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| <div class="section"> |
| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="spirit_repository.karma_components.nonterminal.subrule"></a><a class="link" href="subrule.html" title="Karma subrules"> |
| Karma subrules</a> |
| </h4></div></div></div> |
| <a name="spirit_repository.karma_components.nonterminal.subrule.description"></a><h6> |
| <a name="id774685"></a> |
| <a class="link" href="subrule.html#spirit_repository.karma_components.nonterminal.subrule.description">Description</a> |
| </h6> |
| <p> |
| The <span class="emphasis"><em>Spirit.Karma</em></span> <code class="computeroutput"><span class="identifier">subrule</span></code> |
| is a component allowing to create a named generator, and to refer to it |
| by name -- much like rules and grammars. It is in fact a fully static version |
| of the rule. |
| </p> |
| <p> |
| The strength of subrules is performance. Replacing some rules with subrules |
| can make a generator slightly faster (see <a class="link" href="subrule.html#spirit_repository.karma_components.nonterminal.subrule.performance">Performance</a> |
| below for measurements). The reason is that subrules allow aggressive inlining |
| by the C++ compiler, whereas the implementation of rules is based on a |
| virtual function call which, depending on the compiler, can have some run-time |
| overhead and stop inlining. |
| </p> |
| <p> |
| The weaknesses of subrules are: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"> |
| subrules can only be defined and used within the same generator expression. |
| A subrule cannot be defined at one location, and then used in another |
| location. |
| </li> |
| <li class="listitem"> |
| subrules put a massive strain on the C++ compiler. They increase compile |
| times and memory usage during compilation, and also increase the risk |
| of hitting compiler limits and/or bugs. |
| </li> |
| </ul></div> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="identifier">entry</span> <span class="special">%=</span> <span class="special">(</span> |
| <span class="identifier">ast_node</span> <span class="special">%=</span> <span class="identifier">int_</span> <span class="special">|</span> <span class="identifier">binary_node</span> <span class="special">|</span> <span class="identifier">unary_node</span> |
| |
| <span class="special">,</span> <span class="identifier">binary_node</span> <span class="special">%=</span> <span class="char">'('</span> <span class="special"><<</span> <span class="identifier">ast_node</span> <span class="special"><<</span> <span class="identifier">char_</span> <span class="special"><<</span> <span class="identifier">ast_node</span> <span class="special"><<</span> <span class="char">')'</span> |
| |
| <span class="special">,</span> <span class="identifier">unary_node</span> <span class="special">%=</span> <span class="char">'('</span> <span class="special"><<</span> <span class="identifier">char_</span> <span class="special"><<</span> <span class="identifier">ast_node</span> <span class="special"><<</span> <span class="char">')'</span> |
| <span class="special">);</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| The example above can be found here: <a href="../../../../../example/karma/calc2_ast_dump_sr.cpp" target="_top">../../example/karma/calc2_ast_dump_sr.cpp</a> |
| </p> |
| <p> |
| As shown in this code snippet (an extract from the calc2_ast_dump_sr example), |
| subrules can be freely mixed with rules and grammars. Here, a group of |
| 3 subrules (<code class="computeroutput"><span class="identifier">ast_node</span></code>, |
| <code class="computeroutput"><span class="identifier">binary_node</span></code>, <code class="computeroutput"><span class="identifier">unary_node</span></code>) is assigned to a rule (named |
| <code class="computeroutput"><span class="identifier">entry</span></code>). This means that |
| parts of a generator can use subrules (typically the innermost, most performance-critical |
| parts), whereas the rest can use rules and grammars. |
| </p> |
| <a name="spirit_repository.karma_components.nonterminal.subrule.header"></a><h6> |
| <a name="id775027"></a> |
| <a class="link" href="subrule.html#spirit_repository.karma_components.nonterminal.subrule.header">Header</a> |
| </h6> |
| <pre class="programlisting"><span class="comment">// forwards to <boost/spirit/repository/home/karma/nonterminal/subrule.hpp> |
| </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">repository</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">karma_subrule</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| </pre> |
| <a name="spirit_repository.karma_components.nonterminal.subrule.synopsis__declaration_"></a><h6> |
| <a name="id775127"></a> |
| <a class="link" href="subrule.html#spirit_repository.karma_components.nonterminal.subrule.synopsis__declaration_">Synopsis |
| (declaration)</a> |
| </h6> |
| <pre class="programlisting"><span class="identifier">subrule</span><span class="special"><</span><span class="identifier">ID</span><span class="special">,</span> <span class="identifier">A1</span><span class="special">,</span> <span class="identifier">A2</span><span class="special">></span> <span class="identifier">sr</span><span class="special">(</span><span class="identifier">name</span><span class="special">);</span> |
| </pre> |
| <a name="spirit_repository.karma_components.nonterminal.subrule.parameters__declaration_"></a><h6> |
| <a name="id775212"></a> |
| <a class="link" href="subrule.html#spirit_repository.karma_components.nonterminal.subrule.parameters__declaration_">Parameters |
| (declaration)</a> |
| </h6> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Parameter |
| </p> |
| </th> |
| <th> |
| <p> |
| Description |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">ID</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Required numeric argument. Gives the subrule a unique 'identification |
| tag'. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">A1</span></code>, <code class="computeroutput"><span class="identifier">A2</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Optional types, can be specified in any order. Can be one of |
| 1. signature, 2. locals (see rules reference for more information |
| on those parameters). |
| </p> |
| <p> |
| Note that the delimiter type need not be specified in the parameters, |
| unlike with grammars and rules. Subrules will automatically use |
| the delimiter type which is in effect when they are invoked. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">name</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Optional string. Gives the subrule a name, useful for debugging |
| and error handling. |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <a name="spirit_repository.karma_components.nonterminal.subrule.synopsis__usage_"></a><h6> |
| <a name="id775374"></a> |
| <a class="link" href="subrule.html#spirit_repository.karma_components.nonterminal.subrule.synopsis__usage_">Synopsis |
| (usage)</a> |
| </h6> |
| <p> |
| Subrules are defined and used within groups, typically (and by convention) |
| enclosed inside parentheses. |
| </p> |
| <pre class="programlisting"><span class="comment">// Group containing N subrules |
| </span><span class="special">(</span> |
| <span class="identifier">sr1</span> <span class="special">=</span> <span class="identifier">expr1</span> |
| <span class="special">,</span> <span class="identifier">sr2</span> <span class="special">=</span> <span class="identifier">expr2</span> |
| <span class="special">,</span> <span class="special">...</span> <span class="comment">// Any number of subrules |
| </span><span class="special">}</span> |
| </pre> |
| <p> |
| The IDs of all subrules defined within the same group must be different. |
| It is an error to define several subrules with the same ID (or to define |
| the same subrule multiple times) in the same group. |
| </p> |
| <pre class="programlisting"><span class="comment">// Auto-subrules and inherited attributes |
| </span><span class="special">(</span> |
| <span class="identifier">srA</span> <span class="special">%=</span> <span class="identifier">exprA</span> <span class="special"><<</span> <span class="identifier">srB</span> <span class="special"><<</span> <span class="identifier">srC</span><span class="special">(</span><span class="identifier">c1</span><span class="special">,</span> <span class="identifier">c2</span><span class="special">,</span> <span class="special">...)</span> <span class="comment">// Arguments to subrule srC |
| </span> <span class="special">,</span> <span class="identifier">srB</span> <span class="special">%=</span> <span class="identifier">exprB</span> |
| <span class="special">,</span> <span class="identifier">srC</span> <span class="special">=</span> <span class="identifier">exprC</span> |
| <span class="special">,</span> <span class="special">...</span> |
| <span class="special">)(</span><span class="identifier">a1</span><span class="special">,</span> <span class="identifier">a2</span><span class="special">,</span> <span class="special">...)</span> <span class="comment">// Arguments to group, i.e. to start subrule srA |
| </span></pre> |
| <a name="spirit_repository.karma_components.nonterminal.subrule.parameters__usage_"></a><h6> |
| <a name="id775661"></a> |
| <a class="link" href="subrule.html#spirit_repository.karma_components.nonterminal.subrule.parameters__usage_">Parameters |
| (usage)</a> |
| </h6> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Parameter |
| </p> |
| </th> |
| <th> |
| <p> |
| Description |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">sr1</span></code>, <code class="computeroutput"><span class="identifier">sr2</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Subrules with different IDs. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">expr1</span></code>, <code class="computeroutput"><span class="identifier">expr2</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Generator expressions. Can include <code class="computeroutput"><span class="identifier">sr1</span></code> |
| and <code class="computeroutput"><span class="identifier">sr2</span></code>, as well |
| as any other valid generator expressions. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">srA</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Subrule with a synthesized attribute and inherited attributes. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">srB</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Subrule with a synthesized attribute. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">srC</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Subrule with inherited attributes. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">exprA</span></code>, <code class="computeroutput"><span class="identifier">exprB</span></code>, <code class="computeroutput"><span class="identifier">exprC</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Generator expressions. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">a1</span></code>, <code class="computeroutput"><span class="identifier">a2</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Arguments passed to the subrule group. They are passed as inherited |
| attributes to the group's start subrule, <code class="computeroutput"><span class="identifier">srA</span></code>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">c1</span></code>, <code class="computeroutput"><span class="identifier">c2</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Arguments passed as inherited attributes to subrule <code class="computeroutput"><span class="identifier">srC</span></code>. |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <a name="spirit_repository.karma_components.nonterminal.subrule.groups"></a><h6> |
| <a name="id776039"></a> |
| <a class="link" href="subrule.html#spirit_repository.karma_components.nonterminal.subrule.groups">Groups</a> |
| </h6> |
| <p> |
| A subrule group (a set of subrule definitions) is a generator, which can |
| be used anywhere in a generator expression (in assignments to rules, as |
| well as directly in arguments to functions such as <code class="computeroutput"><span class="identifier">generate</span></code>). |
| In a group, generation proceeds from the start subrule, which is the first |
| (topmost) subrule defined in that group. In the two groups in the synopsis |
| above, <code class="computeroutput"><span class="identifier">sr1</span></code> and <code class="computeroutput"><span class="identifier">srA</span></code> are the start subrules respectively |
| -- for example when the first subrule group is called forth, the <code class="computeroutput"><span class="identifier">sr1</span></code> subrule is called. |
| </p> |
| <p> |
| A subrule can only be used in a group which defines it. Groups can be viewed |
| as scopes: a definition of a subrule is limited to its enclosing group. |
| </p> |
| <pre class="programlisting"><span class="identifier">rule</span><span class="special"><</span><span class="identifier">outiter_type</span><span class="special">></span> <span class="identifier">r1</span><span class="special">,</span> <span class="identifier">r2</span><span class="special">,</span> <span class="identifier">r3</span><span class="special">;</span> |
| <span class="identifier">subrule</span><span class="special"><</span><span class="number">1</span><span class="special">></span> <span class="identifier">sr1</span><span class="special">;</span> |
| <span class="identifier">subrule</span><span class="special"><</span><span class="number">2</span><span class="special">></span> <span class="identifier">sr2</span><span class="special">;</span> |
| |
| <span class="identifier">r1</span> <span class="special">=</span> |
| <span class="special">(</span> <span class="identifier">sr1</span> <span class="special">=</span> <span class="char">'a'</span> <span class="special"><<</span> <span class="identifier">space</span> <span class="special">)</span> <span class="comment">// First group in r1. |
| </span> <span class="special"><<</span> <span class="special">(</span> <span class="identifier">sr2</span> <span class="special">=</span> <span class="special">+</span><span class="identifier">sr1</span> <span class="special">)</span> <span class="comment">// Second group in r1. |
| </span> <span class="comment">// ^^^ |
| </span> <span class="comment">// DOES NOT COMPILE: sr1 is not defined in this |
| </span> <span class="comment">// second group, it cannot be used here (its |
| </span> <span class="comment">// previous definition is out of scope). |
| </span><span class="special">;</span> |
| |
| <span class="identifier">r2</span> <span class="special">=</span> |
| <span class="special">(</span> <span class="identifier">sr1</span> <span class="special">=</span> <span class="char">'a'</span> <span class="special"><<</span> <span class="identifier">space</span> <span class="special">)</span> <span class="comment">// Only group in r2. |
| </span> <span class="special"><<</span> <span class="identifier">sr1</span> |
| <span class="comment">// ^^^ |
| </span> <span class="comment">// DOES NOT COMPILE: not in a subrule group, |
| </span> <span class="comment">// sr1 cannot be used here (here too, its |
| </span> <span class="comment">// previous definition is out of scope). |
| </span><span class="special">;</span> |
| |
| <span class="identifier">r3</span> <span class="special">=</span> |
| <span class="special">(</span> <span class="identifier">sr1</span> <span class="special">=</span> <span class="identifier">space</span> <span class="special"><<</span> <span class="char">'x'</span> <span class="special">)</span> <span class="comment">// Another group. The same subrule `sr1` |
| </span> <span class="comment">// can have another, independent |
| </span> <span class="comment">// definition in this group. |
| </span><span class="special">;</span> |
| </pre> |
| <a name="spirit_repository.karma_components.nonterminal.subrule.attributes"></a><h6> |
| <a name="id776523"></a> |
| <a class="link" href="subrule.html#spirit_repository.karma_components.nonterminal.subrule.attributes">Attributes</a> |
| </h6> |
| <p> |
| A subrule has the same behavior as a rule with respect to attributes. In |
| particular: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"> |
| the type of its synthesized attribute is the one specified in the subrule's |
| signature, if any. Otherwise it is <code class="computeroutput"><span class="identifier">unused_type</span></code>. |
| </li> |
| <li class="listitem"> |
| the types of its inherited attributes are the ones specified in the |
| subrule's signature, if any. Otherwise the subrule has no inherited |
| attributes. |
| </li> |
| <li class="listitem"> |
| an auto-subrule can be defined by assigning it with the <code class="computeroutput"><span class="special">%=</span></code> syntax. In this case, the subrule's |
| synthesized attribute is automatically propagated to the RHS generator's |
| attribute. |
| </li> |
| <li class="listitem"> |
| the Phoenix placeholders <code class="computeroutput"><span class="identifier">_val</span></code>, |
| <code class="computeroutput"><span class="identifier">_r1</span></code>, <code class="computeroutput"><span class="identifier">_r2</span></code>, ... are available to refer to |
| the subrule's synthesized and inherited attributes, if present. |
| </li> |
| </ul></div> |
| <a name="spirit_repository.karma_components.nonterminal.subrule.locals"></a><h6> |
| <a name="id776641"></a> |
| <a class="link" href="subrule.html#spirit_repository.karma_components.nonterminal.subrule.locals">Locals</a> |
| </h6> |
| <p> |
| A subrule has the same behavior as a rule with respect to locals. In particular, |
| the Phoenix placeholders <code class="computeroutput"><span class="identifier">_a</span></code>, |
| <code class="computeroutput"><span class="identifier">_b</span></code>, ... are available to |
| refer to the subrule's locals, if present. |
| </p> |
| <a name="spirit_repository.karma_components.nonterminal.subrule.example"></a><h6> |
| <a name="id776689"></a> |
| <a class="link" href="subrule.html#spirit_repository.karma_components.nonterminal.subrule.example">Example</a> |
| </h6> |
| <p> |
| Some includes: |
| </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">karma</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">repository</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">karma_subrule</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_core</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">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_fusion</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| Some using declarations: |
| </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="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">ascii</span><span class="special">;</span> |
| <span class="keyword">namespace</span> <span class="identifier">repo</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">repository</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| A grammar containing only one rule, defined with a group of 2 subrules: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">OutputIterator</span><span class="special">></span> |
| <span class="keyword">struct</span> <span class="identifier">mini_xml_generator</span> |
| <span class="special">:</span> <span class="identifier">karma</span><span class="special">::</span><span class="identifier">grammar</span><span class="special"><</span><span class="identifier">OutputIterator</span><span class="special">,</span> <span class="identifier">mini_xml</span><span class="special">()></span> |
| <span class="special">{</span> |
| <span class="identifier">mini_xml_generator</span><span class="special">()</span> <span class="special">:</span> <span class="identifier">mini_xml_generator</span><span class="special">::</span><span class="identifier">base_type</span><span class="special">(</span><span class="identifier">entry</span><span class="special">)</span> |
| <span class="special">{</span> |
| <span class="identifier">entry</span> <span class="special">%=</span> <span class="special">(</span> |
| <span class="identifier">xml</span> <span class="special">=</span> |
| <span class="char">'<'</span> <span class="special"><<</span> <span class="identifier">string</span><span class="special">[</span><span class="identifier">_1</span> <span class="special">=</span> <span class="identifier">at_c</span><span class="special"><</span><span class="number">0</span><span class="special">>(</span><span class="identifier">_val</span><span class="special">)]</span> <span class="special"><<</span> <span class="char">'>'</span> |
| <span class="special"><<</span> <span class="special">(*</span><span class="identifier">node</span><span class="special">)[</span><span class="identifier">_1</span> <span class="special">=</span> <span class="identifier">at_c</span><span class="special"><</span><span class="number">1</span><span class="special">>(</span><span class="identifier">_val</span><span class="special">)]</span> |
| <span class="special"><<</span> <span class="string">"</"</span> <span class="special"><<</span> <span class="identifier">string</span><span class="special">[</span><span class="identifier">_1</span> <span class="special">=</span> <span class="identifier">at_c</span><span class="special"><</span><span class="number">0</span><span class="special">>(</span><span class="identifier">_val</span><span class="special">)]</span> <span class="special"><<</span> <span class="char">'>'</span> |
| |
| <span class="special">,</span> <span class="identifier">node</span> <span class="special">%=</span> <span class="identifier">string</span> <span class="special">|</span> <span class="identifier">xml</span> |
| <span class="special">);</span> |
| <span class="special">}</span> |
| |
| <span class="identifier">karma</span><span class="special">::</span><span class="identifier">rule</span><span class="special"><</span><span class="identifier">OutputIterator</span><span class="special">,</span> <span class="identifier">mini_xml</span><span class="special">()></span> <span class="identifier">entry</span><span class="special">;</span> |
| |
| <span class="identifier">repo</span><span class="special">::</span><span class="identifier">karma</span><span class="special">::</span><span class="identifier">subrule</span><span class="special"><</span><span class="number">0</span><span class="special">,</span> <span class="identifier">mini_xml</span><span class="special">()></span> <span class="identifier">xml</span><span class="special">;</span> |
| <span class="identifier">repo</span><span class="special">::</span><span class="identifier">karma</span><span class="special">::</span><span class="identifier">subrule</span><span class="special"><</span><span class="number">1</span><span class="special">,</span> <span class="identifier">mini_xml_node</span><span class="special">()></span> <span class="identifier">node</span><span class="special">;</span> |
| <span class="special">};</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| The definitions of the <code class="computeroutput"><span class="identifier">mini_xml</span></code> |
| and <code class="computeroutput"><span class="identifier">mini_xml_node</span></code> data |
| structures are not shown here. The full example above can be found here: |
| <a href="../../../../../example/karma/mini_xml_karma_sr.cpp" target="_top">../../example/karma/mini_xml_karma_sr.cpp</a> |
| </p> |
| <a name="spirit_repository.karma_components.nonterminal.subrule.performance"></a><h6> |
| <a name="id777754"></a> |
| <a class="link" href="subrule.html#spirit_repository.karma_components.nonterminal.subrule.performance">Performance</a> |
| </h6> |
| <p> |
| For comparison of run-time and compile-time performance when using subrules, |
| please see the <a class="link" href="../../qi_components/nonterminal/subrule.html#spirit_repository.qi_components.nonterminal.subrule.performance">Performance</a> |
| section of <span class="emphasis"><em>Spirit.Qi</em></span> subrules (the implementation |
| of <span class="emphasis"><em>Spirit.Karma</em></span> and <span class="emphasis"><em>Spirit.Qi</em></span> |
| subrules is very similar, so performance is very similar too). |
| </p> |
| <a name="spirit_repository.karma_components.nonterminal.subrule.notes"></a><h6> |
| <a name="id777801"></a> |
| <a class="link" href="subrule.html#spirit_repository.karma_components.nonterminal.subrule.notes">Notes</a> |
| </h6> |
| <p> |
| Subrules push the C++ compiler hard. A group of subrules is a single C++ |
| expression. Current C++ compilers cannot handle very complex expressions |
| very well. One restricting factor is the typical compiler's limit on template |
| recursion depth. Some, but not all, compilers allow this limit to be configured. |
| </p> |
| <p> |
| g++'s maximum can be set using a compiler flag: <code class="computeroutput"><span class="special">-</span><span class="identifier">ftemplate</span><span class="special">-</span><span class="identifier">depth</span></code>. Set this appropriately if you |
| use relatively complex subrules. |
| </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> |
| <hr> |
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