williamr@2: // Copyright 2002 The Trustees of Indiana University.
williamr@2: 
williamr@2: // Use, modification and distribution is subject to the Boost Software 
williamr@2: // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: 
williamr@2: //  Boost.MultiArray Library
williamr@2: //  Authors: Ronald Garcia
williamr@2: //           Jeremy Siek
williamr@2: //           Andrew Lumsdaine
williamr@2: //  See http://www.boost.org/libs/multi_array for documentation.
williamr@2: 
williamr@2: #ifndef BOOST_INDEX_RANGE_RG071801_HPP
williamr@2: #define BOOST_INDEX_RANGE_RG071801_HPP
williamr@2: 
williamr@2: #include <boost/config.hpp>
williamr@2: #include <utility>
williamr@2: #include <boost/limits.hpp>
williamr@2: 
williamr@2: // For representing intervals, also with stride.
williamr@2: // A degenerate range is a range with one element.
williamr@2: 
williamr@2: // Thanks to Doug Gregor for the really cool idea of using the
williamr@2: // comparison operators to express various interval types!
williamr@2: 
williamr@2: // Internally, we represent the interval as half-open.
williamr@2: 
williamr@2: namespace boost {
williamr@2: namespace detail {
williamr@2: namespace multi_array {
williamr@2: 
williamr@2:   template <typename Index,typename SizeType>
williamr@2:   class index_range {
williamr@2:   public:
williamr@2:     typedef Index index;
williamr@2:     typedef SizeType size_type;
williamr@2: 
williamr@2:   private:
williamr@2:     static index from_start()
williamr@2:       { return (std::numeric_limits<index>::min)(); }
williamr@2: 
williamr@2:     static index to_end()
williamr@2:       { return (std::numeric_limits<index>::max)(); }
williamr@2: 
williamr@2:   public:
williamr@2: 
williamr@2:     index_range()
williamr@2:     {
williamr@2:       start_ = from_start();
williamr@2:       finish_ = to_end();
williamr@2:       stride_ = 1;
williamr@2:       degenerate_ = false;
williamr@2:     }
williamr@2: 
williamr@2:     explicit index_range(index pos)
williamr@2:     {
williamr@2:       start_ = pos;
williamr@2:       finish_ = pos+1;
williamr@2:       stride_ = 1;
williamr@2:       degenerate_ = true;
williamr@2:     }
williamr@2: 
williamr@2:     explicit index_range(index start, index finish, index stride=1)
williamr@2:       : start_(start), finish_(finish), stride_(stride),
williamr@2:         degenerate_(false)
williamr@2:     { }
williamr@2: 
williamr@2: 
williamr@2:     // These are for chaining assignments to an index_range
williamr@2:     index_range& start(index s) {
williamr@2:       start_ = s;
williamr@2:       degenerate_ = false;
williamr@2:       return *this;
williamr@2:     }
williamr@2: 
williamr@2:     index_range& finish(index f) {
williamr@2:       finish_ = f;
williamr@2:       degenerate_ = false;
williamr@2:       return *this;
williamr@2:     }
williamr@2: 
williamr@2:     index_range& stride(index s) { stride_ = s; return *this; }
williamr@2: 
williamr@2:     index start() const
williamr@2:     { 
williamr@2:       return start_; 
williamr@2:     }
williamr@2: 
williamr@2:     index get_start(index low_index_range = index_range::from_start()) const
williamr@2:     { 
williamr@2:       if (start_ == from_start())
williamr@2:         return low_index_range;
williamr@2:       return start_; 
williamr@2:     }
williamr@2: 
williamr@2:     index finish() const
williamr@2:     {
williamr@2:       return finish_;
williamr@2:     }
williamr@2: 
williamr@2:     index get_finish(index high_index_range = index_range::to_end()) const
williamr@2:     {
williamr@2:       if (finish_ == to_end())
williamr@2:         return high_index_range;
williamr@2:       return finish_;
williamr@2:     }
williamr@2: 
williamr@2:     index stride() const { return stride_; }
williamr@2: 
williamr@2:     void set_index_range(index start, index finish, index stride=1)
williamr@2:     {
williamr@2:       start_ = start;
williamr@2:       finish_ = finish;
williamr@2:       stride_ = stride;
williamr@2:     }
williamr@2: 
williamr@2:     static index_range all() 
williamr@2:     { return index_range(from_start(), to_end(), 1); }
williamr@2: 
williamr@2:     bool is_degenerate() const { return degenerate_; }
williamr@2: 
williamr@2:     index_range operator-(index shift) const
williamr@2:     { 
williamr@2:       return index_range(start_ - shift, finish_ - shift, stride_); 
williamr@2:     }
williamr@2: 
williamr@2:     index_range operator+(index shift) const
williamr@2:     { 
williamr@2:       return index_range(start_ + shift, finish_ + shift, stride_); 
williamr@2:     }
williamr@2: 
williamr@2:     index operator[](unsigned i) const
williamr@2:     {
williamr@2:       return start_ + i * stride_;
williamr@2:     }
williamr@2: 
williamr@2:     index operator()(unsigned i) const
williamr@2:     {
williamr@2:       return start_ + i * stride_;
williamr@2:     }
williamr@2: 
williamr@2:     // add conversion to std::slice?
williamr@2: 
williamr@2:   public:
williamr@2:     index start_, finish_, stride_;
williamr@2:     bool degenerate_;
williamr@2:   };
williamr@2: 
williamr@2:   // Express open and closed interval end-points using the comparison
williamr@2:   // operators.
williamr@2: 
williamr@2:   // left closed
williamr@2:   template <typename Index, typename SizeType>
williamr@2:   inline index_range<Index,SizeType>
williamr@2:   operator<=(Index s, const index_range<Index,SizeType>& r)
williamr@2:   {
williamr@2:     return index_range<Index,SizeType>(s, r.finish(), r.stride());
williamr@2:   }
williamr@2: 
williamr@2:   // left open
williamr@2:   template <typename Index, typename SizeType>
williamr@2:   inline index_range<Index,SizeType>
williamr@2:   operator<(Index s, const index_range<Index,SizeType>& r)
williamr@2:   {
williamr@2:     return index_range<Index,SizeType>(s + 1, r.finish(), r.stride());
williamr@2:   }
williamr@2: 
williamr@2:   // right open
williamr@2:   template <typename Index, typename SizeType>
williamr@2:   inline index_range<Index,SizeType>
williamr@2:   operator<(const index_range<Index,SizeType>& r, Index f)
williamr@2:   {
williamr@2:     return index_range<Index,SizeType>(r.start(), f, r.stride());
williamr@2:   }
williamr@2: 
williamr@2:   // right closed
williamr@2:   template <typename Index, typename SizeType>
williamr@2:   inline index_range<Index,SizeType>
williamr@2:   operator<=(const index_range<Index,SizeType>& r, Index f)
williamr@2:   {
williamr@2:     return index_range<Index,SizeType>(r.start(), f + 1, r.stride());
williamr@2:   }
williamr@2: 
williamr@2: } // namespace multi_array
williamr@2: } // namespace detail  
williamr@2: } // namespace boost
williamr@2: 
williamr@2: #endif // BOOST_INDEX_RANGE_RG071801_HPP