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9.4.2 Classes
A class type is represented by either a RECORD_TYPE or a
UNION_TYPE. A class declared with the union tag is
represented by a UNION_TYPE, while classes declared with either
the struct or the class tag are represented by
RECORD_TYPEs. You can use the CLASSTYPE_DECLARED_CLASS
macro to discern whether or not a particular type is a class as
opposed to a struct. This macro will be true only for classes
declared with the class tag.
Almost all non-function members are available on the TYPE_FIELDS
list. Given one member, the next can be found by following the
TREE_CHAIN. You should not depend in any way on the order in
which fields appear on this list. All nodes on this list will be
`DECL' nodes. A FIELD_DECL is used to represent a non-static
data member, a VAR_DECL is used to represent a static data
member, and a TYPE_DECL is used to represent a type. Note that
the CONST_DECL for an enumeration constant will appear on this
list, if the enumeration type was declared in the class. (Of course,
the TYPE_DECL for the enumeration type will appear here as well.)
There are no entries for base classes on this list. In particular,
there is no FIELD_DECL for the “base-class portion” of an
object.
The TYPE_VFIELD is a compiler-generated field used to point to
virtual function tables. It may or may not appear on the
TYPE_FIELDS list. However, back ends should handle the
TYPE_VFIELD just like all the entries on the TYPE_FIELDS
list.
The function members are available on the TYPE_METHODS list.
Again, subsequent members are found by following the TREE_CHAIN
field. If a function is overloaded, each of the overloaded functions
appears; no OVERLOAD nodes appear on the TYPE_METHODS
list. Implicitly declared functions (including default constructors,
copy constructors, assignment operators, and destructors) will appear on
this list as well.
Every class has an associated binfo, which can be obtained with
TYPE_BINFO. Binfos are used to represent base-classes. The
binfo given by TYPE_BINFO 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
BINFO_N_BASE_BINFOS. The base binfos themselves are obtained
with BINFO_BASE_BINFO and BINFO_BASE_ITERATE. To add a
new binfo, use BINFO_BASE_APPEND. The vector of base binfos can
be obtained with BINFO_BASE_BINFOS, but normally you do not need
to use that. The class type associated with a binfo is given by
BINFO_TYPE. It is not always the case that BINFO_TYPE
(TYPE_BINFO (x)), because of typedefs and qualified types. Neither is
it the case that TYPE_BINFO (BINFO_TYPE (y)) is the same binfo as
y. The reason is that if y is a binfo representing a
base-class B of a derived class D, then BINFO_TYPE
(y) will be B, and TYPE_BINFO (BINFO_TYPE (y)) will be
B as its own base-class, rather than as a base-class of D.
The access to a base type can be found with BINFO_BASE_ACCESS.
This will produce access_public_node, access_private_node
or access_protected_node. If bases are always public,
BINFO_BASE_ACCESSES may be NULL.
BINFO_VIRTUAL_P is used to specify whether the binfo is inherited
virtually or not. The other flags, BINFO_MARKED_P and
BINFO_FLAG_1 to BINFO_FLAG_6 can be used for language
specific use.
The following macros can be used on a tree node representing a class-type.
LOCAL_CLASS_P- This predicate holds if the class is local class i.e. declared
inside a function body.
TYPE_POLYMORPHIC_P- This predicate holds if the class has at least one virtual function
(declared or inherited).
TYPE_HAS_DEFAULT_CONSTRUCTOR- This predicate holds whenever its argument represents a class-type with
default constructor.
CLASSTYPE_HAS_MUTABLETYPE_HAS_MUTABLE_P- These predicates hold for a class-type having a mutable data member.
CLASSTYPE_NON_POD_P- This predicate holds only for class-types that are not PODs.
TYPE_HAS_NEW_OPERATOR- This predicate holds for a class-type that defines
operator new. TYPE_HAS_ARRAY_NEW_OPERATOR- This predicate holds for a class-type for which
operator new[]is defined. TYPE_OVERLOADS_CALL_EXPR- This predicate holds for class-type for which the function call
operator()is overloaded. TYPE_OVERLOADS_ARRAY_REF- This predicate holds for a class-type that overloads
operator[] TYPE_OVERLOADS_ARROW- This predicate holds for a class-type for which
operator->is overloaded.