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Derivatives of Regular Expressions with Lookahead

Takayuki Miyazaki, Yasuhiko Minamide
2019 Journal of Information Processing  
Next, we define two kinds of left quotient for languages with lookahead and give corresponding derivatives.  ...  Lookahead is an extension of regular expressions that has been adopted in many implementations and is widely used. Lookahead represents what is allowed as the rest of input.  ...  As a corollary of conversion to DFA, we show that the semantics of REwLA is a finite union of sets of the form A × B where A and B are regular languages.  ... 
doi:10.2197/ipsjjip.27.422 fatcat:5iocpps3hnfgrbculvympt777a

Translating regular expression matching into transducers

Yuto Sakuma, Yasuhiko Minamide, Andrei Voronkov
2012 Journal of Applied Logic  
From the definition of the deterministic parser, we can easily construct transducers through transducers with regular lookahead.  ...  The deterministic parser is formulated with the option monad instead of the list monad and derived through equational reasoning involving monads.  ...  We then derived the construction of transducers with regular lookahead, which can be converted into those without lookahead by an existing technique.  ... 
doi:10.1016/j.jal.2011.11.003 fatcat:6pir66qnonh23cci27q3j3vthe

RE2C: A lexer generator based on lookahead-TDFA

U. Trofimovich
2020 Software Impacts  
RE2C is a regular expression compiler: it transforms regular expressions into finite state machines and encodes them as programs in the target language.  ...  At the core of RE2C is the lookahead-TDFA algorithm that allows it to perform fast and lightweight submatch extraction.  ...  Submatch extraction is a special case of the parsing problem: in addition to solving the recognition problem it has to find the derivation of the input string in the grammar defined by the regular expression  ... 
doi:10.1016/j.simpa.2020.100027 fatcat:nneqzhzmy5dzfb2u2cfyv53grm

Regular Expressions with Lookahead

Martin Berglund, Brink van der Merwe, Steyn van Litsenborgh
2021 Journal of universal computer science (Online)  
We show how to translate regular expressions with lookaheads (REwLA) to equivalent Boolean automata having at most 3 states more than the length of the REwLA.  ...  This paper investigates regular expressions which in addition to the standard operators of union, concatenation, and Kleene star, have lookaheads.  ...  Acknowledgement We would like to thank Michal Hospodár for fruitful discussions on how to add εtransitions to the definition of alternating automata.  ... 
doi:10.3897/jucs.66330 dblp:journals/jucs/BerglundML21 fatcat:xqyyykddcjbejge35yf2nemazu

LL(*)

Terence Parr, Kathleen Fisher
2011 Proceedings of the 32nd ACM SIGPLAN conference on Programming language design and implementation - PLDI '11  
Despite the power of Parser Expression Grammars (PEGs) and GLR, parsing is not a solved problem.  ...  At parse-time, decisions gracefully throttle up from conventional fixed k ≥ 1 lookahead to arbitrary lookahead and, finally, fail over to backtracking depending on the complexity of the parsing decision  ...  The key idea behind LL(*) parsers is to use regular-expressions rather than a fixed constant or backtracking with a full parser to do lookahead.  ... 
doi:10.1145/1993498.1993548 dblp:conf/pldi/ParrF11 fatcat:uqitvlxdfrhs3j2sd4grb4p47u

Checking Time Linearity of Regular Expression Matching Based on Backtracking

Satoshi Sugiyama, Yasuhiko Minamide
2014 IPSJ Online Transactions  
We construct a top-down tree transducer with regular lookahead that translates the input string into a tree corresponding to the execution steps of matching based on backtracking.  ...  Our implementation showed that 47 of 393 regular expressions were not linear.  ...  Japan We now define the derivation relation ⇒ M of a top-down tree transducer M with regular lookahead.  ... 
doi:10.2197/ipsjtrans.7.82 fatcat:e55skq5uerempaioci36ns6owa

Recognising and Generating Terms using Derivatives of Parsing Expression Grammars [article]

Tony Garnock-Jones, Mahdi Eslamimehr, Alessandro Warth
2018 arXiv   pre-print
In this paper, we extend the idea of derivatives, originally formulated for regular expressions, to PEGs.  ...  Lacking tool support, language designers using PEGs have difficulty predicting the behaviour of their parsers.  ...  Nonterminal: (A, x) ⇒ o if (R(A), x) ⇒ Recognising with derivatives The method of derivatives, introduced for regular expressions (REs) in 1964 by Brzozowski [6] , revisited in 2009 by Owens et al.  ... 
arXiv:1801.10490v1 fatcat:v2u4g5rwyjbfflruaahca3cpgu

Strongly Regular Grammars and Regular Approximation of Context-Free Languages [chapter]

Ömer Eğecioğlu
2009 Lecture Notes in Computer Science  
In another direction, the generalization by a 1-lookahead extends Mohri and Nederhof's transformation by incorporating more context into the regular approximation at the expense of a larger grammar.  ...  We consider algorithms for approximating context-free grammars by regular grammars, making use of Chomsky's characterization of non-self-embedding grammars as generating regular languages and a transformation  ...  We will demonstrate the 1-lookahead idea with the help of an example. Example 5.  ... 
doi:10.1007/978-3-642-02737-6_16 fatcat:pciul52lafbrxduexw4yz5mlzu

Structured Grammars are Effective [article]

Ondřej Bílka
2012 arXiv   pre-print
We use alternative formalism of relativized regular expressions REGREG for which top-down backtracking parser runs in linear time.  ...  Parsing expression grammars (PEG) allows construction of linear time parsers using packrat algorithm. These techniques however suffer from problem of prefix hiding.  ...  With some bookkeeping we can transform left recursion to recursive descend. Idea is that each alternative returns its derivation an we choose a lexicographically smallest in recursion tree.  ... 
arXiv:1205.1877v1 fatcat:446npmjw5zalxovn3hsqoktee4

A Bounded Graph-Connect Construction for LR-regular Parsers [chapter]

Jacques Farré, José Fortes Gálvez
2001 Lecture Notes in Computer Science  
Resulting parsers are deterministic and linear, and accept a large class of LR-regular grammars including LALR(k).  ...  Here practical LR(0)-based parser generation is introduced, with automatic conflict resolution by potentially-unbounded lookahead exploration.  ...  A user of antlr (or Yacc+Lex ) should give these regular expressions as syntactic predicates for a clean solution.  ... 
doi:10.1007/3-540-45306-7_17 fatcat:yrvayufz2fdrvmlod4zlr7ey34

Mealy machines are a better model of lexical analyzers

Wuu Yang
1996 Computer languages  
operator in a regular expression corresponds to one or more states in the automaton for the regular expression. These states are called cutofS states.  ...  When the regular expressions defining tokens correspond to an infinite-lookahead automaton, the suffix automata technique becomes handicapped.  ...  He is also very interested in the study of human languages and human intelligence.  ... 
doi:10.1016/0096-0551(96)00003-3 fatcat:pucqmy2xwjai3nanzm3xgedtgu

Page 2952 of Mathematical Reviews Vol. , Issue 95e [page]

1995 Mathematical Reviews  
On the expressivity of feature logics with negation, functional uncertainty, and sort equations.  ...  We investigate the expressivity of feature terms with negation and the functional uncertainty construct needed for the description of long-distance dependencies and obtain the following results: satisfiability  ... 

A Speculative Parallel DFA Membership Test for Multicore, SIMD and Cloud Computing Environments

Yousun Ko, Minyoung Jung, Yo-Sub Han, Bernd Burgstaller
2013 International journal of parallel programming  
We evaluated our speculative DFA membership test for a representative set of benchmarks from the Perl-compatible Regular Expression (PCRE) library and the PROSITE protein database.  ...  Our method searches arbitrary regular expressions by matching multiple bytes in parallel using speculation.  ...  A standard technique to perform regular expression matching is to convert a regular expression to a DFA and run the DFA on the input text.  ... 
doi:10.1007/s10766-013-0258-5 fatcat:zfcq6pj3pbhincc6ufrspkde7e

On the Semantics of Atomic Subgroups in Practical Regular Expressions [chapter]

Martin Berglund, Brink van der Merwe, Bruce Watson, Nicolaas Weideman
2017 Lecture Notes in Computer Science  
Most regular expression matching engines have operators and features to enhance the succinctness of classical regular expressions, such as interval quantifiers and regular lookahead.  ...  As such it is essential to develop a theoretical sound basis for the matching semantics of regular expressions with atomic operators.  ...  with a regular expression equivalent to the intersection of encountered lookaheads.  ... 
doi:10.1007/978-3-319-60134-2_2 fatcat:ktk6igpvzjhqbiamtsx66pngxe

Pattern matching in compilers [article]

Ondřej Bílka
2012 arXiv   pre-print
Linear time complexity is obtained by introducing the novel notion of structured grammars and regularized regular expressions.  ...  Amethyst is not only a generator of parsers of programming languages, but can also serve as an alternative to tools for matching regular expressions. Our framework also produces dynamic parsers.  ...  Amethyst grammars and expressions The syntax of a regular expression and its equivalent amethyst expression is similar. We embed amethyst expressions with (| e |) syntax.  ... 
arXiv:1210.3593v1 fatcat:ythkapb6drexnhyicdyfvcksuu
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