TMatColRowsIterator_decl.h

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// -*- C++ -*-

// PLearn (A C++ Machine Learning Library)
// Copyright (C) 1998 Pascal Vincent
// Copyright (C) 1999-2002 Pascal Vincent, Yoshua Bengio and University of Montreal
//

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// modification, are permitted provided that the following conditions are met:
// 
//  1. Redistributions of source code must retain the above copyright
//     notice, this list of conditions and the following disclaimer.
// 
//  2. Redistributions in binary form must reproduce the above copyright
//     notice, this list of conditions and the following disclaimer in the
//     documentation and/or other materials provided with the distribution.
// 
//  3. The name of the authors may not be used to endorse or promote
//     products derived from this software without specific prior written
//     permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
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// This file is part of the PLearn library. For more information on the PLearn
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/* *******************************************************      
   * $Id: TMatColRowsIterator_decl.h,v 1.1 2004/04/17 00:44:55 plearner Exp $
   * AUTHORS: Pascal Vincent & Yoshua Bengio
   * This file is part of the PLearn library.
   ******************************************************* */


#ifndef TMatColRowsIterator_decl_INC
#define TMatColRowsIterator_decl_INC

namespace PLearn {
using namespace std;

template <class T>
class TMatColRowsIterator
{
public:
  typedef random_access_iterator_tag iterator_category;
  typedef T                          value_type;
  typedef ptrdiff_t                  difference_type;
  typedef T*                         pointer;
  typedef T&                         reference;
  
private:
  T* ptr;                                    
  int mod;                                   

public:
  TMatColRowsIterator()
    : ptr(), mod() {}

  TMatColRowsIterator(T* p, int m)
    : ptr(p), mod(m) {}

  // Implement trivial iterator functions
  bool operator==(const TMatColRowsIterator& other) const {
    return ptr == other.ptr && mod == other.mod;
  }

  reference operator*() {
    return *ptr;
  }

  reference operator->() {                   
    return *ptr;                             
  }
  
  // Implement forward iterator functions
  TMatColRowsIterator<T>& operator++() {
    ptr += mod;
    return *this;
  }

  TMatColRowsIterator<T> operator++(int) {
    TMatColRowsIterator<T> r(*this);
    ptr += mod;
    return r;
  }

  // Implement bidirectional iterator functions
  TMatColRowsIterator<T>& operator--() {
    ptr -= mod;
    return *this;
  }

  TMatColRowsIterator<T> operator--(int) {
    TMatColRowsIterator<T> r(*this);
    ptr -= mod;
    return r;
  }

  // Implement random access iterator functions
  TMatColRowsIterator<T>& operator+=(difference_type n) {
    ptr += n*mod;
    return *this;
  }

  TMatColRowsIterator<T> operator+(difference_type n) {
    TMatColRowsIterator<T> r(*this);
    r += n;
    return r;
  }
  
  TMatColRowsIterator<T>& operator-=(difference_type n) {
    ptr -= n*mod;
    return *this;
  }

  TMatColRowsIterator<T> operator-(difference_type n) {
    TMatColRowsIterator<T> r(*this);
    r -= n;
    return r;
  }

  difference_type operator-(const TMatColRowsIterator<T>& y) {
    return (ptr - y.ptr) / mod;
  }
  
  reference operator[](difference_type n) {
    return *(ptr + n*mod);
  }

  bool operator<(const TMatColRowsIterator<T>& y) {
    return ptr < y.ptr;
  }
};

} // end of namespace PLearn

#endif

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