forked from boostorg/regex
71 lines
3.8 KiB
HTML
71 lines
3.8 KiB
HTML
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<html>
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<head>
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<title>Regular Expression Performance Comparison</title>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">
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<meta name="Template" content="C:\PROGRAM FILES\MICROSOFT OFFICE\OFFICE\html.dot">
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<meta name="GENERATOR" content="Microsoft FrontPage Express 2.0">
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</head>
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<body bgcolor="#ffffff" link="#0000ff" vlink="#800080">
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<h2>Regular Expression Performance Comparison</h2>
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<p>
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The following tables provide comparisons between the following regular
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expression libraries:</p>
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<p><a href="http://research.microsoft.com/projects/greta">GRETA</a>.</p>
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<p><a href="http://www.boost.org/">The Boost regex library</a>.</p>
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<p><a href="http://arglist.com/regex/">Henry Spencer's regular expression library</a>
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- this is provided for comparison as a typical non-backtracking implementation.</p>
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<P>Philip Hazel's <A href="http://www.pcre.org">PCRE</A> library.</P>
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<H3>Details</H3>
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<P>Machine: Intel Pentium 4 2.8GHz PC.</P>
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<P>Compiler: %compiler%.</P>
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<P>C++ Standard Library: %library%.</P>
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<P>OS: %os%.</P>
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<P>Boost version: %boost%.</P>
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<P>PCRE version: %pcre%.</P>
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<P>
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As ever care should be taken in interpreting the results, only sensible regular
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expressions (rather than pathological cases) are given, most are taken from the
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Boost regex examples, or from the <a href="http://www.regxlib.com/">Library of
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Regular Expressions</a>. In addition, some variation in the relative
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performance of these libraries can be expected on other machines - as memory
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access and processor caching effects can be quite large for most finite state
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machine algorithms.</P>
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<H3>Averages</H3>
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<P>The following are the average relative scores for all the tests: the perfect
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regular expression library would score 1, in practice anything less than 2
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is pretty good.</P>
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<P>%averages%</P>
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<h3>Comparison 1: Long Search</h3>
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<p>For each of the following regular expressions the time taken to find all
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occurrences of the expression within a long English language text was measured
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(<a href="ftp://ibiblio.org/pub/docs/books/gutenberg/etext02/mtent12.zip">mtent12.txt</a>
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from <a href="http://promo.net/pg/">Project Gutenberg</a>, 19Mb). </p>
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<P>%long_twain_search%</P>
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<h3>Comparison 2: Medium Sized Search</h3>
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<p>For each of the following regular expressions the time taken to find all
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occurrences of the expression within a medium sized English language text was
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measured (the first 50K from mtent12.txt). </p>
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<P>%short_twain_search%</P>
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<H3>Comparison 3: C++ Code Search</H3>
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<P>For each of the following regular expressions the time taken to find all
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occurrences of the expression within the C++ source file <A href="../../../boost/crc.hpp">
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boost/crc.hpp</A> was measured. </P>
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<P>%code_search%</P>
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<H3>
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<H3>Comparison 4: HTML Document Search</H3>
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</H3>
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<P>For each of the following regular expressions the time taken to find all
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occurrences of the expression within the html file <A href="../../libraries.htm">libs/libraries.htm</A>
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was measured. </P>
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<P>%html_search%</P>
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<H3>Comparison 3: Simple Matches</H3>
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<p>
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For each of the following regular expressions the time taken to match against
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the text indicated was measured. </p>
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<P>%short_matches%</P>
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<hr>
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<p>Copyright John Maddock April 2003, all rights reserved.</p>
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</body>
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</html>
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