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| <a name="Classes-1"></a> |
| <h4 class="subsection">10.10.3 Classes</h4> |
| <a name="index-class_002c-scope"></a> |
| <a name="index-RECORD_005fTYPE-1"></a> |
| <a name="index-UNION_005fTYPE-1"></a> |
| <a name="index-CLASSTYPE_005fDECLARED_005fCLASS"></a> |
| <a name="index-TYPE_005fBINFO"></a> |
| <a name="index-BINFO_005fTYPE"></a> |
| <a name="index-TYPE_005fFIELDS-2"></a> |
| <a name="index-TYPE_005fVFIELD"></a> |
| <a name="index-TYPE_005fMETHODS"></a> |
| |
| <p>Besides namespaces, the other high-level scoping construct in C++ is the |
| class. (Throughout this manual the term <em>class</em> is used to mean the |
| types referred to in the ANSI/ISO C++ Standard as classes; these include |
| types defined with the <code>class</code>, <code>struct</code>, and <code>union</code> |
| keywords.) |
| </p> |
| <p>A class type is represented by either a <code>RECORD_TYPE</code> or a |
| <code>UNION_TYPE</code>. A class declared with the <code>union</code> tag is |
| represented by a <code>UNION_TYPE</code>, while classes declared with either |
| the <code>struct</code> or the <code>class</code> tag are represented by |
| <code>RECORD_TYPE</code>s. You can use the <code>CLASSTYPE_DECLARED_CLASS</code> |
| macro to discern whether or not a particular type is a <code>class</code> as |
| opposed to a <code>struct</code>. This macro will be true only for classes |
| declared with the <code>class</code> tag. |
| </p> |
| <p>Almost all non-function members are available on the <code>TYPE_FIELDS</code> |
| list. Given one member, the next can be found by following the |
| <code>TREE_CHAIN</code>. You should not depend in any way on the order in |
| which fields appear on this list. All nodes on this list will be |
| ‘<samp>DECL</samp>’ nodes. A <code>FIELD_DECL</code> is used to represent a non-static |
| data member, a <code>VAR_DECL</code> is used to represent a static data |
| member, and a <code>TYPE_DECL</code> is used to represent a type. Note that |
| the <code>CONST_DECL</code> for an enumeration constant will appear on this |
| list, if the enumeration type was declared in the class. (Of course, |
| the <code>TYPE_DECL</code> for the enumeration type will appear here as well.) |
| There are no entries for base classes on this list. In particular, |
| there is no <code>FIELD_DECL</code> for the “base-class portion” of an |
| object. |
| </p> |
| <p>The <code>TYPE_VFIELD</code> is a compiler-generated field used to point to |
| virtual function tables. It may or may not appear on the |
| <code>TYPE_FIELDS</code> list. However, back ends should handle the |
| <code>TYPE_VFIELD</code> just like all the entries on the <code>TYPE_FIELDS</code> |
| list. |
| </p> |
| <p>The function members are available on the <code>TYPE_METHODS</code> list. |
| Again, subsequent members are found by following the <code>TREE_CHAIN</code> |
| field. If a function is overloaded, each of the overloaded functions |
| appears; no <code>OVERLOAD</code> nodes appear on the <code>TYPE_METHODS</code> |
| list. Implicitly declared functions (including default constructors, |
| copy constructors, assignment operators, and destructors) will appear on |
| this list as well. |
| </p> |
| <p>Every class has an associated <em>binfo</em>, which can be obtained with |
| <code>TYPE_BINFO</code>. Binfos are used to represent base-classes. The |
| binfo given by <code>TYPE_BINFO</code> is the degenerate case, whereby every |
| class is considered to be its own base-class. The base binfos for a |
| particular binfo are held in a vector, whose length is obtained with |
| <code>BINFO_N_BASE_BINFOS</code>. The base binfos themselves are obtained |
| with <code>BINFO_BASE_BINFO</code> and <code>BINFO_BASE_ITERATE</code>. To add a |
| new binfo, use <code>BINFO_BASE_APPEND</code>. The vector of base binfos can |
| be obtained with <code>BINFO_BASE_BINFOS</code>, but normally you do not need |
| to use that. The class type associated with a binfo is given by |
| <code>BINFO_TYPE</code>. It is not always the case that <code>BINFO_TYPE |
| (TYPE_BINFO (x))</code>, because of typedefs and qualified types. Neither is |
| it the case that <code>TYPE_BINFO (BINFO_TYPE (y))</code> is the same binfo as |
| <code>y</code>. The reason is that if <code>y</code> is a binfo representing a |
| base-class <code>B</code> of a derived class <code>D</code>, then <code>BINFO_TYPE |
| (y)</code> will be <code>B</code>, and <code>TYPE_BINFO (BINFO_TYPE (y))</code> will be |
| <code>B</code> as its own base-class, rather than as a base-class of <code>D</code>. |
| </p> |
| <p>The access to a base type can be found with <code>BINFO_BASE_ACCESS</code>. |
| This will produce <code>access_public_node</code>, <code>access_private_node</code> |
| or <code>access_protected_node</code>. If bases are always public, |
| <code>BINFO_BASE_ACCESSES</code> may be <code>NULL</code>. |
| </p> |
| <p><code>BINFO_VIRTUAL_P</code> is used to specify whether the binfo is inherited |
| virtually or not. The other flags, <code>BINFO_MARKED_P</code> and |
| <code>BINFO_FLAG_1</code> to <code>BINFO_FLAG_6</code> can be used for language |
| specific use. |
| </p> |
| <p>The following macros can be used on a tree node representing a class-type. |
| </p> |
| <dl compact="compact"> |
| <dt><code>LOCAL_CLASS_P</code> |
| <a name="index-LOCAL_005fCLASS_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds if the class is local class <em>i.e.</em> declared |
| inside a function body. |
| </p> |
| </dd> |
| <dt><code>TYPE_POLYMORPHIC_P</code> |
| <a name="index-TYPE_005fPOLYMORPHIC_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds if the class has at least one virtual function |
| (declared or inherited). |
| </p> |
| </dd> |
| <dt><code>TYPE_HAS_DEFAULT_CONSTRUCTOR</code> |
| <a name="index-TYPE_005fHAS_005fDEFAULT_005fCONSTRUCTOR"></a> |
| </dt> |
| <dd><p>This predicate holds whenever its argument represents a class-type with |
| default constructor. |
| </p> |
| </dd> |
| <dt><code>CLASSTYPE_HAS_MUTABLE</code> |
| <a name="index-CLASSTYPE_005fHAS_005fMUTABLE"></a> |
| </dt> |
| <dt><code>TYPE_HAS_MUTABLE_P</code> |
| <a name="index-TYPE_005fHAS_005fMUTABLE_005fP"></a> |
| </dt> |
| <dd><p>These predicates hold for a class-type having a mutable data member. |
| </p> |
| </dd> |
| <dt><code>CLASSTYPE_NON_POD_P</code> |
| <a name="index-CLASSTYPE_005fNON_005fPOD_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds only for class-types that are not PODs. |
| </p> |
| </dd> |
| <dt><code>TYPE_HAS_NEW_OPERATOR</code> |
| <a name="index-TYPE_005fHAS_005fNEW_005fOPERATOR"></a> |
| </dt> |
| <dd><p>This predicate holds for a class-type that defines |
| <code>operator new</code>. |
| </p> |
| </dd> |
| <dt><code>TYPE_HAS_ARRAY_NEW_OPERATOR</code> |
| <a name="index-TYPE_005fHAS_005fARRAY_005fNEW_005fOPERATOR"></a> |
| </dt> |
| <dd><p>This predicate holds for a class-type for which |
| <code>operator new[]</code> is defined. |
| </p> |
| </dd> |
| <dt><code>TYPE_OVERLOADS_CALL_EXPR</code> |
| <a name="index-TYPE_005fOVERLOADS_005fCALL_005fEXPR"></a> |
| </dt> |
| <dd><p>This predicate holds for class-type for which the function call |
| <code>operator()</code> is overloaded. |
| </p> |
| </dd> |
| <dt><code>TYPE_OVERLOADS_ARRAY_REF</code> |
| <a name="index-TYPE_005fOVERLOADS_005fARRAY_005fREF"></a> |
| </dt> |
| <dd><p>This predicate holds for a class-type that overloads |
| <code>operator[]</code> |
| </p> |
| </dd> |
| <dt><code>TYPE_OVERLOADS_ARROW</code> |
| <a name="index-TYPE_005fOVERLOADS_005fARROW"></a> |
| </dt> |
| <dd><p>This predicate holds for a class-type for which <code>operator-></code> is |
| overloaded. |
| </p> |
| </dd> |
| </dl> |
| |
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