File : asgc-hash-dynamic.adb
-- The Ada Structured Library - A set of container classes and general
-- tools for use with Ada95.
-- Copyright (C) 1998-1999 Corey Minyard (minyard@acm.org)
--
-- This library is free software; you can redistribute it and/or modify it
-- under the terms of the GNU General Public License as published by the
-- Free Software Foundation; either version 2 of the License, or (at your
-- option) any later version.
--
-- This library is distributed in the hope that it will be useful, but
-- WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-- General Public License for more details.
--
-- You should have received a copy of the GNU General Public License along
-- with this library; if not, write to the Free Software Foundation, Inc.,
-- 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
--
-- As a special exception, if other files instantiate generics from this
-- unit, or you link this unit with other files to produce an executable,
-- this unit does not by itself cause the resulting executable to be
-- covered by the GNU General Public License. This exception does not
-- however invalidate any other reasons why the executable file might be
-- covered by the GNU Public License.
--
-- An open hash table.
with Ada.Unchecked_Deallocation;
package body Asgc.Hash.Dynamic is
procedure Free_Node is new Ada.Unchecked_Deallocation(Node,
Node_Ptr);
procedure Free_Iterator is new Ada.Unchecked_Deallocation(Iterator,
Iterator_Ptr);
------------------------------------------------------------------------
-- Check that an object is valid, that is has not been freed. This is
-- not a perfect check, but will hopefully help find some bugs.
procedure Check_Object (O : in Object'Class) is
begin
if (O.Is_Free) then
raise Object_Free;
end if;
end Check_Object;
------------------------------------------------------------------------
-- Check that an iterator is valid. It must not have been freed, it
-- must be initialized, its object must be valid, and it must not have
-- been modified since the last time the iterator was positioned.
procedure Check_Iterator (Iter : in Iterator'Class) is
begin
if (Iter.Is_Free) then
raise Iterator_Free;
end if;
if (Iter.Robj = null) then
raise Invalid_Iterator;
end if;
Check_Object(Iter.Robj.all);
if (Iter.Update /= Iter.Robj.Update) then
raise Object_Updated;
end if;
if ((Iter.Pos = null) or (Iter.Row > Iter.Robj.Data'Last)) then
raise Invalid_Iterator;
end if;
end Check_Iterator;
------------------------------------------------------------------------
-- Check an iterator, but don't bother checking its positions. This is
-- primarily for methods that set some the position of the iterator.
procedure Check_Iterator_No_Pos (Iter : in Iterator'Class) is
begin
if (Iter.Is_Free) then
raise Iterator_Free;
end if;
if (Iter.Robj = null) then
raise Invalid_Iterator;
end if;
Check_Object(Iter.Robj.all);
end Check_Iterator_No_Pos;
------------------------------------------------------------------------
-- Search for the given value in the container. This will return the
-- Row (The hash table index), the Pos (a pointer to the node), the
-- Prev_Pos (a pointer to the previous node, null if the list beginning)
-- and Found, which is True if the value was found and False if not.
procedure Local_Search (O : in Object'Class;
Val : in Contained_Type;
Row : out Positive;
Pos : out Node_Ptr;
Prev_Pos : out Node_Ptr;
Found : out Boolean) is
Hash_Val : Positive;
List : Node_Ptr;
Prev : Node_Ptr;
begin
Hash_Val := (Do_Hash(Val) mod O.Size) + 1;
List := O.Data(Hash_Val);
Prev := null;
while ((List /= null) and then (List.Val /= Val)) loop
Prev := List;
List := List.Next;
end loop;
if (List = null) then
Found := False;
else
Pos := List;
Prev_Pos := Prev;
Row := Hash_Val;
Found := True;
end if;
end Local_Search;
------------------------------------------------------------------------
-- Return the number of members in the object with the specified value.
function Member_Count (O : in Object'Class;
Val : in Contained_Type)
return Natural is
Hash_Val : Positive;
Curr : Node_Ptr;
Count : Natural;
begin
-- Find the first value.
Hash_Val := (Do_Hash(Val) mod O.Size) + 1;
Curr := O.Data(Hash_Val);
while ((Curr /= null)
and then (Curr.Val /= Val))
loop
Curr := Curr.Next;
end loop;
-- Now find the next thing that is not this value.
Count := 0;
while ((Curr /= null)
and then (Curr.Val = Val))
loop
Count := Count + 1;
Curr := Curr.Next;
end loop;
return Count;
end Member_Count;
------------------------------------------------------------------------
procedure Local_Add (O : in out Object'Class;
Val : in Contained_Type;
Added_Row : out Positive;
Added_Prev : out Node_Ptr;
Added_Node : out Node_Ptr) is
Hash_Val : Positive;
Curr : Node_Ptr;
Prev : Node_Ptr;
New_Node : Node_Ptr;
begin
Hash_Val := (Do_Hash(Val) mod O.Size) + 1;
Curr := O.Data(Hash_Val);
if (Curr = null) then
-- The current list is empty, so just add the value.
New_Node := new Node;
New_Node.Val := Val;
O.Data(Hash_Val) := New_Node;
else
-- Search for the value in the list. If we find the value, leave
-- the list immediately.
Prev := null;
while (Curr /= null) loop
if (Curr.Val = Val) then
if (O.Allow_Duplicates) then
-- If we are allowing duplicates, add this before the
-- other members of the same value.
exit;
else
raise Item_Already_Exists;
end if;
end if;
Prev := Curr;
Curr := Curr.Next;
end loop;
New_Node := new Node;
New_Node.Val := Val;
if (Prev = null) then
-- We found the value at the beginning of the list, so add this
-- value there.
New_Node.Next := O.Data(Hash_Val);
O.Data(Hash_Val) := New_Node;
else
-- Not at the list beginning, add after the Prev value and
-- before the Curr value.
New_Node.Next := Curr;
Prev.Next := New_Node;
end if;
Added_Row := Hash_Val;
Added_Prev := Prev;
Added_Node := New_Node;
end if;
O.Update := O.Update + 1;
O.Count := O.Count + 1;
if (O.Cb /= null) then
Added(O.Cb, O, New_Node.Val);
end if;
end Local_Add;
------------------------------------------------------------------------
-- This is a controlled type, so we have those methods to handle.
------------------------------------------------------------------------
procedure Initialize (O : in out Object) is
begin
null;
end Initialize;
------------------------------------------------------------------------
procedure Adjust (O : in out Object) is
function Copy_List (L : in Node_Ptr) return Node_Ptr is
Ol : Node_Ptr := L;
Nl : Node_Ptr := null;
Cl : Node_Ptr;
begin
while (Ol /= null) loop
if (Nl = null) then
Nl := new Node;
Cl := Nl;
else
Cl.Next := new Node;
Cl := Cl.Next;
end if;
Cl.Val := Ol.Val;
if (O.Cb /= null) then
Copied(O.Cb, O, Cl.Val);
end if;
Ol := Ol.Next;
end loop;
return Nl;
end Copy_List;
begin
for I in O.Data'Range loop
O.Data(I) := Copy_List(O.Data(I));
end loop;
end Adjust;
------------------------------------------------------------------------
procedure Finalize (O : in out Object) is
procedure Free_List (L : in out Node_Ptr) is
Tl : Node_Ptr;
begin
while (L /= null) loop
Tl := L;
L := L.Next;
if (O.Cb /= null) then
Deleted(O.Cb, O, Tl.Val);
end if;
Free_Node(Tl);
end loop;
end Free_List;
begin
for I in O.Data'Range loop
Free_List(O.Data(I));
end loop;
end Finalize;
------------------------------------------------------------------------
procedure Finalize (Iter : in out Iterator) is
begin
Iter.Is_Free := True;
end Finalize;
------------------------------------------------------------------------
-- The functions that follow are defined as abstract in previous
-- packages. See those packages for descriptions of what these
-- methods do.
------------------------------------------------------------------------
procedure Add (O : in out Object; Val : in Contained_Type) is
Row : Positive;
Prev : Node_Ptr;
New_Node : Node_Ptr;
begin
Check_Object(O);
Local_Add(O, Val, Row, Prev, New_Node);
end Add;
------------------------------------------------------------------------
procedure Delete (O : in out Object;
Val : in Contained_Type) is
Prev : Node_Ptr;
Curr : Node_Ptr;
Row : Positive;
Found : Boolean;
begin
Check_Object(O);
Local_Search(O, Val, Row, Curr, Prev, Found);
if (Found) then
if (Prev = null) then
-- It's at the beginning of the list.
O.Data(Row) := Curr.Next;
else
-- Not at the list beginning.
Prev.Next := Curr.Next;
end if;
O.Update := O.Update + 1;
if (O.Cb /= null) then
Deleted(O.Cb, O, Curr.Val);
end if;
Free_Node(Curr);
else
raise Item_Not_Found;
end if;
end Delete;
------------------------------------------------------------------------
function Value_Exists (O : in Object;
Val : in Contained_Type)
return Boolean is
Prev : Node_Ptr;
Curr : Node_Ptr;
Row : Positive;
Found : Boolean;
begin
Check_Object(O);
Local_Search(O, Val, Row, Curr, Prev, Found);
return Found;
end Value_Exists;
------------------------------------------------------------------------
function "=" (O1, O2 : in Object) return Boolean is
Curr : Node_Ptr;
Next : Node_Ptr;
Count : Natural;
begin
Check_Object(O1);
Check_Object(O2);
if (O1.Size /= O2.Size) then
return False;
else
-- Our sizes are the same, verify that for every member in O1 that
-- O2 has an equivalent number of those members.
for I in O1.Data'Range loop
Curr := O1.Data(I);
while (Curr /= null) loop
-- Count the number of things that have the same value as
-- what we currently reference.
Next := Curr.Next;
Count := 1;
while ((Next /= null)
and then (Next.Val = Curr.Val))
loop
Next := Next.Next;
Count := Count + 1;
end loop;
-- Verify that the counts are the same.
if (Count /= Member_Count(O2, Curr.Val)) then
return False;
end if;
Curr := Next;
end loop;
end loop;
end if;
return True;
end "=";
------------------------------------------------------------------------
function Member_Count (O : in Object)
return Natural is
begin
Check_Object(O);
return O.Count;
end Member_Count;
------------------------------------------------------------------------
procedure Verify_Integrity (O : in Object) is
-- Count the number of items in the list.
function Count_List (Il : in Node_Ptr) return Natural is
L : Node_Ptr := Il;
Count : Natural := 0;
begin
while (L /= null) loop
Count := Count + 1;
L := L.Next;
end loop;
return Count;
end Count_List;
Count : Natural := 0;
begin
Check_Object(O);
-- Verify that the member count and the actual count of members is
-- the same.
for I in O.Data'Range loop
Count := Count + Count_List(O.Data(I));
end loop;
if (Count /= O.Count) then
raise Internal_Hash_Error;
end if;
end Verify_Integrity;
------------------------------------------------------------------------
function Copy (O : in Object) return Asgc.Object_Class is
Retval : Object_Ptr;
begin
Retval := new Object(Allow_Duplicates => O.Allow_Duplicates,
Size => O.Size);
-- Adjust will take care of copying all the data.
Retval.all := O;
return Asgc.Object_Class(Retval);
end Copy;
------------------------------------------------------------------------
function New_Iterator (O : access Object) return Asgc.Iterator_Class is
Retval : Iterator_Ptr;
begin
Check_Object(O.all);
Retval := new Iterator;
Retval.Robj := Object_Class(O);
return Asgc.Iterator_Class(Retval);
end New_Iterator;
------------------------------------------------------------------------
function New_Iterator (O : in Object_Class) return Iterator is
Retval : Iterator;
begin
Retval.Robj := O;
return Retval;
end New_Iterator;
------------------------------------------------------------------------
procedure Free (Iter : access Iterator) is
To_Free : Iterator_Ptr := Iterator_Ptr(Iter);
begin
if (Iter.Is_Free) then
raise Iterator_Free;
end if;
Free_Iterator(To_Free);
end Free;
------------------------------------------------------------------------
procedure Set_Container (Iter : in out Iterator;
O : in Asgc.Object_Class) is
begin
Check_Object(Object'Class(O.all));
Iter.Robj := Object_Class(O);
Iter.Update := Invalid_Update;
end Set_Container;
------------------------------------------------------------------------
procedure First (Iter : in out Iterator; Is_End : out End_Marker) is
begin
Check_Iterator_No_Pos(Iter);
-- This can happen a lot, so do a short circuit for it.
if (Iter.Robj.Count /= 0) then
for I in Iter.Robj.Data'Range loop
if (Iter.Robj.Data(I) /= null) then
Iter.Row := I;
Iter.Pos := Iter.Robj.Data(I);
Iter.Prev := null;
Iter.Update := Iter.Robj.Update;
Is_End := Not_Past_End;
return;
end if;
end loop;
end if;
Is_End := Past_End;
end First;
------------------------------------------------------------------------
procedure Add (Iter : in out Iterator;
Val : in Contained_Type) is
begin
Check_Iterator_No_Pos(Iter);
Local_Add(Iter.Robj.all, Val, Iter.Row, Iter.Prev, Iter.Pos);
end Add;
------------------------------------------------------------------------
procedure Search (Iter : in out Iterator;
Val : in Contained_Type;
Found : out Boolean) is
Local_Found : Boolean;
begin
Check_Iterator_No_Pos(Iter);
Local_Search(Iter.Robj.all,
Val,
Iter.Row,
Iter.Pos,
Iter.Prev,
Local_Found);
Found := Local_Found;
if (Local_Found) then
Iter.Update := Iter.Robj.Update;
end if;
end Search;
------------------------------------------------------------------------
procedure Search_Again (Iter : in out Iterator;
Found : out Boolean) is
begin
Check_Iterator(Iter);
-- Since values that are the same are guaranteed to be contiguous and
-- in the same hash index, all we need to do is look at the next
-- value in the list.
if (Iter.Pos.Next /= null) then
Iter.Prev := Iter.Pos;
Iter.Pos := Iter.Pos.Next;
if (Iter.Pos.Val = Iter.Prev.Val) then
Found := True;
else
Found := False;
Iter.Update := Iter.Robj.Update - 1;
end if;
else
Found := False;
Iter.Update := Iter.Robj.Update - 1;
end if;
end Search_Again;
------------------------------------------------------------------------
procedure Next (Iter : in out Iterator; Is_End : out End_Marker) is
Row : Positive;
Curr : Node_Ptr;
begin
Check_Iterator(Iter);
Curr := Iter.Pos;
if (Curr.Next /= null) then
Iter.Prev := Curr;
Iter.Pos := Curr.Next;
Is_End := Not_Past_End;
elsif (Iter.Row = Iter.Robj.Size) then
Is_End := Past_End;
else
Row := Iter.Row + 1;
while ((Row < Iter.Robj.Size)
and then Iter.Robj.Data(Row) = null)
loop
Row := Row + 1;
end loop;
if (Iter.Robj.Data(Row) = null) then
Is_End := Past_End;
else
Is_End := Not_Past_End;
Iter.Row := Row;
Iter.Pos := Iter.Robj.Data(Row);
Iter.Prev := null;
end if;
end if;
end Next;
------------------------------------------------------------------------
procedure Delete (Iter : in out Iterator; Is_End : out End_Marker) is
To_Free : Node_Ptr;
Row : Positive;
begin
Check_Iterator(Iter);
-- Remove the value from the list.
if (Iter.Prev = null) then
if (Iter.Pos /= Iter.Robj.Data(Iter.Row)) then
raise Internal_Hash_Error;
end if;
Iter.Robj.Data(Iter.Row) := Iter.Pos.Next;
else
Iter.Prev.Next := Iter.Pos.Next;
end if;
To_Free := Iter.Pos;
Iter.Robj.Update := Iter.Robj.Update + 1;
-- Now we need to set the new current value to be the next thing in
-- the hash table.
if (Iter.Pos.Next /= null) then
-- This is an easy case, the next value in the list is there.
Iter.Pos := Iter.Pos.Next;
Iter.Update := Iter.Robj.Update;
Is_End := Not_Past_End;
elsif (Iter.Row = Iter.Robj.Data'Last) then
-- We are at the end of the table, another easy case.
Is_End := Past_End;
else
-- Bummer, we have to search forward in the table for the next
-- index that has something in it.
Row := Iter.Row + 1;
while ((Row < Iter.Robj.Size)
and then Iter.Robj.Data(Row) = null)
loop
Row := Row + 1;
end loop;
if (Iter.Robj.Data(Row) = null) then
Is_End := Past_End;
else
Iter.Update := Iter.Robj.Update;
Is_End := Not_Past_End;
Iter.Row := Row;
Iter.Pos := Iter.Robj.Data(Row);
Iter.Prev := null;
end if;
end if;
Iter.Robj.Count := Iter.Robj.Count - 1;
if (Iter.Robj.Cb /= null) then
Deleted(Iter.Robj.Cb, Iter.Robj.all, To_Free.Val);
end if;
Free_Node(To_Free);
end Delete;
------------------------------------------------------------------------
function Is_Same (Iter1, Iter2 : in Iterator) return Boolean is
begin
Check_Iterator(Iter1);
Check_Iterator(Iter2);
if (Iter1.Robj /= Iter2.Robj) then
raise Iterator_Mismatch;
end if;
return (Iter1.Pos = Iter2.Pos);
end Is_Same;
------------------------------------------------------------------------
function Get (Iter : in Iterator) return Contained_Type is
begin
Check_Iterator(Iter);
return Iter.Pos.Val;
end Get;
------------------------------------------------------------------------
procedure Get_Incr (Iter : in out Iterator;
Val : out Contained_Type;
Is_End : out End_Marker) is
begin
Check_Iterator(Iter);
Val := Iter.Pos.Val;
Next(Iter, Is_End);
end Get_Incr;
------------------------------------------------------------------------
function "=" (Iter1, Iter2 : in Iterator) return Boolean is
begin
Check_Iterator(Iter1);
Check_Iterator(Iter2);
return (Iter1.Pos.Val = Iter2.Pos.Val);
end "=";
------------------------------------------------------------------------
function "=" (Iter : in Iterator; Val : in Contained_Type) return Boolean is
begin
Check_Iterator(Iter);
return (Iter.Pos.Val = Val);
end "=";
------------------------------------------------------------------------
function "=" (Val : in Contained_Type; Iter : in Iterator) return Boolean is
begin
Check_Iterator(Iter);
return (Iter.Pos.Val = Val);
end "=";
end Asgc.Hash.Dynamic;