[doc] Add more docs and unify indentation

dune/solvers/common/algorithm.hh

@@ -178,9 +178,7 @@ public:
     }
 
     constexpr T operator[](const T&i) const
-  {
-    return begin()+i;
-  }
+    { return begin()+i; }
 
   private:
     T begin_;
@@ -268,6 +266,7 @@ constexpr void forEach(Range&& range, F&& f, PriorityTag<0>)
   {
     for(std::size_t i=0; i<range.size(); ++i)
       f(range[i]);
+  // \ToDo Why does the following not compile?
   //  for(auto e : range)
   //    f(e);
   }
@@ -276,12 +275,30 @@ constexpr void forEach(Range&& range, F&& f, PriorityTag<0>)
 
 
 
+/**
+ * \brief Range based for loop
+ *
+ * \tparam Range Type of given range
+ * \tparam F Type of given predicate
+ *
+ * \param range The range to loop over
+ * \param f A predicate that will be called with each entry of the range
+ *
+ * This supports looping over the following ranges
+ * * ranges obtained from integralRange()
+ * * all ranges that provide HybridAlgorithm::size() and HybridAlgorithm::elementAt()
+ *
+ * This especially included instances of std::integer_sequence,
+ * std::tuple, Dune::TupleVector, and Dune::MultiTypeBlockVector.
+ */
 template<class Range, class F>
 constexpr void forEach(Range&& range, F&& f)
 {
   HybridAlgorithm::Imp::forEach(std::forward<Range>(range), std::forward<F>(f), PriorityTag<42>());
 }
 
+
+
 } // namespace HybridAlgorithm