which.cc

// -*- mode: c++; fill-column: 80; c-basic-offset: 2; indent-tabs-mode: nil -*-
/*
    Copyright (c) 2010 Juan Jose Garcia Ripoll

    Tensor 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 program 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 General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include <algorithm>
#include <tensor/indices.h>

namespace tensor {

  const Indices which(const Booleans &b)
  {
    index size = std::count(b.begin(), b.end(), true);
    Indices output(size);
    Indices::iterator oit = output.begin();
    index i = 0;
    for (Booleans::const_iterator it = b.begin(); it != b.end(); it++, i++) {
      if (*it) {
        *oit = i;
        ++oit;
      }
    }
    return output;
  }

} // namespace tensor