Abstract
I introduce two performance improvements to the Commentz-Walter family of multiple-keyword (exact) pattern matching algorithms. These algorithms (which are in the Boyer-Moore-Horspool style of keyword pattern matchers) consist of two nested loops: the outer one to process the input text and the inner one processing possible keyword matches. The guard of each loop is improved, thereby leading to non-trivial speedup, which could reach 20 % in practice, depending up on the input text and keywords.
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Notes
- 1.
For example on Knuth’s MMIX [8], which is broadly representative.
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Acknowledgements
This chapter is dedicated to Judith Bishop—good friend and colleague, and an outstanding computer scientist. In the 1990’s, I was invited by Judith to present a colloquium on keyword pattern matching algorithms, then at the University of Pretoria. This research work grew directly out of the discussions surrounding the colloquium and research visit.
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Watson, B.W. (2012). Tuning Keyword Pattern Matching. In: Breitman, K., Horspool, R. (eds) Patterns, Programming and Everything. Springer, London. https://doi.org/10.1007/978-1-4471-2350-7_11
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