------------------------------------------------------------------------------ -- -- -- GNAT LIBRARY COMPONENTS -- -- -- -- ADA.CONTAINERS.FORMAL_DOUBLY_LINKED_LISTS -- -- -- -- B o d y -- -- -- -- Copyright (C) 2010-2020, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 3, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. -- -- -- -- As a special exception under Section 7 of GPL version 3, you are granted -- -- additional permissions described in the GCC Runtime Library Exception, -- -- version 3.1, as published by the Free Software Foundation. -- -- -- -- You should have received a copy of the GNU General Public License and -- -- a copy of the GCC Runtime Library Exception along with this program; -- -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- -- . -- ------------------------------------------------------------------------------ with System; use type System.Address; package body Ada.Containers.Formal_Doubly_Linked_Lists with SPARK_Mode => Off is ----------------------- -- Local Subprograms -- ----------------------- procedure Allocate (Container : in out List; New_Item : Element_Type; New_Node : out Count_Type); procedure Free (Container : in out List; X : Count_Type); procedure Insert_Internal (Container : in out List; Before : Count_Type; New_Node : Count_Type); function Vet (L : List; Position : Cursor) return Boolean; --------- -- "=" -- --------- function "=" (Left : List; Right : List) return Boolean is LI : Count_Type; RI : Count_Type; begin if Left'Address = Right'Address then return True; end if; if Left.Length /= Right.Length then return False; end if; LI := Left.First; RI := Left.First; while LI /= 0 loop if Left.Nodes (LI).Element /= Right.Nodes (LI).Element then return False; end if; LI := Left.Nodes (LI).Next; RI := Right.Nodes (RI).Next; end loop; return True; end "="; -------------- -- Allocate -- -------------- procedure Allocate (Container : in out List; New_Item : Element_Type; New_Node : out Count_Type) is N : Node_Array renames Container.Nodes; begin if Container.Free >= 0 then New_Node := Container.Free; N (New_Node).Element := New_Item; Container.Free := N (New_Node).Next; else New_Node := abs Container.Free; N (New_Node).Element := New_Item; Container.Free := Container.Free - 1; end if; end Allocate; ------------ -- Append -- ------------ procedure Append (Container : in out List; New_Item : Element_Type) is begin Insert (Container, No_Element, New_Item, 1); end Append; procedure Append (Container : in out List; New_Item : Element_Type; Count : Count_Type) is begin Insert (Container, No_Element, New_Item, Count); end Append; ------------ -- Assign -- ------------ procedure Assign (Target : in out List; Source : List) is N : Node_Array renames Source.Nodes; J : Count_Type; begin if Target'Address = Source'Address then return; end if; if Target.Capacity < Source.Length then raise Constraint_Error with -- ??? "Source length exceeds Target capacity"; end if; Clear (Target); J := Source.First; while J /= 0 loop Append (Target, N (J).Element, 1); J := N (J).Next; end loop; end Assign; ----------- -- Clear -- ----------- procedure Clear (Container : in out List) is N : Node_Array renames Container.Nodes; X : Count_Type; begin if Container.Length = 0 then pragma Assert (Container.First = 0); pragma Assert (Container.Last = 0); return; end if; pragma Assert (Container.First >= 1); pragma Assert (Container.Last >= 1); pragma Assert (N (Container.First).Prev = 0); pragma Assert (N (Container.Last).Next = 0); while Container.Length > 1 loop X := Container.First; Container.First := N (X).Next; N (Container.First).Prev := 0; Container.Length := Container.Length - 1; Free (Container, X); end loop; X := Container.First; Container.First := 0; Container.Last := 0; Container.Length := 0; Free (Container, X); end Clear; -------------- -- Contains -- -------------- function Contains (Container : List; Item : Element_Type) return Boolean is begin return Find (Container, Item) /= No_Element; end Contains; ---------- -- Copy -- ---------- function Copy (Source : List; Capacity : Count_Type := 0) return List is C : constant Count_Type := Count_Type'Max (Source.Capacity, Capacity); N : Count_Type; P : List (C); begin if 0 < Capacity and then Capacity < Source.Capacity then raise Capacity_Error; end if; N := 1; while N <= Source.Capacity loop P.Nodes (N).Prev := Source.Nodes (N).Prev; P.Nodes (N).Next := Source.Nodes (N).Next; P.Nodes (N).Element := Source.Nodes (N).Element; N := N + 1; end loop; P.Free := Source.Free; P.Length := Source.Length; P.First := Source.First; P.Last := Source.Last; if P.Free >= 0 then N := Source.Capacity + 1; while N <= C loop Free (P, N); N := N + 1; end loop; end if; return P; end Copy; ------------ -- Delete -- ------------ procedure Delete (Container : in out List; Position : in out Cursor) is begin Delete (Container => Container, Position => Position, Count => 1); end Delete; procedure Delete (Container : in out List; Position : in out Cursor; Count : Count_Type) is N : Node_Array renames Container.Nodes; X : Count_Type; begin if not Has_Element (Container => Container, Position => Position) then raise Constraint_Error with "Position cursor has no element"; end if; pragma Assert (Vet (Container, Position), "bad cursor in Delete"); pragma Assert (Container.First >= 1); pragma Assert (Container.Last >= 1); pragma Assert (N (Container.First).Prev = 0); pragma Assert (N (Container.Last).Next = 0); if Position.Node = Container.First then Delete_First (Container, Count); Position := No_Element; return; end if; if Count = 0 then Position := No_Element; return; end if; for Index in 1 .. Count loop pragma Assert (Container.Length >= 2); X := Position.Node; Container.Length := Container.Length - 1; if X = Container.Last then Position := No_Element; Container.Last := N (X).Prev; N (Container.Last).Next := 0; Free (Container, X); return; end if; Position.Node := N (X).Next; pragma Assert (N (Position.Node).Prev >= 0); N (N (X).Next).Prev := N (X).Prev; N (N (X).Prev).Next := N (X).Next; Free (Container, X); end loop; Position := No_Element; end Delete; ------------------ -- Delete_First -- ------------------ procedure Delete_First (Container : in out List) is begin Delete_First (Container => Container, Count => 1); end Delete_First; procedure Delete_First (Container : in out List; Count : Count_Type) is N : Node_Array renames Container.Nodes; X : Count_Type; begin if Count >= Container.Length then Clear (Container); return; end if; if Count = 0 then return; end if; for J in 1 .. Count loop X := Container.First; pragma Assert (N (N (X).Next).Prev = Container.First); Container.First := N (X).Next; N (Container.First).Prev := 0; Container.Length := Container.Length - 1; Free (Container, X); end loop; end Delete_First; ----------------- -- Delete_Last -- ----------------- procedure Delete_Last (Container : in out List) is begin Delete_Last (Container => Container, Count => 1); end Delete_Last; procedure Delete_Last (Container : in out List; Count : Count_Type) is N : Node_Array renames Container.Nodes; X : Count_Type; begin if Count >= Container.Length then Clear (Container); return; end if; if Count = 0 then return; end if; for J in 1 .. Count loop X := Container.Last; pragma Assert (N (N (X).Prev).Next = Container.Last); Container.Last := N (X).Prev; N (Container.Last).Next := 0; Container.Length := Container.Length - 1; Free (Container, X); end loop; end Delete_Last; ------------- -- Element -- ------------- function Element (Container : List; Position : Cursor) return Element_Type is begin if not Has_Element (Container => Container, Position => Position) then raise Constraint_Error with "Position cursor has no element"; end if; return Container.Nodes (Position.Node).Element; end Element; ---------- -- Find -- ---------- function Find (Container : List; Item : Element_Type; Position : Cursor := No_Element) return Cursor is From : Count_Type := Position.Node; begin if From = 0 and Container.Length = 0 then return No_Element; end if; if From = 0 then From := Container.First; end if; if Position.Node /= 0 and then not Has_Element (Container, Position) then raise Constraint_Error with "Position cursor has no element"; end if; while From /= 0 loop if Container.Nodes (From).Element = Item then return (Node => From); end if; From := Container.Nodes (From).Next; end loop; return No_Element; end Find; ----------- -- First -- ----------- function First (Container : List) return Cursor is begin if Container.First = 0 then return No_Element; end if; return (Node => Container.First); end First; ------------------- -- First_Element -- ------------------- function First_Element (Container : List) return Element_Type is F : constant Count_Type := Container.First; begin if F = 0 then raise Constraint_Error with "list is empty"; else return Container.Nodes (F).Element; end if; end First_Element; ------------------ -- Formal_Model -- ------------------ package body Formal_Model is ---------------------------- -- Lift_Abstraction_Level -- ---------------------------- procedure Lift_Abstraction_Level (Container : List) is null; ------------------------- -- M_Elements_In_Union -- ------------------------- function M_Elements_In_Union (Container : M.Sequence; Left : M.Sequence; Right : M.Sequence) return Boolean is Elem : Element_Type; begin for Index in 1 .. M.Length (Container) loop Elem := Element (Container, Index); if not M.Contains (Left, 1, M.Length (Left), Elem) and then not M.Contains (Right, 1, M.Length (Right), Elem) then return False; end if; end loop; return True; end M_Elements_In_Union; ------------------------- -- M_Elements_Included -- ------------------------- function M_Elements_Included (Left : M.Sequence; L_Fst : Positive_Count_Type := 1; L_Lst : Count_Type; Right : M.Sequence; R_Fst : Positive_Count_Type := 1; R_Lst : Count_Type) return Boolean is begin for I in L_Fst .. L_Lst loop declare Found : Boolean := False; J : Count_Type := R_Fst - 1; begin while not Found and J < R_Lst loop J := J + 1; if Element (Left, I) = Element (Right, J) then Found := True; end if; end loop; if not Found then return False; end if; end; end loop; return True; end M_Elements_Included; ------------------------- -- M_Elements_Reversed -- ------------------------- function M_Elements_Reversed (Left : M.Sequence; Right : M.Sequence) return Boolean is L : constant Count_Type := M.Length (Left); begin if L /= M.Length (Right) then return False; end if; for I in 1 .. L loop if Element (Left, I) /= Element (Right, L - I + 1) then return False; end if; end loop; return True; end M_Elements_Reversed; ------------------------ -- M_Elements_Swapped -- ------------------------ function M_Elements_Swapped (Left : M.Sequence; Right : M.Sequence; X : Positive_Count_Type; Y : Positive_Count_Type) return Boolean is begin if M.Length (Left) /= M.Length (Right) or else Element (Left, X) /= Element (Right, Y) or else Element (Left, Y) /= Element (Right, X) then return False; end if; for I in 1 .. M.Length (Left) loop if I /= X and then I /= Y and then Element (Left, I) /= Element (Right, I) then return False; end if; end loop; return True; end M_Elements_Swapped; ----------- -- Model -- ----------- function Model (Container : List) return M.Sequence is Position : Count_Type := Container.First; R : M.Sequence; begin -- Can't use First, Next or Element here, since they depend on models -- for their postconditions. while Position /= 0 loop R := M.Add (R, Container.Nodes (Position).Element); Position := Container.Nodes (Position).Next; end loop; return R; end Model; ----------------------- -- Mapping_Preserved -- ----------------------- function Mapping_Preserved (M_Left : M.Sequence; M_Right : M.Sequence; P_Left : P.Map; P_Right : P.Map) return Boolean is begin for C of P_Left loop if not P.Has_Key (P_Right, C) or else P.Get (P_Left, C) > M.Length (M_Left) or else P.Get (P_Right, C) > M.Length (M_Right) or else M.Get (M_Left, P.Get (P_Left, C)) /= M.Get (M_Right, P.Get (P_Right, C)) then return False; end if; end loop; for C of P_Right loop if not P.Has_Key (P_Left, C) then return False; end if; end loop; return True; end Mapping_Preserved; ------------------------- -- P_Positions_Shifted -- ------------------------- function P_Positions_Shifted (Small : P.Map; Big : P.Map; Cut : Positive_Count_Type; Count : Count_Type := 1) return Boolean is begin for Cu of Small loop if not P.Has_Key (Big, Cu) then return False; end if; end loop; for Cu of Big loop declare Pos : constant Positive_Count_Type := P.Get (Big, Cu); begin if Pos < Cut then if not P.Has_Key (Small, Cu) or else Pos /= P.Get (Small, Cu) then return False; end if; elsif Pos >= Cut + Count then if not P.Has_Key (Small, Cu) or else Pos /= P.Get (Small, Cu) + Count then return False; end if; else if P.Has_Key (Small, Cu) then return False; end if; end if; end; end loop; return True; end P_Positions_Shifted; ------------------------- -- P_Positions_Swapped -- ------------------------- function P_Positions_Swapped (Left : P.Map; Right : P.Map; X : Cursor; Y : Cursor) return Boolean is begin if not P.Has_Key (Left, X) or not P.Has_Key (Left, Y) or not P.Has_Key (Right, X) or not P.Has_Key (Right, Y) then return False; end if; if P.Get (Left, X) /= P.Get (Right, Y) or P.Get (Left, Y) /= P.Get (Right, X) then return False; end if; for C of Left loop if not P.Has_Key (Right, C) then return False; end if; end loop; for C of Right loop if not P.Has_Key (Left, C) or else (C /= X and C /= Y and P.Get (Left, C) /= P.Get (Right, C)) then return False; end if; end loop; return True; end P_Positions_Swapped; --------------------------- -- P_Positions_Truncated -- --------------------------- function P_Positions_Truncated (Small : P.Map; Big : P.Map; Cut : Positive_Count_Type; Count : Count_Type := 1) return Boolean is begin for Cu of Small loop if not P.Has_Key (Big, Cu) then return False; end if; end loop; for Cu of Big loop declare Pos : constant Positive_Count_Type := P.Get (Big, Cu); begin if Pos < Cut then if not P.Has_Key (Small, Cu) or else Pos /= P.Get (Small, Cu) then return False; end if; elsif Pos >= Cut + Count then return False; elsif P.Has_Key (Small, Cu) then return False; end if; end; end loop; return True; end P_Positions_Truncated; --------------- -- Positions -- --------------- function Positions (Container : List) return P.Map is I : Count_Type := 1; Position : Count_Type := Container.First; R : P.Map; begin -- Can't use First, Next or Element here, since they depend on models -- for their postconditions. while Position /= 0 loop R := P.Add (R, (Node => Position), I); pragma Assert (P.Length (R) = I); Position := Container.Nodes (Position).Next; I := I + 1; end loop; return R; end Positions; end Formal_Model; ---------- -- Free -- ---------- procedure Free (Container : in out List; X : Count_Type) is pragma Assert (X > 0); pragma Assert (X <= Container.Capacity); N : Node_Array renames Container.Nodes; begin N (X).Prev := -1; -- Node is deallocated (not on active list) if Container.Free >= 0 then N (X).Next := Container.Free; Container.Free := X; elsif X + 1 = abs Container.Free then N (X).Next := 0; -- Not strictly necessary, but marginally safer Container.Free := Container.Free + 1; else Container.Free := abs Container.Free; if Container.Free > Container.Capacity then Container.Free := 0; else for J in Container.Free .. Container.Capacity - 1 loop N (J).Next := J + 1; end loop; N (Container.Capacity).Next := 0; end if; N (X).Next := Container.Free; Container.Free := X; end if; end Free; --------------------- -- Generic_Sorting -- --------------------- package body Generic_Sorting with SPARK_Mode => Off is ------------------ -- Formal_Model -- ------------------ package body Formal_Model is ----------------------- -- M_Elements_Sorted -- ----------------------- function M_Elements_Sorted (Container : M.Sequence) return Boolean is begin if M.Length (Container) = 0 then return True; end if; declare E1 : Element_Type := Element (Container, 1); begin for I in 2 .. M.Length (Container) loop declare E2 : constant Element_Type := Element (Container, I); begin if E2 < E1 then return False; end if; E1 := E2; end; end loop; end; return True; end M_Elements_Sorted; end Formal_Model; --------------- -- Is_Sorted -- --------------- function Is_Sorted (Container : List) return Boolean is Nodes : Node_Array renames Container.Nodes; Node : Count_Type := Container.First; begin for J in 2 .. Container.Length loop if Nodes (Nodes (Node).Next).Element < Nodes (Node).Element then return False; else Node := Nodes (Node).Next; end if; end loop; return True; end Is_Sorted; ----------- -- Merge -- ----------- procedure Merge (Target : in out List; Source : in out List) is LN : Node_Array renames Target.Nodes; RN : Node_Array renames Source.Nodes; LI : Cursor; RI : Cursor; begin if Target'Address = Source'Address then raise Program_Error with "Target and Source denote same container"; end if; LI := First (Target); RI := First (Source); while RI.Node /= 0 loop pragma Assert (RN (RI.Node).Next = 0 or else not (RN (RN (RI.Node).Next).Element < RN (RI.Node).Element)); if LI.Node = 0 then Splice (Target, No_Element, Source); return; end if; pragma Assert (LN (LI.Node).Next = 0 or else not (LN (LN (LI.Node).Next).Element < LN (LI.Node).Element)); if RN (RI.Node).Element < LN (LI.Node).Element then declare RJ : Cursor := RI; pragma Warnings (Off, RJ); begin RI.Node := RN (RI.Node).Next; Splice (Target, LI, Source, RJ); end; else LI.Node := LN (LI.Node).Next; end if; end loop; end Merge; ---------- -- Sort -- ---------- procedure Sort (Container : in out List) is N : Node_Array renames Container.Nodes; procedure Partition (Pivot : Count_Type; Back : Count_Type); procedure Sort (Front : Count_Type; Back : Count_Type); --------------- -- Partition -- --------------- procedure Partition (Pivot : Count_Type; Back : Count_Type) is Node : Count_Type; begin Node := N (Pivot).Next; while Node /= Back loop if N (Node).Element < N (Pivot).Element then declare Prev : constant Count_Type := N (Node).Prev; Next : constant Count_Type := N (Node).Next; begin N (Prev).Next := Next; if Next = 0 then Container.Last := Prev; else N (Next).Prev := Prev; end if; N (Node).Next := Pivot; N (Node).Prev := N (Pivot).Prev; N (Pivot).Prev := Node; if N (Node).Prev = 0 then Container.First := Node; else N (N (Node).Prev).Next := Node; end if; Node := Next; end; else Node := N (Node).Next; end if; end loop; end Partition; ---------- -- Sort -- ---------- procedure Sort (Front : Count_Type; Back : Count_Type) is Pivot : Count_Type; begin if Front = 0 then Pivot := Container.First; else Pivot := N (Front).Next; end if; if Pivot /= Back then Partition (Pivot, Back); Sort (Front, Pivot); Sort (Pivot, Back); end if; end Sort; -- Start of processing for Sort begin if Container.Length <= 1 then return; end if; pragma Assert (N (Container.First).Prev = 0); pragma Assert (N (Container.Last).Next = 0); Sort (Front => 0, Back => 0); pragma Assert (N (Container.First).Prev = 0); pragma Assert (N (Container.Last).Next = 0); end Sort; end Generic_Sorting; ----------------- -- Has_Element -- ----------------- function Has_Element (Container : List; Position : Cursor) return Boolean is begin if Position.Node = 0 then return False; end if; return Container.Nodes (Position.Node).Prev /= -1; end Has_Element; ------------ -- Insert -- ------------ procedure Insert (Container : in out List; Before : Cursor; New_Item : Element_Type; Position : out Cursor; Count : Count_Type) is J : Count_Type; begin if Before.Node /= 0 then pragma Assert (Vet (Container, Before), "bad cursor in Insert"); end if; if Count = 0 then Position := Before; return; end if; if Container.Length > Container.Capacity - Count then raise Constraint_Error with "new length exceeds capacity"; end if; Allocate (Container, New_Item, New_Node => J); Insert_Internal (Container, Before.Node, New_Node => J); Position := (Node => J); for Index in 2 .. Count loop Allocate (Container, New_Item, New_Node => J); Insert_Internal (Container, Before.Node, New_Node => J); end loop; end Insert; procedure Insert (Container : in out List; Before : Cursor; New_Item : Element_Type; Position : out Cursor) is begin Insert (Container => Container, Before => Before, New_Item => New_Item, Position => Position, Count => 1); end Insert; procedure Insert (Container : in out List; Before : Cursor; New_Item : Element_Type; Count : Count_Type) is Position : Cursor; begin Insert (Container, Before, New_Item, Position, Count); end Insert; procedure Insert (Container : in out List; Before : Cursor; New_Item : Element_Type) is Position : Cursor; begin Insert (Container, Before, New_Item, Position, 1); end Insert; --------------------- -- Insert_Internal -- --------------------- procedure Insert_Internal (Container : in out List; Before : Count_Type; New_Node : Count_Type) is N : Node_Array renames Container.Nodes; begin if Container.Length = 0 then pragma Assert (Before = 0); pragma Assert (Container.First = 0); pragma Assert (Container.Last = 0); Container.First := New_Node; Container.Last := New_Node; N (Container.First).Prev := 0; N (Container.Last).Next := 0; elsif Before = 0 then pragma Assert (N (Container.Last).Next = 0); N (Container.Last).Next := New_Node; N (New_Node).Prev := Container.Last; Container.Last := New_Node; N (Container.Last).Next := 0; elsif Before = Container.First then pragma Assert (N (Container.First).Prev = 0); N (Container.First).Prev := New_Node; N (New_Node).Next := Container.First; Container.First := New_Node; N (Container.First).Prev := 0; else pragma Assert (N (Container.First).Prev = 0); pragma Assert (N (Container.Last).Next = 0); N (New_Node).Next := Before; N (New_Node).Prev := N (Before).Prev; N (N (Before).Prev).Next := New_Node; N (Before).Prev := New_Node; end if; Container.Length := Container.Length + 1; end Insert_Internal; -------------- -- Is_Empty -- -------------- function Is_Empty (Container : List) return Boolean is begin return Length (Container) = 0; end Is_Empty; ---------- -- Last -- ---------- function Last (Container : List) return Cursor is begin if Container.Last = 0 then return No_Element; end if; return (Node => Container.Last); end Last; ------------------ -- Last_Element -- ------------------ function Last_Element (Container : List) return Element_Type is L : constant Count_Type := Container.Last; begin if L = 0 then raise Constraint_Error with "list is empty"; else return Container.Nodes (L).Element; end if; end Last_Element; ------------ -- Length -- ------------ function Length (Container : List) return Count_Type is begin return Container.Length; end Length; ---------- -- Move -- ---------- procedure Move (Target : in out List; Source : in out List) is N : Node_Array renames Source.Nodes; X : Count_Type; begin if Target'Address = Source'Address then return; end if; if Target.Capacity < Source.Length then raise Constraint_Error with -- ??? "Source length exceeds Target capacity"; end if; Clear (Target); while Source.Length > 1 loop pragma Assert (Source.First in 1 .. Source.Capacity); pragma Assert (Source.Last /= Source.First); pragma Assert (N (Source.First).Prev = 0); pragma Assert (N (Source.Last).Next = 0); -- Copy first element from Source to Target X := Source.First; Append (Target, N (X).Element); -- optimize away??? -- Unlink first node of Source Source.First := N (X).Next; N (Source.First).Prev := 0; Source.Length := Source.Length - 1; -- The representation invariants for Source have been restored. It is -- now safe to free the unlinked node, without fear of corrupting the -- active links of Source. -- Note that the algorithm we use here models similar algorithms used -- in the unbounded form of the doubly-linked list container. In that -- case, Free is an instantation of Unchecked_Deallocation, which can -- fail (because PE will be raised if controlled Finalize fails), so -- we must defer the call until the last step. Here in the bounded -- form, Free merely links the node we have just "deallocated" onto a -- list of inactive nodes, so technically Free cannot fail. However, -- for consistency, we handle Free the same way here as we do for the -- unbounded form, with the pessimistic assumption that it can fail. Free (Source, X); end loop; if Source.Length = 1 then pragma Assert (Source.First in 1 .. Source.Capacity); pragma Assert (Source.Last = Source.First); pragma Assert (N (Source.First).Prev = 0); pragma Assert (N (Source.Last).Next = 0); -- Copy element from Source to Target X := Source.First; Append (Target, N (X).Element); -- Unlink node of Source Source.First := 0; Source.Last := 0; Source.Length := 0; -- Return the unlinked node to the free store Free (Source, X); end if; end Move; ---------- -- Next -- ---------- procedure Next (Container : List; Position : in out Cursor) is begin Position := Next (Container, Position); end Next; function Next (Container : List; Position : Cursor) return Cursor is begin if Position.Node = 0 then return No_Element; end if; if not Has_Element (Container, Position) then raise Program_Error with "Position cursor has no element"; end if; return (Node => Container.Nodes (Position.Node).Next); end Next; ------------- -- Prepend -- ------------- procedure Prepend (Container : in out List; New_Item : Element_Type) is begin Insert (Container, First (Container), New_Item, 1); end Prepend; procedure Prepend (Container : in out List; New_Item : Element_Type; Count : Count_Type) is begin Insert (Container, First (Container), New_Item, Count); end Prepend; -------------- -- Previous -- -------------- procedure Previous (Container : List; Position : in out Cursor) is begin Position := Previous (Container, Position); end Previous; function Previous (Container : List; Position : Cursor) return Cursor is begin if Position.Node = 0 then return No_Element; end if; if not Has_Element (Container, Position) then raise Program_Error with "Position cursor has no element"; end if; return (Node => Container.Nodes (Position.Node).Prev); end Previous; --------------------- -- Replace_Element -- --------------------- procedure Replace_Element (Container : in out List; Position : Cursor; New_Item : Element_Type) is begin if not Has_Element (Container, Position) then raise Constraint_Error with "Position cursor has no element"; end if; pragma Assert (Vet (Container, Position), "bad cursor in Replace_Element"); Container.Nodes (Position.Node).Element := New_Item; end Replace_Element; ---------------------- -- Reverse_Elements -- ---------------------- procedure Reverse_Elements (Container : in out List) is N : Node_Array renames Container.Nodes; I : Count_Type := Container.First; J : Count_Type := Container.Last; procedure Swap (L : Count_Type; R : Count_Type); ---------- -- Swap -- ---------- procedure Swap (L : Count_Type; R : Count_Type) is LN : constant Count_Type := N (L).Next; LP : constant Count_Type := N (L).Prev; RN : constant Count_Type := N (R).Next; RP : constant Count_Type := N (R).Prev; begin if LP /= 0 then N (LP).Next := R; end if; if RN /= 0 then N (RN).Prev := L; end if; N (L).Next := RN; N (R).Prev := LP; if LN = R then pragma Assert (RP = L); N (L).Prev := R; N (R).Next := L; else N (L).Prev := RP; N (RP).Next := L; N (R).Next := LN; N (LN).Prev := R; end if; end Swap; -- Start of processing for Reverse_Elements begin if Container.Length <= 1 then return; end if; pragma Assert (N (Container.First).Prev = 0); pragma Assert (N (Container.Last).Next = 0); Container.First := J; Container.Last := I; loop Swap (L => I, R => J); J := N (J).Next; exit when I = J; I := N (I).Prev; exit when I = J; Swap (L => J, R => I); I := N (I).Next; exit when I = J; J := N (J).Prev; exit when I = J; end loop; pragma Assert (N (Container.First).Prev = 0); pragma Assert (N (Container.Last).Next = 0); end Reverse_Elements; ------------------ -- Reverse_Find -- ------------------ function Reverse_Find (Container : List; Item : Element_Type; Position : Cursor := No_Element) return Cursor is CFirst : Count_Type := Position.Node; begin if CFirst = 0 then CFirst := Container.Last; end if; if Container.Length = 0 then return No_Element; else while CFirst /= 0 loop if Container.Nodes (CFirst).Element = Item then return (Node => CFirst); else CFirst := Container.Nodes (CFirst).Prev; end if; end loop; return No_Element; end if; end Reverse_Find; ------------ -- Splice -- ------------ procedure Splice (Target : in out List; Before : Cursor; Source : in out List) is SN : Node_Array renames Source.Nodes; begin if Target'Address = Source'Address then raise Program_Error with "Target and Source denote same container"; end if; if Before.Node /= 0 then pragma Assert (Vet (Target, Before), "bad cursor in Splice"); end if; pragma Assert (SN (Source.First).Prev = 0); pragma Assert (SN (Source.Last).Next = 0); if Target.Length > Count_Type'Base'Last - Source.Length then raise Constraint_Error with "new length exceeds maximum"; end if; if Target.Length + Source.Length > Target.Capacity then raise Constraint_Error; end if; loop Insert (Target, Before, SN (Source.Last).Element); Delete_Last (Source); exit when Is_Empty (Source); end loop; end Splice; procedure Splice (Target : in out List; Before : Cursor; Source : in out List; Position : in out Cursor) is Target_Position : Cursor; begin if Target'Address = Source'Address then raise Program_Error with "Target and Source denote same container"; end if; if Position.Node = 0 then raise Constraint_Error with "Position cursor has no element"; end if; pragma Assert (Vet (Source, Position), "bad Position cursor in Splice"); if Target.Length >= Target.Capacity then raise Constraint_Error; end if; Insert (Container => Target, Before => Before, New_Item => Source.Nodes (Position.Node).Element, Position => Target_Position); Delete (Source, Position); Position := Target_Position; end Splice; procedure Splice (Container : in out List; Before : Cursor; Position : Cursor) is N : Node_Array renames Container.Nodes; begin if Before.Node /= 0 then pragma Assert (Vet (Container, Before), "bad Before cursor in Splice"); end if; if Position.Node = 0 then raise Constraint_Error with "Position cursor has no element"; end if; pragma Assert (Vet (Container, Position), "bad Position cursor in Splice"); if Position.Node = Before.Node or else N (Position.Node).Next = Before.Node then return; end if; pragma Assert (Container.Length >= 2); if Before.Node = 0 then pragma Assert (Position.Node /= Container.Last); if Position.Node = Container.First then Container.First := N (Position.Node).Next; N (Container.First).Prev := 0; else N (N (Position.Node).Prev).Next := N (Position.Node).Next; N (N (Position.Node).Next).Prev := N (Position.Node).Prev; end if; N (Container.Last).Next := Position.Node; N (Position.Node).Prev := Container.Last; Container.Last := Position.Node; N (Container.Last).Next := 0; return; end if; if Before.Node = Container.First then pragma Assert (Position.Node /= Container.First); if Position.Node = Container.Last then Container.Last := N (Position.Node).Prev; N (Container.Last).Next := 0; else N (N (Position.Node).Prev).Next := N (Position.Node).Next; N (N (Position.Node).Next).Prev := N (Position.Node).Prev; end if; N (Container.First).Prev := Position.Node; N (Position.Node).Next := Container.First; Container.First := Position.Node; N (Container.First).Prev := 0; return; end if; if Position.Node = Container.First then Container.First := N (Position.Node).Next; N (Container.First).Prev := 0; elsif Position.Node = Container.Last then Container.Last := N (Position.Node).Prev; N (Container.Last).Next := 0; else N (N (Position.Node).Prev).Next := N (Position.Node).Next; N (N (Position.Node).Next).Prev := N (Position.Node).Prev; end if; N (N (Before.Node).Prev).Next := Position.Node; N (Position.Node).Prev := N (Before.Node).Prev; N (Before.Node).Prev := Position.Node; N (Position.Node).Next := Before.Node; pragma Assert (N (Container.First).Prev = 0); pragma Assert (N (Container.Last).Next = 0); end Splice; ---------- -- Swap -- ---------- procedure Swap (Container : in out List; I : Cursor; J : Cursor) is begin if I.Node = 0 then raise Constraint_Error with "I cursor has no element"; end if; if J.Node = 0 then raise Constraint_Error with "J cursor has no element"; end if; if I.Node = J.Node then return; end if; pragma Assert (Vet (Container, I), "bad I cursor in Swap"); pragma Assert (Vet (Container, J), "bad J cursor in Swap"); declare NN : Node_Array renames Container.Nodes; NI : Node_Type renames NN (I.Node); NJ : Node_Type renames NN (J.Node); EI_Copy : constant Element_Type := NI.Element; begin NI.Element := NJ.Element; NJ.Element := EI_Copy; end; end Swap; ---------------- -- Swap_Links -- ---------------- procedure Swap_Links (Container : in out List; I : Cursor; J : Cursor) is I_Next : Cursor; J_Next : Cursor; begin if I.Node = 0 then raise Constraint_Error with "I cursor has no element"; end if; if J.Node = 0 then raise Constraint_Error with "J cursor has no element"; end if; if I.Node = J.Node then return; end if; pragma Assert (Vet (Container, I), "bad I cursor in Swap_Links"); pragma Assert (Vet (Container, J), "bad J cursor in Swap_Links"); I_Next := Next (Container, I); if I_Next = J then Splice (Container, Before => I, Position => J); else J_Next := Next (Container, J); if J_Next = I then Splice (Container, Before => J, Position => I); else pragma Assert (Container.Length >= 3); Splice (Container, Before => I_Next, Position => J); Splice (Container, Before => J_Next, Position => I); end if; end if; end Swap_Links; --------- -- Vet -- --------- function Vet (L : List; Position : Cursor) return Boolean is N : Node_Array renames L.Nodes; begin if L.Length = 0 then return False; end if; if L.First = 0 then return False; end if; if L.Last = 0 then return False; end if; if Position.Node > L.Capacity then return False; end if; if N (Position.Node).Prev < 0 or else N (Position.Node).Prev > L.Capacity then return False; end if; if N (Position.Node).Next > L.Capacity then return False; end if; if N (L.First).Prev /= 0 then return False; end if; if N (L.Last).Next /= 0 then return False; end if; if N (Position.Node).Prev = 0 and then Position.Node /= L.First then return False; end if; if N (Position.Node).Next = 0 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 N (L.First).Next = 0 then return False; end if; if N (L.Last).Prev = 0 then return False; end if; if N (N (L.First).Next).Prev /= L.First then return False; end if; if N (N (L.Last).Prev).Next /= L.Last then return False; end if; if L.Length = 2 then if N (L.First).Next /= L.Last then return False; end if; if N (L.Last).Prev /= L.First then return False; end if; return True; end if; if N (L.First).Next = L.Last then return False; end if; if N (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 N (Position.Node).Next = 0 then return False; end if; if N (Position.Node).Prev = 0 then return False; end if; if N (N (Position.Node).Next).Prev /= Position.Node then return False; end if; if N (N (Position.Node).Prev).Next /= Position.Node then return False; end if; if L.Length = 3 then if N (L.First).Next /= Position.Node then return False; end if; if N (L.Last).Prev /= Position.Node then return False; end if; end if; return True; end Vet; end Ada.Containers.Formal_Doubly_Linked_Lists;