GPERF : a perfect hash function generator

gperf is a widely available perfect hash function generator written in C++. It automates a common system software operation: keyword recognition. gperf translates an n element user-specified keyword list keyfile into source code containing a k element lookup table and a pair of functions, phash and in_word_set. phash uniquely maps keywords in keyfile onto the range 0 .. k - 1, where k >/= n. If k = n, then phash is considered a minimal perfect hash function. in_word_set uses phash to determine whether a particular string of characters str occurs in the keyfile, using at most one string comparison.This paper describes the user-interface, options, features, algorithm design and implementation strategies incorporated in gperf. It also presents the results from an empirical comparison between gperf-generated recognizers and other popular techniques for reserved word lookup

A New Linear-Time Dynamic Dictionary Matching Algorithm

This research presents inverted lists as a new data structure for the dynamic dictionary matching algorithm. The inverted lists structure, which derives from the inverted index, is implemented by the perfect hashing table. The dictionary is constructed in optimal time and the individual patterns can be updated in minimal time. The searching phase scans the given text in a single pass, even in a worst case scenario. In experimental results, the inverted lists used less time and space than the traditional structures; the searches were processed and showed an efficient linear time