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| <div class="section"> |
| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="spirit.notes.porting_from_spirit_1_8_x"></a><a class="link" href="porting_from_spirit_1_8_x.html" title="Porting from Spirit 1.8.x">Porting from |
| Spirit 1.8.x</a> |
| </h3></div></div></div> |
| <p> |
| The current version of <a href="http://boost-spirit.com" target="_top">Spirit</a> |
| is a complete rewrite of earlier versions (we refer to earlier versions as |
| <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a>). |
| The parser generators are now only one part of the whole library. The parser |
| submodule of <a href="http://boost-spirit.com" target="_top">Spirit</a> is now called |
| <span class="emphasis"><em>Spirit.Qi</em></span>. It is conceptually different and exposes |
| a completely different interface. Generally, there is no easy (or automated) |
| way of converting parsers written for <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a> |
| to <span class="emphasis"><em>Spirit.Qi</em></span>. Therefore this section can give only guidelines |
| on how to approach porting your older parsers to the current version of |
| <a href="http://boost-spirit.com" target="_top">Spirit</a>. |
| </p> |
| <a name="spirit.notes.porting_from_spirit_1_8_x.include_files"></a><h5> |
| <a name="id1212604"></a> |
| <a class="link" href="porting_from_spirit_1_8_x.html#spirit.notes.porting_from_spirit_1_8_x.include_files">Include |
| Files</a> |
| </h5> |
| <p> |
| The overall directory structure of the <a href="http://boost-spirit.com" target="_top">Spirit</a> |
| directories is described in the section <a class="link" href="../structure/include.html" title="Include">Include |
| Structure</a> and the FAQ entry <a class="link" href="../faq.html#spirit.faq.i_m_very_confused_about_the_header_hell_in_my_boost_spirit_directory__what_s_all_this_about_">Header |
| Hell</a>. This should give you a good overview on how to find the needed |
| header files for your new parsers. Moreover, each section in the <a class="link" href="../qi/reference.html" title="Reference">Qi |
| Reference</a> lists the required include files needed for any particular |
| component. |
| </p> |
| <p> |
| It is possible to tell from the name of a header file, what version it belongs |
| to. While all main include files for <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a> |
| have the string 'classic_' in their name, for instance: |
| </p> |
| <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">classic_core</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| </pre> |
| <p> |
| we named all main include files for <span class="emphasis"><em>Spirit.Qi</em></span> to have |
| the string 'qi_' as part of their name, for instance: |
| </p> |
| <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">qi_core</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| </pre> |
| <p> |
| The following table gives a rough list of corresponding header file between |
| <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a> |
| and <span class="emphasis"><em>Spirit.Qi</em></span>, but this can be used as a starting point |
| only, as several components have either been moved to different submodules |
| or might not exist in the never version anymore. We list only include files |
| for the topmost submodules. For header files required for more lower level |
| components please refer to the corresponding reference documentation of this |
| component. |
| </p> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Include file in <span class="emphasis"><em>Spirit.Classic</em></span> |
| </p> |
| </th> |
| <th> |
| <p> |
| Include file in <span class="emphasis"><em>Spirit.Qi</em></span> |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">classic</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">qi</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">classic_actor</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| none, use <a href="../../../../phoenix/doc/html/index.html" target="_top">Boost.Phoenix</a> |
| for writing semantic actions |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">classic_attribute</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| none, use local variables for rules instead of closures, the primitives |
| parsers now directly support lazy parameterization |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">classic_core</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">qi_core</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">classic_debug</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">qi_debug</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">classic_dynamic</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| none, use <span class="emphasis"><em>Spirit.Qi</em></span> predicates instead of |
| if_p, while_p, for_p (included by <code class="computeroutput"><span class="identifier">qi_core</span><span class="special">.</span><span class="identifier">hpp</span></code>), |
| the equivalent for lazy_p is now included by <code class="computeroutput"><span class="identifier">qi_auxiliary</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">classic_error_handling</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| none, included in <code class="computeroutput"><span class="identifier">qi_core</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">classic_meta</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| none |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">classic_symbols</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| none, included in <code class="computeroutput"><span class="identifier">qi_core</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">classic_utility</span><span class="special">.</span><span class="identifier">hpp</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| none, not part of <span class="emphasis"><em>Spirit.Qi</em></span> anymore, these |
| components will be added over time to the <a href="../../../../repository/doc/html/index.html" target="_top">Repository</a> |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <a name="spirit.notes.porting_from_spirit_1_8_x.the_free_parse_functions"></a><h5> |
| <a name="id1213254"></a> |
| <a class="link" href="porting_from_spirit_1_8_x.html#spirit.notes.porting_from_spirit_1_8_x.the_free_parse_functions">The |
| Free Parse Functions</a> |
| </h5> |
| <p> |
| The free parse functions (i.e. the main parser API) has been changed. This |
| includes the names of the free functions as well as their interface. In |
| <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a> |
| all free functions were named <code class="computeroutput"><span class="identifier">parse</span></code>. |
| In <span class="emphasis"><em>Spirit.Qi</em></span> they are are named either <code class="computeroutput"><span class="identifier">qi</span><span class="special">::</span><span class="identifier">parse</span></code> |
| or <code class="computeroutput"><span class="identifier">qi</span><span class="special">::</span><span class="identifier">phrase_parse</span></code> depending on whether the parsing |
| should be done using a skipper (<code class="computeroutput"><span class="identifier">qi</span><span class="special">::</span><span class="identifier">phrase_parse</span></code>) |
| or not (<code class="computeroutput"><span class="identifier">qi</span><span class="special">::</span><span class="identifier">parse</span></code>). All free functions now return a |
| simple <code class="computeroutput"><span class="keyword">bool</span></code>. A returned <code class="computeroutput"><span class="keyword">true</span></code> means success (i.e. the parser has matched) |
| or <code class="computeroutput"><span class="keyword">false</span></code> (i.e. the parser didn't |
| match). This is equivalent to the former old <code class="computeroutput"><span class="identifier">parse_info</span></code> |
| member <code class="computeroutput"><span class="identifier">hit</span></code>. <span class="emphasis"><em>Spirit.Qi</em></span> |
| doesn't support tracking of the matched input length anymore. The old <code class="computeroutput"><span class="identifier">parse_info</span></code> member <code class="computeroutput"><span class="identifier">full</span></code> |
| can be emulated by comparing the iterators after <code class="computeroutput"><span class="identifier">qi</span><span class="special">::</span><span class="identifier">parse</span></code> |
| returned. |
| </p> |
| <p> |
| All code examples in this section assume the following include statements |
| and using directives to be inserted. For <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a>: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">classic</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">phoenix1</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">string</span><span class="special">></span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">classic</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| and for <span class="emphasis"><em>Spirit.Qi</em></span>: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">qi</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">phoenix_operator</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">string</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">algorithm</span><span class="special">></span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| The following similar examples should clarify the differences. First the |
| base example in <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a>: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">input</span><span class="special">(</span><span class="string">"1,1"</span><span class="special">);</span> |
| <span class="identifier">parse_info</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">::</span><span class="identifier">iterator</span><span class="special">></span> <span class="identifier">pi</span> <span class="special">=</span> <span class="identifier">parse</span><span class="special">(</span><span class="identifier">input</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span> <span class="identifier">int_p</span><span class="special">);</span> |
| |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">pi</span><span class="special">.</span><span class="identifier">hit</span><span class="special">)</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"successful match!\n"</span><span class="special">;</span> |
| |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">pi</span><span class="special">.</span><span class="identifier">full</span><span class="special">)</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"full match!\n"</span><span class="special">;</span> |
| <span class="keyword">else</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"stopped at: "</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">(</span><span class="identifier">pi</span><span class="special">.</span><span class="identifier">stop</span><span class="special">,</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">end</span><span class="special">())</span> <span class="special"><<</span> <span class="string">"\n"</span><span class="special">;</span> |
| |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"matched length: "</span> <span class="special"><<</span> <span class="identifier">pi</span><span class="special">.</span><span class="identifier">length</span> <span class="special"><<</span> <span class="string">"\n"</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| And here is the equivalent piece of code using <span class="emphasis"><em>Spirit.Qi</em></span>: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">input</span><span class="special">(</span><span class="string">"1,1"</span><span class="special">);</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">it</span> <span class="special">=</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">begin</span><span class="special">();</span> |
| <span class="keyword">bool</span> <span class="identifier">result</span> <span class="special">=</span> <span class="identifier">qi</span><span class="special">::</span><span class="identifier">parse</span><span class="special">(</span><span class="identifier">it</span><span class="special">,</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span> <span class="identifier">qi</span><span class="special">::</span><span class="identifier">int_</span><span class="special">);</span> |
| |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">result</span><span class="special">)</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"successful match!\n"</span><span class="special">;</span> |
| |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">it</span> <span class="special">==</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">end</span><span class="special">())</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"full match!\n"</span><span class="special">;</span> |
| <span class="keyword">else</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"stopped at: "</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">(</span><span class="identifier">it</span><span class="special">,</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">end</span><span class="special">())</span> <span class="special"><<</span> <span class="string">"\n"</span><span class="special">;</span> |
| |
| <span class="comment">// seldomly needed: use std::distance to calculate the length of the match |
| </span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"matched length: "</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">distance</span><span class="special">(</span><span class="identifier">input</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">it</span><span class="special">)</span> <span class="special"><<</span> <span class="string">"\n"</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| The changes required for phrase parsing (i.e. parsing using a skipper) are |
| similar. Here is how phrase parsing works in <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a>: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">input</span><span class="special">(</span><span class="string">" 1, 1"</span><span class="special">);</span> |
| <span class="identifier">parse_info</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">::</span><span class="identifier">iterator</span><span class="special">></span> <span class="identifier">pi</span> <span class="special">=</span> <span class="identifier">parse</span><span class="special">(</span><span class="identifier">input</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span> <span class="identifier">int_p</span><span class="special">,</span> <span class="identifier">space_p</span><span class="special">);</span> |
| |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">pi</span><span class="special">.</span><span class="identifier">hit</span><span class="special">)</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"successful match!\n"</span><span class="special">;</span> |
| |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">pi</span><span class="special">.</span><span class="identifier">full</span><span class="special">)</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"full match!\n"</span><span class="special">;</span> |
| <span class="keyword">else</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"stopped at: "</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">(</span><span class="identifier">pi</span><span class="special">.</span><span class="identifier">stop</span><span class="special">,</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">end</span><span class="special">())</span> <span class="special"><<</span> <span class="string">"\n"</span><span class="special">;</span> |
| |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"matched length: "</span> <span class="special"><<</span> <span class="identifier">pi</span><span class="special">.</span><span class="identifier">length</span> <span class="special"><<</span> <span class="string">"\n"</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| And here the equivalent example in <span class="emphasis"><em>Spirit.Qi</em></span>: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">input</span><span class="special">(</span><span class="string">" 1, 1"</span><span class="special">);</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">it</span> <span class="special">=</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">begin</span><span class="special">();</span> |
| <span class="keyword">bool</span> <span class="identifier">result</span> <span class="special">=</span> <span class="identifier">qi</span><span class="special">::</span><span class="identifier">phrase_parse</span><span class="special">(</span><span class="identifier">it</span><span class="special">,</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span> <span class="identifier">qi</span><span class="special">::</span><span class="identifier">int_</span><span class="special">,</span> <span class="identifier">ascii</span><span class="special">::</span><span class="identifier">space</span><span class="special">);</span> |
| |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">result</span><span class="special">)</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"successful match!\n"</span><span class="special">;</span> |
| |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">it</span> <span class="special">==</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">end</span><span class="special">())</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"full match!\n"</span><span class="special">;</span> |
| <span class="keyword">else</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"stopped at: "</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">(</span><span class="identifier">it</span><span class="special">,</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">end</span><span class="special">())</span> <span class="special"><<</span> <span class="string">"\n"</span><span class="special">;</span> |
| |
| <span class="comment">// seldomly needed: use std::distance to calculate the length of the match |
| </span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"matched length: "</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">distance</span><span class="special">(</span><span class="identifier">input</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">it</span><span class="special">)</span> <span class="special"><<</span> <span class="string">"\n"</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| Note, how character parsers are in a separate namespace (here <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">ascii</span><span class="special">::</span><span class="identifier">space</span></code>) as <span class="emphasis"><em>Spirit.Qi</em></span> |
| now supports working with different character sets. See the section <a class="link" href="../qi/reference/basics.html#spirit.qi.reference.basics.character_encoding_namespace">Character |
| Encoding Namespace</a> for more information. |
| </p> |
| <a name="spirit.notes.porting_from_spirit_1_8_x.naming_conventions"></a><h5> |
| <a name="id1218413"></a> |
| <a class="link" href="porting_from_spirit_1_8_x.html#spirit.notes.porting_from_spirit_1_8_x.naming_conventions">Naming |
| Conventions</a> |
| </h5> |
| <p> |
| In <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a> |
| all parser primitives have suffixes appended to their names, encoding their |
| type: <code class="computeroutput"><span class="string">"_p"</span></code> for parsers, |
| <code class="computeroutput"><span class="string">"_a"</span></code> for lazy actions, |
| <code class="computeroutput"><span class="string">"_d"</span></code> for directives, |
| etc. In <span class="emphasis"><em>Spirit.Qi</em></span> we don't have anything similar. The |
| only suffixes are single underscore letters <code class="computeroutput"><span class="string">"_"</span></code> |
| applied where the name would otherwise conflict with a keyword or predefined |
| name (such as <code class="computeroutput"><span class="identifier">int_</span></code> for the |
| integer parser). Overall, most, if not all primitive parsers and directives |
| have been renamed. Please see the <a class="link" href="../qi/quick_reference.html" title="Quick Reference">Qi |
| Quick Reference</a> for an overview on the names for the different available |
| parser primitives, directives and operators. |
| </p> |
| <a name="spirit.notes.porting_from_spirit_1_8_x.parser_attributes"></a><h5> |
| <a name="id1218485"></a> |
| <a class="link" href="porting_from_spirit_1_8_x.html#spirit.notes.porting_from_spirit_1_8_x.parser_attributes">Parser |
| Attributes</a> |
| </h5> |
| <p> |
| In <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a> |
| most of the parser primitives don't expose a specific attribute type. Most |
| parsers expose the pair of iterators pointing to the matched input sequence. |
| As in <span class="emphasis"><em>Spirit.Qi</em></span> all parsers expose a parser specific |
| attribute type it introduces a special directive <a class="link" href="../qi/reference/directive/raw.html" title="Transduction Parsing (raw[])"><code class="computeroutput"><span class="identifier">raw</span></code></a><code class="computeroutput"><span class="special">[]</span></code> |
| allowing to achieve a similar effect as in <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a>. |
| The <a class="link" href="../qi/reference/directive/raw.html" title="Transduction Parsing (raw[])"><code class="computeroutput"><span class="identifier">raw</span></code></a><code class="computeroutput"><span class="special">[]</span></code> directive exposes the pair of iterators |
| pointing to the matching sequence of its embedded parser. Even if we very |
| much encourage you to rewrite your parsers to take advantage of the generated |
| parser specific attributes, sometimes it is helpful to get access to the |
| underlying matched input sequence. |
| </p> |
| <a name="spirit.notes.porting_from_spirit_1_8_x.grammars_and_rules"></a><h5> |
| <a name="id1218554"></a> |
| <a class="link" href="porting_from_spirit_1_8_x.html#spirit.notes.porting_from_spirit_1_8_x.grammars_and_rules">Grammars |
| and Rules</a> |
| </h5> |
| <p> |
| The <code class="computeroutput"><span class="identifier">grammar</span><span class="special"><></span></code> |
| and <code class="computeroutput"><span class="identifier">rule</span><span class="special"><></span></code> |
| types are of equal importance to <span class="emphasis"><em>Spirit.Qi</em></span> as they are |
| for <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a>. |
| Their main purpose is still the same: they allow to define non-terminals |
| and they are the main building blocks for more complex parsers. Nevertheless, |
| both types have been redesigned and their interfaces have changed. Let's |
| have a look at two examples first, we'll explain the differences afterwards. |
| Here is a simple grammar and its usage in <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a>: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">roman</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">grammar</span><span class="special"><</span><span class="identifier">roman</span><span class="special">></span> |
| <span class="special">{</span> |
| <span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">ScannerT</span><span class="special">></span> |
| <span class="keyword">struct</span> <span class="identifier">definition</span> |
| <span class="special">{</span> |
| <span class="identifier">definition</span><span class="special">(</span><span class="identifier">roman</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">self</span><span class="special">)</span> |
| <span class="special">{</span> |
| <span class="identifier">hundreds</span><span class="special">.</span><span class="identifier">add</span> |
| <span class="special">(</span><span class="string">"C"</span> <span class="special">,</span> <span class="number">100</span><span class="special">)(</span><span class="string">"CC"</span> <span class="special">,</span> <span class="number">200</span><span class="special">)(</span><span class="string">"CCC"</span> <span class="special">,</span> <span class="number">300</span><span class="special">)(</span><span class="string">"CD"</span> <span class="special">,</span> <span class="number">400</span><span class="special">)(</span><span class="string">"D"</span> <span class="special">,</span> <span class="number">500</span><span class="special">)</span> |
| <span class="special">(</span><span class="string">"DC"</span> <span class="special">,</span> <span class="number">600</span><span class="special">)(</span><span class="string">"DCC"</span> <span class="special">,</span> <span class="number">700</span><span class="special">)(</span><span class="string">"DCCC"</span> <span class="special">,</span> <span class="number">800</span><span class="special">)(</span><span class="string">"CM"</span> <span class="special">,</span> <span class="number">900</span><span class="special">)</span> <span class="special">;</span> |
| |
| <span class="identifier">tens</span><span class="special">.</span><span class="identifier">add</span> |
| <span class="special">(</span><span class="string">"X"</span> <span class="special">,</span> <span class="number">10</span><span class="special">)(</span><span class="string">"XX"</span> <span class="special">,</span> <span class="number">20</span><span class="special">)(</span><span class="string">"XXX"</span> <span class="special">,</span> <span class="number">30</span><span class="special">)(</span><span class="string">"XL"</span> <span class="special">,</span> <span class="number">40</span><span class="special">)(</span><span class="string">"L"</span> <span class="special">,</span> <span class="number">50</span><span class="special">)</span> |
| <span class="special">(</span><span class="string">"LX"</span> <span class="special">,</span> <span class="number">60</span><span class="special">)(</span><span class="string">"LXX"</span> <span class="special">,</span> <span class="number">70</span><span class="special">)(</span><span class="string">"LXXX"</span> <span class="special">,</span> <span class="number">80</span><span class="special">)(</span><span class="string">"XC"</span> <span class="special">,</span> <span class="number">90</span><span class="special">)</span> <span class="special">;</span> |
| |
| <span class="identifier">ones</span><span class="special">.</span><span class="identifier">add</span> |
| <span class="special">(</span><span class="string">"I"</span> <span class="special">,</span> <span class="number">1</span><span class="special">)(</span><span class="string">"II"</span> <span class="special">,</span> <span class="number">2</span><span class="special">)(</span><span class="string">"III"</span> <span class="special">,</span> <span class="number">3</span><span class="special">)(</span><span class="string">"IV"</span> <span class="special">,</span> <span class="number">4</span><span class="special">)(</span><span class="string">"V"</span> <span class="special">,</span> <span class="number">5</span><span class="special">)</span> |
| <span class="special">(</span><span class="string">"VI"</span> <span class="special">,</span> <span class="number">6</span><span class="special">)(</span><span class="string">"VII"</span> <span class="special">,</span> <span class="number">7</span><span class="special">)(</span><span class="string">"VIII"</span> <span class="special">,</span> <span class="number">8</span><span class="special">)(</span><span class="string">"IX"</span> <span class="special">,</span> <span class="number">9</span><span class="special">)</span> <span class="special">;</span> |
| |
| <span class="identifier">first</span> <span class="special">=</span> <span class="identifier">eps_p</span> <span class="special">[</span><span class="identifier">phoenix</span><span class="special">::</span><span class="identifier">var</span><span class="special">(</span><span class="identifier">self</span><span class="special">.</span><span class="identifier">r</span><span class="special">)</span> <span class="special">=</span> <span class="identifier">phoenix</span><span class="special">::</span><span class="identifier">val</span><span class="special">(</span><span class="number">0</span><span class="special">)]</span> |
| <span class="special">>></span> <span class="special">(</span> <span class="special">+</span><span class="identifier">ch_p</span><span class="special">(</span><span class="char">'M'</span><span class="special">)</span> <span class="special">[</span><span class="identifier">phoenix</span><span class="special">::</span><span class="identifier">var</span><span class="special">(</span><span class="identifier">self</span><span class="special">.</span><span class="identifier">r</span><span class="special">)</span> <span class="special">+=</span> <span class="identifier">phoenix</span><span class="special">::</span><span class="identifier">val</span><span class="special">(</span><span class="number">1000</span><span class="special">)]</span> |
| <span class="special">||</span> <span class="identifier">hundreds</span> <span class="special">[</span><span class="identifier">phoenix</span><span class="special">::</span><span class="identifier">var</span><span class="special">(</span><span class="identifier">self</span><span class="special">.</span><span class="identifier">r</span><span class="special">)</span> <span class="special">+=</span> <span class="identifier">phoenix</span><span class="special">::</span><span class="identifier">_1</span><span class="special">]</span> |
| <span class="special">||</span> <span class="identifier">tens</span> <span class="special">[</span><span class="identifier">phoenix</span><span class="special">::</span><span class="identifier">var</span><span class="special">(</span><span class="identifier">self</span><span class="special">.</span><span class="identifier">r</span><span class="special">)</span> <span class="special">+=</span> <span class="identifier">phoenix</span><span class="special">::</span><span class="identifier">_1</span><span class="special">]</span> |
| <span class="special">||</span> <span class="identifier">ones</span> <span class="special">[</span><span class="identifier">phoenix</span><span class="special">::</span><span class="identifier">var</span><span class="special">(</span><span class="identifier">self</span><span class="special">.</span><span class="identifier">r</span><span class="special">)</span> <span class="special">+=</span> <span class="identifier">phoenix</span><span class="special">::</span><span class="identifier">_1</span><span class="special">]</span> |
| <span class="special">)</span> <span class="special">;</span> |
| <span class="special">}</span> |
| |
| <span class="identifier">rule</span><span class="special"><</span><span class="identifier">ScannerT</span><span class="special">></span> <span class="identifier">first</span><span class="special">;</span> |
| <span class="identifier">symbols</span><span class="special"><</span><span class="keyword">unsigned</span><span class="special">></span> <span class="identifier">hundreds</span><span class="special">;</span> |
| <span class="identifier">symbols</span><span class="special"><</span><span class="keyword">unsigned</span><span class="special">></span> <span class="identifier">tens</span><span class="special">;</span> |
| <span class="identifier">symbols</span><span class="special"><</span><span class="keyword">unsigned</span><span class="special">></span> <span class="identifier">ones</span><span class="special">;</span> |
| |
| <span class="identifier">rule</span><span class="special"><</span><span class="identifier">ScannerT</span><span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">start</span><span class="special">()</span> <span class="keyword">const</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">first</span><span class="special">;</span> <span class="special">}</span> |
| <span class="special">};</span> |
| |
| <span class="identifier">roman</span><span class="special">(</span><span class="keyword">unsigned</span><span class="special">&</span> <span class="identifier">r_</span><span class="special">)</span> <span class="special">:</span> <span class="identifier">r</span><span class="special">(</span><span class="identifier">r_</span><span class="special">)</span> <span class="special">{}</span> |
| <span class="keyword">unsigned</span><span class="special">&</span> <span class="identifier">r</span><span class="special">;</span> |
| <span class="special">};</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">input</span><span class="special">(</span><span class="string">"MMIX"</span><span class="special">);</span> <span class="comment">// MMIX == 2009 |
| </span><span class="keyword">unsigned</span> <span class="identifier">value</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> |
| <span class="identifier">roman</span> <span class="identifier">r</span><span class="special">(</span><span class="identifier">value</span><span class="special">);</span> |
| <span class="identifier">parse_info</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">::</span><span class="identifier">iterator</span><span class="special">></span> <span class="identifier">pi</span> <span class="special">=</span> <span class="identifier">parse</span><span class="special">(</span><span class="identifier">input</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span> <span class="identifier">r</span><span class="special">);</span> |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">pi</span><span class="special">.</span><span class="identifier">hit</span><span class="special">)</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"successfully matched: "</span> <span class="special"><<</span> <span class="identifier">value</span> <span class="special"><<</span> <span class="string">"\n"</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| And here is a similar grammar and its usage in <span class="emphasis"><em>Spirit.Qi</em></span>: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Iterator</span><span class="special">></span> |
| <span class="keyword">struct</span> <span class="identifier">roman</span> <span class="special">:</span> <span class="identifier">qi</span><span class="special">::</span><span class="identifier">grammar</span><span class="special"><</span><span class="identifier">Iterator</span><span class="special">,</span> <span class="keyword">unsigned</span><span class="special">()></span> |
| <span class="special">{</span> |
| <span class="identifier">roman</span><span class="special">()</span> <span class="special">:</span> <span class="identifier">roman</span><span class="special">::</span><span class="identifier">base_type</span><span class="special">(</span><span class="identifier">first</span><span class="special">)</span> |
| <span class="special">{</span> |
| <span class="identifier">hundreds</span><span class="special">.</span><span class="identifier">add</span> |
| <span class="special">(</span><span class="string">"C"</span> <span class="special">,</span> <span class="number">100</span><span class="special">)(</span><span class="string">"CC"</span> <span class="special">,</span> <span class="number">200</span><span class="special">)(</span><span class="string">"CCC"</span> <span class="special">,</span> <span class="number">300</span><span class="special">)(</span><span class="string">"CD"</span> <span class="special">,</span> <span class="number">400</span><span class="special">)(</span><span class="string">"D"</span> <span class="special">,</span> <span class="number">500</span><span class="special">)</span> |
| <span class="special">(</span><span class="string">"DC"</span> <span class="special">,</span> <span class="number">600</span><span class="special">)(</span><span class="string">"DCC"</span> <span class="special">,</span> <span class="number">700</span><span class="special">)(</span><span class="string">"DCCC"</span> <span class="special">,</span> <span class="number">800</span><span class="special">)(</span><span class="string">"CM"</span> <span class="special">,</span> <span class="number">900</span><span class="special">)</span> <span class="special">;</span> |
| |
| <span class="identifier">tens</span><span class="special">.</span><span class="identifier">add</span> |
| <span class="special">(</span><span class="string">"X"</span> <span class="special">,</span> <span class="number">10</span><span class="special">)(</span><span class="string">"XX"</span> <span class="special">,</span> <span class="number">20</span><span class="special">)(</span><span class="string">"XXX"</span> <span class="special">,</span> <span class="number">30</span><span class="special">)(</span><span class="string">"XL"</span> <span class="special">,</span> <span class="number">40</span><span class="special">)(</span><span class="string">"L"</span> <span class="special">,</span> <span class="number">50</span><span class="special">)</span> |
| <span class="special">(</span><span class="string">"LX"</span> <span class="special">,</span> <span class="number">60</span><span class="special">)(</span><span class="string">"LXX"</span> <span class="special">,</span> <span class="number">70</span><span class="special">)(</span><span class="string">"LXXX"</span> <span class="special">,</span> <span class="number">80</span><span class="special">)(</span><span class="string">"XC"</span> <span class="special">,</span> <span class="number">90</span><span class="special">)</span> <span class="special">;</span> |
| |
| <span class="identifier">ones</span><span class="special">.</span><span class="identifier">add</span> |
| <span class="special">(</span><span class="string">"I"</span> <span class="special">,</span> <span class="number">1</span><span class="special">)(</span><span class="string">"II"</span> <span class="special">,</span> <span class="number">2</span><span class="special">)(</span><span class="string">"III"</span> <span class="special">,</span> <span class="number">3</span><span class="special">)(</span><span class="string">"IV"</span> <span class="special">,</span> <span class="number">4</span><span class="special">)(</span><span class="string">"V"</span> <span class="special">,</span> <span class="number">5</span><span class="special">)</span> |
| <span class="special">(</span><span class="string">"VI"</span> <span class="special">,</span> <span class="number">6</span><span class="special">)(</span><span class="string">"VII"</span> <span class="special">,</span> <span class="number">7</span><span class="special">)(</span><span class="string">"VIII"</span> <span class="special">,</span> <span class="number">8</span><span class="special">)(</span><span class="string">"IX"</span> <span class="special">,</span> <span class="number">9</span><span class="special">)</span> <span class="special">;</span> |
| |
| <span class="comment">// qi::_val refers to the attribute of the rule on the left hand side |
| </span> <span class="identifier">first</span> <span class="special">=</span> <span class="identifier">eps</span> <span class="special">[</span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">_val</span> <span class="special">=</span> <span class="number">0</span><span class="special">]</span> |
| <span class="special">>></span> <span class="special">(</span> <span class="special">+</span><span class="identifier">lit</span><span class="special">(</span><span class="char">'M'</span><span class="special">)</span> <span class="special">[</span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">_val</span> <span class="special">+=</span> <span class="number">1000</span><span class="special">]</span> |
| <span class="special">||</span> <span class="identifier">hundreds</span> <span class="special">[</span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">_val</span> <span class="special">+=</span> <span class="identifier">qi</span><span class="special">::</span><span class="identifier">_1</span><span class="special">]</span> |
| <span class="special">||</span> <span class="identifier">tens</span> <span class="special">[</span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">_val</span> <span class="special">+=</span> <span class="identifier">qi</span><span class="special">::</span><span class="identifier">_1</span><span class="special">]</span> |
| <span class="special">||</span> <span class="identifier">ones</span> <span class="special">[</span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">_val</span> <span class="special">+=</span> <span class="identifier">qi</span><span class="special">::</span><span class="identifier">_1</span><span class="special">]</span> |
| <span class="special">)</span> <span class="special">;</span> |
| <span class="special">}</span> |
| |
| <span class="identifier">qi</span><span class="special">::</span><span class="identifier">rule</span><span class="special"><</span><span class="identifier">Iterator</span><span class="special">,</span> <span class="keyword">unsigned</span><span class="special">()></span> <span class="identifier">first</span><span class="special">;</span> |
| <span class="identifier">qi</span><span class="special">::</span><span class="identifier">symbols</span><span class="special"><</span><span class="keyword">char</span><span class="special">,</span> <span class="keyword">unsigned</span><span class="special">></span> <span class="identifier">hundreds</span><span class="special">;</span> |
| <span class="identifier">qi</span><span class="special">::</span><span class="identifier">symbols</span><span class="special"><</span><span class="keyword">char</span><span class="special">,</span> <span class="keyword">unsigned</span><span class="special">></span> <span class="identifier">tens</span><span class="special">;</span> |
| <span class="identifier">qi</span><span class="special">::</span><span class="identifier">symbols</span><span class="special"><</span><span class="keyword">char</span><span class="special">,</span> <span class="keyword">unsigned</span><span class="special">></span> <span class="identifier">ones</span><span class="special">;</span> |
| <span class="special">};</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">input</span><span class="special">(</span><span class="string">"MMIX"</span><span class="special">);</span> <span class="comment">// MMIX == 2009 |
| </span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">it</span> <span class="special">=</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">begin</span><span class="special">();</span> |
| <span class="keyword">unsigned</span> <span class="identifier">value</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> |
| <span class="identifier">roman</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">::</span><span class="identifier">iterator</span><span class="special">></span> <span class="identifier">r</span><span class="special">;</span> |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">parse</span><span class="special">(</span><span class="identifier">it</span><span class="special">,</span> <span class="identifier">input</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span> <span class="identifier">r</span><span class="special">,</span> <span class="identifier">value</span><span class="special">))</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"successfully matched: "</span> <span class="special"><<</span> <span class="identifier">value</span> <span class="special"><<</span> <span class="string">"\n"</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| Both versions look similar enough, but we see several differences (we will |
| cover each of those differences in more detail below): |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"> |
| Neither the grammars nor the rules depend on a scanner type anymore, |
| both depend only on the underlying iterator type. That means the dreaded |
| scanner business is no issue anymore! |
| </li> |
| <li class="listitem"> |
| Grammars have no embedded class <code class="computeroutput"><span class="identifier">definition</span></code> |
| anymore |
| </li> |
| <li class="listitem"> |
| Grammars and rules may have an explicit attribute type specified in their |
| definition |
| </li> |
| <li class="listitem"> |
| Grammars do not have any explicit start rules anymore. Instead one of |
| the contained rules is used as a start rule by default. |
| </li> |
| </ul></div> |
| <p> |
| The first two points are tightly interrelated. The scanner business (see |
| the FAQ number one of <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a> |
| here: <a href="../../../../../../libs/spirit/classic/doc/faq.html#scanner_business" target="_top">The |
| Scanner Business</a>) has been a problem for a long time. The grammar |
| and rule types have been specifically redesigned to avoid this problem in |
| the future. This also means that we don't need any delayed instantiation |
| of the inner definition class in a grammar anymore. So the redesign not only |
| helped fixing a long standing design problem, it helped to simplify things |
| considerably. |
| </p> |
| <p> |
| All <span class="emphasis"><em>Spirit.Qi</em></span> parser components have well defined attribute |
| types. Grammars and rules are no exception. But since both need to be generic |
| enough to be usable for any parser their attribute type has to be explicitly |
| specified. In the example above the <code class="computeroutput"><span class="identifier">roman</span></code> |
| grammar and the rule <code class="computeroutput"><span class="identifier">first</span></code> |
| both have an <code class="computeroutput"><span class="keyword">unsigned</span></code> attribute: |
| </p> |
| <pre class="programlisting"><span class="comment">// grammar definition |
| </span><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Iterator</span><span class="special">></span> |
| <span class="keyword">struct</span> <span class="identifier">roman</span> <span class="special">:</span> <span class="identifier">qi</span><span class="special">::</span><span class="identifier">grammar</span><span class="special"><</span><span class="identifier">Iterator</span><span class="special">,</span> <span class="keyword">unsigned</span><span class="special">()></span> <span class="special">{...};</span> |
| |
| <span class="comment">// rule definition |
| </span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">rule</span><span class="special"><</span><span class="identifier">Iterator</span><span class="special">,</span> <span class="keyword">unsigned</span><span class="special">()></span> <span class="identifier">first</span><span class="special">;</span> |
| </pre> |
| <p> |
| The used notation resembles the definition of a function type. This is very |
| natural as you can think of the synthesized attribute of the grammar and |
| the rule as of its 'return value'. In fact the rule and the grammar both |
| 'return' an unsigned value - the value they matched. |
| </p> |
| <div class="note"><table border="0" summary="Note"> |
| <tr> |
| <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../images/note.png"></td> |
| <th align="left">Note</th> |
| </tr> |
| <tr><td align="left" valign="top"><p> |
| The function type notation allows to specify parameters as well. These |
| are interpreted as the types of inherited attributes the rule or grammar |
| expect to be passed during parsing. For more information please see the |
| section about inherited and synthesized attributes for rules and grammars |
| (<a class="link" href="../abstracts/attributes.html" title="Attributes">Attributes</a>). |
| </p></td></tr> |
| </table></div> |
| <p> |
| If no attribute is desired none needs to be specified. The default attribute |
| type for both, grammars and rules, is <code class="computeroutput"><span class="identifier">unused_type</span></code>, |
| which is a special placeholder type. Generally, using <code class="computeroutput"><span class="identifier">unused_type</span></code> |
| as the attribute of a parser is interpreted as 'this parser has no attribute'. |
| This is mostly used for parsers applied to parts of the input not carrying |
| any significant information, rather being delimiters or structural elements |
| needed for correct interpretation of the input. |
| </p> |
| <p> |
| The last difference might seem to be rather cosmetic and insignificant. But |
| it turns out that not having to specify which rule in a grammar is the start |
| rule (by returning it from the function <code class="computeroutput"><span class="identifier">start</span><span class="special">()</span></code>) also means that any rule in a grammar |
| can be directly used as the start rule. Nevertheless, the grammar base class |
| gets initialized with the rule it has to use as the start rule in case the |
| grammar instance is directly used as a parser. |
| </p> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2001-2010 Joel de Guzman, Hartmut Kaiser<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></td> |
| </tr></table> |
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