------------------------------------------------------------------------------
--                                                                          --
--                         GNAT LIBRARY COMPONENTS                          --
--                                                                          --
--       ADA.CONTAINERS.RED_BLACK_TREES.GENERIC_BOUNDED_SET_OPERATIONS      --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--          Copyright (C) 2004-2020, 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    --
-- <http://www.gnu.org/licenses/>.                                          --
--                                                                          --
-- This unit was originally developed by Matthew J Heaney.                  --
------------------------------------------------------------------------------

with System; use type System.Address;

package body Ada.Containers.Red_Black_Trees.Generic_Bounded_Set_Operations is

   pragma Warnings (Off, "variable ""Busy*"" is not referenced");
   pragma Warnings (Off, "variable ""Lock*"" is not referenced");
   --  See comment in Ada.Containers.Helpers

   -----------------------
   -- Local Subprograms --
   -----------------------

   function Copy (Source : Set_Type) return Set_Type;

   ----------
   -- Copy --
   ----------

   function Copy (Source : Set_Type) return Set_Type is
   begin
      return Target : Set_Type (Source.Length) do
         Assign (Target => Target, Source => Source);
      end return;
   end Copy;

   --------------------
   -- Set_Difference --
   --------------------

   procedure Set_Difference (Target : in out Set_Type; Source : Set_Type) is
      Tgt, Src : Count_Type;

      TN : Nodes_Type renames Target.Nodes;
      SN : Nodes_Type renames Source.Nodes;

      Compare : Integer;

   begin
      if Target'Address = Source'Address then
         TC_Check (Target.TC);

         Tree_Operations.Clear_Tree (Target);
         return;
      end if;

      if Source.Length = 0 then
         return;
      end if;

      TC_Check (Target.TC);

      Tgt := Target.First;
      Src := Source.First;
      loop
         if Tgt = 0 then
            exit;
         end if;

         if Src = 0 then
            exit;
         end if;

         --  Per AI05-0022, the container implementation is required to detect
         --  element tampering by a generic actual subprogram.

         declare
            Lock_Target : With_Lock (Target.TC'Unrestricted_Access);
            Lock_Source : With_Lock (Source.TC'Unrestricted_Access);
         begin
            if Is_Less (TN (Tgt), SN (Src)) then
               Compare := -1;
            elsif Is_Less (SN (Src), TN (Tgt)) then
               Compare := 1;
            else
               Compare := 0;
            end if;
         end;

         if Compare < 0 then
            Tgt := Tree_Operations.Next (Target, Tgt);

         elsif Compare > 0 then
            Src := Tree_Operations.Next (Source, Src);

         else
            declare
               X : constant Count_Type := Tgt;
            begin
               Tgt := Tree_Operations.Next (Target, Tgt);

               Tree_Operations.Delete_Node_Sans_Free (Target, X);
               Tree_Operations.Free (Target, X);
            end;

            Src := Tree_Operations.Next (Source, Src);
         end if;
      end loop;
   end Set_Difference;

   function Set_Difference (Left, Right : Set_Type) return Set_Type is
   begin
      if Left'Address = Right'Address then
         return S : Set_Type (0);  -- Empty set
      end if;

      if Left.Length = 0 then
         return S : Set_Type (0);  -- Empty set
      end if;

      if Right.Length = 0 then
         return Copy (Left);
      end if;

      return Result : Set_Type (Left.Length) do
         --  Per AI05-0022, the container implementation is required to detect
         --  element tampering by a generic actual subprogram.

         declare
            Lock_Left : With_Lock (Left.TC'Unrestricted_Access);
            Lock_Right : With_Lock (Right.TC'Unrestricted_Access);

            L_Node : Count_Type;
            R_Node : Count_Type;

            Dst_Node : Count_Type;
            pragma Warnings (Off, Dst_Node);

         begin
            L_Node := Left.First;
            R_Node := Right.First;
            loop
               if L_Node = 0 then
                  exit;
               end if;

               if R_Node = 0 then
                  while L_Node /= 0 loop
                     Insert_With_Hint
                       (Dst_Set  => Result,
                        Dst_Hint => 0,
                        Src_Node => Left.Nodes (L_Node),
                        Dst_Node => Dst_Node);

                     L_Node := Tree_Operations.Next (Left, L_Node);
                  end loop;

                  exit;
               end if;

               if Is_Less (Left.Nodes (L_Node), Right.Nodes (R_Node)) then
                  Insert_With_Hint
                    (Dst_Set  => Result,
                     Dst_Hint => 0,
                     Src_Node => Left.Nodes (L_Node),
                     Dst_Node => Dst_Node);

                  L_Node := Tree_Operations.Next (Left, L_Node);

               elsif Is_Less (Right.Nodes (R_Node), Left.Nodes (L_Node)) then
                  R_Node := Tree_Operations.Next (Right, R_Node);

               else
                  L_Node := Tree_Operations.Next (Left, L_Node);
                  R_Node := Tree_Operations.Next (Right, R_Node);
               end if;
            end loop;
         end;
      end return;
   end Set_Difference;

   ----------------------
   -- Set_Intersection --
   ----------------------

   procedure Set_Intersection
     (Target : in out Set_Type;
      Source : Set_Type)
   is
      Tgt : Count_Type;
      Src : Count_Type;

      Compare : Integer;

   begin
      if Target'Address = Source'Address then
         return;
      end if;

      TC_Check (Target.TC);

      if Source.Length = 0 then
         Tree_Operations.Clear_Tree (Target);
         return;
      end if;

      Tgt := Target.First;
      Src := Source.First;
      while Tgt /= 0
        and then Src /= 0
      loop
         --  Per AI05-0022, the container implementation is required to detect
         --  element tampering by a generic actual subprogram.

         declare
            Lock_Target : With_Lock (Target.TC'Unrestricted_Access);
            Lock_Source : With_Lock (Source.TC'Unrestricted_Access);
         begin
            if Is_Less (Target.Nodes (Tgt), Source.Nodes (Src)) then
               Compare := -1;
            elsif Is_Less (Source.Nodes (Src), Target.Nodes (Tgt)) then
               Compare := 1;
            else
               Compare := 0;
            end if;
         end;

         if Compare < 0 then
            declare
               X : constant Count_Type := Tgt;
            begin
               Tgt := Tree_Operations.Next (Target, Tgt);

               Tree_Operations.Delete_Node_Sans_Free (Target, X);
               Tree_Operations.Free (Target, X);
            end;

         elsif Compare > 0 then
            Src := Tree_Operations.Next (Source, Src);

         else
            Tgt := Tree_Operations.Next (Target, Tgt);
            Src := Tree_Operations.Next (Source, Src);
         end if;
      end loop;

      while Tgt /= 0 loop
         declare
            X : constant Count_Type := Tgt;
         begin
            Tgt := Tree_Operations.Next (Target, Tgt);

            Tree_Operations.Delete_Node_Sans_Free (Target, X);
            Tree_Operations.Free (Target, X);
         end;
      end loop;
   end Set_Intersection;

   function Set_Intersection (Left, Right : Set_Type) return Set_Type is
   begin
      if Left'Address = Right'Address then
         return Copy (Left);
      end if;

      return Result : Set_Type (Count_Type'Min (Left.Length, Right.Length)) do

         --  Per AI05-0022, the container implementation is required to detect
         --  element tampering by a generic actual subprogram.

         declare
            Lock_Left : With_Lock (Left.TC'Unrestricted_Access);
            Lock_Right : With_Lock (Right.TC'Unrestricted_Access);

            L_Node : Count_Type;
            R_Node : Count_Type;

            Dst_Node : Count_Type;
            pragma Warnings (Off, Dst_Node);

         begin
            L_Node := Left.First;
            R_Node := Right.First;
            loop
               if L_Node = 0 then
                  exit;
               end if;

               if R_Node = 0 then
                  exit;
               end if;

               if Is_Less (Left.Nodes (L_Node), Right.Nodes (R_Node)) then
                  L_Node := Tree_Operations.Next (Left, L_Node);

               elsif Is_Less (Right.Nodes (R_Node), Left.Nodes (L_Node)) then
                  R_Node := Tree_Operations.Next (Right, R_Node);

               else
                  Insert_With_Hint
                    (Dst_Set  => Result,
                     Dst_Hint => 0,
                     Src_Node => Left.Nodes (L_Node),
                     Dst_Node => Dst_Node);

                  L_Node := Tree_Operations.Next (Left, L_Node);
                  R_Node := Tree_Operations.Next (Right, R_Node);
               end if;
            end loop;
         end;
      end return;
   end Set_Intersection;

   ----------------
   -- Set_Subset --
   ----------------

   function Set_Subset
     (Subset : Set_Type;
      Of_Set : Set_Type) return Boolean
   is
   begin
      if Subset'Address = Of_Set'Address then
         return True;
      end if;

      if Subset.Length > Of_Set.Length then
         return False;
      end if;

      --  Per AI05-0022, the container implementation is required to detect
      --  element tampering by a generic actual subprogram.

      declare
         Lock_Subset : With_Lock (Subset.TC'Unrestricted_Access);
         Lock_Of_Set : With_Lock (Of_Set.TC'Unrestricted_Access);

         Subset_Node : Count_Type;
         Set_Node    : Count_Type;
      begin
         Subset_Node := Subset.First;
         Set_Node    := Of_Set.First;
         loop
            if Set_Node = 0 then
               return Subset_Node = 0;
            end if;

            if Subset_Node = 0 then
               return True;
            end if;

            if Is_Less (Subset.Nodes (Subset_Node),
                        Of_Set.Nodes (Set_Node))
            then
               return False;
            end if;

            if Is_Less (Of_Set.Nodes (Set_Node),
                        Subset.Nodes (Subset_Node))
            then
               Set_Node := Tree_Operations.Next (Of_Set, Set_Node);
            else
               Set_Node := Tree_Operations.Next (Of_Set, Set_Node);
               Subset_Node := Tree_Operations.Next (Subset, Subset_Node);
            end if;
         end loop;
      end;
   end Set_Subset;

   -----------------
   -- Set_Overlap --
   -----------------

   function Set_Overlap (Left, Right : Set_Type) return Boolean is
   begin
      if Left'Address = Right'Address then
         return Left.Length /= 0;
      end if;

      --  Per AI05-0022, the container implementation is required to detect
      --  element tampering by a generic actual subprogram.

      declare
         Lock_Left : With_Lock (Left.TC'Unrestricted_Access);
         Lock_Right : With_Lock (Right.TC'Unrestricted_Access);

         L_Node : Count_Type;
         R_Node : Count_Type;
      begin
         L_Node := Left.First;
         R_Node := Right.First;
         loop
            if L_Node = 0
              or else R_Node = 0
            then
               return False;
            end if;

            if Is_Less (Left.Nodes (L_Node), Right.Nodes (R_Node)) then
               L_Node := Tree_Operations.Next (Left, L_Node);
            elsif Is_Less (Right.Nodes (R_Node), Left.Nodes (L_Node)) then
               R_Node := Tree_Operations.Next (Right, R_Node);
            else
               return True;
            end if;
         end loop;
      end;
   end Set_Overlap;

   ------------------------------
   -- Set_Symmetric_Difference --
   ------------------------------

   procedure Set_Symmetric_Difference
     (Target : in out Set_Type;
      Source : Set_Type)
   is
      Tgt : Count_Type;
      Src : Count_Type;

      New_Tgt_Node : Count_Type;
      pragma Warnings (Off, New_Tgt_Node);

      Compare : Integer;

   begin
      if Target'Address = Source'Address then
         Tree_Operations.Clear_Tree (Target);
         return;
      end if;

      Tgt := Target.First;
      Src := Source.First;
      loop
         if Tgt = 0 then
            while Src /= 0 loop
               Insert_With_Hint
                 (Dst_Set  => Target,
                  Dst_Hint => 0,
                  Src_Node => Source.Nodes (Src),
                  Dst_Node => New_Tgt_Node);

               Src := Tree_Operations.Next (Source, Src);
            end loop;

            return;
         end if;

         if Src = 0 then
            return;
         end if;

         --  Per AI05-0022, the container implementation is required to detect
         --  element tampering by a generic actual subprogram.

         declare
            Lock_Target : With_Lock (Target.TC'Unrestricted_Access);
            Lock_Source : With_Lock (Source.TC'Unrestricted_Access);
         begin
            if Is_Less (Target.Nodes (Tgt), Source.Nodes (Src)) then
               Compare := -1;
            elsif Is_Less (Source.Nodes (Src), Target.Nodes (Tgt)) then
               Compare := 1;
            else
               Compare := 0;
            end if;
         end;

         if Compare < 0 then
            Tgt := Tree_Operations.Next (Target, Tgt);

         elsif Compare > 0 then
            Insert_With_Hint
              (Dst_Set  => Target,
               Dst_Hint => Tgt,
               Src_Node => Source.Nodes (Src),
               Dst_Node => New_Tgt_Node);

            Src := Tree_Operations.Next (Source, Src);

         else
            declare
               X : constant Count_Type := Tgt;
            begin
               Tgt := Tree_Operations.Next (Target, Tgt);

               Tree_Operations.Delete_Node_Sans_Free (Target, X);
               Tree_Operations.Free (Target, X);
            end;

            Src := Tree_Operations.Next (Source, Src);
         end if;
      end loop;
   end Set_Symmetric_Difference;

   function Set_Symmetric_Difference
     (Left, Right : Set_Type) return Set_Type
   is
   begin
      if Left'Address = Right'Address then
         return S : Set_Type (0);  -- Empty set
      end if;

      if Right.Length = 0 then
         return Copy (Left);
      end if;

      if Left.Length = 0 then
         return Copy (Right);
      end if;

      return Result : Set_Type (Left.Length + Right.Length) do

         --  Per AI05-0022, the container implementation is required to detect
         --  element tampering by a generic actual subprogram.

         declare
            Lock_Left : With_Lock (Left.TC'Unrestricted_Access);
            Lock_Right : With_Lock (Right.TC'Unrestricted_Access);

            L_Node : Count_Type;
            R_Node : Count_Type;

            Dst_Node : Count_Type;
            pragma Warnings (Off, Dst_Node);

         begin
            L_Node := Left.First;
            R_Node := Right.First;
            loop
               if L_Node = 0 then
                  while R_Node /= 0 loop
                     Insert_With_Hint
                       (Dst_Set  => Result,
                        Dst_Hint => 0,
                        Src_Node => Right.Nodes (R_Node),
                        Dst_Node => Dst_Node);

                     R_Node := Tree_Operations.Next (Right, R_Node);
                  end loop;

                  exit;
               end if;

               if R_Node = 0 then
                  while L_Node /= 0 loop
                     Insert_With_Hint
                       (Dst_Set  => Result,
                        Dst_Hint => 0,
                        Src_Node => Left.Nodes (L_Node),
                        Dst_Node => Dst_Node);

                     L_Node := Tree_Operations.Next (Left, L_Node);
                  end loop;

                  exit;
               end if;

               if Is_Less (Left.Nodes (L_Node), Right.Nodes (R_Node)) then
                  Insert_With_Hint
                    (Dst_Set  => Result,
                     Dst_Hint => 0,
                     Src_Node => Left.Nodes (L_Node),
                     Dst_Node => Dst_Node);

                  L_Node := Tree_Operations.Next (Left, L_Node);

               elsif Is_Less (Right.Nodes (R_Node), Left.Nodes (L_Node)) then
                  Insert_With_Hint
                    (Dst_Set  => Result,
                     Dst_Hint => 0,
                     Src_Node => Right.Nodes (R_Node),
                     Dst_Node => Dst_Node);

                  R_Node := Tree_Operations.Next (Right, R_Node);

               else
                  L_Node := Tree_Operations.Next (Left, L_Node);
                  R_Node := Tree_Operations.Next (Right, R_Node);
               end if;
            end loop;
         end;
      end return;
   end Set_Symmetric_Difference;

   ---------------
   -- Set_Union --
   ---------------

   procedure Set_Union (Target : in out Set_Type; Source : Set_Type) is
      Hint : Count_Type := 0;

      procedure Process (Node : Count_Type);
      pragma Inline (Process);

      procedure Iterate is new Tree_Operations.Generic_Iteration (Process);

      -------------
      -- Process --
      -------------

      procedure Process (Node : Count_Type) is
      begin
         Insert_With_Hint
           (Dst_Set  => Target,
            Dst_Hint => Hint,
            Src_Node => Source.Nodes (Node),
            Dst_Node => Hint);
      end Process;

   --  Start of processing for Union

   begin
      if Target'Address = Source'Address then
         return;
      end if;

      --  Per AI05-0022, the container implementation is required to detect
      --  element tampering by a generic actual subprogram.

      declare
         Lock_Source : With_Lock (Source.TC'Unrestricted_Access);
      begin
         --  Note that there's no way to decide a priori whether the target has
         --  enough capacity for the union with source. We cannot simply
         --  compare the sum of the existing lengths to the capacity of the
         --  target, because equivalent items from source are not included in
         --  the union.

         Iterate (Source);
      end;
   end Set_Union;

   function Set_Union (Left, Right : Set_Type) return Set_Type is
   begin
      if Left'Address = Right'Address then
         return Copy (Left);
      end if;

      if Left.Length = 0 then
         return Copy (Right);
      end if;

      if Right.Length = 0 then
         return Copy (Left);
      end if;

      return Result : Set_Type (Left.Length + Right.Length) do
         declare
            Lock_Left : With_Lock (Left.TC'Unrestricted_Access);
            Lock_Right : With_Lock (Right.TC'Unrestricted_Access);
         begin
            Assign (Target => Result, Source => Left);

            Insert_Right : declare
               Hint : Count_Type := 0;

               procedure Process (Node : Count_Type);
               pragma Inline (Process);

               procedure Iterate is
                 new Tree_Operations.Generic_Iteration (Process);

               -------------
               -- Process --
               -------------

               procedure Process (Node : Count_Type) is
               begin
                  Insert_With_Hint
                    (Dst_Set  => Result,
                     Dst_Hint => Hint,
                     Src_Node => Right.Nodes (Node),
                     Dst_Node => Hint);
               end Process;

            --  Start of processing for Insert_Right

            begin
               Iterate (Right);
            end Insert_Right;
         end;
      end return;
   end Set_Union;

end Ada.Containers.Red_Black_Trees.Generic_Bounded_Set_Operations;
