| 1 | <html> |
|---|
| 2 | <head> |
|---|
| 3 | <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> |
|---|
| 4 | <title>Chapter 21. Boost.Xpressive</title> |
|---|
| 5 | <link rel="stylesheet" href="boostbook.css" type="text/css"> |
|---|
| 6 | <meta name="generator" content="DocBook XSL Stylesheets V1.68.1"> |
|---|
| 7 | <link rel="start" href="index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> |
|---|
| 8 | <link rel="up" href="libraries.html" title="Part I. The Boost C++ Libraries (BoostBook Subset)"> |
|---|
| 9 | <link rel="prev" href="variant/refs.html" title="References"> |
|---|
| 10 | <link rel="next" href="xpressive/user_s_guide.html" title="User's Guide"> |
|---|
| 11 | </head> |
|---|
| 12 | <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> |
|---|
| 13 | <table cellpadding="2" width="100%"> |
|---|
| 14 | <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../boost.png"></td> |
|---|
| 15 | <td align="center"><a href="../../index.htm">Home</a></td> |
|---|
| 16 | <td align="center"><a href="../../libs/libraries.htm">Libraries</a></td> |
|---|
| 17 | <td align="center"><a href="../../people/people.htm">People</a></td> |
|---|
| 18 | <td align="center"><a href="../../more/faq.htm">FAQ</a></td> |
|---|
| 19 | <td align="center"><a href="../../more/index.htm">More</a></td> |
|---|
| 20 | </table> |
|---|
| 21 | <hr> |
|---|
| 22 | <div class="spirit-nav"> |
|---|
| 23 | <a accesskey="p" href="variant/refs.html"><img src="images/prev.png" alt="Prev"></a><a accesskey="u" href="libraries.html"><img src="images/up.png" alt="Up"></a><a accesskey="h" href="index.html"><img src="images/home.png" alt="Home"></a><a accesskey="n" href="xpressive/user_s_guide.html"><img src="images/next.png" alt="Next"></a> |
|---|
| 24 | </div> |
|---|
| 25 | <div class="chapter" lang="en"> |
|---|
| 26 | <div class="titlepage"><div> |
|---|
| 27 | <div><h2 class="title"> |
|---|
| 28 | <a name="xpressive"></a>Chapter 21. Boost.Xpressive</h2></div> |
|---|
| 29 | <div><div class="author"><h3 class="author"> |
|---|
| 30 | <span class="firstname">Eric</span> <span class="surname">Niebler</span> |
|---|
| 31 | </h3></div></div> |
|---|
| 32 | <div><p class="copyright">Copyright © 2003, 2004 Eric Niebler</p></div> |
|---|
| 33 | <div><div class="legalnotice"> |
|---|
| 34 | <a name="id1953490"></a><p> |
|---|
| 35 | Distributed under the Boost Software License, Version 1.0. (See accompanying |
|---|
| 36 | file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) |
|---|
| 37 | </p> |
|---|
| 38 | </div></div> |
|---|
| 39 | </div></div> |
|---|
| 40 | <div class="toc"> |
|---|
| 41 | <p><b>Table of Contents</b></p> |
|---|
| 42 | <dl> |
|---|
| 43 | <dt><span class="section"><a href="xpressive.html#boost_xpressive.preface">Preface</a></span></dt> |
|---|
| 44 | <dt><span class="section"><a href="xpressive/user_s_guide.html">User's Guide</a></span></dt> |
|---|
| 45 | <dd><dl> |
|---|
| 46 | <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.introduction">Introduction</a></span></dt> |
|---|
| 47 | <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.installing_xpressive">Installing xpressive</a></span></dt> |
|---|
| 48 | <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.quick_start">Quick Start</a></span></dt> |
|---|
| 49 | <dt><span class="section"><a href="xpressive/user_s_guide.html#xpressive.user_s_guide.creating_a_regex_object">Creating a Regex Object</a></span></dt> |
|---|
| 50 | <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.matching_and_searching">Matching and Searching</a></span></dt> |
|---|
| 51 | <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.accessing_results">Accessing Results</a></span></dt> |
|---|
| 52 | <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.string_substitutions">String Substitutions</a></span></dt> |
|---|
| 53 | <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.string_splitting_and_tokenization">String Splitting and Tokenization</a></span></dt> |
|---|
| 54 | <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.grammars_and_nested_matches">Grammars and Nested Matches</a></span></dt> |
|---|
| 55 | <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.localization_and_regex_traits">Localization and Regex Traits</a></span></dt> |
|---|
| 56 | <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.tips_n_tricks"> Tips 'N Tricks</a></span></dt> |
|---|
| 57 | <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.concepts">Concepts</a></span></dt> |
|---|
| 58 | <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.examples">Examples</a></span></dt> |
|---|
| 59 | </dl></dd> |
|---|
| 60 | <dt><span class="section"><a href="xpressive/reference.html">Reference</a></span></dt> |
|---|
| 61 | <dd><dl> |
|---|
| 62 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.basic_regex.hpp">Header <boost/xpressive/basic_regex.hpp></a></span></dt> |
|---|
| 63 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.traits.c_regex_traits.hpp">Header <boost/xpressive/traits/c_regex_traits.hpp></a></span></dt> |
|---|
| 64 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.traits.cpp_regex_traits.hpp">Header <boost/xpressive/traits/cpp_regex_traits.hpp></a></span></dt> |
|---|
| 65 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.match_results.hpp">Header <boost/xpressive/match_results.hpp></a></span></dt> |
|---|
| 66 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.traits.null_regex_traits.hpp">Header <boost/xpressive/traits/null_regex_traits.hpp></a></span></dt> |
|---|
| 67 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_algorithms.hpp">Header <boost/xpressive/regex_algorithms.hpp></a></span></dt> |
|---|
| 68 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_compiler.hpp">Header <boost/xpressive/regex_compiler.hpp></a></span></dt> |
|---|
| 69 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_constants.hpp">Header <boost/xpressive/regex_constants.hpp></a></span></dt> |
|---|
| 70 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_error.hpp">Header <boost/xpressive/regex_error.hpp></a></span></dt> |
|---|
| 71 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_iterator.hpp">Header <boost/xpressive/regex_iterator.hpp></a></span></dt> |
|---|
| 72 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_primitives.hpp">Header <boost/xpressive/regex_primitives.hpp></a></span></dt> |
|---|
| 73 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_token_iterator.hpp">Header <boost/xpressive/regex_token_iterator.hpp></a></span></dt> |
|---|
| 74 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_traits.hpp">Header <boost/xpressive/regex_traits.hpp></a></span></dt> |
|---|
| 75 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.sub_match.hpp">Header <boost/xpressive/sub_match.hpp></a></span></dt> |
|---|
| 76 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.xpressive.hpp">Header <boost/xpressive/xpressive.hpp></a></span></dt> |
|---|
| 77 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.xpressive_dynamic.hpp">Header <boost/xpressive/xpressive_dynamic.hpp></a></span></dt> |
|---|
| 78 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.xpressive_fwd.hpp">Header <boost/xpressive/xpressive_fwd.hpp></a></span></dt> |
|---|
| 79 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.xpressive_static.hpp">Header <boost/xpressive/xpressive_static.hpp></a></span></dt> |
|---|
| 80 | <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.xpressive_typeof.hpp">Header <boost/xpressive/xpressive_typeof.hpp></a></span></dt> |
|---|
| 81 | </dl></dd> |
|---|
| 82 | <dt><span class="section"><a href="boost_xpressive/acknowledgments.html">Acknowledgments</a></span></dt> |
|---|
| 83 | <dt><span class="section"><a href="xpressive/appendices.html">Appendices</a></span></dt> |
|---|
| 84 | <dd><dl> |
|---|
| 85 | <dt><span class="section"><a href="xpressive/appendices.html#boost_xpressive.appendices.appendix_1__not_yet_implemented">Appendix 1: Not Yet Implemented</a></span></dt> |
|---|
| 86 | <dt><span class="section"><a href="xpressive/appendices.html#boost_xpressive.appendices.appendix_2__differences_from_boost_regex">Appendix 2: Differences from Boost.Regex</a></span></dt> |
|---|
| 87 | <dt><span class="section"><a href="xpressive/appendices.html#boost_xpressive.appendices.perf"> Appendix 3: Performance Comparison</a></span></dt> |
|---|
| 88 | </dl></dd> |
|---|
| 89 | </dl> |
|---|
| 90 | </div> |
|---|
| 91 | <div class="section" lang="en"> |
|---|
| 92 | <div class="titlepage"><div><div><h2 class="title" style="clear: both"> |
|---|
| 93 | <a name="boost_xpressive.preface"></a>Preface</h2></div></div></div> |
|---|
| 94 | <div class="blockquote"><blockquote class="blockquote"><p> |
|---|
| 95 | <span class="emphasis"><em>Wife:</em></span> It's a floor wax!<br> <span class="emphasis"><em>Husband:</em></span> |
|---|
| 96 | No, it's a dessert topping!<br> <span class="emphasis"><em>Announcer:</em></span> Stop! You're |
|---|
| 97 | both right. It's a floor wax <span class="emphasis"><em>and</em></span> a dessert topping! |
|---|
| 98 | </p></blockquote></div> |
|---|
| 99 | <div class="blockquote"><blockquote class="blockquote"><p> |
|---|
| 100 | <span class="bold"><strong><span class="emphasis"><em>-- Saturday Night Live</em></span></strong></span> |
|---|
| 101 | </p></blockquote></div> |
|---|
| 102 | <a name="boost_xpressive.preface.description"></a><h2> |
|---|
| 103 | <a name="id1953567"></a> |
|---|
| 104 | Description |
|---|
| 105 | </h2> |
|---|
| 106 | <p> |
|---|
| 107 | xpressive is an advanced, object-oriented regular expression template library |
|---|
| 108 | for C++. Regular expressions can be written as strings that are parsed at run-time, |
|---|
| 109 | or as expression templates that are parsed at compile-time. Regular expressions |
|---|
| 110 | can refer to each other and to themselves recursively, allowing you to build |
|---|
| 111 | arbitrarily complicated grammars out of them. |
|---|
| 112 | </p> |
|---|
| 113 | <a name="boost_xpressive.preface.motivation"></a><h2> |
|---|
| 114 | <a name="id1953590"></a> |
|---|
| 115 | Motivation |
|---|
| 116 | </h2> |
|---|
| 117 | <p> |
|---|
| 118 | If you need to manipulate text in C++, you have typically had two disjoint |
|---|
| 119 | options: a regular expression engine or a parser generator. Regular expression |
|---|
| 120 | engines (like <a href="../../libs/regex" target="_top">Boost.Regex</a>) are powerful |
|---|
| 121 | and flexible; patterns are represented as strings which can be specified at |
|---|
| 122 | runtime. However, that means that syntax errors are likewise not detected until |
|---|
| 123 | runtime. Also, regular expressions are ill-suited to advanced text processing |
|---|
| 124 | tasks such as matching balanced, nested tags. Those tasks have traditionally |
|---|
| 125 | been handled by parser generators (like the <a href="http://spirit.sourceforge.net" target="_top">Spirit |
|---|
| 126 | Parser Framework</a>). These beasts are more powerful but less flexible. |
|---|
| 127 | They generally don't allow you to arbitrarily modify your grammar rules on |
|---|
| 128 | the fly. In addition, they don't have the exhaustive backtracking semantics |
|---|
| 129 | of regular expressions, which can make it more challenging to author some types |
|---|
| 130 | of patterns. |
|---|
| 131 | </p> |
|---|
| 132 | <p> |
|---|
| 133 | xpressive brings these two approaches seamlessly together and occupies a unique |
|---|
| 134 | niche in the world of C++ text processing. With xpressive, you can choose to |
|---|
| 135 | use it much as you would use <a href="../../libs/regex" target="_top">Boost.Regex</a>, |
|---|
| 136 | representing regular expressions as strings. Or you can use it as you would |
|---|
| 137 | use <a href="http://spirit.sourceforge.net" target="_top">Spirit</a>, writing your |
|---|
| 138 | regexes as C++ expressions, enjoying all the benefits of an embedded language |
|---|
| 139 | dedicated to text manipulation. What's more, you can mix the two to get the |
|---|
| 140 | benefits of both, writing regular expression <span class="emphasis"><em>grammars</em></span> |
|---|
| 141 | in which some of the regular expressions are statically bound -- hard-coded |
|---|
| 142 | and syntax-checked by the compiler -- and others are dynamically bound and |
|---|
| 143 | specified at runtime. These regular expressions can refer to each other recursively, |
|---|
| 144 | matching patterns in strings that ordinary regular expressions cannot. |
|---|
| 145 | </p> |
|---|
| 146 | <a name="boost_xpressive.preface.influences_and_related_work"></a><h2> |
|---|
| 147 | <a name="id1953666"></a> |
|---|
| 148 | Influences and Related Work |
|---|
| 149 | </h2> |
|---|
| 150 | <p> |
|---|
| 151 | The design of xpressive's interface has been strongly influenced by John Maddock's |
|---|
| 152 | <a href="../../libs/regex" target="_top">Boost.Regex</a> library and his <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2003/n1429.htm" target="_top">proposal</a> |
|---|
| 153 | to add regular expressions to the Standard Library. I also drew a great deal |
|---|
| 154 | of inspiration from Joel de Guzman's <a href="http://spirit.sourceforge.net" target="_top">Spirit |
|---|
| 155 | Parser Framework</a>, which served as the model for static xpressive. Other |
|---|
| 156 | sources of inspiration are the <a href="http://www.perl.com/pub/a/2002/06/04/apo5.html" target="_top">Perl |
|---|
| 157 | 6</a> redesign and <a href="http://research.microsoft.com/projects/greta" target="_top">GRETA</a>. |
|---|
| 158 | (You can read a summary of the changes Perl 6 will bring to regex culture |
|---|
| 159 | <a href="http://dev.perl.org/perl6/doc/design/syn/S05.html" target="_top">here</a>.) |
|---|
| 160 | </p> |
|---|
| 161 | </div> |
|---|
| 162 | </div> |
|---|
| 163 | <table width="100%"><tr> |
|---|
| 164 | <td align="left"><small><p>Last revised: July 16, 2007 at 17:52:22 GMT</p></small></td> |
|---|
| 165 | <td align="right"><small></small></td> |
|---|
| 166 | </tr></table> |
|---|
| 167 | <hr> |
|---|
| 168 | <div class="spirit-nav"> |
|---|
| 169 | <a accesskey="p" href="variant/refs.html"><img src="images/prev.png" alt="Prev"></a><a accesskey="u" href="libraries.html"><img src="images/up.png" alt="Up"></a><a accesskey="h" href="index.html"><img src="images/home.png" alt="Home"></a><a accesskey="n" href="xpressive/user_s_guide.html"><img src="images/next.png" alt="Next"></a> |
|---|
| 170 | </div> |
|---|
| 171 | </body> |
|---|
| 172 | </html> |
|---|
