added source set functions

Heat_method_3/include/CGAL/Heat_method_3/Heat_method_3.h

@@ -17,7 +17,7 @@
 // SPDX-License-Identifier: GPL-3.0+
 //
 //
-// Author(s) : Christina Cruz, Keenan Crane, Andreas Fabri
+// Author(s) : Christina Vaz, Keenan Crane, Andreas Fabri
 
 #ifndef CGAL_HEAT_METHOD_3_HEAT_METHOD_3_H
 #define CGAL_HEAT_METHOD_3_HEAT_METHOD_3_H
@@ -93,6 +93,43 @@ namespace Heat_method_3 {
       return sources.insert(vd).second;
     }
 
+    /**
+     *remove 'vd' from the source set, returning 'true' if 'vd' was in the set
+     */
+    bool remove_source(vertex_descriptor vd)
+    {
+      if(sources.find(vd))
+      {
+        sources.erase(vd);
+        return true;
+      }
+      else
+      {
+        return false;
+      }
+    }
+
+    vertex_descriptor getSources()
+    {
+      return sources;
+    }
+
+    void clearSources()
+    {
+      sources.clear();
+      return;
+    }
+
+    vertex_descriptor sourcesBegin()
+    {
+      return sources.begin();
+    }
+
+    vertex_descriptor sourcesEnd()
+    {
+      return sources.end();
+    }
+
     /**
      * get distance from the current source set to a vertex ` vd`.
      */