cache.cpp

这是遗传算法的源代码

// -*- c++ -*- 
//
//  File:         cache.cpp
//
//  Description:  C++ implementation of the class cache.
//                The cache is used to speed up the MPM search
//                as suggested in Harik's paper.
//
//  Author:       Fernando Lobo
//
//  Date:         June/1999
//
//  Extended to deal with chi-ary problems by Luis de la Ossa
//  GCC 3.4 and 4 series compliance by Kumara Sastry 
//
//  Date:         March/2006

#include <iostream>
#include <math.h>
#include <stdlib.h>

#include "cache.hpp"
#include "subset.hpp"
#include "parameter.hpp"

int const EMPTY = -1;

//
// initializes a cache of subsets.
//
cache::cache()
{
  long ell = parameter::lchrom;
  maxSz = (ell * (ell-1)) / 2;
  mergedSet = new subset [ maxSz ];
  subset1_id = new int [ maxSz ];
  subset2_id = new int [ maxSz ];
  sz = 0;
  E = new long [ 2*ell ];
  Esize = 0;
}

//
// destructor
//
cache::~cache()
{
  delete [] mergedSet;
  delete [] subset1_id;
  delete [] subset2_id;
  delete [] E;
}

//
// store a subset and its complexity in the cache
//
void cache::insert( int id1, int id2, subset &S, int popsize )
{
  assert ( S.numCounts() <= popsize );
  assert( sz>=0 && sz<maxSz );
  long p;  // the position where S will be inserted
  if( Esize == 0 )  // there are no empty entries in the cache
    p = sz;
  else // pick an empty slot.
    {
      p = E[ Esize-1 ];
      Esize--;
    }
  //
  // now insert S
  //
  mergedSet[p] = S;
  subset1_id[p] = id1;
  subset2_id[p] = id2;
  sz++;
}

//
// remove all cache entries that have value 'id' in one of its IDs
// I don't actually remove the entries. Just marked them EMPTY;
//
void cache::removeEntry( int id )
{
  subset emptySet;
  for( int i=0; i< maxSz; i++ )
    if( subset1_id[i] == id || subset2_id[i] == id ) {
      mergedSet[i] = emptySet;
      subset1_id[i]= EMPTY;
      subset2_id[i]= EMPTY;
      assert( Esize < 2*parameter::lchrom );
      E[ Esize ] = i;
      Esize++;
      sz--;
    }
}

//
// replace all subset_ids that have 'x' by 'y'.
//
void cache::replace_X_by_Y( int x, int y )
{
  for( int i=0; i< maxSz; i++ ) {
    if( subset1_id[i] == x ) subset1_id[i] = y;
    if( subset2_id[i] == x ) subset2_id[i] = y;
  }
}

//
// compact the cache so that it doesn't have holes.
//
void cache::compact()
{
  long newMaxSz = maxSz - Esize;
  long p = maxSz-1;
  for( int i=0; i< Esize; i++ ) {
    long e = E[i];
    if( e >= newMaxSz )
      // do nothing
      ;
    else {
      //
      // find a non-empty slot
      //
      while( subset1_id[p] == EMPTY )
	p--;
      //
      // make element 'e' of the cache become element 'p'
      //
      mergedSet[e] = mergedSet[p];
      subset1_id[e] = subset1_id[p];
      subset2_id[e] = subset2_id[p];
      p--;
    }
  }
  Esize = 0;
  maxSz= newMaxSz;
}

//
// print the cache
//
std::ostream &operator<< (std::ostream &out, cache &C)
{
  out << "sz: " << C.sz << "  maxSz: " << C.maxSz << std::endl;
  out << "# Empty slots: " << C.Esize << std::endl;
  out << "Empty slots: ";
  for( int i=0; i< C.Esize; i++ )
    out << C.E[i] << " ";
  out << std::endl;
  for( int i=0; i< C.maxSz; i++ ) 
    out << "(" << C.subset1_id[i] << ")"
	<< "(" << C.subset2_id[i] << ")"
	<< " " <<C.mergedSet[i] << std::endl;
  return out;
}