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| <a name="Registering-custom-attributes-or-pragmas"></a> |
| <h3 class="section">23.6 Registering custom attributes or pragmas</h3> |
| |
| <p>For analysis (or other) purposes it is useful to be able to add custom |
| attributes or pragmas. |
| </p> |
| <p>The <code>PLUGIN_ATTRIBUTES</code> callback is called during attribute |
| registration. Use the <code>register_attribute</code> function to register |
| custom attributes. |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">/* Attribute handler callback */ |
| static tree |
| handle_user_attribute (tree *node, tree name, tree args, |
| int flags, bool *no_add_attrs) |
| { |
| return NULL_TREE; |
| } |
| |
| /* Attribute definition */ |
| static struct attribute_spec user_attr = |
| { "user", 1, 1, false, false, false, handle_user_attribute, false }; |
| |
| /* Plugin callback called during attribute registration. |
| Registered with register_callback (plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL) |
| */ |
| static void |
| register_attributes (void *event_data, void *data) |
| { |
| warning (0, G_("Callback to register attributes")); |
| register_attribute (&user_attr); |
| } |
| |
| </pre></div> |
| |
| |
| <p>The <i>PLUGIN_PRAGMAS</i> callback is called once during pragmas |
| registration. Use the <code>c_register_pragma</code>, |
| <code>c_register_pragma_with_data</code>, |
| <code>c_register_pragma_with_expansion</code>, |
| <code>c_register_pragma_with_expansion_and_data</code> functions to register |
| custom pragmas and their handlers (which often want to call |
| <code>pragma_lex</code>) from <samp>c-family/c-pragma.h</samp>. |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">/* Plugin callback called during pragmas registration. Registered with |
| register_callback (plugin_name, PLUGIN_PRAGMAS, |
| register_my_pragma, NULL); |
| */ |
| static void |
| register_my_pragma (void *event_data, void *data) |
| { |
| warning (0, G_("Callback to register pragmas")); |
| c_register_pragma ("GCCPLUGIN", "sayhello", handle_pragma_sayhello); |
| } |
| </pre></div> |
| |
| <p>It is suggested to pass <code>"GCCPLUGIN"</code> (or a short name identifying |
| your plugin) as the “space” argument of your pragma. |
| </p> |
| <p>Pragmas registered with <code>c_register_pragma_with_expansion</code> or |
| <code>c_register_pragma_with_expansion_and_data</code> support |
| preprocessor expansions. For example: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">#define NUMBER 10 |
| #pragma GCCPLUGIN foothreshold (NUMBER) |
| </pre></div> |
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