forked from boostorg/regex
60 lines
3.3 KiB
HTML
60 lines
3.3 KiB
HTML
<html>
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<title>Regular Expression Performance Comparison</title>
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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>The Boost and GRETA regular expression libraries have slightly different
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interfaces, and it has been suggested that GRETA's interface allows for a more
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efficient implementation. The following tables provide comparisons between:</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>
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Times were obtained on a 2.8GHz Pentium 4 PC running Windows XP, and the
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code was compiled with Visual C++ 7.1 with all optimisations turned on. As ever
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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>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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