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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 <string.h>
#include <memory>
#include <iostream>
#include "bu/exceptionbase.h"
#include "bu/util.h"
namespace Bu
{
subExceptionDecl( HeapException );
template<typename item, typename cmpfunc=__basicLTCmp<item>, typename itemalloc=std::allocator<item> >
class Heap
{
public:
Heap() :
iSize( 7 ),
iFill( 0 ),
aItem( ia.allocate( iSize ) )
{
}
virtual ~Heap()
{
for( int j = 0; j < iFill; j++ )
ia.destroy( &aItem[j] );
ia.deallocate( aItem, iSize );
aItem = NULL;
}
void enqueue( item i )
{
if( iFill+1 >= iSize )
upSize();
for( int j = 0; j < iFill; )
{
if( cmp( i, aItem[j] ) )
{
swap( i, aItem[j] );
}
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( cmp( aItem[k], aItem[j] ) )
break;
swap( aItem[k], aItem[j] );
j = k;
}
}
iFill++;
}
item &peek()
{
if( iFill == 0 )
throw HeapException("Heap empty.");
return aItem[0];
}
item dequeue()
{
if( iFill == 0 )
throw HeapException("Heap empty.");
item iRet = aItem[0];
int j;
for( j = 0; j < iFill; )
{
if( cmp( aItem[j*2+2], aItem[j*2+1] ) && j*2+2 < iFill )
{
aItem[j] = aItem[j*2+2];
j = j*2+2;
}
else if( j*2+1 < iFill )
{
aItem[j] = aItem[j*2+1];
j = j*2+1;
}
else
break;
}
aItem[j] = aItem[iFill-1];
ia.destroy( &aItem[iFill-1] );
iFill--;
return iRet;
}
bool isEmpty()
{
return (iFill==0);
}
int getSize()
{
return iFill;
}
void print()
{
printf("graph G {\n");
for( int j = 0; j < iFill; j++ )
{
if( j*2+1 < iFill )
printf(" %d -- %d;\n",
j, j*2+1
);
if( j*2+2 < iFill )
printf(" %d -- %d;\n",
j, j*2+2
);
}
for( int j = 0; j < iFill; j++ )
{
printf(" %d [label=\"%d\"];\n",
j, aItem[j]
);
}
printf("}\n");
}
private:
void upSize()
{
item *aNewItems = ia.allocate( iSize*2+1 );
memcpy( aNewItems, aItem, sizeof(item)*iFill );
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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