Impulse regular expression matching

摘要

Disclosed is a method and apparatus for matching regular expressions. A buffer of symbols giving a number of the last occurrence positions of each symbol is maintained. When two constants match on either side of a regular expression operator, the buffer of symbols is queried to determine if a member of the complement of the regular expression operator occurred between the two constants. If so, then the operator was not satisfied. If not, then the operator was satisfied.

主权项

1. A system that matches a string of symbols to a regular expression pattern, said regular expression pattern comprising a first constant, a second constant, and a first operator, said first operator occurring between said first constant and said second constant in said regular expression pattern, comprising:
a processor; a memory; a deterministic finite automaton (DFA) engine that matches said first constant to said regular expression pattern starting at a first position in said string of symbols, the first DFA engine matching said second constant to said regular expression pattern ending at a second position in said string of symbols; and a buffer of symbols that associates a plurality of positions of occurrences of a plurality of symbols in said string of symbols, said buffer of symbols producing an indicator that a position of a symbol from a complementary set of symbols is between said first position and said second position, said complementary set of symbols being based on a complement of said first operator, said indicator corresponding to whether the first operator is satisfied.