author | Christian Urban <urbanc@in.tum.de> |
Tue, 18 Jul 2017 18:39:20 +0100 | |
changeset 265 | d36be1e356c0 |
parent 218 | 16af5b8bd285 |
child 267 | 32b222d77fa0 |
permissions | -rwxr-xr-x |
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\documentclass[runningheads]{llncs} |
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\usepackage{times} |
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\usepackage{isabelle} |
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\usepackage{isabellesym} |
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\usepackage{amsmath} |
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\usepackage{amssymb} |
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\usepackage{mathpartir} |
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\usepackage{tikz} |
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\usepackage{pgf} |
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\usetikzlibrary{positioning} |
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\usepackage{pdfsetup} |
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%%\usepackage{stmaryrd} |
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\usepackage{url} |
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\usepackage{color} |
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\titlerunning{POSIX Lexing with Derivatives of Regular Expressions} |
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\urlstyle{rm} |
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\isabellestyle{it} |
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\renewcommand{\isastyleminor}{\it}% |
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\renewcommand{\isastyle}{\normalsize\it}% |
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\def\dn{\,\stackrel{\mbox{\scriptsize def}}{=}\,} |
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\renewcommand{\isasymequiv}{$\dn$} |
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\renewcommand{\isasymemptyset}{$\varnothing$} |
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\renewcommand{\isacharunderscore}{\mbox{$\_\!\_$}} |
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\renewcommand{\isasymiota}{\makebox[0mm]{${}^{\prime}$}} |
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\def\Brz{Brzozowski} |
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\def\der{\backslash} |
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\newtheorem{falsehood}{Falsehood} |
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\newtheorem{conject}{Conjecture} |
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\begin{document} |
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\renewcommand{\thefootnote}{$\star$} \footnotetext[1]{This paper is a |
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revised and expanded version of \cite{AusafDyckhoffUrban2016}. |
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Compared with that paper we give a second definition for POSIX |
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values and prove that it is equivalent to the original one. This |
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definition is based on an ordering of values and very similar to the |
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definition given by Sulzmann and Lu~\cite{Sulzmann2014}. We also |
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extend our results to additional constructors of regular |
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expressions.} \renewcommand{\thefootnote}{\arabic{footnote}} |
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\title{POSIX {L}exing with {D}erivatives of {R}egular {E}xpressions} |
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\author{Fahad Ausaf\inst{1} \and Roy Dyckhoff\inst{2} \and Christian Urban\inst{3}} |
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\institute{King's College London\\ |
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\email{fahad.ausaf@icloud.com} |
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\and University of St Andrews\\ |
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\email{roy.dyckhoff@st-andrews.ac.uk} |
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\and King's College London\\ |
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\email{christian.urban@kcl.ac.uk}} |
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\maketitle |
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\begin{abstract} |
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Brzozowski introduced the notion of derivatives for regular |
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expressions. They can be used for a very simple regular expression |
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matching algorithm. Sulzmann and Lu cleverly extended this algorithm |
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in order to deal with POSIX matching, which is the underlying |
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disambiguation strategy for regular expressions needed in lexers. In |
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the first part of this paper we give our inductive definition of what |
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a POSIX value is and show $(i)$ that such a value is unique (for given |
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regular expression and string being matched) and $(ii)$ that Sulzmann |
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and Lu's algorithm always generates such a value (provided that the |
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regular expression matches the string). We also prove the correctness |
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of an optimised version of the POSIX matching algorithm. In the |
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second part we show that $(iii)$ our inductive definition of a POSIX |
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value is equivalent to an alternative definition by Okui and Suzuki |
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which identifies a POSIX value as least element according to an |
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ordering of values. The advantage of the definition based on the |
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ordering is that it implements more directly the POSIX |
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longest-leftmost matching semantics.\smallskip |
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{\bf Keywords:} POSIX matching, Derivatives of Regular Expressions, |
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Isabelle/HOL |
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\end{abstract} |
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\input{session} |
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\end{document} |
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