Utils - combine

- Implemented combine, which takes two integer vectors and combines
  them resulting in a single vector contianing the unique values of
  both.

src/util.cpp

@@ -381,6 +381,27 @@ std::string compressIds (const std::vector <int>& ids)
   return result.str ();
 }
 
+////////////////////////////////////////////////////////////////////////////////
+void combine (std::vector <int>& dest, const std::vector <int>& source)
+{
+  // Create a map using the sequence elements as keys.  This will create a
+  // unique list, with no duplicates.
+  std::map <int, int> both;
+  std::vector <int>::iterator i1;
+  for (i1 = dest.begin (); i1 != dest.end (); ++i1) both[*i1] = 0;
+
+  std::vector <int>::const_iterator i2;
+  for (i2 = source.begin (); i2 != source.end (); ++i2) both[*i2] = 0;
+
+  // Now make a sequence out of the keys of the map.
+  dest.clear ();
+  std::map <int, int>::iterator i3;
+  for (i3 = both.begin (); i3 != both.end (); ++i3)
+    dest.push_back (i3->first);
+
+  std::sort (dest.begin (), dest.end ());
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Run an external executable with execvp. This means stdio goes to 
 // the child process, so that it can receive user input (e.g. passwords).