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| <a name="Namespaces-1"></a> |
| <h4 class="subsection">10.10.2 Namespaces</h4> |
| <a name="index-namespace_002c-scope"></a> |
| <a name="index-NAMESPACE_005fDECL-1"></a> |
| |
| <p>The root of the entire intermediate representation is the variable |
| <code>global_namespace</code>. This is the namespace specified with <code>::</code> |
| in C++ source code. All other namespaces, types, variables, functions, |
| and so forth can be found starting with this namespace. |
| </p> |
| <p>However, except for the fact that it is distinguished as the root of the |
| representation, the global namespace is no different from any other |
| namespace. Thus, in what follows, we describe namespaces generally, |
| rather than the global namespace in particular. |
| </p> |
| <p>A namespace is represented by a <code>NAMESPACE_DECL</code> node. |
| </p> |
| <p>The following macros and functions can be used on a <code>NAMESPACE_DECL</code>: |
| </p> |
| <dl compact="compact"> |
| <dt><code>DECL_NAME</code> |
| <a name="index-DECL_005fNAME-3"></a> |
| </dt> |
| <dd><p>This macro is used to obtain the <code>IDENTIFIER_NODE</code> corresponding to |
| the unqualified name of the name of the namespace (see <a href="Identifiers.html#Identifiers">Identifiers</a>). |
| The name of the global namespace is ‘<samp>::</samp>’, even though in C++ the |
| global namespace is unnamed. However, you should use comparison with |
| <code>global_namespace</code>, rather than <code>DECL_NAME</code> to determine |
| whether or not a namespace is the global one. An unnamed namespace |
| will have a <code>DECL_NAME</code> equal to <code>anonymous_namespace_name</code>. |
| Within a single translation unit, all unnamed namespaces will have the |
| same name. |
| </p> |
| </dd> |
| <dt><code>DECL_CONTEXT</code> |
| <a name="index-DECL_005fCONTEXT"></a> |
| </dt> |
| <dd><p>This macro returns the enclosing namespace. The <code>DECL_CONTEXT</code> for |
| the <code>global_namespace</code> is <code>NULL_TREE</code>. |
| </p> |
| </dd> |
| <dt><code>DECL_NAMESPACE_ALIAS</code> |
| <a name="index-DECL_005fNAMESPACE_005fALIAS"></a> |
| </dt> |
| <dd><p>If this declaration is for a namespace alias, then |
| <code>DECL_NAMESPACE_ALIAS</code> is the namespace for which this one is an |
| alias. |
| </p> |
| <p>Do not attempt to use <code>cp_namespace_decls</code> for a namespace which is |
| an alias. Instead, follow <code>DECL_NAMESPACE_ALIAS</code> links until you |
| reach an ordinary, non-alias, namespace, and call |
| <code>cp_namespace_decls</code> there. |
| </p> |
| </dd> |
| <dt><code>DECL_NAMESPACE_STD_P</code> |
| <a name="index-DECL_005fNAMESPACE_005fSTD_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds if the namespace is the special <code>::std</code> |
| namespace. |
| </p> |
| </dd> |
| <dt><code>cp_namespace_decls</code> |
| <a name="index-cp_005fnamespace_005fdecls"></a> |
| </dt> |
| <dd><p>This function will return the declarations contained in the namespace, |
| including types, overloaded functions, other namespaces, and so forth. |
| If there are no declarations, this function will return |
| <code>NULL_TREE</code>. The declarations are connected through their |
| <code>TREE_CHAIN</code> fields. |
| </p> |
| <p>Although most entries on this list will be declarations, |
| <code>TREE_LIST</code> nodes may also appear. In this case, the |
| <code>TREE_VALUE</code> will be an <code>OVERLOAD</code>. The value of the |
| <code>TREE_PURPOSE</code> is unspecified; back ends should ignore this value. |
| As with the other kinds of declarations returned by |
| <code>cp_namespace_decls</code>, the <code>TREE_CHAIN</code> will point to the next |
| declaration in this list. |
| </p> |
| <p>For more information on the kinds of declarations that can occur on this |
| list, See <a href="Declarations.html#Declarations">Declarations</a>. Some declarations will not appear on this |
| list. In particular, no <code>FIELD_DECL</code>, <code>LABEL_DECL</code>, or |
| <code>PARM_DECL</code> nodes will appear here. |
| </p> |
| <p>This function cannot be used with namespaces that have |
| <code>DECL_NAMESPACE_ALIAS</code> set. |
| </p> |
| </dd> |
| </dl> |
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