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copied!<p>I am the author of LRSTAR, an open-source LR(k) parser generator. Because people are showing interest in it, I have put the product back online at <a href="http://lrstar.org" rel="nofollow noreferrer"><strong>LRSTAR.ORG</strong></a>. </p> <p>I have studied the speed of LALR parsers and DFA lexers for many years. Tom Pennello's paper is very interesting, but is more of an academic exercise than a real-world solution for compilers. However, if all you want is a pattern recognizer, then it may be the perfect solution for you. </p> <p>The problem is that real-world compilers usually need to do more than pattern recognition, such as symbol-table look-up for incoming symbols, error recovery, provide an expecting list (statement completion information), and build an abstract-syntax tree while parsing. </p> <p>In 1989, I compared the parsing speed of LRSTAR parsers to "yacc" and found that they are 2 times the speed of "yacc" parsers. LRSTAR parsers use the ideas published in the paper: "Optimization of Parser Tables for Portable Compilers".</p> <p>For lexer (lexical analysis) speed I discovered in 2009 that "re2c" was generating the fastest lexers, about twice the speed of those generated by "flex". I was rewriting the LRSTAR lexer generator section at that time and found a way to make lexers that are almost as fast as "re2c" and much smaller. However, I prefer the table-driven lexers that LRSTAR generates, because they are almost as fast and the code compiles much quicker. </p> <p>BTW, compiler front-ends generated by LRSTAR can process source code at a speed of 2,400,000 lines per second or faster. The lexers generated by LRSTAR can process 30,000,000 tokens per second. The testing computer was a 3.5 GHz machine (from 2010). </p>

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