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| <div class="chapter"> |
| <div class="titlepage"><div> |
| <div><h2 class="title"> |
| <a name="xpressive"></a>Chapter 29. Boost.Xpressive</h2></div> |
| <div><div class="author"><h3 class="author"> |
| <span class="firstname">Eric</span> <span class="surname">Niebler</span> |
| </h3></div></div> |
| <div><p class="copyright">Copyright © 2007 Eric Niebler</p></div> |
| <div><div class="legalnotice"> |
| <a name="id3091056"></a><p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| 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>) |
| </p> |
| </div></div> |
| </div></div> |
| <div class="toc"> |
| <p><b>Table of Contents</b></p> |
| <dl> |
| <dt><span class="section"><a href="xpressive.html#boost_xpressive.preface">Preface</a></span></dt> |
| <dt><span class="section"><a href="xpressive/user_s_guide.html">User's Guide</a></span></dt> |
| <dd><dl> |
| <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.introduction">Introduction</a></span></dt> |
| <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.installing_xpressive">Installing |
| xpressive</a></span></dt> |
| <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.quick_start">Quick Start</a></span></dt> |
| <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> |
| <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> |
| <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.accessing_results">Accessing |
| Results</a></span></dt> |
| <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.string_substitutions">String |
| Substitutions</a></span></dt> |
| <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> |
| <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.named_captures">Named Captures</a></span></dt> |
| <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> |
| <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.semantic_actions_and_user_defined_assertions">Semantic |
| Actions and User-Defined Assertions</a></span></dt> |
| <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.symbol_tables_and_attributes">Symbol |
| Tables and Attributes</a></span></dt> |
| <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> |
| <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> |
| <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.concepts">Concepts</a></span></dt> |
| <dt><span class="section"><a href="xpressive/user_s_guide.html#boost_xpressive.user_s_guide.examples">Examples</a></span></dt> |
| </dl></dd> |
| <dt><span class="section"><a href="xpressive/reference.html">Reference</a></span></dt> |
| <dd><dl> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.basic_regex_hpp">Header <boost/xpressive/basic_regex.hpp></a></span></dt> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.match_results_hpp">Header <boost/xpressive/match_results.hpp></a></span></dt> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_actions_hpp">Header <boost/xpressive/regex_actions.hpp></a></span></dt> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_algorithms_hpp">Header <boost/xpressive/regex_algorithms.hpp></a></span></dt> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_compiler_hpp">Header <boost/xpressive/regex_compiler.hpp></a></span></dt> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_constants_hpp">Header <boost/xpressive/regex_constants.hpp></a></span></dt> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_error_hpp">Header <boost/xpressive/regex_error.hpp></a></span></dt> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_iterator_hpp">Header <boost/xpressive/regex_iterator.hpp></a></span></dt> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_primitives_hpp">Header <boost/xpressive/regex_primitives.hpp></a></span></dt> |
| <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> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.regex_traits_hpp">Header <boost/xpressive/regex_traits.hpp></a></span></dt> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.sub_match_hpp">Header <boost/xpressive/sub_match.hpp></a></span></dt> |
| <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> |
| <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> |
| <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> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.xpressive_hpp">Header <boost/xpressive/xpressive.hpp></a></span></dt> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.xpressive_dynamic_hpp">Header <boost/xpressive/xpressive_dynamic.hpp></a></span></dt> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.xpressive_fwd_hpp">Header <boost/xpressive/xpressive_fwd.hpp></a></span></dt> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.xpressive_static_hpp">Header <boost/xpressive/xpressive_static.hpp></a></span></dt> |
| <dt><span class="section"><a href="xpressive/reference.html#header.boost.xpressive.xpressive_typeof_hpp">Header <boost/xpressive/xpressive_typeof.hpp></a></span></dt> |
| </dl></dd> |
| <dt><span class="section"><a href="boost_xpressive/acknowledgments.html">Acknowledgments</a></span></dt> |
| <dt><span class="section"><a href="xpressive/appendices.html">Appendices</a></span></dt> |
| <dd><dl> |
| <dt><span class="section"><a href="xpressive/appendices.html#boost_xpressive.appendices.appendix_1__history">Appendix |
| 1: History</a></span></dt> |
| <dt><span class="section"><a href="xpressive/appendices.html#boost_xpressive.appendices.appendix_2__not_yet_implemented">Appendix |
| 2: Not Yet Implemented</a></span></dt> |
| <dt><span class="section"><a href="xpressive/appendices.html#boost_xpressive.appendices.appendix_3__differences_from_boost_regex">Appendix |
| 3: Differences from Boost.Regex</a></span></dt> |
| <dt><span class="section"><a href="xpressive/appendices.html#boost_xpressive.appendices.perf">Appendix 4: Performance |
| Comparison</a></span></dt> |
| <dt><span class="section"><a href="xpressive/appendices.html#xpressive.appendices.appendix_5__implementation_notes">Appendix |
| 5: Implementation Notes</a></span></dt> |
| </dl></dd> |
| </dl> |
| </div> |
| <div class="section"> |
| <div class="titlepage"><div><div><h2 class="title" style="clear: both"> |
| <a name="boost_xpressive.preface"></a><a class="link" href="xpressive.html#boost_xpressive.preface" title="Preface">Preface</a> |
| </h2></div></div></div> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| <span class="emphasis"><em>Wife:</em></span> New Shimmer is a floor wax!<br> <span class="emphasis"><em>Husband:</em></span> |
| No, new Shimmer is a dessert topping!<br> <span class="emphasis"><em>Wife:</em></span> It's |
| a floor wax!<br> <span class="emphasis"><em>Husband:</em></span> It's a dessert topping!<br> |
| <span class="emphasis"><em>Wife:</em></span> It's a floor wax, I'm telling you!<br> <span class="emphasis"><em>Husband:</em></span> |
| It's a dessert topping, you cow!<br> <span class="emphasis"><em>Announcer:</em></span> Hey, |
| hey, hey, calm down, you two. New Shimmer is both a floor wax <span class="emphasis"><em>and</em></span> |
| a dessert topping! |
| </p></blockquote></div> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| <span class="bold"><strong><span class="emphasis"><em>-- Saturday Night Live</em></span></strong></span> |
| </p></blockquote></div> |
| <a name="boost_xpressive.preface.description"></a><h3> |
| <a name="id3091165"></a> |
| <a class="link" href="xpressive.html#boost_xpressive.preface.description">Description</a> |
| </h3> |
| <p> |
| xpressive is an advanced, object-oriented regular expression template library |
| for C++. Regular expressions can be written as strings that are parsed at run-time, |
| or as expression templates that are parsed at compile-time. Regular expressions |
| can refer to each other and to themselves recursively, allowing you to build |
| arbitrarily complicated grammars out of them. |
| </p> |
| <a name="boost_xpressive.preface.motivation"></a><h3> |
| <a name="id3091196"></a> |
| <a class="link" href="xpressive.html#boost_xpressive.preface.motivation">Motivation</a> |
| </h3> |
| <p> |
| If you need to manipulate text in C++, you have typically had two disjoint |
| options: a regular expression engine or a parser generator. Regular expression |
| engines (like <a href="../../libs/regex" target="_top">Boost.Regex</a>) are powerful |
| and flexible; patterns are represented as strings which can be specified at |
| runtime. However, that means that syntax errors are likewise not detected until |
| runtime. Also, regular expressions are ill-suited to advanced text processing |
| tasks such as matching balanced, nested tags. Those tasks have traditionally |
| been handled by parser generators (like the <a href="http://spirit.sourceforge.net" target="_top">Spirit |
| Parser Framework</a>). These beasts are more powerful but less flexible. |
| They generally don't allow you to arbitrarily modify your grammar rules on |
| the fly. In addition, they don't have the exhaustive backtracking semantics |
| of regular expressions, which can make it more challenging to author some types |
| of patterns. |
| </p> |
| <p> |
| xpressive brings these two approaches seamlessly together and occupies a unique |
| niche in the world of C++ text processing. With xpressive, you can choose to |
| use it much as you would use <a href="../../libs/regex" target="_top">Boost.Regex</a>, |
| representing regular expressions as strings. Or you can use it as you would |
| use <a href="http://spirit.sourceforge.net" target="_top">Spirit</a>, writing your |
| regexes as C++ expressions, enjoying all the benefits of an embedded language |
| dedicated to text manipulation. What's more, you can mix the two to get the |
| benefits of both, writing regular expression <span class="emphasis"><em>grammars</em></span> |
| in which some of the regular expressions are statically bound -- hard-coded |
| and syntax-checked by the compiler -- and others are dynamically bound and |
| specified at runtime. These regular expressions can refer to each other recursively, |
| matching patterns in strings that ordinary regular expressions cannot. |
| </p> |
| <a name="boost_xpressive.preface.influences_and_related_work"></a><h3> |
| <a name="id3091280"></a> |
| <a class="link" href="xpressive.html#boost_xpressive.preface.influences_and_related_work">Influences |
| and Related Work</a> |
| </h3> |
| <p> |
| The design of xpressive's interface has been strongly influenced by John Maddock's |
| <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> |
| to add regular expressions to the Standard Library. I also drew a great deal |
| of inspiration from Joel de Guzman's <a href="http://spirit.sourceforge.net" target="_top">Spirit |
| Parser Framework</a>, which served as the model for static xpressive. Other |
| sources of inspiration are the <a href="http://www.perl.com/pub/a/2002/06/04/apo5.html" target="_top">Perl |
| 6</a> redesign and <a href="http://research.microsoft.com/projects/greta" target="_top">GRETA</a>. |
| (You can read a summary of the changes Perl 6 will bring to regex culture |
| <a href="http://dev.perl.org/perl6/doc/design/syn/S05.html" target="_top">here</a>.) |
| </p> |
| </div> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"><p><small>Last revised: November 10, 2010 at 00:46:01 GMT</small></p></td> |
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