Search Results for "backtracking"

RE2/J is a high-performance regular expression engine implemented in pure Java as a port of Google’s C++ RE2 library. Unlike traditional regex engines such as Java’s java.util.regex, PCRE, or Perl’s implementation—which rely on backtracking and can suffer from catastrophic exponential runtimes—RE2/J guarantees linear-time matching relative to input size. It achieves this efficiency by simulating all possible matches in a single pass using a nondeterministic finite automaton (NFA), ensuring predictable and safe performance even with complex patterns. This makes RE2/J ideal for applications that must handle user-supplied regular expressions securely without the risk of denial-of-service through regex backtracking. ...

RE2 is a fast, safe, thread-friendly alternative to backtracking regular expression engines like those used in PCRE, Perl, and Python. It is a C++ library. This is the source code repository for RE2, a regular expression library. There is a fair amount of documentation (including code snippets) in the re2.h header file. Unless otherwise noted, the RE2 source files are distributed under the BSD-style license found in the LICENSE file.

Angstrom is a parser-combinator library in OCaml designed for high-performance applications. It provides monadic and applicative interfaces for composing parsers and supports incremental input processing. ​

Tool to transcribe Parsing Expression Grammar into a parser written in Java. Parsing Expression Grammar (PEG) is a way to specify recursive-descent parsers with limited backtracking. The use of backtracking lifts the LL(1) restriction usually imposed by top-down parsers. In addition, PEG can define parsers with integrated lexing. Unlike some existing parser generators for PEG, the tool does not produce a complex and storage-hungry "packrat parser", but a collection of transparent recursive procedures. ...

The subgraph matching problem (subgraph isomorphism) is NP-complete. Previously, we designed an exact subgraph matching (ESM) algorithm for dependency graphs using a backtracking approach (http://esmalgorithm.sourceforge.net). We further designed an approximate subgraph matching (ASM) algorithm that is capable of detecting approximate subgraph matching based on a subgraph distance. Assume that the graph G and the subgraph Gs have m and n vertices, and km and kn edges respectively, the total worst-case algorithm complexity is O(m^n * n(n-1)/2 * km * log m). ...

The subgraph matching problem (subgraph isomorphism) is NP-complete. We designed a simple exact subgraph matching (ESM) algorithm for dependency graphs using a backtracking approach. The total worst-case algorithm complexity is O(n^2 * k^n) where n is the number of vertices and k is the vertex degree. We have demonstrated the successful usage of our algorithm in three biomedical relation and event extraction applications: BioNLP 2011 shared tasks on event extraction, Protein-Residue association detection and Protein-Protein interaction identification. ...