source: branches/0.4-stable/yat/utility/stl_utility.h @ 1743

#ifndef _theplu_yat_utility_stl_utility_
#define _theplu_yat_utility_stl_utility_ 

// $Id: stl_utility.h 1743 2009-01-23 14:20:30Z peter $

/*
  Copyright (C) 2004 Jari Häkkinen
  Copyright (C) 2005 Jari Häkkinen, Peter Johansson, Markus Ringnér
  Copyright (C) 2006 Jari Häkkinen
  Copyright (C) 2007 Jari Häkkinen, Peter Johansson
  Copyright (C) 2008 Peter Johansson

  This file is part of the yat library, http://dev.thep.lu.se/yat

  The yat library 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 2 of the
  License, or (at your option) any later version.

  The yat library 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, write to the Free Software
  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  02111-1307, USA.
*/

///
/// \file stl_utility.h
///
/// There are a number of useful functionality missing in the Standard
/// Template Library, STL. This file is an effort to provide
/// extensions to STL functionality.
///

#include <algorithm>
#include <functional>
#include <ostream>
#include <string>
#include <utility>

namespace std {

  ///
  /// Print out a pair 
  ///
  // This is in namespace std because we have not figured out how to have
  // pair and its operator<< in different namespaces
  template <class T1, class T2>  
  std::ostream& operator<<(std::ostream& out, const std::pair<T1,T2>& p) 
  { out << p.first << "\t" << p.second; return out; }

}

namespace theplu {
namespace yat {
namespace utility {

  /**
     Functor class taking absolute value
  */
  template<typename T>
  struct abs : std::unary_function<T, T>
  {
    /**
       \return absolute value
     */
    inline T operator()(T x) const
    { return std::abs(x); }
  };

  /**
     See The C++ Standard Library - A Tutorial and Reference by
     Nicolai M. Josuttis

     If f is a binary functor, both g and h are unary functors, and
     return type of g (and h) is convertible to F's argument type,
     then compose_f_gx_hy can be used to create a functor equivalent
     to \f$ f(g(x), h(y)) \f$
   */
  template<class F, class G, class H>
  class compose_f_gx_hy
  {
  public:
    /**
       \brief Constructor
     */
    compose_f_gx_hy(F f, G g, H h)
      : f_(f), g_(g), h_(h) {}

    /**
       \brief Does the work
     */
    bool
    operator()(double x, 
               double y) const
    {
      return f_(g_(x), h_(y));
    }

  private:
    F f_;
    G g_;
    H h_;
  };

  /**
     Convenient function to create a compose_f_gx_hy.

     \see std::make_pair
  */
  template<class F, class G, class H>
  compose_f_gx_hy<F, G, H> make_compose_f_gx_hy(F f, G g, H h)
  {
    return compose_f_gx_hy<F,G,H>(f,g,h);
  }  

  /**
     \return max of values
   */
  template <typename T>
  T max(const T& a, const T& b, const T& c)
  {
    return std::max(std::max(a,b),c);
  }


  /**
     \return max of values
   */
  template <typename T>
  T max(const T& a, const T& b, const T& c, const T& d)
  {
    return std::max(std::max(a,b), std::max(c,d));
  }


  /**
     \return max of values
   */
  template <typename T>
  T max(const T& a, const T& b, const T& c, const T& d, const T& e)
  {
    return std::max(max(a,b,c,d), e);
  }


  /**
     \return max of values
   */
  template <typename T>
  T max(const T& a, const T& b, const T& c, const T& d, const T& e, const T& f)
  {
    return std::max(max(a,b,c,d), std::max(e,f));
  }


  ///
  /// @brief Functor comparing pairs using second.
  ///
  /// STL provides operator< for the pair.first element, but none for
  /// pair.second. This template provides this and can be used as the
  /// comparison object in generic functions such as the STL sort.
  ///
  template <class T1,class T2>
  struct pair_value_compare
  {
    ///
    /// @return true if x.second<y.second or (x.second==y.second and
    /// x.first<y.first)
    ///
    inline bool operator()(const std::pair<T1,T2>& x,
                           const std::pair<T1,T2>& y) {
      return ((x.second<y.second) ||
              (!(y.second<x.second) && (x.first<y.first))); 
    }
  };

  ///
  /// @brief Function converting a string to lower case
  ///
  std::string& to_lower(std::string& s);

  ///
  /// @brief Function converting a string to upper case
  ///
  std::string& to_upper(std::string& s);

}}} // of namespace utility, yat, and theplu

#endif