counter.h
//
// Distributed under the ITensor Library License, Version 1.1.
// (See accompanying LICENSE file.)
//
#ifndef __ITENSOR_COUNTER_H
#define __ITENSOR_COUNTER_H
#include "indexset.h"
#define Cout std::cout
#define Endl std::endl
namespace itensor {
//
// Counter
//
//
// A Counter "C" is iterated as
// for(; C.notDone(); ++C) { ... }
//
// When iterated, each index C.i[j]
// runs from 1 to C.n[j] such that taken
// together the C.i run over all values
// compatible with their ranges.
//
// The index C.i[1] changes every step,
// C.i[2] after every C.n[1] steps, etc.
//
// For example: (if C.n[1] == C.n[2] == 2, say)
// C.i[1] C.i[2] C.i[3]
// 0 0 0
// 1 0 0
// 0 1 0
// 1 1 0
// 0 0 1
// 1 0 1
// ...
//
// Counters also keep a straight count of which
// step they are on through the field C.ind
// (which starts from 0).
//
// ITensor data is ordered and the method
// ITensor::_ind is defined such that
// v[C.ind] == v[_ind(C.i[1],C.i[2],...,C.i[8]]
// where v is the Vector in an ITDat.
//
class Counter
{
public:
array<int,NMAX+1> n,
i;
int ind,
rn,
r;
Counter();
template <class IndexT>
Counter(const array<IndexT,NMAX+1>& ii,int rn,int r);
template <class IndexT>
explicit
Counter(const IndexSet<IndexT>& is);
Counter&
operator++();
bool
notDone() const { return i[1] >= 0; }
void
reset();
};
//
// Counter implementation
//
inline Counter::
Counter()
: rn(0), r(0)
{
n.fill(1);
n[0] = 0;
reset();
}
void inline Counter::
reset()
{
i.fill(0);
ind = 0;
}
template <class IndexT>
Counter::
Counter(const array<IndexT,NMAX+1>& ii, int rn_, int r_)
{
rn = rn_;
r = r_;
n[0] = 0;
for(int j = 1; j <= rn; ++j)
n[j] = ii[j].m();
for(int j = rn+1; j <= NMAX; ++j)
n[j] = 1;
reset();
}
template <class IndexT>
Counter::
Counter(const IndexSet<IndexT>& is)
{
rn = is.rn();
r = is.r();
n[0] = 0;
for(int j = 1; j <= rn; ++j)
n[j] = is.index(j).m();
for(int j = rn+1; j <= NMAX; ++j)
n[j] = 1;
reset();
}
inline
Counter& Counter::
operator++()
{
++ind;
++i[1];
if(i[1] >= n[1])
{
for(int j = 2; j <= rn; ++j)
{
i[j-1] = 0;
++i[j];
if(i[j] < n[j]) break;
}
}
//set 'done' condition
if(i[rn] >= n[rn])
{
i[1] = -1;
}
return *this;
}
inline
std::ostream&
operator<<(std::ostream& s, const Counter& c)
{
s << "(";
if(c.r >= 1) s << (c.i[1]+1);
for(int i = 2; i <= c.r; ++i)
{
s << "," << (c.i[i]+1);
}
s << ")";
return s;
}
}; //namespace itensor
#undef Cout
#undef Endl
#endif