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SkipMap.hP
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1993-06-29
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// This may look like C code, but it is really -*- C++ -*-
/*
Copyright (C) 1991 Free Software Foundation
This file is part of the GNU C++ Library. This library is free
software; you can redistribute it and/or modify it under the terms of
the GNU Library 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 Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free Software
Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
* Bags implemented via William Pugh SkipList algorithms.
* CACM, June 1990, p 668-676.
*
*/
#ifndef _<T><C>SkipMap_h
#ifdef __GNUG__
#pragma interface
#endif
#define _<T><C>SkipMap_h 1
#include "<T>.<C>.Map.h"
#include <values.h>
#include <MLCG.h>
class <T><C>SkipMap;
class <T><C>RealSkipMapNode;
class <T><C>SkipMapNode
{
friend class <T><C>SkipMap;
private:
<T><C>RealSkipMapNode * * forward;
protected:
<T><C>SkipMapNode(int size);
};
class <T><C>RealSkipMapNode : public <T><C>SkipMapNode
{
friend class <T><C>SkipMap;
private:
<T> item;
<C> cont;
<T><C>RealSkipMapNode(<T&> h, <C&> i, int size);
};
typedef <T><C>RealSkipMapNode* <T><C>SkipMapNodePtr;
inline <T><C>SkipMapNode::<T><C>SkipMapNode(int size)
: forward(new <T><C>SkipMapNodePtr[size+1])
{
}
inline <T><C>RealSkipMapNode::<T><C>RealSkipMapNode(<T&> h, <C&> i, int size)
: item(h), cont(i),
<T><C>SkipMapNode(size)
{
}
class <T><C>SkipMap : public <T><C>Map
{
friend class <T><C>SkipMapinit;
protected:
<T><C>SkipMapNode* header;
int level;
int max_levels;
int randoms_left;
long random_bits;
static MLCG* gen;
int random_level(void);
<T><C>SkipMapNodePtr leftmost();
<T><C>SkipMapNodePtr rightmost();
<T><C>SkipMapNodePtr pred(<T><C>SkipMapNodePtr t);
<T><C>SkipMapNodePtr succ(<T><C>SkipMapNodePtr t);
void _kill();
private:
enum { BITS_IN_RANDOM = LONGBITS-1 };
public:
<T><C>SkipMap( <C&> dflt, long size=DEFAULT_INITIAL_CAPACITY);
<T><C>SkipMap(<T><C>SkipMap& a);
~<T><C>SkipMap();
<C>& operator [] (<T&> key);
void del(<T&> key);
Pix first();
void next(Pix& i);
<T>& key(Pix i);
<C>& contents(Pix i);
Pix seek(<T&> key);
int contains(<T&> key);
void clear();
Pix last();
void prev(Pix& i);
int OK();
};
inline <T><C>SkipMap::~<T><C>SkipMap()
{
_kill();
delete header;
}
inline <T><C>SkipMapNodePtr <T><C>SkipMap::leftmost()
{
return header->forward[0]==header ? 0 : header->forward[0];
}
inline Pix <T><C>SkipMap::first()
{
return Pix(leftmost());
}
inline Pix <T><C>SkipMap::last()
{
return Pix(rightmost());
}
inline <T><C>SkipMapNodePtr <T><C>SkipMap::succ(<T><C>SkipMapNodePtr t)
{
return t->forward[0]==header ? 0 : t->forward[0];
}
inline void <T><C>SkipMap::next(Pix& i)
{
if (i != 0) i = Pix(succ((<T><C>SkipMapNodePtr)i));
}
inline void <T><C>SkipMap::prev(Pix& i)
{
if (i != 0) i = Pix(pred((<T><C>SkipMapNodePtr)i));
}
inline <T>& <T><C>SkipMap::key (Pix i)
{
if (i == 0) error("null Pix");
return ((<T><C>SkipMapNodePtr)i)->item;
}
inline <C>& <T><C>SkipMap::contents (Pix i)
{
if (i == 0) error("null Pix");
return ((<T><C>SkipMapNodePtr)i)->cont;
}
inline int <T><C>SkipMap::contains(<T&> key)
{
return seek(key) != 0;
}
static class <T><C>SkipMapinit
{
public:
<T><C>SkipMapinit();
~<T><C>SkipMapinit();
private:
static int count;
} <T><C>skipMapinit;
#endif