add support for offset linear combinations

src/lib/time/timevalue.hpp

@@ -148,7 +148,7 @@ namespace time {
       // Supporting multiplication with integral factor
       TimeVar& operator*= (int fact)           { t_ *= fact;  return *this; }
       
-      // Supporting flip sign
+      // Supporting sign flip
       TimeVar  operator-  ()         const     { return TimeVar(*this)*=-1; }
        
       // baseclass TimeValue is already totally_ordered 
@@ -185,16 +185,32 @@ namespace time {
         {
           return TimeValue(std::llabs (t_));
         }
-      
-      Offset
-      operator+ (Offset const& toChain)  const
-        {
-          TimeVar distance(*this);
-          distance += toChain;
-          return Offset(distance);
-        }
     };
   
+  //-- support linear offset chaining ---------------
+  
+  inline Offset
+  operator+ (Offset const& start, Offset const& toChain)
+  {
+    TimeVar distance(start);
+    distance += toChain;
+    return Offset(distance);
+  }
+  
+  inline Offset
+  operator* (int factor, Offset const& o)
+  {
+    TimeVar distance(o);
+    distance *= factor;
+    return Offset(distance);
+  }
+  
+  inline Offset
+  operator* (Offset const& distance, int factor)
+  {
+    return factor*distance;
+  }
+  
   
   
   

tests/lib/time/time-value-test.cpp

@@ -230,6 +230,8 @@ namespace test{
           // chaining and copy construction
           Offset off9 (off5 + Offset(four));
           CHECK (9 == off9);
+          // simple linear combinations
+          CHECK (7 == -2*off9 + off5*5);
         }