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| <div class="section"> |
| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="spirit_repository.qi_components.operators.keyword_list"></a><a class="link" href="keyword_list.html" title="Keyword List Operator">Keyword |
| List Operator</a> |
| </h4></div></div></div> |
| <h6> |
| <a name="spirit_repository.qi_components.operators.keyword_list.h0"></a> |
| <span class="phrase"><a name="spirit_repository.qi_components.operators.keyword_list.description"></a></span><a class="link" href="keyword_list.html#spirit_repository.qi_components.operators.keyword_list.description">Description</a> |
| </h6> |
| <p> |
| The keyword list operator, <code class="computeroutput"><span class="identifier">kwd</span><span class="special">(</span><span class="string">"k1"</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span> |
| <span class="special">/</span> <span class="identifier">kwd</span><span class="special">(</span><span class="string">"k2"</span><span class="special">)[</span><span class="identifier">b</span><span class="special">]</span></code>, |
| works tightly with the kwd, ikwd, dkwd and idkwd directives to effeciently |
| match keyword lists. As long as one of the keywords specified through the |
| kwd, ikwd, dkwd or idkwd directive matches, the keyword will be immediatly |
| followed by the keyword's associated subject parser. The parser will continue |
| parsing input as long as the one of the keywords and it's associated parser |
| succeed. Writing : (kwd("k1")[a] / kwd("k2")[b] / ... |
| ) is equivalent to: *( "k1" > a | "k2" > b ... |
| ). |
| </p> |
| <h6> |
| <a name="spirit_repository.qi_components.operators.keyword_list.h1"></a> |
| <span class="phrase"><a name="spirit_repository.qi_components.operators.keyword_list.header"></a></span><a class="link" href="keyword_list.html#spirit_repository.qi_components.operators.keyword_list.header">Header</a> |
| </h6> |
| <pre class="programlisting"><span class="comment">// forwards to <boost/spirit/repository/home/qi/operator/keywords.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">qi_keywords</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| </pre> |
| <h6> |
| <a name="spirit_repository.qi_components.operators.keyword_list.h2"></a> |
| <span class="phrase"><a name="spirit_repository.qi_components.operators.keyword_list.expression_semantics"></a></span><a class="link" href="keyword_list.html#spirit_repository.qi_components.operators.keyword_list.expression_semantics">Expression |
| Semantics</a> |
| </h6> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Expression |
| </p> |
| </th> |
| <th> |
| <p> |
| Semantics |
| </p> |
| </th> |
| </tr></thead> |
| <tbody><tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">kwd</span><span class="special">(</span><span class="identifier">k1</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span> |
| <span class="special">/</span> <span class="identifier">kwd</span><span class="special">(</span><span class="identifier">k2</span><span class="special">)[</span><span class="identifier">b</span><span class="special">]</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Match <code class="computeroutput"><span class="identifier">lit</span><span class="special">(</span><span class="identifier">k1</span><span class="special">)</span> |
| <span class="special">></span> <span class="identifier">a</span></code> |
| or <code class="computeroutput"><span class="identifier">lit</span><span class="special">(</span><span class="identifier">k2</span><span class="special">)</span> |
| <span class="special">></span> <span class="identifier">b</span></code>, |
| equivalent to <code class="computeroutput"><span class="identifier">lit</span><span class="special">(</span><span class="identifier">k1</span><span class="special">)</span> <span class="special">></span> |
| <span class="identifier">a</span> <span class="special">|</span> |
| <span class="identifier">lit</span><span class="special">(</span><span class="identifier">k2</span><span class="special">)</span> |
| <span class="special">></span> <span class="identifier">b</span></code> |
| </p> |
| </td> |
| </tr></tbody> |
| </table></div> |
| <h6> |
| <a name="spirit_repository.qi_components.operators.keyword_list.h3"></a> |
| <span class="phrase"><a name="spirit_repository.qi_components.operators.keyword_list.attributes"></a></span><a class="link" href="keyword_list.html#spirit_repository.qi_components.operators.keyword_list.attributes">Attributes</a> |
| </h6> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Expression |
| </p> |
| </th> |
| <th> |
| <p> |
| Attribute |
| </p> |
| </th> |
| </tr></thead> |
| <tbody><tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">kwd</span><span class="special">(</span><span class="string">"k1"</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span> |
| <span class="special">/</span> <span class="identifier">kwd</span><span class="special">(</span><span class="string">"k2"</span><span class="special">)[</span><span class="identifier">b</span><span class="special">]</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| </p> |
| <pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">a</span><span class="special">:</span> <span class="identifier">A</span><span class="special">,</span> <span class="identifier">b</span><span class="special">:</span> <span class="identifier">B</span> <span class="special">--></span> <span class="special">(</span><span class="identifier">kwd</span><span class="special">(</span><span class="identifier">k1</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span> <span class="special">/</span> <span class="identifier">kwd</span><span class="special">(</span><span class="identifier">k2</span><span class="special">)[</span><span class="identifier">b</span><span class="special">]):</span> <span class="identifier">tuple</span><span class="special"><</span><span class="identifier">A</span><span class="special">,</span> <span class="identifier">B</span><span class="special">></span> |
| <span class="identifier">a</span><span class="special">:</span> <span class="identifier">A</span><span class="special">,</span> <span class="identifier">b</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--></span> <span class="special">(</span><span class="identifier">kwd</span><span class="special">(</span><span class="identifier">k1</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span> <span class="special">/</span> <span class="identifier">kwd</span><span class="special">(</span><span class="identifier">k2</span><span class="special">)[</span><span class="identifier">b</span><span class="special">]):</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">A</span><span class="special">></span> |
| <span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span><span class="special">,</span> <span class="identifier">b</span><span class="special">:</span> <span class="identifier">B</span> <span class="special">--></span> <span class="special">(</span><span class="identifier">kwd</span><span class="special">(</span><span class="string">"k1"</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span> <span class="special">/</span> <span class="identifier">kwd</span><span class="special">(</span><span class="identifier">k2</span><span class="special">)[</span><span class="identifier">b</span><span class="special">]):</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">B</span><span class="special">></span> |
| <span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span><span class="special">,</span> <span class="identifier">b</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--></span> <span class="special">(</span><span class="identifier">kwd</span><span class="special">(</span><span class="identifier">k1</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span> <span class="special">/</span> <span class="identifier">kwd</span><span class="special">(</span><span class="identifier">k2</span><span class="special">)[</span><span class="identifier">b</span><span class="special">]):</span> <span class="identifier">Unused</span> |
| |
| <span class="identifier">a</span><span class="special">:</span> <span class="identifier">A</span><span class="special">,</span> <span class="identifier">b</span><span class="special">:</span> <span class="identifier">A</span> <span class="special">-->(</span><span class="identifier">kwd</span><span class="special">(</span><span class="identifier">k1</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span> <span class="special">/</span> <span class="identifier">kwd</span><span class="special">(</span><span class="identifier">k2</span><span class="special">)[</span><span class="identifier">b</span><span class="special">]):</span> <span class="identifier">tuple</span><span class="special"><</span><span class="identifier">A</span><span class="special">,</span> <span class="identifier">A</span><span class="special">></span></pre> |
| <p> |
| </p> |
| </td> |
| </tr></tbody> |
| </table></div> |
| <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 keyword list parser works tightly with the kwd, ikwd, dkwd and idkwd |
| directives and can't be used without it. A compile time error will warn |
| you of any mistakes. This parser collects all the kwd directives and |
| extracts the keyword literals or parsers from the directives to internaly |
| build a Ternary Search Tree (TST) and permutation loop (for complex parsers) |
| to effectively parse the keywords. Because you can't mix character types |
| inside a TST you must take care not to mix wide strings with normal strings |
| in the keywords you supply to a keyword list. Should it happen the compiler |
| will trap the mistake for you. |
| </p></td></tr> |
| </table></div> |
| <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 kwd directive also works a bit like the repeat directive and can |
| be used to formulate additional contraints on the number of times a keyword |
| can or must occur while parsing a keyword list. |
| </p></td></tr> |
| </table></div> |
| <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 kwd, dkwd and ikwd, idkwd directives can be mixed inside a keyword |
| list. This has however a small overhead and should be avoided when possible. |
| </p></td></tr> |
| </table></div> |
| <h6> |
| <a name="spirit_repository.qi_components.operators.keyword_list.h4"></a> |
| <span class="phrase"><a name="spirit_repository.qi_components.operators.keyword_list.complexity"></a></span><a class="link" href="keyword_list.html#spirit_repository.qi_components.operators.keyword_list.complexity">Complexity</a> |
| </h6> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| The overall complexity of the keyword list parser is defined by the sum |
| of the complexities of its elements. |
| </p></blockquote></div> |
| <h6> |
| <a name="spirit_repository.qi_components.operators.keyword_list.h5"></a> |
| <span class="phrase"><a name="spirit_repository.qi_components.operators.keyword_list.example"></a></span><a class="link" href="keyword_list.html#spirit_repository.qi_components.operators.keyword_list.example">Example</a> |
| </h6> |
| <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 test harness for the example(s) below is presented in the <a href="../../../../../../doc/html/spirit/qi/reference/basics.html#spirit.qi.reference.basics.examples" target="_top">Basics |
| Examples</a> section. |
| </p></td></tr> |
| </table></div> |
| <p> |
| Declare a small data structure representing a person: |
| </p> |
| <p> |
| </p> |
| <pre class="programlisting"><span class="comment">// Data structure definitions to test the kwd directive</span> |
| <span class="comment">// and the keywords list operator</span> |
| |
| <span class="keyword">struct</span> <span class="identifier">person</span> <span class="special">{</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">name</span><span class="special">;</span> |
| <span class="keyword">int</span> <span class="identifier">age</span><span class="special">;</span> |
| <span class="keyword">double</span> <span class="identifier">size</span><span class="special">;</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</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">favorite_colors</span><span class="special">;</span> |
| |
| <span class="special">};</span> |
| |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">ostream</span> <span class="special">&</span><span class="keyword">operator</span><span class="special"><<(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">ostream</span> <span class="special">&</span><span class="identifier">os</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">person</span> <span class="special">&</span><span class="identifier">p</span><span class="special">)</span> |
| <span class="special">{</span> |
| <span class="identifier">os</span><span class="special"><<</span><span class="string">"Person : "</span><span class="special"><<</span><span class="identifier">p</span><span class="special">.</span><span class="identifier">name</span><span class="special"><<</span><span class="string">", "</span><span class="special"><<</span><span class="identifier">p</span><span class="special">.</span><span class="identifier">age</span><span class="special"><<</span><span class="string">", "</span><span class="special"><<</span><span class="identifier">p</span><span class="special">.</span><span class="identifier">size</span><span class="special"><<</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">copy</span><span class="special">(</span><span class="identifier">p</span><span class="special">.</span><span class="identifier">favorite_colors</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span><span class="identifier">p</span><span class="special">.</span><span class="identifier">favorite_colors</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">ostream_iterator</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">os</span><span class="special">,</span><span class="string">"\n"</span><span class="special">));</span> |
| <span class="keyword">return</span> <span class="identifier">os</span><span class="special">;</span> |
| <span class="special">}</span> |
| |
| <span class="identifier">BOOST_FUSION_ADAPT_STRUCT</span><span class="special">(</span> <span class="identifier">person</span><span class="special">,</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">name</span><span class="special">)</span> |
| <span class="special">(</span><span class="keyword">int</span><span class="special">,</span> <span class="identifier">age</span><span class="special">)</span> |
| <span class="special">(</span><span class="keyword">double</span><span class="special">,</span> <span class="identifier">size</span><span class="special">)</span> |
| <span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</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">favorite_colors</span><span class="special">)</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="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">qi</span><span class="special">::</span><span class="identifier">kwd</span><span class="special">;</span> |
| <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">inf</span><span class="special">;</span> |
| <span class="keyword">using</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="identifier">space_type</span><span class="special">;</span> |
| <span class="keyword">using</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="identifier">char_</span><span class="special">;</span> |
| <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">double_</span><span class="special">;</span> |
| <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</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">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">rule</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| Now let's declare a keyword parser: |
| </p> |
| <p> |
| </p> |
| <pre class="programlisting"><span class="identifier">no_constraint_person_rule</span> <span class="special">%=</span> |
| <span class="identifier">kwd</span><span class="special">(</span><span class="string">"name"</span><span class="special">)[</span><span class="char">'='</span> <span class="special">></span> <span class="identifier">parse_string</span> <span class="special">]</span> |
| <span class="special">/</span> <span class="identifier">kwd</span><span class="special">(</span><span class="string">"age"</span><span class="special">)</span> <span class="special">[</span><span class="char">'='</span> <span class="special">></span> <span class="identifier">int_</span><span class="special">]</span> |
| <span class="special">/</span> <span class="identifier">kwd</span><span class="special">(</span><span class="string">"size"</span><span class="special">)</span> <span class="special">[</span><span class="char">'='</span> <span class="special">></span> <span class="identifier">double_</span> <span class="special">></span> <span class="char">'m'</span><span class="special">]</span> |
| <span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| A couple of input string variations run on the same parser: |
| </p> |
| <p> |
| Parsing a keyword list: |
| </p> |
| <p> |
| </p> |
| <pre class="programlisting"><span class="comment">// Let's declare a small list of people for which we want to collect information.</span> |
| <span class="identifier">person</span> <span class="identifier">John</span><span class="special">,</span><span class="identifier">Mary</span><span class="special">,</span><span class="identifier">Mike</span><span class="special">,</span><span class="identifier">Hellen</span><span class="special">,</span><span class="identifier">Johny</span><span class="special">;</span> |
| <span class="identifier">test_phrase_parser_attr</span><span class="special">(</span> |
| <span class="string">"name = \"John\" \n age = 10 \n size = 1.69m "</span> |
| <span class="special">,</span><span class="identifier">no_constraint_person_rule</span> |
| <span class="special">,</span><span class="identifier">John</span><span class="special">);</span> <span class="comment">// full in orginal order</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special"><<</span><span class="identifier">John</span><span class="special">;</span> |
| |
| <span class="identifier">test_phrase_parser_attr</span><span class="special">(</span> |
| <span class="string">"age = 10 \n size = 1.69m \n name = \"Mary\""</span> |
| <span class="special">,</span><span class="identifier">no_constraint_person_rule</span> |
| <span class="special">,</span><span class="identifier">Mary</span><span class="special">);</span> <span class="comment">// keyword oder doesn't matter</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special"><<</span><span class="identifier">Mary</span><span class="special">;</span> |
| |
| <span class="identifier">test_phrase_parser_attr</span><span class="special">(</span> |
| <span class="string">"size = 1.69m \n name = \"Mike\" \n age = 10 "</span> |
| <span class="special">,</span><span class="identifier">no_constraint_person_rule</span> |
| <span class="special">,</span><span class="identifier">Mike</span><span class="special">);</span> <span class="comment">// still the same result</span> |
| |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special"><<</span><span class="identifier">Mike</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| The code above will print: |
| </p> |
| <pre class="programlisting">Person : John, 10, 1.69 |
| Person : Mary, 10, 1.69 |
| Person : Mike, 10, 1.69 |
| </pre> |
| <p> |
| Now let's delcare a parser with some occurence constraints: |
| </p> |
| <p> |
| The parser definition below uses the kwd directive occurence constraint |
| variants to make sure that the name and age keyword occur only once and |
| allows the favorite color entry to appear 0 or more times. |
| </p> |
| <p> |
| </p> |
| <pre class="programlisting"><span class="identifier">constraint_person_rule</span> <span class="special">%=</span> |
| <span class="identifier">kwd</span><span class="special">(</span><span class="string">"name"</span><span class="special">,</span><span class="number">1</span><span class="special">)</span> <span class="special">[</span><span class="char">'='</span> <span class="special">></span> <span class="identifier">parse_string</span> <span class="special">]</span> |
| <span class="special">/</span> <span class="identifier">kwd</span><span class="special">(</span><span class="string">"age"</span> <span class="special">,</span><span class="number">1</span><span class="special">)</span> <span class="special">[</span><span class="char">'='</span> <span class="special">></span> <span class="identifier">int_</span><span class="special">]</span> |
| <span class="special">/</span> <span class="identifier">kwd</span><span class="special">(</span><span class="string">"size"</span> <span class="special">,</span><span class="number">1</span><span class="special">)</span> <span class="special">[</span><span class="char">'='</span> <span class="special">></span> <span class="identifier">double_</span> <span class="special">></span> <span class="char">'m'</span><span class="special">]</span> |
| <span class="special">/</span> <span class="identifier">kwd</span><span class="special">(</span><span class="string">"favorite color"</span><span class="special">,</span><span class="number">0</span><span class="special">,</span><span class="identifier">inf</span><span class="special">)</span> <span class="special">[</span> <span class="char">'='</span> <span class="special">></span> <span class="identifier">parse_string</span> <span class="special">]</span> |
| <span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| And see how it works in these two cases: |
| </p> |
| <p> |
| </p> |
| <pre class="programlisting"> <span class="comment">// Here all the give constraint are resepected : parsing will succeed.</span> |
| <span class="identifier">test_phrase_parser_attr</span><span class="special">(</span> |
| <span class="string">"name = \"Hellen\" \n age = 10 \n size = 1.80m \n favorite color = \"blue\" \n favorite color = \"green\" "</span> |
| <span class="special">,</span><span class="identifier">constraint_person_rule</span> |
| <span class="special">,</span><span class="identifier">Hellen</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="identifier">Hellen</span><span class="special">;</span> |
| |
| <span class="comment">// Parsing this string will fail because the age and size minimum occurence requirements aren't met.</span> |
| <span class="identifier">test_phrase_parser_attr</span><span class="special">(</span> |
| <span class="string">"name = \"Johny\" \n favorite color = \"blue\" \n favorite color = \"green\" "</span> |
| <span class="special">,</span><span class="identifier">constraint_person_rule</span> |
| <span class="special">,</span><span class="identifier">Johny</span> <span class="special">);</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| Parsing the first string will succeed but fail for the second string as |
| the occurence constraints aren't met. This code should print: |
| </p> |
| <pre class="programlisting">Person : Hellen, 10, 1.8 |
| blue |
| green |
| </pre> |
| </div> |
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| <td align="right"><div class="copyright-footer">Copyright © 2001-2011 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>) |
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