flower/include/interval.hh

   1 /*
   2   interval.hh -- part of flowerlib
   3
   4   (c) 1996 Han-Wen Nienhuys
   5 */
   6
   7 #ifndef INTERVAL_HH
   8 #define INTERVAL_HH
   9
  10 #include <assert.h>
  11 #include "flower-proto.hh"
  12 #include "real.hh"
  13 #include "drul-array.hh"
  14
  15 /** a T interval.  this represents the closed interval [left,right].
  16   No invariants. T must be a totally ordered ring (with division, anyway ..)
  17   At instantiation, the function infinity () has to be defined explicitely.
  18
  19   */
  20 template<class T>
  21 struct Interval_t : public Drul_array<T> {
  22
  23   /* ************** */
  24
  25   static T infinity () ;
  26   static String T_to_string (T arg);
  27   T center () const {
  28     assert (!empty_b ());
  29     return (elem (LEFT) + elem (RIGHT)) / T (2);
  30   }
  31   void translate (T t)
  32     {
  33       elem (LEFT) += t;
  34       elem (RIGHT) += t;
  35     }
  36   void widen (T t)
  37   {
  38     elem (LEFT) -= t;
  39     elem (RIGHT) += t;
  40   }
  41
  42   /**
  43     PRE
  44     *this and h are comparable
  45     */
  46   void unite (Interval_t<T> h);
  47   void intersect (Interval_t<T> h);
  48   void add_point (T p) {
  49     elem(LEFT) = elem (LEFT) <? p;
  50     elem(RIGHT) = elem (RIGHT) >? p;
  51   }
  52   T length () const;
  53   T delta () const;
  54   void set_empty () ;
  55   void set_full ();
  56   bool empty_b () const { return elem (LEFT) > elem (RIGHT); }
  57   bool contains_b (Interval_t<T> const&) const;
  58   Interval_t () {
  59     set_empty ();
  60   }
  61   Interval_t (T m, T M) : Drul_array<T> (m,M)
  62     {
  63     }
  64   Interval_t<T> &operator -= (T r) {
  65     *this += -r;
  66     return *this;
  67   }
  68
  69   Interval_t<T> &operator += (T r) {
  70     elem (LEFT) += r;
  71     elem (RIGHT) +=r;
  72     return *this;
  73   }
  74   Interval_t<T> &operator *= (T r) {
  75     if (!empty_b ())
  76       {
  77         elem (LEFT) *= r;
  78         elem (RIGHT) *= r;
  79         if (r < T (0))
  80           swap();
  81
  82       }
  83     return *this;
  84   }
  85
  86   Real linear_combination (Real x) const {
  87     return ((1.0 - x) * Real (elem (LEFT))  + (x + 1.0) * Real (elem (RIGHT))) * 0.5;
  88   }
  89   String to_string () const;
  90
  91   bool elem_b (T r);
  92   void negate () {
  93     T r = -elem (LEFT);
  94     T l = -elem (RIGHT);
  95     elem (LEFT) = l;
  96     elem (RIGHT) =r;
  97   }
  98
  99   void swap ()
 100   {
 101     T t = elem (LEFT);
 102     elem (LEFT) = elem (RIGHT);
 103     elem (RIGHT) = t;
 104   }
 105 };
 106
 107
 108 /**
 109   inclusion ordering. Crash if not  comparable.
 110   */
 111 template<class T>
 112 int Interval__compare (const Interval_t<T>&,Interval_t<T> const&);
 113
 114 /**
 115    Inclusion ordering.  return -2 if not comparable
 116  */
 117 template<class T>
 118 int
 119 _Interval__compare (const Interval_t<T>&a,Interval_t<T> const&b);
 120
 121
 122 /*
 123   INLINE
 124  */
 125
 126 #include "compare.hh"
 127
 128 TEMPLATE_INSTANTIATE_COMPARE (Interval_t<T>&, Interval__compare, template<class T>);
 129
 130
 131 template<class T>
 132 inline Interval_t<T>
 133 intersection (Interval_t<T> a, Interval_t<T> const&b)
 134 {
 135   a.intersect (b);
 136   return a;
 137
 138 }
 139
 140 template<class T>
 141 inline
 142 Interval_t<T> operator + (T a,Interval_t<T> i)
 143 {
 144   i += a;
 145   return i;
 146 }
 147
 148 template<class T>
 149 inline
 150 Interval_t<T> operator - (Interval_t<T> i, T a)
 151 {
 152   i += -a;
 153   return i;
 154 }
 155
 156 template<class T>
 157 inline
 158 Interval_t<T> operator - (T a,Interval_t<T> i)
 159 {
 160   i.negate ();
 161   i += a;
 162   return i;
 163 }
 164
 165 template<class T>
 166 inline
 167 Interval_t<T> operator + (Interval_t<T> i,T a){
 168   return a+i;
 169 }
 170
 171 template<class T>
 172 inline
 173 Interval_t<T> operator * (T a,Interval_t<T> i)
 174 {
 175   i *= a;
 176   return i;
 177 }
 178
 179 template<class T>
 180 inline
 181 Interval_t<T> operator * (Interval_t<T> i,T a){
 182   return a*i;
 183 }
 184
 185 // again? see flower-proto.hh
 186 typedef Interval_t<Real> Interval;
 187 typedef Interval_t<int> Slice;  // weird name
 188
 189
 190 #endif // INTERVAL_HH
 191