Paper Info
Title
Optimally Streaming Greedy Regular Expression Parsing.
Abstract
We study the problem of streaming regular expression parsing: Given a regular expression and an input stream of symbols, how to output a serialized syntax tree representation as an output stream during input stream processing. We show that optimally streaming regular expression parsing, outputting bits of the output as early as is semantically possible for any regular expression of size m and any input string of length n, can be performed in time O(2(mlogm) + mn) on a unit-cost random-access machine. This is for the wide-spread greedy disambiguation strategy for choosing parse trees of grammatically ambiguous regular expressions. In particular, for a fixed regular expression, the algorithm's run-time scales linearly with the input string length. The exponential is due to the need for preprocessing the regular expression to analyze state coverage of its associated NFA, a PSPACE-hard problem, and tabulating all reachable ordered sets of NFA-states. Previous regular expression parsing algorithms operate in multiple phases, always requiring processing or storing the whole input string before outputting the first bit of output, not only for those regular expressions and input prefixes where reading to the end of the input is strictly necessary.
Year
DOI
Venue
2014
10.1007/978-3-319-10882-7_14
Lecture Notes in Computer Science
Field
DocType
Volume
Discrete mathematics,Regular expression,Programming language,Parse tree,Computer science,Abstract syntax tree,Theoretical computer science,Parsing,Stream processing
Conference
8687
ISSN
Citations 
PageRank 
0302-9743
2
0.36
References 
Authors
15
3
Name
Order
Citations
PageRank
Niels Bjørn Bugge Grathwohl1112.21
Fritz Henglein268869.17
Ulrik Terp Rasmussen381.47