view: add implicit bool operator for 'not empty'

view.hpp

@@ -259,6 +259,15 @@ namespace cruft {
             return m_begin == m_end;
         }
 
+
+        ///--------------------------------------------------------------------
+        /// Returns true if the view is not empty; ie, there is data remaining.
+        constexpr operator bool () const noexcept
+        {
+            return not empty ();
+        }
+
+
         ///--------------------------------------------------------------------
         /// Returns the number of items in the view.
         constexpr auto