177 lines
7.8 KiB
HTML
177 lines
7.8 KiB
HTML
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<head>
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<title>GNU Compiler Collection (GCC) Internals: Namespaces</title>
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<meta name="description" content="GNU Compiler Collection (GCC) Internals: Namespaces">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="C-and-C_002b_002b-Trees.html#C-and-C_002b_002b-Trees" rel="up" title="C and C++ Trees">
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<link href="Classes.html#Classes" rel="next" title="Classes">
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="Namespaces"></a>
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<div class="header">
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<p>
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Next: <a href="Classes.html#Classes" accesskey="n" rel="next">Classes</a>, Previous: <a href="Types-for-C_002b_002b.html#Types-for-C_002b_002b" accesskey="p" rel="prev">Types for C++</a>, Up: <a href="C-and-C_002b_002b-Trees.html#C-and-C_002b_002b-Trees" accesskey="u" rel="up">C and C++ Trees</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Namespaces-1"></a>
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<h4 class="subsection">10.10.2 Namespaces</h4>
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<a name="index-namespace_002c-scope"></a>
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<a name="index-NAMESPACE_005fDECL-1"></a>
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<p>The root of the entire intermediate representation is the variable
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<code>global_namespace</code>. This is the namespace specified with <code>::</code>
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in C++ source code. All other namespaces, types, variables, functions,
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and so forth can be found starting with this namespace.
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</p>
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<p>However, except for the fact that it is distinguished as the root of the
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representation, the global namespace is no different from any other
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namespace. Thus, in what follows, we describe namespaces generally,
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rather than the global namespace in particular.
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</p>
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<p>A namespace is represented by a <code>NAMESPACE_DECL</code> node.
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</p>
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<p>The following macros and functions can be used on a <code>NAMESPACE_DECL</code>:
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</p>
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<dl compact="compact">
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<dt><code>DECL_NAME</code>
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<a name="index-DECL_005fNAME-3"></a>
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</dt>
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<dd><p>This macro is used to obtain the <code>IDENTIFIER_NODE</code> corresponding to
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the unqualified name of the name of the namespace (see <a href="Identifiers.html#Identifiers">Identifiers</a>).
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The name of the global namespace is ‘<samp>::</samp>’, even though in C++ the
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global namespace is unnamed. However, you should use comparison with
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<code>global_namespace</code>, rather than <code>DECL_NAME</code> to determine
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whether or not a namespace is the global one. An unnamed namespace
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will have a <code>DECL_NAME</code> equal to <code>anonymous_namespace_name</code>.
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Within a single translation unit, all unnamed namespaces will have the
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same name.
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</p>
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</dd>
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<dt><code>DECL_CONTEXT</code>
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<a name="index-DECL_005fCONTEXT"></a>
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</dt>
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<dd><p>This macro returns the enclosing namespace. The <code>DECL_CONTEXT</code> for
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the <code>global_namespace</code> is <code>NULL_TREE</code>.
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</p>
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</dd>
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<dt><code>DECL_NAMESPACE_ALIAS</code>
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<a name="index-DECL_005fNAMESPACE_005fALIAS"></a>
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</dt>
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<dd><p>If this declaration is for a namespace alias, then
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<code>DECL_NAMESPACE_ALIAS</code> is the namespace for which this one is an
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alias.
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</p>
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<p>Do not attempt to use <code>cp_namespace_decls</code> for a namespace which is
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an alias. Instead, follow <code>DECL_NAMESPACE_ALIAS</code> links until you
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reach an ordinary, non-alias, namespace, and call
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<code>cp_namespace_decls</code> there.
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</p>
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</dd>
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<dt><code>DECL_NAMESPACE_STD_P</code>
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<a name="index-DECL_005fNAMESPACE_005fSTD_005fP"></a>
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</dt>
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<dd><p>This predicate holds if the namespace is the special <code>::std</code>
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namespace.
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</p>
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</dd>
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<dt><code>cp_namespace_decls</code>
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<a name="index-cp_005fnamespace_005fdecls"></a>
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</dt>
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<dd><p>This function will return the declarations contained in the namespace,
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including types, overloaded functions, other namespaces, and so forth.
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If there are no declarations, this function will return
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<code>NULL_TREE</code>. The declarations are connected through their
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<code>TREE_CHAIN</code> fields.
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</p>
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<p>Although most entries on this list will be declarations,
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<code>TREE_LIST</code> nodes may also appear. In this case, the
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<code>TREE_VALUE</code> will be an <code>OVERLOAD</code>. The value of the
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<code>TREE_PURPOSE</code> is unspecified; back ends should ignore this value.
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As with the other kinds of declarations returned by
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<code>cp_namespace_decls</code>, the <code>TREE_CHAIN</code> will point to the next
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declaration in this list.
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</p>
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<p>For more information on the kinds of declarations that can occur on this
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list, See <a href="Declarations.html#Declarations">Declarations</a>. Some declarations will not appear on this
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list. In particular, no <code>FIELD_DECL</code>, <code>LABEL_DECL</code>, or
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<code>PARM_DECL</code> nodes will appear here.
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</p>
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<p>This function cannot be used with namespaces that have
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<code>DECL_NAMESPACE_ALIAS</code> set.
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</p>
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</dd>
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</dl>
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<hr>
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<div class="header">
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<p>
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Next: <a href="Classes.html#Classes" accesskey="n" rel="next">Classes</a>, Previous: <a href="Types-for-C_002b_002b.html#Types-for-C_002b_002b" accesskey="p" rel="prev">Types for C++</a>, Up: <a href="C-and-C_002b_002b-Trees.html#C-and-C_002b_002b-Trees" accesskey="u" rel="up">C and C++ Trees</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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</body>
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