-- --
-- GNAT LIBRARY COMPONENTS --
-- --
--- A D A . C O N T A I N E R S . --
--- I N D E F I N I T E _ D O U B L Y _ L I N K E D _ L I S T S --
+-- ADA.CONTAINERS.INDEFINITE_DOUBLY_LINKED_LISTS --
-- --
-- B o d y --
-- --
--- Copyright (C) 2004-2005 Free Software Foundation, Inc. --
--- --
--- This specification is derived from the Ada Reference Manual for use with --
--- GNAT. The copyright notice above, and the license provisions that follow --
--- apply solely to the contents of the part following the private keyword. --
+-- 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- --
--- ware Foundation; either version 2, or (at your option) any later ver- --
+-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
--- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
--- for more details. You should have received a copy of the GNU General --
--- Public License distributed with GNAT; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
+-- or FITNESS FOR A PARTICULAR PURPOSE. --
+-- --
+-- As a special exception under Section 7 of GPL version 3, you are granted --
+-- additional permissions described in the GCC Runtime Library Exception, --
+-- version 3.1, as published by the Free Software Foundation. --
-- --
--- As a special exception, if other files instantiate generics from this --
--- unit, or you link this unit with other files to produce an executable, --
--- this unit does not by itself cause the resulting executable to be --
--- covered by the GNU General Public License. This exception does not --
--- however invalidate any other reasons why the executable file might be --
--- covered by the GNU Public License. --
+-- You should have received a copy of the GNU General Public License and --
+-- a copy of the GCC Runtime Library Exception along with this program; --
+-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
+-- <http://www.gnu.org/licenses/>. --
-- --
-- This unit was originally developed by Matthew J Heaney. --
------------------------------------------------------------------------------
-with System; use type System.Address;
with Ada.Unchecked_Deallocation;
-package body Ada.Containers.Indefinite_Doubly_Linked_Lists is
+with System; use type System.Address;
- procedure Free is
- new Ada.Unchecked_Deallocation (Node_Type, Node_Access);
+package body Ada.Containers.Indefinite_Doubly_Linked_Lists is
procedure Free is
new Ada.Unchecked_Deallocation (Element_Type, Element_Access);
+ type Iterator is new Limited_Controlled and
+ List_Iterator_Interfaces.Reversible_Iterator with
+ record
+ Container : List_Access;
+ Node : Node_Access;
+ 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;
+
-----------------------
-- Local Subprograms --
-----------------------
+ procedure Free (X : in out Node_Access);
+
procedure Insert_Internal
(Container : in out List;
Before : Node_Access;
New_Node : Node_Access);
+ function Vet (Position : Cursor) return Boolean;
+ -- Checks invariants of the cursor and its designated container, as a
+ -- simple way of detecting dangling references (see operation Free for a
+ -- description of the detection mechanism), returning True if all checks
+ -- pass. Invocations of Vet are used here as the argument of pragma Assert,
+ -- so the checks are performed only when assertions are enabled.
+
---------
-- "=" --
---------
end loop;
end Adjust;
+ procedure Adjust (Control : in out Reference_Control_Type) is
+ begin
+ if Control.Container /= null then
+ declare
+ C : List 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 --
------------
Insert (Container, No_Element, New_Item, Count);
end Append;
+ ------------
+ -- Assign --
+ ------------
+
+ procedure Assign (Target : in out List; Source : List) is
+ Node : Node_Access;
+
+ begin
+ if Target'Address = Source'Address then
+ return;
+ end if;
+
+ Target.Clear;
+
+ Node := Source.First;
+ while Node /= null loop
+ Target.Append (Node.Element.all);
+ Node := Node.Next;
+ end loop;
+ end Assign;
+
-----------
-- Clear --
-----------
procedure Clear (Container : in out List) is
X : Node_Access;
+ pragma Warnings (Off, X);
begin
if Container.Length = 0 then
pragma Assert (Container.Last.Next = null);
if Container.Busy > 0 then
- raise Program_Error;
+ raise Program_Error with
+ "attempt to tamper with cursors (list is busy)";
end if;
while Container.Length > 1 loop
Container.First := X.Next;
Container.First.Prev := null;
- Container.Length := Container.Length - 1;
- X.Next := null; -- prevent mischief
-
- begin
- Free (X.Element);
- exception
- when others =>
- X.Element := null;
- Free (X);
- raise;
- end;
+ Container.Length := Container.Length - 1;
Free (X);
end loop;
Container.Last := null;
Container.Length := 0;
- begin
- Free (X.Element);
- exception
- when others =>
- X.Element := null;
- Free (X);
- raise;
- end;
-
Free (X);
end Clear;
+ ------------------------
+ -- Constant_Reference --
+ ------------------------
+
+ function Constant_Reference
+ (Container : aliased List;
+ 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 designates wrong container";
+ end if;
+
+ if Position.Node.Element = null then
+ raise Program_Error with "Node has no element";
+ end if;
+
+ pragma Assert (Vet (Position), "bad cursor in Constant_Reference");
+
+ declare
+ C : List renames Position.Container.all;
+ B : Natural renames C.Busy;
+ L : Natural renames C.Lock;
+ begin
+ return R : constant Constant_Reference_Type :=
+ (Element => Position.Node.Element.all'Access,
+ Control => (Controlled with Position.Container))
+ do
+ B := B + 1;
+ L := L + 1;
+ end return;
+ end;
+ end Constant_Reference;
+
--------------
-- Contains --
--------------
function Contains
(Container : List;
- Item : Element_Type) return Boolean is
+ Item : Element_Type) return Boolean
+ is
begin
return Find (Container, Item) /= No_Element;
end Contains;
+ ----------
+ -- Copy --
+ ----------
+
+ function Copy (Source : List) return List is
+ begin
+ return Target : List do
+ Target.Assign (Source);
+ end return;
+ end Copy;
+
------------
-- Delete --
------------
begin
if Position.Node = null then
- raise Constraint_Error;
+ raise Constraint_Error with
+ "Position cursor has no element";
end if;
- if Position.Container /= List_Access'(Container'Unchecked_Access) then
- raise Program_Error;
+ if Position.Node.Element = null then
+ raise Program_Error with
+ "Position cursor has no element";
end if;
- pragma Assert (Container.Length > 0);
- pragma Assert (Container.First.Prev = null);
- pragma Assert (Container.Last.Next = null);
+ if Position.Container /= Container'Unrestricted_Access then
+ raise Program_Error with
+ "Position cursor designates wrong container";
+ end if;
- pragma Assert (Position.Node.Element /= null);
- pragma Assert (Position.Node.Prev = null
- or else Position.Node.Prev.Next = Position.Node);
- pragma Assert (Position.Node.Next = null
- or else Position.Node.Next.Prev = Position.Node);
- pragma Assert (Position.Node.Prev /= null
- or else Position.Node = Container.First);
- pragma Assert (Position.Node.Next /= null
- or else Position.Node = Container.Last);
+ pragma Assert (Vet (Position), "bad cursor in Delete");
if Position.Node = Container.First then
Delete_First (Container, Count);
- Position := First (Container);
+ Position := No_Element; -- Post-York behavior
return;
end if;
if Count = 0 then
+ Position := No_Element; -- Post-York behavior
return;
end if;
if Container.Busy > 0 then
- raise Program_Error;
+ raise Program_Error with
+ "attempt to tamper with cursors (list is busy)";
end if;
for Index in 1 .. Count loop
Container.Last := X.Prev;
Container.Last.Next := null;
- X.Prev := null; -- prevent mischief
-
- begin
- Free (X.Element);
- exception
- when others =>
- X.Element := null;
- Free (X);
- raise;
- end;
-
Free (X);
return;
end if;
X.Next.Prev := X.Prev;
X.Prev.Next := X.Next;
- X.Prev := null;
- X.Next := null;
-
- begin
- Free (X.Element);
- exception
- when others =>
- X.Element := null;
- Free (X);
- raise;
- end;
-
Free (X);
end loop;
+
+ Position := No_Element; -- Post-York behavior
end Delete;
------------------
end if;
if Container.Busy > 0 then
- raise Program_Error;
+ raise Program_Error with
+ "attempt to tamper with cursors (list is busy)";
end if;
for I in 1 .. Count loop
Container.Length := Container.Length - 1;
- X.Next := null; -- prevent mischief
-
- begin
- Free (X.Element);
- exception
- when others =>
- X.Element := null;
- Free (X);
- raise;
- end;
-
Free (X);
end loop;
end Delete_First;
end if;
if Container.Busy > 0 then
- raise Program_Error;
+ raise Program_Error with
+ "attempt to tamper with cursors (list is busy)";
end if;
for I in 1 .. Count loop
Container.Length := Container.Length - 1;
- X.Prev := null; -- prevent mischief
-
- begin
- Free (X.Element);
- exception
- when others =>
- X.Element := null;
- Free (X);
- raise;
- end;
-
Free (X);
end loop;
end Delete_Last;
function Element (Position : Cursor) return Element_Type is
begin
- pragma Assert (Position.Container /= null);
- pragma Assert (Position.Container.Length > 0);
- pragma Assert (Position.Container.First.Prev = null);
- pragma Assert (Position.Container.Last.Next = null);
-
- pragma Assert (Position.Node /= null);
- pragma Assert (Position.Node.Element /= null);
- pragma Assert (Position.Node.Prev = null
- or else Position.Node.Prev.Next = Position.Node);
- pragma Assert (Position.Node.Next = null
- or else Position.Node.Next.Prev = Position.Node);
- pragma Assert (Position.Node.Prev /= null
- or else Position.Node = Position.Container.First);
- pragma Assert (Position.Node.Next /= null
- or else Position.Node = Position.Container.Last);
+ if Position.Node = null then
+ raise Constraint_Error with
+ "Position cursor has no element";
+ end if;
+
+ if Position.Node.Element = null then
+ raise Program_Error with
+ "Position cursor has no element";
+ end if;
+
+ pragma Assert (Vet (Position), "bad cursor in Element");
return Position.Node.Element.all;
end Element;
+ --------------
+ -- Finalize --
+ --------------
+
+ procedure Finalize (Object : in out Iterator) is
+ begin
+ if Object.Container /= null then
+ declare
+ B : Natural renames Object.Container.all.Busy;
+ begin
+ B := B - 1;
+ end;
+ end if;
+ end Finalize;
+
+ procedure Finalize (Control : in out Reference_Control_Type) is
+ begin
+ if Control.Container /= null then
+ declare
+ C : List 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 --
----------
Node := Container.First;
else
- if Position.Container /= List_Access'(Container'Unchecked_Access) then
+ if Node.Element = null then
raise Program_Error;
end if;
- pragma Assert (Container.Length > 0);
- pragma Assert (Container.First.Prev = null);
- pragma Assert (Container.Last.Next = null);
+ if Position.Container /= Container'Unrestricted_Access then
+ raise Program_Error with
+ "Position cursor designates wrong container";
+ end if;
- pragma Assert (Position.Node.Element /= null);
- pragma Assert (Position.Node.Prev = null
- or else Position.Node.Prev.Next = Position.Node);
- pragma Assert (Position.Node.Next = null
- or else Position.Node.Next.Prev = Position.Node);
- pragma Assert (Position.Node.Prev /= null
- or else Position.Node = Container.First);
- pragma Assert (Position.Node.Next /= null
- or else Position.Node = Container.Last);
+ pragma Assert (Vet (Position), "bad cursor in Find");
end if;
while Node /= null loop
if Node.Element.all = Item then
- return Cursor'(Container'Unchecked_Access, Node);
+ return Cursor'(Container'Unrestricted_Access, Node);
end if;
Node := Node.Next;
return No_Element;
end if;
- return Cursor'(Container'Unchecked_Access, Container.First);
+ return Cursor'(Container'Unrestricted_Access, Container.First);
+ end First;
+
+ function First (Object : Iterator) return Cursor is
+ begin
+ -- The value of the iterator object's Node component influences the
+ -- behavior of the First (and Last) selector function.
+
+ -- When the Node component is null, this means the iterator object was
+ -- constructed without a start expression, in which case the (forward)
+ -- iteration starts from the (logical) beginning of the entire sequence
+ -- of items (corresponding to Container.First, for a forward iterator).
+
+ -- Otherwise, this is iteration over a partial sequence of items. When
+ -- the Node component is non-null, the iterator object was constructed
+ -- with a start expression, that specifies the position from which the
+ -- (forward) partial iteration begins.
+
+ if Object.Node = null then
+ return Indefinite_Doubly_Linked_Lists.First (Object.Container.all);
+ else
+ return Cursor'(Object.Container, Object.Node);
+ end if;
end First;
-------------------
function First_Element (Container : List) return Element_Type is
begin
+ if Container.First = null then
+ raise Constraint_Error with "list is empty";
+ end if;
+
return Container.First.Element.all;
end First_Element;
+ ----------
+ -- Free --
+ ----------
+
+ procedure Free (X : in out Node_Access) is
+ procedure Deallocate is
+ new Ada.Unchecked_Deallocation (Node_Type, Node_Access);
+
+ begin
+ -- While a node is in use, as an active link in a list, its Previous and
+ -- Next components must be null, or designate a different node; this is
+ -- a node invariant. For this indefinite list, there is an additional
+ -- invariant: that the element access value be non-null. Before actually
+ -- deallocating the node, we set the node access value components of the
+ -- node to point to the node itself, and set the element access value to
+ -- null (by deallocating the node's element), thus falsifying the node
+ -- invariant. Subprogram Vet inspects the value of the node components
+ -- when interrogating the node, in order to detect whether the cursor's
+ -- node access value is dangling.
+
+ -- Note that we have no guarantee that the storage for the node isn't
+ -- modified when it is deallocated, but there are other tests that Vet
+ -- does if node invariants appear to be satisifed. However, in practice
+ -- this simple test works well enough, detecting dangling references
+ -- immediately, without needing further interrogation.
+
+ X.Next := X;
+ X.Prev := X;
+
+ begin
+ Free (X.Element);
+ exception
+ when others =>
+ X.Element := null;
+ Deallocate (X);
+ raise;
+ end;
+
+ Deallocate (X);
+ end Free;
+
---------------------
-- Generic_Sorting --
---------------------
(Target : in out List;
Source : in out List)
is
- LI : Cursor;
- RI : Cursor;
+ LI, RI : Cursor;
begin
- if Target'Address = Source'Address then
+
+ -- 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.Is_Empty then
return;
end if;
- if Target.Busy > 0
- or else Source.Busy > 0
- then
- raise Program_Error;
+ if Target'Address = Source'Address then
+ raise Program_Error with
+ "Target and Source denote same non-empty container";
+ end if;
+
+ if Target.Busy > 0 then
+ raise Program_Error with
+ "attempt to tamper with cursors of Target (list is busy)";
+ end if;
+
+ if Source.Busy > 0 then
+ raise Program_Error with
+ "attempt to tamper with cursors of Source (list is busy)";
end if;
LI := First (Target);
RI := First (Source);
while RI.Node /= null loop
+ pragma Assert (RI.Node.Next = null
+ or else not (RI.Node.Next.Element.all <
+ RI.Node.Element.all));
+
if LI.Node = null then
Splice (Target, No_Element, Source);
return;
end if;
+ pragma Assert (LI.Node.Next = null
+ or else not (LI.Node.Next.Element.all <
+ LI.Node.Element.all));
+
if RI.Node.Element.all < LI.Node.Element.all then
declare
RJ : Cursor := RI;
+ pragma Warnings (Off, RJ);
begin
RI.Node := RI.Node.Next;
Splice (Target, LI, Source, RJ);
----------
procedure Sort (Front, Back : Node_Access) is
- Pivot : Node_Access;
-
+ Pivot : constant Node_Access :=
+ (if Front = null then Container.First else Front.Next);
begin
- if Front = null then
- Pivot := Container.First;
- else
- Pivot := Front.Next;
- end if;
-
if Pivot /= Back then
Partition (Pivot, Back);
Sort (Front, Pivot);
pragma Assert (Container.Last.Next = null);
if Container.Busy > 0 then
- raise Program_Error;
+ raise Program_Error with
+ "attempt to tamper with cursors (list is busy)";
end if;
Sort (Front => null, Back => null);
function Has_Element (Position : Cursor) return Boolean is
begin
- if Position.Node = null then
- pragma Assert (Position.Container = null);
- return False;
- end if;
-
- pragma Assert (Position.Container /= null);
- pragma Assert (Position.Container.Length > 0);
- pragma Assert (Position.Container.First.Prev = null);
- pragma Assert (Position.Container.Last.Next = null);
-
- pragma Assert (Position.Node.Element /= null);
- pragma Assert (Position.Node.Prev = null
- or else Position.Node.Prev.Next = Position.Node);
- pragma Assert (Position.Node.Next = null
- or else Position.Node.Next.Prev = Position.Node);
- pragma Assert (Position.Node.Prev /= null
- or else Position.Node = Position.Container.First);
- pragma Assert (Position.Node.Next /= null
- or else Position.Node = Position.Container.Last);
-
- return True;
+ pragma Assert (Vet (Position), "bad cursor in Has_Element");
+ return Position.Node /= null;
end Has_Element;
------------
New_Node : Node_Access;
begin
- if Before.Node /= null then
- if Before.Container /= List_Access'(Container'Unchecked_Access) then
- raise Program_Error;
+ if Before.Container /= null then
+ if Before.Container /= Container'Unrestricted_Access then
+ raise Program_Error with
+ "attempt to tamper with cursors (list is busy)";
end if;
- pragma Assert (Container.Length > 0);
- pragma Assert (Container.First.Prev = null);
- pragma Assert (Container.Last.Next = null);
+ if Before.Node = null
+ or else Before.Node.Element = null
+ then
+ raise Program_Error with
+ "Before cursor has no element";
+ end if;
- pragma Assert (Before.Node.Element /= null);
- pragma Assert (Before.Node.Prev = null
- or else Before.Node.Prev.Next = Before.Node);
- pragma Assert (Before.Node.Next = null
- or else Before.Node.Next.Prev = Before.Node);
- pragma Assert (Before.Node.Prev /= null
- or else Before.Node = Container.First);
- pragma Assert (Before.Node.Next /= null
- or else Before.Node = Container.Last);
+ pragma Assert (Vet (Before), "bad cursor in Insert");
end if;
if Count = 0 then
end if;
if Container.Length > Count_Type'Last - Count then
- raise Constraint_Error;
+ raise Constraint_Error with "new length exceeds maximum";
end if;
if Container.Busy > 0 then
- raise Program_Error;
+ raise Program_Error with
+ "attempt to tamper with cursors (list is busy)";
end if;
declare
Count : Count_Type := 1)
is
Position : Cursor;
+ pragma Unreferenced (Position);
begin
Insert (Container, Before, New_Item, Position, Count);
end Insert;
procedure Iterate
(Container : List;
- Process : not null access procedure (Position : in Cursor))
+ Process : not null access procedure (Position : Cursor))
is
- C : List renames Container'Unrestricted_Access.all;
- B : Natural renames C.Busy;
-
+ B : Natural renames Container'Unrestricted_Access.all.Busy;
Node : Node_Access := Container.First;
begin
begin
while Node /= null loop
- Process (Cursor'(Container'Unchecked_Access, Node));
+ Process (Cursor'(Container'Unrestricted_Access, Node));
Node := Node.Next;
end loop;
exception
B := B - 1;
end Iterate;
- ----------
- -- Move --
- ----------
+ function Iterate
+ (Container : List)
+ return List_Iterator_Interfaces.Reversible_Iterator'class
+ is
+ B : Natural renames Container'Unrestricted_Access.all.Busy;
- procedure Move (Target : in out List; Source : in out List) is
begin
- if Target'Address = Source'Address then
- return;
- end if;
-
- if Source.Busy > 0 then
- raise Program_Error;
- end if;
-
- Clear (Target);
-
- Target.First := Source.First;
- Source.First := null;
+ -- The value of the Node component influences the behavior of the First
+ -- and Last selector functions of the iterator object. When the Node
+ -- component is null (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 :=
+ Iterator'(Limited_Controlled with
+ Container => Container'Unrestricted_Access,
+ Node => null)
+ do
+ B := B + 1;
+ end return;
+ end Iterate;
- Target.Last := Source.Last;
- Source.Last := null;
+ function Iterate
+ (Container : List;
+ Start : Cursor)
+ return List_Iterator_Interfaces.Reversible_Iterator'Class
+ is
+ B : Natural renames Container'Unrestricted_Access.all.Busy;
- Target.Length := Source.Length;
- Source.Length := 0;
- end Move;
+ 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 = No_Element then
+ raise Constraint_Error with
+ "Start position for iterator equals No_Element";
+ end if;
+
+ if Start.Container /= Container'Unrestricted_Access then
+ raise Program_Error with
+ "Start cursor of Iterate designates wrong list";
+ end if;
+
+ pragma Assert (Vet (Start), "Start cursor of Iterate is bad");
+
+ -- The value of the Node component influences the behavior of the First
+ -- and Last selector functions of the iterator object. When the Node
+ -- component is non-null (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 :=
+ Iterator'(Limited_Controlled with
+ Container => Container'Unrestricted_Access,
+ Node => Start.Node)
+ do
+ B := B + 1;
+ end return;
+ end Iterate;
----------
-- Last --
return No_Element;
end if;
- return Cursor'(Container'Unchecked_Access, Container.Last);
+ return Cursor'(Container'Unrestricted_Access, Container.Last);
+ end Last;
+
+ function Last (Object : Iterator) return Cursor is
+ begin
+ -- The value of the iterator object's Node component influences the
+ -- behavior of the Last (and First) selector function.
+
+ -- When the Node component is null, 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 Node component is non-null, the iterator object was constructed
+ -- with a start expression, that specifies the position from which the
+ -- (reverse) partial iteration begins.
+
+ if Object.Node = null then
+ return Indefinite_Doubly_Linked_Lists.Last (Object.Container.all);
+ else
+ return Cursor'(Object.Container, Object.Node);
+ end if;
end Last;
------------------
function Last_Element (Container : List) return Element_Type is
begin
+ if Container.Last = null then
+ raise Constraint_Error with "list is empty";
+ end if;
+
return Container.Last.Element.all;
end Last_Element;
end Length;
----------
- -- Next --
+ -- Move --
----------
- procedure Next (Position : in out Cursor) is
+ procedure Move (Target : in out List; Source : in out List) is
begin
- if Position.Node = null then
- pragma Assert (Position.Container = null);
+ if Target'Address = Source'Address then
return;
end if;
- pragma Assert (Position.Container /= null);
- pragma Assert (Position.Container.Length > 0);
- pragma Assert (Position.Container.First.Prev = null);
- pragma Assert (Position.Container.Last.Next = null);
+ if Source.Busy > 0 then
+ raise Program_Error with
+ "attempt to tamper with cursors of Source (list is busy)";
+ end if;
+
+ Clear (Target);
- pragma Assert (Position.Node.Element /= null);
- pragma Assert (Position.Node.Prev = null
- or else Position.Node.Prev.Next = Position.Node);
- pragma Assert (Position.Node.Next = null
- or else Position.Node.Next.Prev = Position.Node);
- pragma Assert (Position.Node.Prev /= null
- or else Position.Node = Position.Container.First);
- pragma Assert (Position.Node.Next /= null
- or else Position.Node = Position.Container.Last);
+ Target.First := Source.First;
+ Source.First := null;
- Position.Node := Position.Node.Next;
+ Target.Last := Source.Last;
+ Source.Last := null;
- if Position.Node = null then
- Position.Container := null;
- end if;
+ Target.Length := Source.Length;
+ Source.Length := 0;
+ end Move;
+
+ ----------
+ -- Next --
+ ----------
+
+ procedure Next (Position : in out Cursor) is
+ begin
+ Position := Next (Position);
end Next;
function Next (Position : Cursor) return Cursor is
begin
if Position.Node = null then
- pragma Assert (Position.Container = null);
return No_Element;
end if;
- pragma Assert (Position.Container /= null);
- pragma Assert (Position.Container.Length > 0);
- pragma Assert (Position.Container.First.Prev = null);
- pragma Assert (Position.Container.Last.Next = null);
-
- pragma Assert (Position.Node.Element /= null);
- pragma Assert (Position.Node.Prev = null
- or else Position.Node.Prev.Next = Position.Node);
- pragma Assert (Position.Node.Next = null
- or else Position.Node.Next.Prev = Position.Node);
- pragma Assert (Position.Node.Prev /= null
- or else Position.Node = Position.Container.First);
- pragma Assert (Position.Node.Next /= null
- or else Position.Node = Position.Container.Last);
+ pragma Assert (Vet (Position), "bad cursor in Next");
declare
Next_Node : constant Node_Access := Position.Node.Next;
end;
end Next;
- -------------
- -- Prepend --
- -------------
+ function Next (Object : Iterator; Position : Cursor) return Cursor is
+ begin
+ if Position.Container = null then
+ return No_Element;
+ end if;
- procedure Prepend
+ if Position.Container /= Object.Container then
+ raise Program_Error with
+ "Position cursor of Next designates wrong list";
+ end if;
+
+ return Next (Position);
+ end Next;
+
+ -------------
+ -- Prepend --
+ -------------
+
+ procedure Prepend
(Container : in out List;
New_Item : Element_Type;
Count : Count_Type := 1)
procedure Previous (Position : in out Cursor) is
begin
- if Position.Node = null then
- pragma Assert (Position.Container = null);
- return;
- end if;
-
- pragma Assert (Position.Container /= null);
- pragma Assert (Position.Container.Length > 0);
- pragma Assert (Position.Container.First.Prev = null);
- pragma Assert (Position.Container.Last.Next = null);
-
- pragma Assert (Position.Node.Element /= null);
- pragma Assert (Position.Node.Prev = null
- or else Position.Node.Prev.Next = Position.Node);
- pragma Assert (Position.Node.Next = null
- or else Position.Node.Next.Prev = Position.Node);
- pragma Assert (Position.Node.Prev /= null
- or else Position.Node = Position.Container.First);
- pragma Assert (Position.Node.Next /= null
- or else Position.Node = Position.Container.Last);
-
- Position.Node := Position.Node.Prev;
-
- if Position.Node = null then
- Position.Container := null;
- end if;
+ Position := Previous (Position);
end Previous;
function Previous (Position : Cursor) return Cursor is
begin
if Position.Node = null then
- pragma Assert (Position.Container = null);
return No_Element;
end if;
- pragma Assert (Position.Container /= null);
- pragma Assert (Position.Container.Length > 0);
- pragma Assert (Position.Container.First.Prev = null);
- pragma Assert (Position.Container.Last.Next = null);
-
- pragma Assert (Position.Node.Element /= null);
- pragma Assert (Position.Node.Prev = null
- or else Position.Node.Prev.Next = Position.Node);
- pragma Assert (Position.Node.Next = null
- or else Position.Node.Next.Prev = Position.Node);
- pragma Assert (Position.Node.Prev /= null
- or else Position.Node = Position.Container.First);
- pragma Assert (Position.Node.Next /= null
- or else Position.Node = Position.Container.Last);
+ pragma Assert (Vet (Position), "bad cursor in Previous");
declare
Prev_Node : constant Node_Access := Position.Node.Prev;
end;
end Previous;
+ function Previous (Object : Iterator; Position : Cursor) return Cursor is
+ begin
+ if Position.Container = null then
+ return No_Element;
+ end if;
+
+ if Position.Container /= Object.Container then
+ raise Program_Error with
+ "Position cursor of Previous designates wrong list";
+ end if;
+
+ return Previous (Position);
+ end Previous;
+
-------------------
-- Query_Element --
-------------------
procedure Query_Element
(Position : Cursor;
- Process : not null access procedure (Element : in Element_Type))
+ Process : not null access procedure (Element : Element_Type))
is
- pragma Assert (Position.Container /= null);
- pragma Assert (Position.Container.Length > 0);
- pragma Assert (Position.Container.First.Prev = null);
- pragma Assert (Position.Container.Last.Next = null);
-
- pragma Assert (Position.Node /= null);
- pragma Assert (Position.Node.Element /= null);
- pragma Assert (Position.Node.Prev = null
- or else Position.Node.Prev.Next = Position.Node);
- pragma Assert (Position.Node.Next = null
- or else Position.Node.Next.Prev = Position.Node);
- pragma Assert (Position.Node.Prev /= null
- or else Position.Node = Position.Container.First);
- pragma Assert (Position.Node.Next /= null
- or else Position.Node = Position.Container.Last);
-
- E : Element_Type renames Position.Node.Element.all;
-
- C : List renames Position.Container.all'Unrestricted_Access.all;
- B : Natural renames C.Busy;
- L : Natural renames C.Lock;
-
begin
- B := B + 1;
- L := L + 1;
+ if Position.Node = null then
+ raise Constraint_Error with
+ "Position cursor has no element";
+ end if;
+
+ if Position.Node.Element = null then
+ raise Program_Error with
+ "Position cursor has no element";
+ end if;
+
+ pragma Assert (Vet (Position), "bad cursor in Query_Element");
+
+ declare
+ C : List renames Position.Container.all'Unrestricted_Access.all;
+ B : Natural renames C.Busy;
+ L : Natural renames C.Lock;
begin
- Process (E);
- exception
- when others =>
- L := L - 1;
- B := B - 1;
- raise;
- end;
+ B := B + 1;
+ L := L + 1;
- L := L - 1;
- B := B - 1;
+ begin
+ Process (Position.Node.Element.all);
+ exception
+ when others =>
+ L := L - 1;
+ B := B - 1;
+ raise;
+ end;
+
+ L := L - 1;
+ B := B - 1;
+ end;
end Query_Element;
----------
----------
procedure Read
- (Stream : access Root_Stream_Type'Class;
+ (Stream : not null access Root_Stream_Type'Class;
Item : out List)
is
N : Count_Type'Base;
end loop;
end Read;
- ---------------------
- -- Replace_Element --
- ---------------------
-
- procedure Replace_Element
- (Position : Cursor;
- By : Element_Type)
+ procedure Read
+ (Stream : not null access Root_Stream_Type'Class;
+ Item : out Cursor)
is
- pragma Assert (Position.Container /= null);
- pragma Assert (Position.Container.Length > 0);
- pragma Assert (Position.Container.First.Prev = null);
- pragma Assert (Position.Container.Last.Next = null);
-
- pragma Assert (Position.Node /= null);
- pragma Assert (Position.Node.Element /= null);
- pragma Assert (Position.Node.Prev = null
- or else Position.Node.Prev.Next = Position.Node);
- pragma Assert (Position.Node.Next = null
- or else Position.Node.Next.Prev = Position.Node);
- pragma Assert (Position.Node.Prev /= null
- or else Position.Node = Position.Container.First);
- pragma Assert (Position.Node.Next /= null
- or else Position.Node = Position.Container.Last);
-
- X : Element_Access := Position.Node.Element;
-
begin
- if Position.Container.Lock > 0 then
- raise Program_Error;
- end if;
-
- Position.Node.Element := new Element_Type'(By);
- Free (X);
- end Replace_Element;
-
- ------------------
- -- Reverse_Find --
- ------------------
+ raise Program_Error with "attempt to stream list cursor";
+ end Read;
- function Reverse_Find
- (Container : List;
- Item : Element_Type;
- Position : Cursor := No_Element) return Cursor
+ procedure Read
+ (Stream : not null access Root_Stream_Type'Class;
+ Item : out Reference_Type)
is
- Node : Node_Access := Position.Node;
+ 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
- if Node = null then
- Node := Container.Last;
+ raise Program_Error with "attempt to stream reference";
+ end Read;
- else
- if Position.Container /= List_Access'(Container'Unchecked_Access) then
- raise Program_Error;
- end if;
+ ---------------
+ -- Reference --
+ ---------------
- pragma Assert (Container.Length > 0);
- pragma Assert (Container.First.Prev = null);
- pragma Assert (Container.Last.Next = null);
+ function Reference
+ (Container : aliased in out List;
+ Position : Cursor) return Reference_Type
+ is
+ begin
+ if Position.Container = null then
+ raise Constraint_Error with "Position cursor has no element";
+ end if;
- pragma Assert (Position.Node.Element /= null);
- pragma Assert (Position.Node.Prev = null
- or else Position.Node.Prev.Next = Position.Node);
- pragma Assert (Position.Node.Next = null
- or else Position.Node.Next.Prev = Position.Node);
- pragma Assert (Position.Node.Prev /= null
- or else Position.Node = Container.First);
- pragma Assert (Position.Node.Next /= null
- or else Position.Node = Container.Last);
+ if Position.Container /= Container'Unrestricted_Access then
+ raise Program_Error with
+ "Position cursor designates wrong container";
end if;
- while Node /= null loop
- if Node.Element.all = Item then
- return Cursor'(Container'Unchecked_Access, Node);
- end if;
+ if Position.Node.Element = null then
+ raise Program_Error with "Node has no element";
+ end if;
- Node := Node.Prev;
- end loop;
+ pragma Assert (Vet (Position), "bad cursor in function Reference");
- return No_Element;
- end Reverse_Find;
+ declare
+ C : List renames Position.Container.all;
+ B : Natural renames C.Busy;
+ L : Natural renames C.Lock;
+ begin
+ return R : constant Reference_Type :=
+ (Element => Position.Node.Element.all'Access,
+ Control => (Controlled with Position.Container))
+ do
+ B := B + 1;
+ L := L + 1;
+ end return;
+ end;
+ end Reference;
---------------------
- -- Reverse_Iterate --
+ -- Replace_Element --
---------------------
- procedure Reverse_Iterate
- (Container : List;
- Process : not null access procedure (Position : in Cursor))
+ procedure Replace_Element
+ (Container : in out List;
+ Position : Cursor;
+ New_Item : Element_Type)
is
- C : List renames Container'Unrestricted_Access.all;
- B : Natural renames C.Busy;
+ begin
+ if Position.Container = null then
+ raise Constraint_Error with "Position cursor has no element";
+ end if;
- Node : Node_Access := Container.Last;
+ if Position.Container /= Container'Unchecked_Access then
+ raise Program_Error with
+ "Position cursor designates wrong container";
+ end if;
- begin
- B := B + 1;
+ if Container.Lock > 0 then
+ raise Program_Error with
+ "attempt to tamper with elements (list is locked)";
+ end if;
+
+ if Position.Node.Element = null then
+ raise Program_Error with
+ "Position cursor has no element";
+ end if;
+
+ pragma Assert (Vet (Position), "bad cursor in Replace_Element");
+
+ declare
+ X : Element_Access := Position.Node.Element;
begin
- while Node /= null loop
- Process (Cursor'(Container'Unchecked_Access, Node));
- Node := Node.Prev;
- end loop;
- exception
- when others =>
- B := B - 1;
- raise;
+ Position.Node.Element := new Element_Type'(New_Item);
+ Free (X);
end;
+ end Replace_Element;
- B := B - 1;
- end Reverse_Iterate;
-
- ------------------
- -- Reverse_List --
- ------------------
+ ----------------------
+ -- Reverse_Elements --
+ ----------------------
- procedure Reverse_List (Container : in out List) is
+ procedure Reverse_Elements (Container : in out List) is
I : Node_Access := Container.First;
J : Node_Access := Container.Last;
end if;
end Swap;
- -- Start of processing for Reverse_List
+ -- Start of processing for Reverse_Elements
begin
if Container.Length <= 1 then
pragma Assert (Container.Last.Next = null);
if Container.Busy > 0 then
- raise Program_Error;
+ raise Program_Error with
+ "attempt to tamper with cursors (list is busy)";
end if;
Container.First := J;
pragma Assert (Container.First.Prev = null);
pragma Assert (Container.Last.Next = null);
- end Reverse_List;
+ end Reverse_Elements;
+
+ ------------------
+ -- Reverse_Find --
+ ------------------
+
+ function Reverse_Find
+ (Container : List;
+ Item : Element_Type;
+ Position : Cursor := No_Element) return Cursor
+ is
+ Node : Node_Access := Position.Node;
+
+ begin
+ if Node = null then
+ Node := Container.Last;
+
+ else
+ if Node.Element = null then
+ raise Program_Error with "Position cursor has no element";
+ end if;
+
+ if Position.Container /= Container'Unrestricted_Access then
+ raise Program_Error with
+ "Position cursor designates wrong container";
+ end if;
+
+ pragma Assert (Vet (Position), "bad cursor in Reverse_Find");
+ end if;
+
+ while Node /= null loop
+ if Node.Element.all = Item then
+ return Cursor'(Container'Unrestricted_Access, Node);
+ end if;
+
+ Node := Node.Prev;
+ end loop;
+
+ return No_Element;
+ end Reverse_Find;
+
+ ---------------------
+ -- Reverse_Iterate --
+ ---------------------
+
+ procedure Reverse_Iterate
+ (Container : List;
+ Process : not null access procedure (Position : Cursor))
+ is
+ C : List renames Container'Unrestricted_Access.all;
+ B : Natural renames C.Busy;
+
+ Node : Node_Access := Container.Last;
+
+ begin
+ B := B + 1;
+
+ begin
+ while Node /= null loop
+ Process (Cursor'(Container'Unrestricted_Access, Node));
+ Node := Node.Prev;
+ end loop;
+ exception
+ when others =>
+ B := B - 1;
+ raise;
+ end;
+
+ B := B - 1;
+ end Reverse_Iterate;
------------
-- Splice --
Source : in out List)
is
begin
- if Before.Node /= null then
- if Before.Container /= List_Access'(Target'Unchecked_Access) then
- raise Program_Error;
+ if Before.Container /= null then
+ if Before.Container /= Target'Unrestricted_Access then
+ raise Program_Error with
+ "Before cursor designates wrong container";
end if;
- pragma Assert (Target.Length >= 1);
- pragma Assert (Target.First.Prev = null);
- pragma Assert (Target.Last.Next = null);
+ if Before.Node = null
+ or else Before.Node.Element = null
+ then
+ raise Program_Error with
+ "Before cursor has no element";
+ end if;
- pragma Assert (Before.Node.Element /= null);
- pragma Assert (Before.Node.Prev = null
- or else Before.Node.Prev.Next = Before.Node);
- pragma Assert (Before.Node.Next = null
- or else Before.Node.Next.Prev = Before.Node);
- pragma Assert (Before.Node.Prev /= null
- or else Before.Node = Target.First);
- pragma Assert (Before.Node.Next /= null
- or else Before.Node = Target.Last);
+ pragma Assert (Vet (Before), "bad cursor in Splice");
end if;
if Target'Address = Source'Address
pragma Assert (Source.Last.Next = null);
if Target.Length > Count_Type'Last - Source.Length then
- raise Constraint_Error;
+ raise Constraint_Error with "new length exceeds maximum";
end if;
- if Target.Busy > 0
- or else Source.Busy > 0
- then
- raise Program_Error;
+ if Target.Busy > 0 then
+ raise Program_Error with
+ "attempt to tamper with cursors of Target (list is busy)";
+ end if;
+
+ if Source.Busy > 0 then
+ raise Program_Error with
+ "attempt to tamper with cursors of Source (list is busy)";
end if;
if Target.Length = 0 then
end Splice;
procedure Splice
- (Target : in out List;
- Before : Cursor;
- Position : Cursor)
+ (Container : in out List;
+ Before : Cursor;
+ Position : Cursor)
is
begin
- if Before.Node /= null then
- if Before.Container /= List_Access'(Target'Unchecked_Access) then
- raise Program_Error;
+ if Before.Container /= null then
+ if Before.Container /= Container'Unchecked_Access then
+ raise Program_Error with
+ "Before cursor designates wrong container";
end if;
- pragma Assert (Target.Length >= 1);
- pragma Assert (Target.First.Prev = null);
- pragma Assert (Target.Last.Next = null);
+ if Before.Node = null
+ or else Before.Node.Element = null
+ then
+ raise Program_Error with
+ "Before cursor has no element";
+ end if;
- pragma Assert (Before.Node.Element /= null);
- pragma Assert (Before.Node.Prev = null
- or else Before.Node.Prev.Next = Before.Node);
- pragma Assert (Before.Node.Next = null
- or else Before.Node.Next.Prev = Before.Node);
- pragma Assert (Before.Node.Prev /= null
- or else Before.Node = Target.First);
- pragma Assert (Before.Node.Next /= null
- or else Before.Node = Target.Last);
+ pragma Assert (Vet (Before), "bad Before cursor in Splice");
end if;
if Position.Node = null then
- raise Constraint_Error;
+ raise Constraint_Error with "Position cursor has no element";
end if;
- if Position.Container /= List_Access'(Target'Unchecked_Access) then
- raise Program_Error;
+ if Position.Node.Element = null then
+ raise Program_Error with "Position cursor has no element";
end if;
- pragma Assert (Target.Length >= 1);
- pragma Assert (Target.First.Prev = null);
- pragma Assert (Target.Last.Next = null);
+ if Position.Container /= Container'Unrestricted_Access then
+ raise Program_Error with
+ "Position cursor designates wrong container";
+ end if;
- pragma Assert (Position.Node.Element /= null);
- pragma Assert (Position.Node.Prev = null
- or else Position.Node.Prev.Next = Position.Node);
- pragma Assert (Position.Node.Next = null
- or else Position.Node.Next.Prev = Position.Node);
- pragma Assert (Position.Node.Prev /= null
- or else Position.Node = Target.First);
- pragma Assert (Position.Node.Next /= null
- or else Position.Node = Target.Last);
+ pragma Assert (Vet (Position), "bad Position cursor in Splice");
if Position.Node = Before.Node
or else Position.Node.Next = Before.Node
return;
end if;
- pragma Assert (Target.Length >= 2);
+ pragma Assert (Container.Length >= 2);
- if Target.Busy > 0 then
- raise Program_Error;
+ if Container.Busy > 0 then
+ raise Program_Error with
+ "attempt to tamper with cursors (list is busy)";
end if;
if Before.Node = null then
- pragma Assert (Position.Node /= Target.Last);
+ pragma Assert (Position.Node /= Container.Last);
- if Position.Node = Target.First then
- Target.First := Position.Node.Next;
- Target.First.Prev := null;
+ if Position.Node = Container.First then
+ Container.First := Position.Node.Next;
+ Container.First.Prev := null;
else
Position.Node.Prev.Next := Position.Node.Next;
Position.Node.Next.Prev := Position.Node.Prev;
end if;
- Target.Last.Next := Position.Node;
- Position.Node.Prev := Target.Last;
+ Container.Last.Next := Position.Node;
+ Position.Node.Prev := Container.Last;
- Target.Last := Position.Node;
- Target.Last.Next := null;
+ Container.Last := Position.Node;
+ Container.Last.Next := null;
return;
end if;
- if Before.Node = Target.First then
- pragma Assert (Position.Node /= Target.First);
+ if Before.Node = Container.First then
+ pragma Assert (Position.Node /= Container.First);
- if Position.Node = Target.Last then
- Target.Last := Position.Node.Prev;
- Target.Last.Next := null;
+ if Position.Node = Container.Last then
+ Container.Last := Position.Node.Prev;
+ Container.Last.Next := null;
else
Position.Node.Prev.Next := Position.Node.Next;
Position.Node.Next.Prev := Position.Node.Prev;
end if;
- Target.First.Prev := Position.Node;
- Position.Node.Next := Target.First;
+ Container.First.Prev := Position.Node;
+ Position.Node.Next := Container.First;
- Target.First := Position.Node;
- Target.First.Prev := null;
+ Container.First := Position.Node;
+ Container.First.Prev := null;
return;
end if;
- if Position.Node = Target.First then
- Target.First := Position.Node.Next;
- Target.First.Prev := null;
+ if Position.Node = Container.First then
+ Container.First := Position.Node.Next;
+ Container.First.Prev := null;
- elsif Position.Node = Target.Last then
- Target.Last := Position.Node.Prev;
- Target.Last.Next := null;
+ elsif Position.Node = Container.Last then
+ Container.Last := Position.Node.Prev;
+ Container.Last.Next := null;
else
Position.Node.Prev.Next := Position.Node.Next;
Before.Node.Prev := Position.Node;
Position.Node.Next := Before.Node;
- pragma Assert (Target.First.Prev = null);
- pragma Assert (Target.Last.Next = null);
+ pragma Assert (Container.First.Prev = null);
+ pragma Assert (Container.Last.Next = null);
end Splice;
procedure Splice
return;
end if;
- if Before.Node /= null then
- if Before.Container /= List_Access'(Target'Unchecked_Access) then
- raise Program_Error;
+ if Before.Container /= null then
+ if Before.Container /= Target'Unrestricted_Access then
+ raise Program_Error with
+ "Before cursor designates wrong container";
end if;
- pragma Assert (Target.Length >= 1);
- pragma Assert (Target.First.Prev = null);
- pragma Assert (Target.Last.Next = null);
+ if Before.Node = null
+ or else Before.Node.Element = null
+ then
+ raise Program_Error with
+ "Before cursor has no element";
+ end if;
- pragma Assert (Before.Node.Element /= null);
- pragma Assert (Before.Node.Prev = null
- or else Before.Node.Prev.Next = Before.Node);
- pragma Assert (Before.Node.Next = null
- or else Before.Node.Next.Prev = Before.Node);
- pragma Assert (Before.Node.Prev /= null
- or else Before.Node = Target.First);
- pragma Assert (Before.Node.Next /= null
- or else Before.Node = Target.Last);
+ pragma Assert (Vet (Before), "bad Before cursor in Splice");
end if;
if Position.Node = null then
- raise Constraint_Error;
+ raise Constraint_Error with "Position cursor has no element";
end if;
- if Position.Container /= List_Access'(Source'Unchecked_Access) then
- raise Program_Error;
+ if Position.Node.Element = null then
+ raise Program_Error with
+ "Position cursor has no element";
end if;
- pragma Assert (Source.Length >= 1);
- pragma Assert (Source.First.Prev = null);
- pragma Assert (Source.Last.Next = null);
+ if Position.Container /= Source'Unrestricted_Access then
+ raise Program_Error with
+ "Position cursor designates wrong container";
+ end if;
- pragma Assert (Position.Node.Element /= null);
- pragma Assert (Position.Node.Prev = null
- or else Position.Node.Prev.Next = Position.Node);
- pragma Assert (Position.Node.Next = null
- or else Position.Node.Next.Prev = Position.Node);
- pragma Assert (Position.Node.Prev /= null
- or else Position.Node = Source.First);
- pragma Assert (Position.Node.Next /= null
- or else Position.Node = Source.Last);
+ pragma Assert (Vet (Position), "bad Position cursor in Splice");
if Target.Length = Count_Type'Last then
- raise Constraint_Error;
+ raise Constraint_Error with "Target is full";
end if;
- if Target.Busy > 0
- or else Source.Busy > 0
- then
- raise Program_Error;
+ if Target.Busy > 0 then
+ raise Program_Error with
+ "attempt to tamper with cursors of Target (list is busy)";
+ end if;
+
+ if Source.Busy > 0 then
+ raise Program_Error with
+ "attempt to tamper with cursors of Source (list is busy)";
end if;
if Position.Node = Source.First then
Source.First := Position.Node.Next;
- Source.First.Prev := null;
if Position.Node = Source.Last then
pragma Assert (Source.First = null);
pragma Assert (Source.Length = 1);
Source.Last := null;
+
+ else
+ Source.First.Prev := null;
end if;
elsif Position.Node = Source.Last then
-- Swap --
----------
- procedure Swap (I, J : Cursor) is
+ procedure Swap
+ (Container : in out List;
+ I, J : Cursor)
+ is
begin
- if I.Container = null
- or else J.Container = null
- then
- raise Constraint_Error;
+ if I.Node = null then
+ raise Constraint_Error with "I cursor has no element";
end if;
- if I.Container /= J.Container then
- raise Program_Error;
+ if J.Node = null then
+ raise Constraint_Error with "J cursor has no element";
end if;
- declare
- C : List renames I.Container.all;
- begin
- pragma Assert (C.Length > 0);
- pragma Assert (C.First.Prev = null);
- pragma Assert (C.Last.Next = null);
-
- pragma Assert (I.Node /= null);
- pragma Assert (I.Node.Element /= null);
- pragma Assert (I.Node.Prev = null
- or else I.Node.Prev.Next = I.Node);
- pragma Assert (I.Node.Next = null
- or else I.Node.Next.Prev = I.Node);
- pragma Assert (I.Node.Prev /= null
- or else I.Node = C.First);
- pragma Assert (I.Node.Next /= null
- or else I.Node = C.Last);
-
- if I.Node = J.Node then
- return;
- end if;
+ if I.Container /= Container'Unchecked_Access then
+ raise Program_Error with "I cursor designates wrong container";
+ end if;
- pragma Assert (C.Length > 1);
- pragma Assert (J.Node /= null);
- pragma Assert (J.Node.Element /= null);
- pragma Assert (J.Node.Prev = null
- or else J.Node.Prev.Next = J.Node);
- pragma Assert (J.Node.Next = null
- or else J.Node.Next.Prev = J.Node);
- pragma Assert (J.Node.Prev /= null
- or else J.Node = C.First);
- pragma Assert (J.Node.Next /= null
- or else J.Node = C.Last);
-
- if C.Lock > 0 then
- raise Program_Error;
- end if;
+ if J.Container /= Container'Unchecked_Access then
+ raise Program_Error with "J cursor designates wrong container";
+ end if;
- declare
- EI_Copy : constant Element_Access := I.Node.Element;
- begin
- I.Node.Element := J.Node.Element;
- J.Node.Element := EI_Copy;
- end;
+ if I.Node = J.Node then
+ return;
+ end if;
+
+ if Container.Lock > 0 then
+ raise Program_Error with
+ "attempt to tamper with elements (list is locked)";
+ end if;
+
+ pragma Assert (Vet (I), "bad I cursor in Swap");
+ pragma Assert (Vet (J), "bad J cursor in Swap");
+
+ declare
+ EI_Copy : constant Element_Access := I.Node.Element;
+
+ begin
+ I.Node.Element := J.Node.Element;
+ J.Node.Element := EI_Copy;
end;
end Swap;
I, J : Cursor)
is
begin
- if I.Container = null
- or else J.Container = null
- then
- raise Constraint_Error;
+ if I.Node = null then
+ raise Constraint_Error with "I cursor has no element";
end if;
- if I.Container /= List_Access'(Container'Unchecked_Access) then
- raise Program_Error;
+ if J.Node = null then
+ raise Constraint_Error with "J cursor has no element";
end if;
- if J.Container /= I.Container then
- raise Program_Error;
+ if I.Container /= Container'Unrestricted_Access then
+ raise Program_Error with "I cursor designates wrong container";
end if;
- pragma Assert (Container.Length >= 1);
- pragma Assert (Container.First.Prev = null);
- pragma Assert (Container.Last.Next = null);
-
- pragma Assert (I.Node /= null);
- pragma Assert (I.Node.Element /= null);
- pragma Assert (I.Node.Prev = null
- or else I.Node.Prev.Next = I.Node);
- pragma Assert (I.Node.Next = null
- or else I.Node.Next.Prev = I.Node);
- pragma Assert (I.Node.Prev /= null
- or else I.Node = Container.First);
- pragma Assert (I.Node.Next /= null
- or else I.Node = Container.Last);
+ if J.Container /= Container'Unrestricted_Access then
+ raise Program_Error with "J cursor designates wrong container";
+ end if;
if I.Node = J.Node then
return;
end if;
- pragma Assert (Container.Length >= 2);
- pragma Assert (J.Node /= null);
- pragma Assert (J.Node.Element /= null);
- pragma Assert (J.Node.Prev = null
- or else J.Node.Prev.Next = J.Node);
- pragma Assert (J.Node.Next = null
- or else J.Node.Next.Prev = J.Node);
- pragma Assert (J.Node.Prev /= null
- or else J.Node = Container.First);
- pragma Assert (J.Node.Next /= null
- or else J.Node = Container.Last);
-
if Container.Busy > 0 then
- raise Program_Error;
+ raise Program_Error with
+ "attempt to tamper with cursors (list is busy)";
end if;
+ pragma Assert (Vet (I), "bad I cursor in Swap_Links");
+ pragma Assert (Vet (J), "bad J cursor in Swap_Links");
+
declare
I_Next : constant Cursor := Next (I);
else
declare
J_Next : constant Cursor := Next (J);
+
begin
if J_Next = I then
Splice (Container, Before => J, Position => I);
--------------------
procedure Update_Element
- (Position : Cursor;
- Process : not null access procedure (Element : in out Element_Type))
+ (Container : in out List;
+ Position : Cursor;
+ Process : not null access procedure (Element : in out Element_Type))
is
- pragma Assert (Position.Container /= null);
- pragma Assert (Position.Container.Length > 0);
- pragma Assert (Position.Container.First.Prev = null);
- pragma Assert (Position.Container.Last.Next = null);
-
- pragma Assert (Position.Node /= null);
- pragma Assert (Position.Node.Element /= null);
- pragma Assert (Position.Node.Prev = null
- or else Position.Node.Prev.Next = Position.Node);
- pragma Assert (Position.Node.Next = null
- or else Position.Node.Next.Prev = Position.Node);
- pragma Assert (Position.Node.Prev /= null
- or else Position.Node = Position.Container.First);
- pragma Assert (Position.Node.Next /= null
- or else Position.Node = Position.Container.Last);
-
- E : Element_Type renames Position.Node.Element.all;
-
- C : List renames Position.Container.all'Unrestricted_Access.all;
- B : Natural renames C.Busy;
- L : Natural renames C.Lock;
-
begin
- B := B + 1;
- L := L + 1;
+ if Position.Node = null then
+ raise Constraint_Error with "Position cursor has no element";
+ end if;
+
+ if Position.Node.Element = null then
+ raise Program_Error with
+ "Position cursor has no element";
+ end if;
+
+ if Position.Container /= Container'Unchecked_Access then
+ raise Program_Error with
+ "Position cursor designates wrong container";
+ end if;
+
+ pragma Assert (Vet (Position), "bad cursor in Update_Element");
+
+ declare
+ B : Natural renames Container.Busy;
+ L : Natural renames Container.Lock;
begin
- Process (E);
- exception
- when others =>
- L := L - 1;
- B := B - 1;
- raise;
- end;
+ B := B + 1;
+ L := L + 1;
- L := L - 1;
- B := B - 1;
+ begin
+ Process (Position.Node.Element.all);
+ exception
+ when others =>
+ L := L - 1;
+ B := B - 1;
+ raise;
+ end;
+
+ L := L - 1;
+ B := B - 1;
+ end;
end Update_Element;
+ ---------
+ -- Vet --
+ ---------
+
+ function Vet (Position : Cursor) return Boolean is
+ begin
+ if Position.Node = null then
+ return Position.Container = null;
+ end if;
+
+ if Position.Container = null then
+ return False;
+ end if;
+
+ -- An invariant of a node is that its Previous and Next components can
+ -- be null, or designate a different node. Also, its element access
+ -- value must be non-null. Operation Free sets the node access value
+ -- components of the node to designate the node itself, and the element
+ -- access value to null, before actually deallocating the node, thus
+ -- deliberately violating the node invariant. This gives us a simple way
+ -- to detect a dangling reference to a node.
+
+ if Position.Node.Next = Position.Node then
+ return False;
+ end if;
+
+ if Position.Node.Prev = Position.Node then
+ return False;
+ end if;
+
+ if Position.Node.Element = null then
+ return False;
+ end if;
+
+ -- In practice the tests above will detect most instances of a dangling
+ -- reference. If we get here, it means that the invariants of the
+ -- designated node are satisfied (they at least appear to be satisfied),
+ -- so we perform some more tests, to determine whether invariants of the
+ -- designated list are satisfied too.
+
+ declare
+ L : List renames Position.Container.all;
+
+ begin
+ if L.Length = 0 then
+ return False;
+ end if;
+
+ if L.First = null then
+ return False;
+ end if;
+
+ if L.Last = null then
+ return False;
+ end if;
+
+ if L.First.Prev /= null then
+ return False;
+ end if;
+
+ if L.Last.Next /= null then
+ return False;
+ end if;
+
+ if Position.Node.Prev = null and then Position.Node /= L.First then
+ return False;
+ end if;
+
+ if Position.Node.Next = null and then Position.Node /= L.Last then
+ return False;
+ end if;
+
+ if L.Length = 1 then
+ return L.First = L.Last;
+ end if;
+
+ if L.First = L.Last then
+ return False;
+ end if;
+
+ if L.First.Next = null then
+ return False;
+ end if;
+
+ if L.Last.Prev = null then
+ return False;
+ end if;
+
+ if L.First.Next.Prev /= L.First then
+ return False;
+ end if;
+
+ if L.Last.Prev.Next /= L.Last then
+ return False;
+ end if;
+
+ if L.Length = 2 then
+ if L.First.Next /= L.Last then
+ return False;
+ end if;
+
+ if L.Last.Prev /= L.First then
+ return False;
+ end if;
+
+ return True;
+ end if;
+
+ if L.First.Next = L.Last then
+ return False;
+ end if;
+
+ if L.Last.Prev = L.First then
+ return False;
+ end if;
+
+ if Position.Node = L.First then
+ return True;
+ end if;
+
+ if Position.Node = L.Last then
+ return True;
+ end if;
+
+ if Position.Node.Next = null then
+ return False;
+ end if;
+
+ if Position.Node.Prev = null then
+ return False;
+ end if;
+
+ if Position.Node.Next.Prev /= Position.Node then
+ return False;
+ end if;
+
+ if Position.Node.Prev.Next /= Position.Node then
+ return False;
+ end if;
+
+ if L.Length = 3 then
+ if L.First.Next /= Position.Node then
+ return False;
+ end if;
+
+ if L.Last.Prev /= Position.Node then
+ return False;
+ end if;
+ end if;
+
+ return True;
+ end;
+ end Vet;
+
-----------
-- Write --
-----------
procedure Write
- (Stream : access Root_Stream_Type'Class;
+ (Stream : not null access Root_Stream_Type'Class;
Item : List)
is
Node : Node_Access := Item.First;
+
begin
Count_Type'Base'Write (Stream, Item.Length);
+
while Node /= null loop
- Element_Type'Output (Stream, Node.Element.all); -- X.all
+ Element_Type'Output (Stream, Node.Element.all);
Node := Node.Next;
end loop;
end Write;
+ procedure Write
+ (Stream : not null access Root_Stream_Type'Class;
+ Item : Cursor)
+ is
+ begin
+ raise Program_Error with "attempt to stream list 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.Indefinite_Doubly_Linked_Lists;
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