Changes

Summary

1. tuned source structure;
2. clarified signature; minor performance tuning;
3. tuned;
4. minor performance tuning; eliminate clones;
5. minor performance tuning;
6. minor performance tuning;
7. minor performance tuning;
8. minor performance tuning;
9. minor performance tuning;
10. minor performance tuning;
11. tuned;
12. tuned signature;
13. tuned signature;