Followup to !3091: Streamline new decay finder implementation

• do not export component specific headers to the rest of the world (esp. not with such generic names as 'Node' and 'Arrow')
• do not add unnecessary additional namespaces in global scope (i.e. instead of a separate 'finder' namespace just re-use the IDecayFinder scope)
• simplify the Arrow class to the point it is just an enum
• do not move from a const& -- pass by value and then move instead
• do not repeat member initializers in constructors when not needed
• prefer standalone functions over member functions that do not interact with the class they are a member of

Phys/DaVinciInterfaces/include/Kernel/IDecayFinder.h

@@ -18,25 +18,23 @@
 #include <string>
 #include <vector>
 
-namespace finder {
+struct GAUDI_API IDecayFinder : extend_interfaces<IAlgTool> {
+  // interface machinery
+  DeclareInterfaceID( IDecayFinder, 4, 0 );
+
   template <class PARTICLE>
   using vec_ptr     = std::vector<const PARTICLE*>;
   using vec_ptrv1   = vec_ptr<LHCb::Particle>;
   using vec_ptrv1mc = vec_ptr<LHCb::MCParticle>;
-} // namespace finder
-
-struct GAUDI_API IDecayFinder : extend_interfaces<IAlgTool> {
-  // interface machinery
-  DeclareInterfaceID( IDecayFinder, 4, 0 );
 
   /// find decays for Particles
-  virtual StatusCode findDecay( const std::string& decay_descriptor, const finder::vec_ptrv1& input_parts,
-                                finder::vec_ptrv1& out_parts ) const = 0;
+  virtual StatusCode findDecay( const std::string& decay_descriptor, const vec_ptrv1& input_parts,
+                                vec_ptrv1& out_parts ) const = 0;
 
   /// find decays for MCParticles
   // Note: The arrows do NOT mean anything currently for MCParticles
-  virtual StatusCode findDecay( const std::string& decay_descriptor, const finder::vec_ptrv1mc& input_parts,
-                                finder::vec_ptrv1mc& out_parts ) const = 0;
+  virtual StatusCode findDecay( const std::string& decay_descriptor, const vec_ptrv1mc& input_parts,
+                                vec_ptrv1mc& out_parts ) const = 0;
 
   // TODO: add here v2 variant type of composite and charged basic
 
@@ -47,4 +45,4 @@ struct GAUDI_API IDecayFinder : extend_interfaces<IAlgTool> {
   virtual std::vector<std::string> getDescriptorPossibilities( const std::string& decay_descriptor ) const = 0;
 };
 
-#endif // KERNEL_IDECAYFINDER_H
+#endif // KERNEL_IDECAYFINDER_H
\ No newline at end of file