An alternative bit-parallel algorithm for parameterized string matching

Abstract

In the parameterized string matching, a given pattern P is said to match with a substring t of the text T, if there exist a bijection from the symbols of P to the symbols of t. This problem has an important application in software maintenance, where we wish to find the equivalency between two sections of codes. Two sections of codes are said to be equivalent, if one can be transformed into the other by renaming identifiers and variables. In this paper, we have extended exact Two Way Non-Deterministic DAWG Matching (TNDM) algorithm (Hannu Peltola et al., 2003) for parameterized string matching problem. We call this algorithm as PTNDM. We have compared this algorithm with existing bit-parallel parameterized shift-or (PSO) and parameterized BNDM (PBNDM) algorithms. The experimental results show that PTNDM algorithm is better than PSO and close to PBNDM. We also show the performance of these algorithms with respect to duplicity present in the code. The above algorithms are applicable only when pattern length (m) is less than word length (w) of computer used (i.e.m w).