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------------------------------------------------------------------------------
--                                                                          --
--                         GNAT LIBRARY COMPONENTS                          --
--                                                                          --
--              ADA.CONTAINERS.HASH_TABLES.GENERIC_OPERATIONS               --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--          Copyright (C) 2004-2010, Free Software Foundation, Inc.         --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
--                                                                          --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception,   --
-- version 3.1, as published by the Free Software Foundation.               --
--                                                                          --
-- You should have received a copy of the GNU General Public License and    --
-- a copy of the GCC Runtime Library Exception along with this program;     --
-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
-- <http://www.gnu.org/licenses/>.                                          --
--                                                                          --
-- This unit was originally developed by Matthew J Heaney.                  --
------------------------------------------------------------------------------
 
with Ada.Containers.Prime_Numbers;
with Ada.Unchecked_Deallocation;
 
with System;  use type System.Address;
 
package body Ada.Containers.Hash_Tables.Generic_Operations is
 
   type Buckets_Allocation is access all Buckets_Type;
   --  Used for allocation and deallocation (see New_Buckets and Free_Buckets).
   --  This is necessary because Buckets_Access has an empty storage pool.
 
   ------------
   -- Adjust --
   ------------
 
   procedure Adjust (HT : in out Hash_Table_Type) is
      Src_Buckets : constant Buckets_Access := HT.Buckets;
      N           : constant Count_Type := HT.Length;
      Src_Node    : Node_Access;
      Dst_Prev    : Node_Access;
 
   begin
      HT.Buckets := null;
      HT.Length := 0;
 
      if N = 0 then
         return;
      end if;
 
      --  Technically it isn't necessary to allocate the exact same length
      --  buckets array, because our only requirement is that following
      --  assignment the source and target containers compare equal (that is,
      --  operator "=" returns True). We can satisfy this requirement with any
      --  hash table length, but we decide here to match the length of the
      --  source table. This has the benefit that when iterating, elements of
      --  the target are delivered in the exact same order as for the source.
 
      HT.Buckets := New_Buckets (Length => Src_Buckets'Length);
 
      for Src_Index in Src_Buckets'Range loop
         Src_Node := Src_Buckets (Src_Index);
 
         if Src_Node /= null then
            declare
               Dst_Node : constant Node_Access := Copy_Node (Src_Node);
 
               --  See note above
 
               pragma Assert (Index (HT, Dst_Node) = Src_Index);
 
            begin
               HT.Buckets (Src_Index) := Dst_Node;
               HT.Length := HT.Length + 1;
 
               Dst_Prev := Dst_Node;
            end;
 
            Src_Node := Next (Src_Node);
            while Src_Node /= null loop
               declare
                  Dst_Node : constant Node_Access := Copy_Node (Src_Node);
 
                  --  See note above
 
                  pragma Assert (Index (HT, Dst_Node) = Src_Index);
 
               begin
                  Set_Next (Node => Dst_Prev, Next => Dst_Node);
                  HT.Length := HT.Length + 1;
 
                  Dst_Prev := Dst_Node;
               end;
 
               Src_Node := Next (Src_Node);
            end loop;
         end if;
      end loop;
 
      pragma Assert (HT.Length = N);
   end Adjust;
 
   --------------
   -- Capacity --
   --------------
 
   function Capacity (HT : Hash_Table_Type) return Count_Type is
   begin
      if HT.Buckets = null then
         return 0;
      end if;
 
      return HT.Buckets'Length;
   end Capacity;
 
   -----------
   -- Clear --
   -----------
 
   procedure Clear (HT : in out Hash_Table_Type) is
      Index : Hash_Type := 0;
      Node  : Node_Access;
 
   begin
      if HT.Busy > 0 then
         raise Program_Error with
           "attempt to tamper with cursors (container is busy)";
      end if;
 
      while HT.Length > 0 loop
         while HT.Buckets (Index) = null loop
            Index := Index + 1;
         end loop;
 
         declare
            Bucket : Node_Access renames HT.Buckets (Index);
         begin
            loop
               Node := Bucket;
               Bucket := Next (Bucket);
               HT.Length := HT.Length - 1;
               Free (Node);
               exit when Bucket = null;
            end loop;
         end;
      end loop;
   end Clear;
 
   ---------------------------
   -- Delete_Node_Sans_Free --
   ---------------------------
 
   procedure Delete_Node_Sans_Free
     (HT : in out Hash_Table_Type;
      X  : Node_Access)
   is
      pragma Assert (X /= null);
 
      Indx : Hash_Type;
      Prev : Node_Access;
      Curr : Node_Access;
 
   begin
      if HT.Length = 0 then
         raise Program_Error with
           "attempt to delete node from empty hashed container";
      end if;
 
      Indx := Index (HT, X);
      Prev := HT.Buckets (Indx);
 
      if Prev = null then
         raise Program_Error with
           "attempt to delete node from empty hash bucket";
      end if;
 
      if Prev = X then
         HT.Buckets (Indx) := Next (Prev);
         HT.Length := HT.Length - 1;
         return;
      end if;
 
      if HT.Length = 1 then
         raise Program_Error with
           "attempt to delete node not in its proper hash bucket";
      end if;
 
      loop
         Curr := Next (Prev);
 
         if Curr = null then
            raise Program_Error with
              "attempt to delete node not in its proper hash bucket";
         end if;
 
         if Curr = X then
            Set_Next (Node => Prev, Next => Next (Curr));
            HT.Length := HT.Length - 1;
            return;
         end if;
 
         Prev := Curr;
      end loop;
   end Delete_Node_Sans_Free;
 
   --------------
   -- Finalize --
   --------------
 
   procedure Finalize (HT : in out Hash_Table_Type) is
   begin
      Clear (HT);
      Free_Buckets (HT.Buckets);
   end Finalize;
 
   -----------
   -- First --
   -----------
 
   function First (HT : Hash_Table_Type) return Node_Access is
      Indx : Hash_Type;
 
   begin
      if HT.Length = 0 then
         return null;
      end if;
 
      Indx := HT.Buckets'First;
      loop
         if HT.Buckets (Indx) /= null then
            return HT.Buckets (Indx);
         end if;
 
         Indx := Indx + 1;
      end loop;
   end First;
 
   ------------------
   -- Free_Buckets --
   ------------------
 
   procedure Free_Buckets (Buckets : in out Buckets_Access) is
      procedure Free is
        new Ada.Unchecked_Deallocation (Buckets_Type, Buckets_Allocation);
 
   begin
      --  Buckets must have been created by New_Buckets. Here, we convert back
      --  to the Buckets_Allocation type, and do the free on that.
 
      Free (Buckets_Allocation (Buckets));
   end Free_Buckets;
 
   ---------------------
   -- Free_Hash_Table --
   ---------------------
 
   procedure Free_Hash_Table (Buckets : in out Buckets_Access) is
      Node : Node_Access;
 
   begin
      if Buckets = null then
         return;
      end if;
 
      for J in Buckets'Range loop
         while Buckets (J) /= null loop
            Node := Buckets (J);
            Buckets (J) := Next (Node);
            Free (Node);
         end loop;
      end loop;
 
      Free_Buckets (Buckets);
   end Free_Hash_Table;
 
   -------------------
   -- Generic_Equal --
   -------------------
 
   function Generic_Equal
     (L, R : Hash_Table_Type) return Boolean
   is
      L_Index : Hash_Type;
      L_Node  : Node_Access;
 
      N : Count_Type;
 
   begin
      if L'Address = R'Address then
         return True;
      end if;
 
      if L.Length /= R.Length then
         return False;
      end if;
 
      if L.Length = 0 then
         return True;
      end if;
 
      --  Find the first node of hash table L
 
      L_Index := 0;
      loop
         L_Node := L.Buckets (L_Index);
         exit when L_Node /= null;
         L_Index := L_Index + 1;
      end loop;
 
      --  For each node of hash table L, search for an equivalent node in hash
      --  table R.
 
      N := L.Length;
      loop
         if not Find (HT => R, Key => L_Node) then
            return False;
         end if;
 
         N := N - 1;
 
         L_Node := Next (L_Node);
 
         if L_Node = null then
            --  We have exhausted the nodes in this bucket
 
            if N = 0 then
               return True;
            end if;
 
            --  Find the next bucket
 
            loop
               L_Index := L_Index + 1;
               L_Node := L.Buckets (L_Index);
               exit when L_Node /= null;
            end loop;
         end if;
      end loop;
   end Generic_Equal;
 
   -----------------------
   -- Generic_Iteration --
   -----------------------
 
   procedure Generic_Iteration (HT : Hash_Table_Type) is
      Node : Node_Access;
 
   begin
      if HT.Length = 0 then
         return;
      end if;
 
      for Indx in HT.Buckets'Range loop
         Node := HT.Buckets (Indx);
         while Node /= null loop
            Process (Node);
            Node := Next (Node);
         end loop;
      end loop;
   end Generic_Iteration;
 
   ------------------
   -- Generic_Read --
   ------------------
 
   procedure Generic_Read
     (Stream : not null access Root_Stream_Type'Class;
      HT     : out Hash_Table_Type)
   is
      N  : Count_Type'Base;
      NN : Hash_Type;
 
   begin
      Clear (HT);
 
      Count_Type'Base'Read (Stream, N);
 
      if N < 0 then
         raise Program_Error with "stream appears to be corrupt";
      end if;
 
      if N = 0 then
         return;
      end if;
 
      --  The RM does not specify whether or how the capacity changes when a
      --  hash table is streamed in. Therefore we decide here to allocate a new
      --  buckets array only when it's necessary to preserve representation
      --  invariants.
 
      if HT.Buckets = null
        or else HT.Buckets'Length < N
      then
         Free_Buckets (HT.Buckets);
         NN := Prime_Numbers.To_Prime (N);
         HT.Buckets := New_Buckets (Length => NN);
      end if;
 
      for J in 1 .. N loop
         declare
            Node : constant Node_Access := New_Node (Stream);
            Indx : constant Hash_Type := Index (HT, Node);
            B    : Node_Access renames HT.Buckets (Indx);
         begin
            Set_Next (Node => Node, Next => B);
            B := Node;
         end;
 
         HT.Length := HT.Length + 1;
      end loop;
   end Generic_Read;
 
   -------------------
   -- Generic_Write --
   -------------------
 
   procedure Generic_Write
     (Stream : not null access Root_Stream_Type'Class;
      HT     : Hash_Table_Type)
   is
      procedure Write (Node : Node_Access);
      pragma Inline (Write);
 
      procedure Write is new Generic_Iteration (Write);
 
      -----------
      -- Write --
      -----------
 
      procedure Write (Node : Node_Access) is
      begin
         Write (Stream, Node);
      end Write;
 
   begin
      --  See Generic_Read for an explanation of why we do not stream out the
      --  buckets array length too.
 
      Count_Type'Base'Write (Stream, HT.Length);
      Write (HT);
   end Generic_Write;
 
   -----------
   -- Index --
   -----------
 
   function Index
     (Buckets : Buckets_Type;
      Node    : Node_Access) return Hash_Type is
   begin
      return Hash_Node (Node) mod Buckets'Length;
   end Index;
 
   function Index
     (Hash_Table : Hash_Table_Type;
      Node       : Node_Access) return Hash_Type is
   begin
      return Index (Hash_Table.Buckets.all, Node);
   end Index;
 
   ----------
   -- Move --
   ----------
 
   procedure Move (Target, Source : in out Hash_Table_Type) is
   begin
      if Target'Address = Source'Address then
         return;
      end if;
 
      if Source.Busy > 0 then
         raise Program_Error with
           "attempt to tamper with cursors (container is busy)";
      end if;
 
      Clear (Target);
 
      declare
         Buckets : constant Buckets_Access := Target.Buckets;
      begin
         Target.Buckets := Source.Buckets;
         Source.Buckets := Buckets;
      end;
 
      Target.Length := Source.Length;
      Source.Length := 0;
   end Move;
 
   -----------------
   -- New_Buckets --
   -----------------
 
   function New_Buckets (Length : Hash_Type) return Buckets_Access is
      subtype Rng is Hash_Type range 0 .. Length - 1;
 
   begin
      --  Allocate in Buckets_Allocation'Storage_Pool, then convert to
      --  Buckets_Access.
 
      return Buckets_Access (Buckets_Allocation'(new Buckets_Type (Rng)));
   end New_Buckets;
 
   ----------
   -- Next --
   ----------
 
   function Next
     (HT   : Hash_Table_Type;
      Node : Node_Access) return Node_Access
   is
      Result : Node_Access := Next (Node);
 
   begin
      if Result /= null then
         return Result;
      end if;
 
      for Indx in Index (HT, Node) + 1 .. HT.Buckets'Last loop
         Result := HT.Buckets (Indx);
 
         if Result /= null then
            return Result;
         end if;
      end loop;
 
      return null;
   end Next;
 
   ----------------------
   -- Reserve_Capacity --
   ----------------------
 
   procedure Reserve_Capacity
     (HT : in out Hash_Table_Type;
      N  : Count_Type)
   is
      NN : Hash_Type;
 
   begin
      if HT.Buckets = null then
         if N > 0 then
            NN := Prime_Numbers.To_Prime (N);
            HT.Buckets := New_Buckets (Length => NN);
         end if;
 
         return;
      end if;
 
      if HT.Length = 0 then
 
         --  This is the easy case. There are no nodes, so no rehashing is
         --  necessary. All we need to do is allocate a new buckets array
         --  having a length implied by the specified capacity. (We say
         --  "implied by" because bucket arrays are always allocated with a
         --  length that corresponds to a prime number.)
 
         if N = 0 then
            Free_Buckets (HT.Buckets);
            return;
         end if;
 
         if N = HT.Buckets'Length then
            return;
         end if;
 
         NN := Prime_Numbers.To_Prime (N);
 
         if NN = HT.Buckets'Length then
            return;
         end if;
 
         declare
            X : Buckets_Access := HT.Buckets;
            pragma Warnings (Off, X);
         begin
            HT.Buckets := New_Buckets (Length => NN);
            Free_Buckets (X);
         end;
 
         return;
      end if;
 
      if N = HT.Buckets'Length then
         return;
      end if;
 
      if N < HT.Buckets'Length then
 
         --  This is a request to contract the buckets array. The amount of
         --  contraction is bounded in order to preserve the invariant that the
         --  buckets array length is never smaller than the number of elements
         --  (the load factor is 1).
 
         if HT.Length >= HT.Buckets'Length then
            return;
         end if;
 
         NN := Prime_Numbers.To_Prime (HT.Length);
 
         if NN >= HT.Buckets'Length then
            return;
         end if;
 
      else
         NN := Prime_Numbers.To_Prime (Count_Type'Max (N, HT.Length));
 
         if NN = HT.Buckets'Length then -- can't expand any more
            return;
         end if;
      end if;
 
      if HT.Busy > 0 then
         raise Program_Error with
           "attempt to tamper with cursors (container is busy)";
      end if;
 
      Rehash : declare
         Dst_Buckets : Buckets_Access := New_Buckets (Length => NN);
         Src_Buckets : Buckets_Access := HT.Buckets;
         pragma Warnings (Off, Src_Buckets);
 
         L : Count_Type renames HT.Length;
         LL : constant Count_Type := L;
 
         Src_Index : Hash_Type := Src_Buckets'First;
 
      begin
         while L > 0 loop
            declare
               Src_Bucket : Node_Access renames Src_Buckets (Src_Index);
 
            begin
               while Src_Bucket /= null loop
                  declare
                     Src_Node : constant Node_Access := Src_Bucket;
 
                     Dst_Index : constant Hash_Type :=
                       Index (Dst_Buckets.all, Src_Node);
 
                     Dst_Bucket : Node_Access renames Dst_Buckets (Dst_Index);
 
                  begin
                     Src_Bucket := Next (Src_Node);
 
                     Set_Next (Src_Node, Dst_Bucket);
 
                     Dst_Bucket := Src_Node;
                  end;
 
                  pragma Assert (L > 0);
                  L := L - 1;
               end loop;
            exception
               when others =>
                  --  If there's an error computing a hash value during a
                  --  rehash, then AI-302 says the nodes "become lost."  The
                  --  issue is whether to actually deallocate these lost nodes,
                  --  since they might be designated by extant cursors.  Here
                  --  we decide to deallocate the nodes, since it's better to
                  --  solve real problems (storage consumption) rather than
                  --  imaginary ones (the user might, or might not, dereference
                  --  a cursor designating a node that has been deallocated),
                  --  and because we have a way to vet a dangling cursor
                  --  reference anyway, and hence can actually detect the
                  --  problem.
 
                  for Dst_Index in Dst_Buckets'Range loop
                     declare
                        B : Node_Access renames Dst_Buckets (Dst_Index);
                        X : Node_Access;
                     begin
                        while B /= null loop
                           X := B;
                           B := Next (X);
                           Free (X);
                        end loop;
                     end;
                  end loop;
 
                  Free_Buckets (Dst_Buckets);
                  raise Program_Error with
                    "hash function raised exception during rehash";
            end;
 
            Src_Index := Src_Index + 1;
         end loop;
 
         HT.Buckets := Dst_Buckets;
         HT.Length := LL;
 
         Free_Buckets (Src_Buckets);
      end Rehash;
   end Reserve_Capacity;
 
end Ada.Containers.Hash_Tables.Generic_Operations;

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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [gcc/] [ada/] [a-chtgop.adb] - Blame information for rev 753

Line No.	Rev	Author	Line
1	706	jeremybenn	`------------------------------------------------------------------------------`
2			`-- --`
3			`-- GNAT LIBRARY COMPONENTS --`
4			`-- --`
5			`-- ADA.CONTAINERS.HASH_TABLES.GENERIC_OPERATIONS --`
6			`-- --`
7			`-- B o d y --`
8			`-- --`
9			`-- Copyright (C) 2004-2010, Free Software Foundation, Inc. --`
10			`-- --`
11			`-- GNAT is free software; you can redistribute it and/or modify it under --`
12			`-- terms of the GNU General Public License as published by the Free Soft- --`
13			`-- ware Foundation; either version 3, or (at your option) any later ver- --`
14			`-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --`
15			`-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --`
16			`-- or FITNESS FOR A PARTICULAR PURPOSE. --`
17			`-- --`
18			`-- As a special exception under Section 7 of GPL version 3, you are granted --`
19			`-- additional permissions described in the GCC Runtime Library Exception, --`
20			`-- version 3.1, as published by the Free Software Foundation. --`
21			`-- --`
22			`-- You should have received a copy of the GNU General Public License and --`
23			`-- a copy of the GCC Runtime Library Exception along with this program; --`
24			`-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --`
25			`-- <http://www.gnu.org/licenses/>. --`
26			`-- --`
27			`-- This unit was originally developed by Matthew J Heaney. --`
28			`------------------------------------------------------------------------------`
29
30			`with Ada.Containers.Prime_Numbers;`
31			`with Ada.Unchecked_Deallocation;`
32
33			`with System; use type System.Address;`
34
35			`package body Ada.Containers.Hash_Tables.Generic_Operations is`
36
37			`type Buckets_Allocation is access all Buckets_Type;`
38			`-- Used for allocation and deallocation (see New_Buckets and Free_Buckets).`
39			`-- This is necessary because Buckets_Access has an empty storage pool.`
40
41			`------------`
42			`-- Adjust --`
43			`------------`
44
45			`procedure Adjust (HT : in out Hash_Table_Type) is`
46			`Src_Buckets : constant Buckets_Access := HT.Buckets;`
47			`N : constant Count_Type := HT.Length;`
48			`Src_Node : Node_Access;`
49			`Dst_Prev : Node_Access;`
50
51			`begin`
52			`HT.Buckets := null;`
53			`HT.Length := 0;`
54
55			`if N = 0 then`
56			`return;`
57			`end if;`
58
59			`-- Technically it isn't necessary to allocate the exact same length`
60			`-- buckets array, because our only requirement is that following`
61			`-- assignment the source and target containers compare equal (that is,`
62			`-- operator "=" returns True). We can satisfy this requirement with any`
63			`-- hash table length, but we decide here to match the length of the`
64			`-- source table. This has the benefit that when iterating, elements of`
65			`-- the target are delivered in the exact same order as for the source.`
66
67			`HT.Buckets := New_Buckets (Length => Src_Buckets'Length);`
68
69			`for Src_Index in Src_Buckets'Range loop`
70			`Src_Node := Src_Buckets (Src_Index);`
71
72			`if Src_Node /= null then`
73			`declare`
74			`Dst_Node : constant Node_Access := Copy_Node (Src_Node);`
75
76			`-- See note above`
77
78			`pragma Assert (Index (HT, Dst_Node) = Src_Index);`
79
80			`begin`
81			`HT.Buckets (Src_Index) := Dst_Node;`
82			`HT.Length := HT.Length + 1;`
83
84			`Dst_Prev := Dst_Node;`
85			`end;`
86
87			`Src_Node := Next (Src_Node);`
88			`while Src_Node /= null loop`
89			`declare`
90			`Dst_Node : constant Node_Access := Copy_Node (Src_Node);`
91
92			`-- See note above`
93
94			`pragma Assert (Index (HT, Dst_Node) = Src_Index);`
95
96			`begin`
97			`Set_Next (Node => Dst_Prev, Next => Dst_Node);`
98			`HT.Length := HT.Length + 1;`
99
100			`Dst_Prev := Dst_Node;`
101			`end;`
102
103			`Src_Node := Next (Src_Node);`
104			`end loop;`
105			`end if;`
106			`end loop;`
107
108			`pragma Assert (HT.Length = N);`
109			`end Adjust;`
110
111			`--------------`
112			`-- Capacity --`
113			`--------------`
114
115			`function Capacity (HT : Hash_Table_Type) return Count_Type is`
116			`begin`
117			`if HT.Buckets = null then`
118			`return 0;`
119			`end if;`
120
121			`return HT.Buckets'Length;`
122			`end Capacity;`
123
124			`-----------`
125			`-- Clear --`
126			`-----------`
127
128			`procedure Clear (HT : in out Hash_Table_Type) is`
129			`Index : Hash_Type := 0;`
130			`Node : Node_Access;`
131
132			`begin`
133			`if HT.Busy > 0 then`
134			`raise Program_Error with`
135			`"attempt to tamper with cursors (container is busy)";`
136			`end if;`
137
138			`while HT.Length > 0 loop`
139			`while HT.Buckets (Index) = null loop`
140			`Index := Index + 1;`
141			`end loop;`
142
143			`declare`
144			`Bucket : Node_Access renames HT.Buckets (Index);`
145			`begin`
146			`loop`
147			`Node := Bucket;`
148			`Bucket := Next (Bucket);`
149			`HT.Length := HT.Length - 1;`
150			`Free (Node);`
151			`exit when Bucket = null;`
152			`end loop;`
153			`end;`
154			`end loop;`
155			`end Clear;`
156
157			`---------------------------`
158			`-- Delete_Node_Sans_Free --`
159			`---------------------------`
160
161			`procedure Delete_Node_Sans_Free`
162			`(HT : in out Hash_Table_Type;`
163			`X : Node_Access)`
164			`is`
165			`pragma Assert (X /= null);`
166
167			`Indx : Hash_Type;`
168			`Prev : Node_Access;`
169			`Curr : Node_Access;`
170
171			`begin`
172			`if HT.Length = 0 then`
173			`raise Program_Error with`
174			`"attempt to delete node from empty hashed container";`
175			`end if;`
176
177			`Indx := Index (HT, X);`
178			`Prev := HT.Buckets (Indx);`
179
180			`if Prev = null then`
181			`raise Program_Error with`
182			`"attempt to delete node from empty hash bucket";`
183			`end if;`
184
185			`if Prev = X then`
186			`HT.Buckets (Indx) := Next (Prev);`
187			`HT.Length := HT.Length - 1;`
188			`return;`
189			`end if;`
190
191			`if HT.Length = 1 then`
192			`raise Program_Error with`
193			`"attempt to delete node not in its proper hash bucket";`
194			`end if;`
195
196			`loop`
197			`Curr := Next (Prev);`
198
199			`if Curr = null then`
200			`raise Program_Error with`
201			`"attempt to delete node not in its proper hash bucket";`
202			`end if;`
203
204			`if Curr = X then`
205			`Set_Next (Node => Prev, Next => Next (Curr));`
206			`HT.Length := HT.Length - 1;`
207			`return;`
208			`end if;`
209
210			`Prev := Curr;`
211			`end loop;`
212			`end Delete_Node_Sans_Free;`
213
214			`--------------`
215			`-- Finalize --`
216			`--------------`
217
218			`procedure Finalize (HT : in out Hash_Table_Type) is`
219			`begin`
220			`Clear (HT);`
221			`Free_Buckets (HT.Buckets);`
222			`end Finalize;`
223
224			`-----------`
225			`-- First --`
226			`-----------`
227
228			`function First (HT : Hash_Table_Type) return Node_Access is`
229			`Indx : Hash_Type;`
230
231			`begin`
232			`if HT.Length = 0 then`
233			`return null;`
234			`end if;`
235
236			`Indx := HT.Buckets'First;`
237			`loop`
238			`if HT.Buckets (Indx) /= null then`
239			`return HT.Buckets (Indx);`
240			`end if;`
241
242			`Indx := Indx + 1;`
243			`end loop;`
244			`end First;`
245
246			`------------------`
247			`-- Free_Buckets --`
248			`------------------`
249
250			`procedure Free_Buckets (Buckets : in out Buckets_Access) is`
251			`procedure Free is`
252			`new Ada.Unchecked_Deallocation (Buckets_Type, Buckets_Allocation);`
253
254			`begin`
255			`-- Buckets must have been created by New_Buckets. Here, we convert back`
256			`-- to the Buckets_Allocation type, and do the free on that.`
257
258			`Free (Buckets_Allocation (Buckets));`
259			`end Free_Buckets;`
260
261			`---------------------`
262			`-- Free_Hash_Table --`
263			`---------------------`
264
265			`procedure Free_Hash_Table (Buckets : in out Buckets_Access) is`
266			`Node : Node_Access;`
267
268			`begin`
269			`if Buckets = null then`
270			`return;`
271			`end if;`
272
273			`for J in Buckets'Range loop`
274			`while Buckets (J) /= null loop`
275			`Node := Buckets (J);`
276			`Buckets (J) := Next (Node);`
277			`Free (Node);`
278			`end loop;`
279			`end loop;`
280
281			`Free_Buckets (Buckets);`
282			`end Free_Hash_Table;`
283
284			`-------------------`
285			`-- Generic_Equal --`
286			`-------------------`
287
288			`function Generic_Equal`
289			`(L, R : Hash_Table_Type) return Boolean`
290			`is`
291			`L_Index : Hash_Type;`
292			`L_Node : Node_Access;`
293
294			`N : Count_Type;`
295
296			`begin`
297			`if L'Address = R'Address then`
298			`return True;`
299			`end if;`
300
301			`if L.Length /= R.Length then`
302			`return False;`
303			`end if;`
304
305			`if L.Length = 0 then`
306			`return True;`
307			`end if;`
308
309			`-- Find the first node of hash table L`
310
311			`L_Index := 0;`
312			`loop`
313			`L_Node := L.Buckets (L_Index);`
314			`exit when L_Node /= null;`
315			`L_Index := L_Index + 1;`
316			`end loop;`
317
318			`-- For each node of hash table L, search for an equivalent node in hash`
319			`-- table R.`
320
321			`N := L.Length;`
322			`loop`
323			`if not Find (HT => R, Key => L_Node) then`
324			`return False;`
325			`end if;`
326
327			`N := N - 1;`
328
329			`L_Node := Next (L_Node);`
330
331			`if L_Node = null then`
332			`-- We have exhausted the nodes in this bucket`
333
334			`if N = 0 then`
335			`return True;`
336			`end if;`
337
338			`-- Find the next bucket`
339
340			`loop`
341			`L_Index := L_Index + 1;`
342			`L_Node := L.Buckets (L_Index);`
343			`exit when L_Node /= null;`
344			`end loop;`
345			`end if;`
346			`end loop;`
347			`end Generic_Equal;`
348
349			`-----------------------`
350			`-- Generic_Iteration --`
351			`-----------------------`
352
353			`procedure Generic_Iteration (HT : Hash_Table_Type) is`
354			`Node : Node_Access;`
355
356			`begin`
357			`if HT.Length = 0 then`
358			`return;`
359			`end if;`
360
361			`for Indx in HT.Buckets'Range loop`
362			`Node := HT.Buckets (Indx);`
363			`while Node /= null loop`
364			`Process (Node);`
365			`Node := Next (Node);`
366			`end loop;`
367			`end loop;`
368			`end Generic_Iteration;`
369
370			`------------------`
371			`-- Generic_Read --`
372			`------------------`
373
374			`procedure Generic_Read`
375			`(Stream : not null access Root_Stream_Type'Class;`
376			`HT : out Hash_Table_Type)`
377			`is`
378			`N : Count_Type'Base;`
379			`NN : Hash_Type;`
380
381			`begin`
382			`Clear (HT);`
383
384			`Count_Type'Base'Read (Stream, N);`
385
386			`if N < 0 then`
387			`raise Program_Error with "stream appears to be corrupt";`
388			`end if;`
389
390			`if N = 0 then`
391			`return;`
392			`end if;`
393
394			`-- The RM does not specify whether or how the capacity changes when a`
395			`-- hash table is streamed in. Therefore we decide here to allocate a new`
396			`-- buckets array only when it's necessary to preserve representation`
397			`-- invariants.`
398
399			`if HT.Buckets = null`
400			`or else HT.Buckets'Length < N`
401			`then`
402			`Free_Buckets (HT.Buckets);`
403			`NN := Prime_Numbers.To_Prime (N);`
404			`HT.Buckets := New_Buckets (Length => NN);`
405			`end if;`
406
407			`for J in 1 .. N loop`
408			`declare`
409			`Node : constant Node_Access := New_Node (Stream);`
410			`Indx : constant Hash_Type := Index (HT, Node);`
411			`B : Node_Access renames HT.Buckets (Indx);`
412			`begin`
413			`Set_Next (Node => Node, Next => B);`
414			`B := Node;`
415			`end;`
416
417			`HT.Length := HT.Length + 1;`
418			`end loop;`
419			`end Generic_Read;`
420
421			`-------------------`
422			`-- Generic_Write --`
423			`-------------------`
424
425			`procedure Generic_Write`
426			`(Stream : not null access Root_Stream_Type'Class;`
427			`HT : Hash_Table_Type)`
428			`is`
429			`procedure Write (Node : Node_Access);`
430			`pragma Inline (Write);`
431
432			`procedure Write is new Generic_Iteration (Write);`
433
434			`-----------`
435			`-- Write --`
436			`-----------`
437
438			`procedure Write (Node : Node_Access) is`
439			`begin`
440			`Write (Stream, Node);`
441			`end Write;`
442
443			`begin`
444			`-- See Generic_Read for an explanation of why we do not stream out the`
445			`-- buckets array length too.`
446
447			`Count_Type'Base'Write (Stream, HT.Length);`
448			`Write (HT);`
449			`end Generic_Write;`
450
451			`-----------`
452			`-- Index --`
453			`-----------`
454
455			`function Index`
456			`(Buckets : Buckets_Type;`
457			`Node : Node_Access) return Hash_Type is`
458			`begin`
459			`return Hash_Node (Node) mod Buckets'Length;`
460			`end Index;`
461
462			`function Index`
463			`(Hash_Table : Hash_Table_Type;`
464			`Node : Node_Access) return Hash_Type is`
465			`begin`
466			`return Index (Hash_Table.Buckets.all, Node);`
467			`end Index;`
468
469			`----------`
470			`-- Move --`
471			`----------`
472
473			`procedure Move (Target, Source : in out Hash_Table_Type) is`
474			`begin`
475			`if Target'Address = Source'Address then`
476			`return;`
477			`end if;`
478
479			`if Source.Busy > 0 then`
480			`raise Program_Error with`
481			`"attempt to tamper with cursors (container is busy)";`
482			`end if;`
483
484			`Clear (Target);`
485
486			`declare`
487			`Buckets : constant Buckets_Access := Target.Buckets;`
488			`begin`
489			`Target.Buckets := Source.Buckets;`
490			`Source.Buckets := Buckets;`
491			`end;`
492
493			`Target.Length := Source.Length;`
494			`Source.Length := 0;`
495			`end Move;`
496
497			`-----------------`
498			`-- New_Buckets --`
499			`-----------------`
500
501			`function New_Buckets (Length : Hash_Type) return Buckets_Access is`
502			`subtype Rng is Hash_Type range 0 .. Length - 1;`
503
504			`begin`
505			`-- Allocate in Buckets_Allocation'Storage_Pool, then convert to`
506			`-- Buckets_Access.`
507
508			`return Buckets_Access (Buckets_Allocation'(new Buckets_Type (Rng)));`
509			`end New_Buckets;`
510
511			`----------`
512			`-- Next --`
513			`----------`
514
515			`function Next`
516			`(HT : Hash_Table_Type;`
517			`Node : Node_Access) return Node_Access`
518			`is`
519			`Result : Node_Access := Next (Node);`
520
521			`begin`
522			`if Result /= null then`
523			`return Result;`
524			`end if;`
525
526			`for Indx in Index (HT, Node) + 1 .. HT.Buckets'Last loop`
527			`Result := HT.Buckets (Indx);`
528
529			`if Result /= null then`
530			`return Result;`
531			`end if;`
532			`end loop;`
533
534			`return null;`
535			`end Next;`
536
537			`----------------------`
538			`-- Reserve_Capacity --`
539			`----------------------`
540
541			`procedure Reserve_Capacity`
542			`(HT : in out Hash_Table_Type;`
543			`N : Count_Type)`
544			`is`
545			`NN : Hash_Type;`
546
547			`begin`
548			`if HT.Buckets = null then`
549			`if N > 0 then`
550			`NN := Prime_Numbers.To_Prime (N);`
551			`HT.Buckets := New_Buckets (Length => NN);`
552			`end if;`
553
554			`return;`
555			`end if;`
556
557			`if HT.Length = 0 then`
558
559			`-- This is the easy case. There are no nodes, so no rehashing is`
560			`-- necessary. All we need to do is allocate a new buckets array`
561			`-- having a length implied by the specified capacity. (We say`
562			`-- "implied by" because bucket arrays are always allocated with a`
563			`-- length that corresponds to a prime number.)`
564
565			`if N = 0 then`
566			`Free_Buckets (HT.Buckets);`
567			`return;`
568			`end if;`
569
570			`if N = HT.Buckets'Length then`
571			`return;`
572			`end if;`
573
574			`NN := Prime_Numbers.To_Prime (N);`
575
576			`if NN = HT.Buckets'Length then`
577			`return;`
578			`end if;`
579
580			`declare`
581			`X : Buckets_Access := HT.Buckets;`
582			`pragma Warnings (Off, X);`
583			`begin`
584			`HT.Buckets := New_Buckets (Length => NN);`
585			`Free_Buckets (X);`
586			`end;`
587
588			`return;`
589			`end if;`
590
591			`if N = HT.Buckets'Length then`
592			`return;`
593			`end if;`
594
595			`if N < HT.Buckets'Length then`
596
597			`-- This is a request to contract the buckets array. The amount of`
598			`-- contraction is bounded in order to preserve the invariant that the`
599			`-- buckets array length is never smaller than the number of elements`
600			`-- (the load factor is 1).`
601
602			`if HT.Length >= HT.Buckets'Length then`
603			`return;`
604			`end if;`
605
606			`NN := Prime_Numbers.To_Prime (HT.Length);`
607
608			`if NN >= HT.Buckets'Length then`
609			`return;`
610			`end if;`
611
612			`else`
613			`NN := Prime_Numbers.To_Prime (Count_Type'Max (N, HT.Length));`
614
615			`if NN = HT.Buckets'Length then -- can't expand any more`
616			`return;`
617			`end if;`
618			`end if;`
619
620			`if HT.Busy > 0 then`
621			`raise Program_Error with`
622			`"attempt to tamper with cursors (container is busy)";`
623			`end if;`
624
625			`Rehash : declare`
626			`Dst_Buckets : Buckets_Access := New_Buckets (Length => NN);`
627			`Src_Buckets : Buckets_Access := HT.Buckets;`
628			`pragma Warnings (Off, Src_Buckets);`
629
630			`L : Count_Type renames HT.Length;`
631			`LL : constant Count_Type := L;`
632
633			`Src_Index : Hash_Type := Src_Buckets'First;`
634
635			`begin`
636			`while L > 0 loop`
637			`declare`
638			`Src_Bucket : Node_Access renames Src_Buckets (Src_Index);`
639
640			`begin`
641			`while Src_Bucket /= null loop`
642			`declare`
643			`Src_Node : constant Node_Access := Src_Bucket;`
644
645			`Dst_Index : constant Hash_Type :=`
646			`Index (Dst_Buckets.all, Src_Node);`
647
648			`Dst_Bucket : Node_Access renames Dst_Buckets (Dst_Index);`
649
650			`begin`
651			`Src_Bucket := Next (Src_Node);`
652
653			`Set_Next (Src_Node, Dst_Bucket);`
654
655			`Dst_Bucket := Src_Node;`
656			`end;`
657
658			`pragma Assert (L > 0);`
659			`L := L - 1;`
660			`end loop;`
661			`exception`
662			`when others =>`
663			`-- If there's an error computing a hash value during a`
664			`-- rehash, then AI-302 says the nodes "become lost." The`
665			`-- issue is whether to actually deallocate these lost nodes,`
666			`-- since they might be designated by extant cursors. Here`
667			`-- we decide to deallocate the nodes, since it's better to`
668			`-- solve real problems (storage consumption) rather than`
669			`-- imaginary ones (the user might, or might not, dereference`
670			`-- a cursor designating a node that has been deallocated),`
671			`-- and because we have a way to vet a dangling cursor`
672			`-- reference anyway, and hence can actually detect the`
673			`-- problem.`
674
675			`for Dst_Index in Dst_Buckets'Range loop`
676			`declare`
677			`B : Node_Access renames Dst_Buckets (Dst_Index);`
678			`X : Node_Access;`
679			`begin`
680			`while B /= null loop`
681			`X := B;`
682			`B := Next (X);`
683			`Free (X);`
684			`end loop;`
685			`end;`
686			`end loop;`
687
688			`Free_Buckets (Dst_Buckets);`
689			`raise Program_Error with`
690			`"hash function raised exception during rehash";`
691			`end;`
692
693			`Src_Index := Src_Index + 1;`
694			`end loop;`
695
696			`HT.Buckets := Dst_Buckets;`
697			`HT.Length := LL;`
698
699			`Free_Buckets (Src_Buckets);`
700			`end Rehash;`
701			`end Reserve_Capacity;`
702
703			`end Ada.Containers.Hash_Tables.Generic_Operations;`