Changeset 958 for trunk/yat/utility

Timestamp:

Oct 10, 2007, 5:44:06 PM (14 years ago)

Author:

Peter

Message:

allowing mixture of weighted and unweighted iterators in vector_distance

File:

• trunk/yat/utility/iterator_traits.h (modified) (2 diffs)

trunk/yat/utility/iterator_traits.h

@@ -56 +56 @@
 
   // but specialized to return weighted type for some things
+  //
+  // if you add a new weighted iterator, add a new specialization like
+  // this one.
   template <class U, class V>
   struct weighted_iterator_traits<yat::utility::IteratorWeighted<U,V> > {
@@ -64 +67 @@
 
   /*
-    struct used to determine if a pair of iterators should be treated
-    as weighted
-
+    Metafunction that works on a pair weighted-unweighted types and
+    return weighted_type. The metafunction is specialized for
+    unweighted unweighted in which case unweighted is returned.
+   */
   template <class T1, class T2>
-  struct weighted_iterator_traits2 {
+  struct unweighted_type_and {
     typedef weighted_type type;
   };
 
-  // but specialized to return weighted type for some things
+  /*
+    Specialization that sets type to be unweighted when both arguments
+    are unweighted
+   */
+  template <>
+  struct unweighted_type_and<unweighted_type, unweighted_type> {
+    typedef unweighted_type type;
+  };
+
+  /*
+    struct used to determine if a pair of iterators should be treated
+    as weighted. If both iterators are unweighted, type is set to
+    unweighted else weighted.
+  */
   template <class T1, class T2>
-  struct weighted_iterator_traits2<yat::utility::IteratorWeighted<U,V> > {
-    typedef weighted_type type;
+  struct weighted_if_any2 {
+    typedef typename weighted_iterator_traits<T1>::type w_type1;
+    typedef typename weighted_iterator_traits<T2>::type w_type2;
+    typedef typename unweighted_type_and<w_type1, w_type2>::type type;
   };
-  */
+
+  /*
+    Same as weighted_iterator_traits2 but for 3 arguments.
+   */
+  template <class T1, class T2, class T3>
+  struct weighted_if_any3 {
+    typedef typename weighted_if_any2<T1, T2>::type tmp;
+    typedef typename weighted_iterator_traits<T3>::type w_type3;
+    typedef typename unweighted_type_and<tmp, w_type3>::type type;
+  };
 
   // check (at compile time) that iterator is unweighted.