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/*
* Copyright (C) 2007-2008 Xagasoft, All rights reserved.
*
* This file is part of the libbu++ library and is released under the
* terms of the license contained in the file LICENSE.
*/
#ifndef BU_HEAP_H
#define BU_HEAP_H
#include <stddef.h>
#include <memory>
#include "bu/exceptionbase.h"
#include "bu/util.h"
#include "bu/queue.h"
namespace Bu
{
subExceptionDecl( HeapException );
template<typename item, typename cmpfunc=__basicLTCmp<item>, typename itemalloc=std::allocator<item> >
class Heap : public Queue<item>
{
public:
Heap() :
iSize( 7 ),
iFill( 0 ),
aItem( ia.allocate( iSize ) )
{
}
Heap( cmpfunc cmpin ) :
iSize( 7 ),
iFill( 0 ),
aItem( ia.allocate( iSize ) ),
cmp( cmpin )
{
}
Heap( int iInitialCapacity ) :
iSize( 0 ),
iFill( 0 ),
aItem( NULL )
{
for( iSize = 1; iSize < iInitialCapacity; iSize=iSize*2+1 ) { }
aItem = ia.allocate( iSize );
}
Heap( cmpfunc cmpin, int iInitialCapacity ) :
iSize( 0 ),
iFill( 0 ),
aItem( NULL ),
cmp( cmpin )
{
for( iSize = 1; iSize < iInitialCapacity; iSize=iSize*2+1 ) { }
aItem = ia.allocate( iSize );
}
virtual ~Heap()
{
for( int j = 0; j < iFill; j++ )
ia.destroy( &aItem[j] );
ia.deallocate( aItem, iSize );
aItem = NULL;
}
virtual void enqueue( const item &it )
{
item i = it; // TODO: This is a silly workaround, put the i item
// at the end.
if( iFill+1 >= iSize )
upSize();
for( int j = 0; j < iFill; )
{
if( cmp( i, aItem[j] ) )
{
Bu::swap( i, aItem[j] );
}
if( j*2+1 >= iFill )
break;
if( cmp( i, aItem[j*2+1] ) )
{
j = j*2+1;
}
else
{
j = j*2+2;
}
}
ia.construct( &aItem[iFill], i );
if( iFill > 0 )
{
for( int j = iFill; j >= 0; )
{
int k = (j-1)/2;
if( j == k )
break;
if( cmp( aItem[k], aItem[j] ) )
break;
Bu::swap( aItem[k], aItem[j] );
j = k;
}
}
iFill++;
}
virtual item &peek()
{
if( iFill == 0 )
throw HeapException("Heap empty.");
return aItem[0];
}
virtual const item &peek() const
{
if( iFill == 0 )
throw HeapException("Heap empty.");
return aItem[0];
}
virtual item dequeue()
{
if( iFill == 0 )
throw HeapException("Heap empty.");
item iRet = aItem[0];
int j;
for( j = 0; j < iFill; )
{
int k = j*2+1;
if( k+1 < iFill && cmp( aItem[k+1], aItem[k] ) )
{
if( k+1 < iFill-1 && cmp( aItem[iFill-1], aItem[k+1] ) )
break;
aItem[j] = aItem[k+1];
j = k+1;
}
else if( k < iFill )
{
if( k < iFill-1 && cmp( aItem[iFill-1], aItem[k] ) )
break;
aItem[j] = aItem[k];
j = k;
}
else
break;
}
if( j < iFill-1 )
aItem[j] = aItem[iFill-1];
ia.destroy( &aItem[iFill-1] );
iFill--;
return iRet;
}
virtual bool isEmpty() const
{
return (iFill==0);
}
virtual int getSize() const
{
return iFill;
}
/*
void print( class Formatter &f )
{
f << "graph G {" << "\n";
for( int j = 0; j < iFill; j++ )
{
if( j*2+1 < iFill )
f << " " << j << " -- " << j*2+1 << ";" << "\n";
if( j*2+2 < iFill )
f << " " << j << " -- " << j*2+2 << ";" << "\n";
}
for( int j = 0; j < iFill; j++ )
{
f << " " << j << " [label=\"" << aItem[j] << "\"];" << "\n";
}
f << "}" << "\n";
} */
private:
void upSize()
{
item *aNewItems = ia.allocate( iSize*2+1 );
// memcpy( aNewItems, aItem, sizeof(item)*iFill );
for( int j = 0; j < iFill; j++ )
{
ia.construct( &aNewItems[j], aItem[j] );
ia.destroy( &aItem[j] );
}
ia.deallocate( aItem, iSize );
aItem = aNewItems;
iSize = iSize*2+1;
}
private:
int iSize;
int iFill;
item *aItem;
cmpfunc cmp;
itemalloc ia;
};
};
#endif
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