from the
+ -- container and replacing it with the new internal array, before we
+ -- deallocate the old array (which can fail if finalization of
+ -- elements propagates an exception).
+
Container.Elements := Dst;
Container.Last := New_Last;
+
+ -- The container invariants have been restored, so it is now safe to
+ -- attempt to deallocate the old array.
+
Free (X);
end;
end Insert_Space;
begin
if Before.Container /= null
- and then Before.Container /= Container'Unchecked_Access
+ and then Before.Container /= Container'Unrestricted_Access
then
raise Program_Error with "Before cursor denotes wrong container";
end if;
then
Position := No_Element;
else
- Position := (Container'Unchecked_Access, Before.Index);
+ Position := (Container'Unrestricted_Access, Before.Index);
end if;
return;
if Container.Last = Index_Type'Last then
raise Constraint_Error with
"vector is already at its maximum length";
+ else
+ Index := Container.Last + 1;
end if;
- Index := Container.Last + 1;
-
else
Index := Before.Index;
end if;
Insert_Space (Container, Index, Count => Count);
- Position := Cursor'(Container'Unchecked_Access, Index);
+ Position := (Container'Unrestricted_Access, Index);
end Insert_Space;
--------------
(Container : Vector;
Process : not null access procedure (Position : Cursor))
is
- V : Vector renames Container'Unrestricted_Access.all;
- B : Natural renames V.Busy;
+ B : Natural renames Container'Unrestricted_Access.all.Busy;
begin
B := B + 1;
begin
for Indx in Index_Type'First .. Container.Last loop
- Process (Cursor'(Container'Unchecked_Access, Indx));
+ Process (Cursor'(Container'Unrestricted_Access, Indx));
end loop;
exception
when others =>
B := B - 1;
end Iterate;
+ function Iterate
+ (Container : Vector)
+ return Vector_Iterator_Interfaces.Reversible_Iterator'Class
+ is
+ V : constant Vector_Access := Container'Unrestricted_Access;
+ B : Natural renames V.Busy;
+
+ 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
+ B := B + 1;
+ 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;
+ B : Natural renames V.Busy;
+
+ 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 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;
+
+ -- 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
+ B := B + 1;
+ end return;
+ end Iterate;
+
----------
-- Last --
----------
begin
if Is_Empty (Container) then
return No_Element;
+ else
+ return (Container'Unrestricted_Access, Container.Last);
end if;
+ end Last;
- return (Container'Unchecked_Access, Container.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;
------------------
begin
if Container.Last = No_Index then
raise Constraint_Error with "Container is empty";
+ else
+ return Container.Elements.EA (Container.Last);
end if;
-
- return Container.Elements.EA (Container.Last);
end Last_Element;
----------------
------------
function Length (Container : Vector) return Count_Type is
- L : constant Int := Int (Container.Last);
- F : constant Int := Int (Index_Type'First);
- N : constant Int'Base := L - F + 1;
-
- begin
- return Count_Type (N);
+ 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;
----------
if Target.Busy > 0 then
raise Program_Error with
- "attempt to tamper with elements (Target is busy)";
+ "attempt to tamper with cursors (Target is busy)";
end if;
if Source.Busy > 0 then
raise Program_Error with
- "attempt to tamper with elements (Source is busy)";
+ "attempt to tamper with cursors (Source is busy)";
end if;
declare
-- Next --
----------
- function Next (Position : Cursor) return Cursor is
+ 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;
end if;
- if Position.Index < Position.Container.Last then
- return (Position.Container, Position.Index + 1);
+ if Position.Container /= Object.Container then
+ raise Program_Error with
+ "Position cursor of Next designates wrong vector";
end if;
- return No_Element;
+ return Next (Position);
end Next;
- ----------
- -- Next --
- ----------
-
procedure Next (Position : in out Cursor) is
begin
if Position.Container = null then
return;
- end if;
-
- if Position.Index < Position.Container.Last then
+ elsif Position.Index < Position.Container.Last then
Position.Index := Position.Index + 1;
else
Position := No_Element;
-- Previous --
--------------
- procedure Previous (Position : in out Cursor) is
+ function Previous (Position : Cursor) return Cursor is
begin
if Position.Container = null then
- return;
- end if;
-
- if Position.Index > Index_Type'First then
- Position.Index := Position.Index - 1;
+ return No_Element;
+ elsif Position.Index > Index_Type'First then
+ return (Position.Container, Position.Index - 1);
else
- Position := No_Element;
+ return No_Element;
end if;
end Previous;
- function Previous (Position : Cursor) return Cursor is
+ function Previous (Object : Iterator; Position : Cursor) return Cursor is
begin
if Position.Container = null then
return No_Element;
end if;
- if Position.Index > Index_Type'First then
- return (Position.Container, Position.Index - 1);
+ if Position.Container /= Object.Container then
+ raise Program_Error with
+ "Position cursor of Previous designates wrong vector";
end if;
- return No_Element;
+ return Previous (Position);
+ 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;
-------------------
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 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;
+
+ declare
+ C : Vector renames Position.Container.all;
+ B : Natural renames C.Busy;
+ L : Natural renames C.Lock;
+ begin
+ return R : constant Reference_Type :=
+ (Element =>
+ Container.Elements.EA (Position.Index)'Access,
+ Control => (Controlled with Position.Container))
+ do
+ B := B + 1;
+ L := L + 1;
+ end return;
+ end;
+ end Reference;
+
+ function Reference
+ (Container : aliased in out Vector;
+ Index : Index_Type) return Reference_Type
+ is
+ begin
+ if Index > Container.Last then
+ raise Constraint_Error with "Index is out of range";
+ else
+ declare
+ C : Vector renames Container'Unrestricted_Access.all;
+ B : Natural renames C.Busy;
+ L : Natural renames C.Lock;
+ begin
+ return R : constant Reference_Type :=
+ (Element => Container.Elements.EA (Index)'Access,
+ Control =>
+ (Controlled with Container'Unrestricted_Access))
+ do
+ B := B + 1;
+ L := L + 1;
+ end return;
+ end;
+ end if;
+ end Reference;
+
---------------------
-- Replace_Element --
---------------------
if Container.Lock > 0 then
raise Program_Error with
- "attempt to tamper with cursors (vector is locked)";
+ "attempt to tamper with elements (vector is locked)";
end if;
Container.Elements.EA (Index) := New_Item;
if Container.Lock > 0 then
raise Program_Error with
- "attempt to tamper with cursors (vector is locked)";
+ "attempt to tamper with elements (vector is locked)";
end if;
Container.Elements.EA (Position.Index) := New_Item;
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.
+
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).
+
if Container.Busy > 0 then
raise Program_Error with
- "attempt to tamper with elements (vector is busy)";
+ "attempt to tamper with cursors (vector is busy)";
end if;
declare
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 (either because there is not enough
+ -- storage, or because initialization of the elements fails),
+ -- 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 of
+ -- just the active elements in the container), so it is now
+ -- safe to attempt to deallocate the old array. The old array
+ -- has been isolated, and container invariants have been
+ -- restored, so if the deallocation fails (because finalization
+ -- of the elements fails), we simply let it propagate.
+
Free (X);
end;
end if;
return;
end if;
- if Container.Elements = null then
- declare
- Last_As_Int : constant Int'Base :=
- Int (Index_Type'First) + Int (Capacity) - 1;
+ -- Reserve_Capacity can be used to expand the storage available for
+ -- elements, but we do not let the capacity grow beyond the number of
+ -- values in Index_Type'Range. (Were it otherwise, there would be no way
+ -- to refer to the elements with an index value greater than
+ -- Index_Type'Last, so that storage would be wasted.) Here we compute
+ -- the Last index value of the new internal array, in a way that avoids
+ -- any possibility of overflow.
- begin
- if Last_As_Int > Index_Type'Pos (Index_Type'Last) then
- raise Constraint_Error with "new length is out of range";
- end if;
+ if Index_Type'Base'Last >= Count_Type'Pos (Count_Type'Last) then
- declare
- Last : constant Index_Type := Index_Type (Last_As_Int);
+ -- We perform a two-part test. First we determine whether the
+ -- computed Last value lies in the base range of the type, and then
+ -- determine whether it lies in the range of the index (sub)type.
- begin
- Container.Elements := new Elements_Type (Last);
- end;
- end;
+ -- Last must satisfy this relation:
+ -- First + Length - 1 <= Last
+ -- We regroup terms:
+ -- First - 1 <= Last - Length
+ -- Which can rewrite as:
+ -- No_Index <= Last - Length
+
+ if Index_Type'Base'Last - Index_Type'Base (Capacity) < No_Index then
+ raise Constraint_Error with "Capacity is out of range";
+ end if;
+
+ -- We now know that the computed value of Last is within the base
+ -- range of the type, so it is safe to compute its value:
+
+ Last := No_Index + Index_Type'Base (Capacity);
+
+ -- Finally we test whether the value is within the range of the
+ -- generic actual index subtype:
+
+ if Last > Index_Type'Last then
+ raise Constraint_Error with "Capacity is out of range";
+ end if;
+
+ elsif Index_Type'First <= 0 then
+
+ -- Here we can compute Last directly, in the normal way. We know that
+ -- No_Index is less than 0, so there is no danger of overflow when
+ -- adding the (positive) value of Capacity.
+
+ Index := Count_Type'Base (No_Index) + Capacity; -- Last
+
+ if Index > Count_Type'Base (Index_Type'Last) then
+ raise Constraint_Error with "Capacity is out of range";
+ end if;
+
+ -- We know that the computed value (having type Count_Type) of Last
+ -- is within the range of the generic actual index subtype, so it is
+ -- safe to convert to Index_Type:
+
+ Last := Index_Type'Base (Index);
+
+ else
+ -- Here Index_Type'First (and Index_Type'Last) is positive, so we
+ -- must test the length indirectly (by working backwards from the
+ -- largest possible value of Last), in order to prevent overflow.
+
+ Index := Count_Type'Base (Index_Type'Last) - Capacity; -- No_Index
+
+ if Index < Count_Type'Base (No_Index) then
+ raise Constraint_Error with "Capacity is out of range";
+ end if;
+
+ -- We have determined that the value of Capacity would not create a
+ -- Last index value outside of the range of Index_Type, so we can now
+ -- safely compute its value.
+
+ Last := Index_Type'Base (Count_Type'Base (No_Index) + Capacity);
+ end if;
+
+ -- The requested capacity is non-zero, but we don't know yet whether
+ -- this is a request for expansion or contraction of storage.
+
+ if Container.Elements = null then
+
+ -- The container is empty (it doesn't even have an internal array),
+ -- so this represents a request to allocate (expand) storage having
+ -- the given capacity.
+ Container.Elements := new Elements_Type (Last);
return;
end if;
if Capacity <= N then
+
+ -- This is a request to trim back storage, but only to the limit of
+ -- what's already in the container. (Reserve_Capacity never deletes
+ -- active elements, it only reclaims excess storage.)
+
if N < Container.Elements.EA'Length then
+
+ -- The container is not empty (because the requested capacity is
+ -- positive, and less than or equal to the container length), 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.
+
if Container.Busy > 0 then
raise Program_Error with
- "attempt to tamper with elements (vector is busy)";
+ "attempt to tamper with cursors (vector is busy)";
end if;
declare
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 (either because there is not enough
+ -- storage, or because initialization of the elements fails),
+ -- 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 of
+ -- just the active elements in the container), so it is now
+ -- safe to attempt to deallocate the old array. The old array
+ -- has been isolated, and container invariants have been
+ -- restored, so if the deallocation fails (because finalization
+ -- of the elements fails), we simply let it propagate.
+
Free (X);
end;
-
end if;
return;
end if;
+ -- The requested capacity is larger than the container length (the
+ -- number of active elements). Whether this represents a request for
+ -- expansion or contraction of the current capacity depends on what the
+ -- current capacity is.
+
if Capacity = Container.Elements.EA'Length then
+
+ -- The requested capacity matches the existing capacity, so there's
+ -- nothing to do here. We treat this case as a no-op, and simply
+ -- return without checking the busy bit.
+
return;
end if;
+ -- There is a change in the capacity of a non-empty container, so a new
+ -- internal array will be allocated. (The length of the new internal
+ -- array could be less or greater than the old internal array. We know
+ -- only that the length of the new internal array is greater than the
+ -- number of active elements in the container.) We must check whether
+ -- the container is busy before doing anything else.
+
if Container.Busy > 0 then
raise Program_Error with
- "attempt to tamper with elements (vector is busy)";
+ "attempt to tamper with cursors (vector is busy)";
end if;
+ -- We now allocate a new internal array, having a length different from
+ -- its current value.
+
declare
- Last_As_Int : constant Int'Base :=
- Int (Index_Type'First) + Int (Capacity) - 1;
+ E : Elements_Access := new Elements_Type (Last);
begin
- if Last_As_Int > Index_Type'Pos (Index_Type'Last) then
- raise Constraint_Error with "new length is out of range";
- end if;
+ -- We have successfully allocated the new internal array. We first
+ -- attempt to copy the existing elements from the old internal array
+ -- ("src" elements) onto the new internal array ("tgt" elements).
declare
- Last : constant Index_Type := Index_Type (Last_As_Int);
+ subtype Index_Subtype is Index_Type'Base range
+ Index_Type'First .. Container.Last;
+
+ Src : Elements_Array renames
+ Container.Elements.EA (Index_Subtype);
- E : Elements_Access := new Elements_Type (Last);
+ Tgt : Elements_Array renames E.EA (Index_Subtype);
begin
- declare
- subtype Index_Subtype is Index_Type'Base range
- Index_Type'First .. Container.Last;
+ Tgt := Src;
- Src : Elements_Array renames
- Container.Elements.EA (Index_Subtype);
+ exception
+ when others =>
+ Free (E);
+ raise;
+ end;
- Tgt : Elements_Array renames E.EA (Index_Subtype);
+ -- We have successfully copied the existing elements onto the new
+ -- internal array, so now we can attempt to deallocate the old one.
- begin
- Tgt := Src;
+ declare
+ X : Elements_Access := Container.Elements;
- exception
- when others =>
- Free (E);
- raise;
- end;
+ begin
+ -- First we isolate the old internal array, and replace it in the
+ -- container with the new internal array.
- declare
- X : Elements_Access := Container.Elements;
- begin
- Container.Elements := E;
- Free (X);
- end;
+ Container.Elements := E;
+
+ -- Container invariants have been restored, so it is now safe to
+ -- attempt to deallocate the old internal array.
+
+ Free (X);
end;
end;
end Reserve_Capacity;
return;
end if;
- if Container.Lock > 0 then
+ -- 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 Reverse_Elements requires a check for
+ -- cursor tampering.
+
+ if Container.Busy > 0 then
raise Program_Error with
- "attempt to tamper with cursors (vector is locked)";
+ "attempt to tamper with cursors (vector is busy)";
end if;
declare
- I, J : Index_Type;
- E : Elements_Type renames Container.Elements.all;
+ K : Index_Type;
+ J : Index_Type;
+ E : Elements_Type renames Container.Elements.all;
begin
- I := Index_Type'First;
+ K := Index_Type'First;
J := Container.Last;
- while I < J loop
+ while K < J loop
declare
- EI : constant Element_Type := E.EA (I);
-
+ EK : constant Element_Type := E.EA (K);
begin
- E.EA (I) := E.EA (J);
- E.EA (J) := EI;
+ E.EA (K) := E.EA (J);
+ E.EA (J) := EK;
end;
- I := I + 1;
+ K := K + 1;
J := J - 1;
end loop;
end;
begin
if Position.Container /= null
- and then Position.Container /= Container'Unchecked_Access
+ and then Position.Container /= Container'Unrestricted_Access
then
raise Program_Error with "Position cursor denotes wrong container";
end if;
for Indx in reverse Index_Type'First .. Last loop
if Container.Elements.EA (Indx) = Item then
- return (Container'Unchecked_Access, Indx);
+ return (Container'Unrestricted_Access, Indx);
end if;
end loop;
begin
for Indx in reverse Index_Type'First .. Container.Last loop
- Process (Cursor'(Container'Unchecked_Access, Indx));
+ Process (Cursor'(Container'Unrestricted_Access, Indx));
end loop;
exception
when others =>
----------------
procedure Set_Length (Container : in out Vector; Length : Count_Type) is
+ Count : constant Count_Type'Base := Container.Length - Length;
+
begin
- if Length = Vectors.Length (Container) then
- return;
- end if;
+ -- Set_Length allows the user to set the length explicitly, instead
+ -- of implicitly as a side-effect of deletion or insertion. If the
+ -- requested length is less then the current length, this is equivalent
+ -- to deleting items from the back end of the vector. If the requested
+ -- length is greater than the current length, then this is equivalent
+ -- to inserting "space" (nonce items) at the end.
- if Container.Busy > 0 then
- raise Program_Error with
- "attempt to tamper with elements (vector is busy)";
- end if;
+ if Count >= 0 then
+ Container.Delete_Last (Count);
- if Length > Capacity (Container) then
- Reserve_Capacity (Container, Capacity => Length);
- end if;
+ elsif Container.Last >= Index_Type'Last then
+ raise Constraint_Error with "vector is already at its maximum length";
- declare
- Last_As_Int : constant Int'Base :=
- Int (Index_Type'First) + Int (Length) - 1;
- begin
- Container.Last := Index_Type'Base (Last_As_Int);
- end;
+ else
+ Container.Insert_Space (Container.Last + 1, -Count);
+ end if;
end Set_Length;
----------
if Container.Lock > 0 then
raise Program_Error with
- "attempt to tamper with cursors (vector is locked)";
+ "attempt to tamper with elements (vector is locked)";
end if;
declare
begin
if Index not in Index_Type'First .. Container.Last then
return No_Element;
+ else
+ return (Container'Unrestricted_Access, Index);
end if;
-
- return Cursor'(Container'Unchecked_Access, Index);
end To_Cursor;
--------------
---------------
function To_Vector (Length : Count_Type) return Vector is
+ Index : Count_Type'Base;
+ Last : Index_Type'Base;
+ Elements : Elements_Access;
+
begin
if Length = 0 then
return Empty_Vector;
end if;
- declare
- First : constant Int := Int (Index_Type'First);
- Last_As_Int : constant Int'Base := First + Int (Length) - 1;
- Last : Index_Type;
- Elements : Elements_Access;
+ -- We create a vector object with a capacity that matches the specified
+ -- Length, but we do not allow the vector capacity (the length of the
+ -- internal array) to exceed the number of values in Index_Type'Range
+ -- (otherwise, there would be no way to refer to those components via an
+ -- index). We must therefore check whether the specified Length would
+ -- create a Last index value greater than Index_Type'Last.
- begin
- if Last_As_Int > Index_Type'Pos (Index_Type'Last) then
+ if Index_Type'Base'Last >= Count_Type'Pos (Count_Type'Last) then
+
+ -- We perform a two-part test. First we determine whether the
+ -- computed Last value lies in the base range of the type, and then
+ -- determine whether it lies in the range of the index (sub)type.
+
+ -- Last must satisfy this relation:
+ -- First + Length - 1 <= Last
+ -- We regroup terms:
+ -- First - 1 <= Last - Length
+ -- Which can rewrite as:
+ -- No_Index <= Last - Length
+
+ if Index_Type'Base'Last - Index_Type'Base (Length) < No_Index then
raise Constraint_Error with "Length is out of range";
end if;
- Last := Index_Type (Last_As_Int);
- Elements := new Elements_Type (Last);
+ -- We now know that the computed value of Last is within the base
+ -- range of the type, so it is safe to compute its value:
- return Vector'(Controlled with Elements, Last, 0, 0);
- end;
+ Last := No_Index + Index_Type'Base (Length);
+
+ -- Finally we test whether the value is within the range of the
+ -- generic actual index subtype:
+
+ if Last > Index_Type'Last then
+ raise Constraint_Error with "Length is out of range";
+ end if;
+
+ elsif Index_Type'First <= 0 then
+
+ -- Here we can compute Last directly, in the normal way. We know that
+ -- No_Index is less than 0, so there is no danger of overflow when
+ -- adding the (positive) value of Length.
+
+ Index := Count_Type'Base (No_Index) + Length; -- Last
+
+ if Index > Count_Type'Base (Index_Type'Last) then
+ raise Constraint_Error with "Length is out of range";
+ end if;
+
+ -- We know that the computed value (having type Count_Type) of Last
+ -- is within the range of the generic actual index subtype, so it is
+ -- safe to convert to Index_Type:
+
+ Last := Index_Type'Base (Index);
+
+ else
+ -- Here Index_Type'First (and Index_Type'Last) is positive, so we
+ -- must test the length indirectly (by working backwards from the
+ -- largest possible value of Last), in order to prevent overflow.
+
+ Index := Count_Type'Base (Index_Type'Last) - Length; -- No_Index
+
+ if Index < Count_Type'Base (No_Index) then
+ raise Constraint_Error with "Length is out of range";
+ end if;
+
+ -- We have determined that the value of Length would not create a
+ -- Last index value outside of the range of Index_Type, so we can now
+ -- safely compute its value.
+
+ Last := Index_Type'Base (Count_Type'Base (No_Index) + Length);
+ end if;
+
+ Elements := new Elements_Type (Last);
+
+ return Vector'(Controlled with Elements, Last, 0, 0);
end To_Vector;
function To_Vector
(New_Item : Element_Type;
Length : Count_Type) return Vector
is
+ Index : Count_Type'Base;
+ Last : Index_Type'Base;
+ Elements : Elements_Access;
+
begin
if Length = 0 then
return Empty_Vector;
end if;
- declare
- First : constant Int := Int (Index_Type'First);
- Last_As_Int : constant Int'Base := First + Int (Length) - 1;
- Last : Index_Type;
- Elements : Elements_Access;
+ -- We create a vector object with a capacity that matches the specified
+ -- Length, but we do not allow the vector capacity (the length of the
+ -- internal array) to exceed the number of values in Index_Type'Range
+ -- (otherwise, there would be no way to refer to those components via an
+ -- index). We must therefore check whether the specified Length would
+ -- create a Last index value greater than Index_Type'Last.
- begin
- if Last_As_Int > Index_Type'Pos (Index_Type'Last) then
+ if Index_Type'Base'Last >= Count_Type'Pos (Count_Type'Last) then
+
+ -- We perform a two-part test. First we determine whether the
+ -- computed Last value lies in the base range of the type, and then
+ -- determine whether it lies in the range of the index (sub)type.
+
+ -- Last must satisfy this relation:
+ -- First + Length - 1 <= Last
+ -- We regroup terms:
+ -- First - 1 <= Last - Length
+ -- Which can rewrite as:
+ -- No_Index <= Last - Length
+
+ if Index_Type'Base'Last - Index_Type'Base (Length) < No_Index then
raise Constraint_Error with "Length is out of range";
end if;
- Last := Index_Type (Last_As_Int);
- Elements := new Elements_Type'(Last, EA => (others => New_Item));
+ -- We now know that the computed value of Last is within the base
+ -- range of the type, so it is safe to compute its value:
- return Vector'(Controlled with Elements, Last, 0, 0);
- end;
+ Last := No_Index + Index_Type'Base (Length);
+
+ -- Finally we test whether the value is within the range of the
+ -- generic actual index subtype:
+
+ if Last > Index_Type'Last then
+ raise Constraint_Error with "Length is out of range";
+ end if;
+
+ elsif Index_Type'First <= 0 then
+
+ -- Here we can compute Last directly, in the normal way. We know that
+ -- No_Index is less than 0, so there is no danger of overflow when
+ -- adding the (positive) value of Length.
+
+ Index := Count_Type'Base (No_Index) + Length; -- same value as V.Last
+
+ if Index > Count_Type'Base (Index_Type'Last) then
+ raise Constraint_Error with "Length is out of range";
+ end if;
+
+ -- We know that the computed value (having type Count_Type) of Last
+ -- is within the range of the generic actual index subtype, so it is
+ -- safe to convert to Index_Type:
+
+ Last := Index_Type'Base (Index);
+
+ else
+ -- Here Index_Type'First (and Index_Type'Last) is positive, so we
+ -- must test the length indirectly (by working backwards from the
+ -- largest possible value of Last), in order to prevent overflow.
+
+ Index := Count_Type'Base (Index_Type'Last) - Length; -- No_Index
+
+ if Index < Count_Type'Base (No_Index) then
+ raise Constraint_Error with "Length is out of range";
+ end if;
+
+ -- We have determined that the value of Length would not create a
+ -- Last index value outside of the range of Index_Type, so we can now
+ -- safely compute its value.
+
+ Last := Index_Type'Base (Count_Type'Base (No_Index) + Length);
+ end if;
+
+ Elements := new Elements_Type'(Last, EA => (others => New_Item));
+
+ return Vector'(Controlled with Elements, Last, 0, 0);
end To_Vector;
--------------------
begin
if Position.Container = null then
raise Constraint_Error with "Position cursor has no element";
- end if;
-
- if Position.Container /= Container'Unrestricted_Access then
+ elsif Position.Container /= Container'Unrestricted_Access then
raise Program_Error with "Position cursor denotes wrong container";
+ else
+ Update_Element (Container, Position.Index, Process);
end if;
-
- Update_Element (Container, Position.Index, Process);
end Update_Element;
-----------
raise Program_Error with "attempt to stream vector cursor";
end Write;
+ procedure Write
+ (Stream : not null access Root_Stream_Type'Class;
+ Item : Reference_Type)
+ is
+ begin
+ raise Program_Error with "attempt to stream reference";
+ end Write;
+
+ procedure Write
+ (Stream : not null access Root_Stream_Type'Class;
+ Item : Constant_Reference_Type)
+ is
+ begin
+ raise Program_Error with "attempt to stream reference";
+ end Write;
+
end Ada.Containers.Vectors;
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