transform_iterator.h

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/*
 *  This file is a part of TiledArray.
 *  Copyright (C) 2013  Virginia Tech
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
 
#ifndef TILEDARRAY_TRANSFORM_ITERATOR_H__INCLUDED
#define TILEDARRAY_TRANSFORM_ITERATOR_H__INCLUDED
 
#include <TiledArray/external/madness.h>
#include <cstddef>
 
namespace TiledArray {
namespace detail {
 
namespace {
 
 
template <typename T>
class PointerProxy {
 public:
 
  PointerProxy(const T& value) : value_(value) {}
 
 
  T* operator->() const { return &value_; }
 
  operator T*() const { return &value_; }
 
 private:
  mutable T value_;  
};                   // class PointerProxy
}  // namespace
 
 
template <typename Iter1, typename Iter2, typename Op>
class BinaryTransformIterator {
 private:
  // Give access to other Transform iterator types.
  template <typename, typename, typename>
  friend class BinaryTransformIterator;
 
 public:
  typedef std::ptrdiff_t difference_type;  
  typedef typename madness::detail::result_of<Op>::type
      value_type;  
  typedef PointerProxy<value_type> pointer;  
  typedef value_type reference;  
  typedef std::input_iterator_tag
      iterator_category;  
  typedef BinaryTransformIterator<Iter1, Iter2, Op>
      this_type;                 
  typedef Iter1 base_iterator1;  
  typedef Iter2 base_iterator2;  
 
 
  BinaryTransformIterator(Iter1 it1, Iter2 it2, Op op = Op())
      : it1_(it1), it2_(it2), op_(op) {}
 
 
  BinaryTransformIterator(const this_type& other)
      : it1_(other.it1_), it2_(other.it2_), op_(other.op_) {}
 
 
  template <typename It1, typename It2>
  BinaryTransformIterator(const BinaryTransformIterator<It1, It2, Op>& other)
      : it1_(other.it1_), it2_(other.it2_), op_(other.op_) {}
 
 
  this_type& operator=(const this_type& other) {
    it1_ = other.it1_;
    it2_ = other.it2_;
    op_ = other.op_;
 
    return *this;
  }
 
 
  template <typename It1, typename It2>
  this_type& operator=(const BinaryTransformIterator<It1, It2, Op>& other) {
    it1_ = other.it1_;
    it2_ = other.it2_;
    op_ = other.op_;
 
    return *this;
  }
 
 
  this_type& operator++() {
    increment();
    return *this;
  }
 
 
  this_type operator++(int) {
    this_type tmp(*this);
    increment();
    return tmp;
  }
 
 
  template <typename It1, typename It2>
  bool operator==(const BinaryTransformIterator<It1, It2, Op>& other) const {
    return equal(other);
  }
 
 
  template <typename It1, typename It2>
  bool operator!=(const BinaryTransformIterator<It1, It2, Op>& other) const {
    return !equal(other);
  }
 
 
  reference operator*() { return dereference(); }
 
 
  pointer operator->() { return pointer(dereference()); }
 
 
  base_iterator1 base1() const { return it1_; }
 
 
  base_iterator2 base2() const { return it2_; }
 
 private:
  void increment() {
    ++it1_;
    ++it2_;
  }
 
 
  template <typename It1, typename It2>
  bool equal(const BinaryTransformIterator<It1, It2, Op>& other) const {
    return (it1_ == other.it1_) && (it2_ == other.it2_);
  }
 
 
  reference dereference() const { return op_(*it1_, *it2_); }
 
  base_iterator1 it1_;  
  base_iterator2 it2_;  
  Op op_;               
};                      // class BinaryTransformIterator
 
 
template <typename Iter, typename Op>
class UnaryTransformIterator {
 private:
  // Give access to other Transform iterator types.
  template <typename, typename>
  friend class UnaryTransformIterator;
 
 public:
  typedef ptrdiff_t difference_type;  
  typedef typename madness::detail::result_of<Op>::type
      value_type;  
  typedef PointerProxy<value_type> pointer;  
  typedef value_type reference;  
  typedef std::input_iterator_tag
      iterator_category;  
  typedef UnaryTransformIterator<Iter, Op> this_type;  
  typedef Iter base_iterator;  
 
 
  UnaryTransformIterator(Iter it, Op op = Op()) : it_(it), op_(op) {}
 
 
  UnaryTransformIterator(const this_type& other)
      : it_(other.it_), op_(other.op_) {}
 
 
  template <typename It>
  UnaryTransformIterator(const UnaryTransformIterator<It, Op>& other)
      : it_(other.it_), op_(other.op_) {}
 
 
  this_type& operator=(const this_type& other) {
    it_ = other.it_;
    op_ = other.op_;
 
    return *this;
  }
 
 
  template <typename It>
  this_type& operator=(const UnaryTransformIterator<It, Op>& other) {
    it_ = other.it_;
    op_ = other.op_;
 
    return *this;
  }
 
 
  this_type& operator++() {
    increment();
    return *this;
  }
 
 
  this_type operator++(int) {
    this_type tmp(*this);
    increment();
    return tmp;
  }
 
 
  template <typename It>
  bool operator==(const UnaryTransformIterator<It, Op>& other) const {
    return equal(other);
  }
 
 
  template <typename It>
  bool operator!=(const UnaryTransformIterator<It, Op>& other) const {
    return !equal(other);
  }
 
 
  reference operator*() const { return dereference(it_); }
 
 
  pointer operator->() const { return pointer(dereference(it_)); }
 
 
  base_iterator base() const { return it_; }
 
 private:
  void increment() { ++it_; }
 
 
  template <typename It>
  bool equal(const UnaryTransformIterator<It, Op>& other) const {
    return it_ == other.it_;
  }
 
 
  template <typename It>
  std::enable_if_t<!std::is_integral_v<It>, reference> dereference(
      It it) const {
    return op_(*it);
  }
 
 
  template <typename It>
  std::enable_if_t<std::is_integral_v<It>, reference> dereference(It it) const {
    return op_(it);
  }
 
  base_iterator it_;  
  Op op_;             
};                    // class UnaryTransformIterator
 
 
template <typename Iter1, typename Iter2, typename Op>
BinaryTransformIterator<Iter1, Iter2, Op> make_tran_it(Iter1 it1, Iter2 it2,
                                                       Op op) {
  return BinaryTransformIterator<Iter1, Iter2, Op>(it1, it2, op);
}
 
 
template <typename Iter, typename Op>
UnaryTransformIterator<Iter, Op> make_tran_it(Iter it, Op op) {
  return UnaryTransformIterator<Iter, Op>(it, op);
}
 
}  // namespace detail
}  // namespace TiledArray
 
#endif  // TILEDARRAY_TRANSFORM_ITERATOR_H__INCLUDED