mirror of
https://github.com/ruby/ruby.git
synced 2022-11-09 12:17:21 -05:00
142 lines
4.3 KiB
C
142 lines
4.3 KiB
C
/* CC0 (Public domain) - see ccan/licenses/CC0 file for details */
|
|
#ifndef CCAN_CONTAINER_OF_H
|
|
#define CCAN_CONTAINER_OF_H
|
|
#include "ccan/check_type/check_type.h"
|
|
|
|
/**
|
|
* ccan_container_of - get pointer to enclosing structure
|
|
* @member_ptr: pointer to the structure member
|
|
* @containing_type: the type this member is within
|
|
* @member: the name of this member within the structure.
|
|
*
|
|
* Given a pointer to a member of a structure, this macro does pointer
|
|
* subtraction to return the pointer to the enclosing type.
|
|
*
|
|
* Example:
|
|
* struct foo {
|
|
* int fielda, fieldb;
|
|
* // ...
|
|
* };
|
|
* struct info {
|
|
* int some_other_field;
|
|
* struct foo my_foo;
|
|
* };
|
|
*
|
|
* static struct info *foo_to_info(struct foo *foo)
|
|
* {
|
|
* return ccan_container_of(foo, struct info, my_foo);
|
|
* }
|
|
*/
|
|
#define ccan_container_of(member_ptr, containing_type, member) \
|
|
((containing_type *) \
|
|
((char *)(member_ptr) \
|
|
- ccan_container_off(containing_type, member)) \
|
|
+ ccan_check_types_match(*(member_ptr), ((containing_type *)0)->member))
|
|
|
|
|
|
/**
|
|
* ccan_container_of_or_null - get pointer to enclosing structure, or NULL
|
|
* @member_ptr: pointer to the structure member
|
|
* @containing_type: the type this member is within
|
|
* @member: the name of this member within the structure.
|
|
*
|
|
* Given a pointer to a member of a structure, this macro does pointer
|
|
* subtraction to return the pointer to the enclosing type, unless it
|
|
* is given NULL, in which case it also returns NULL.
|
|
*
|
|
* Example:
|
|
* struct foo {
|
|
* int fielda, fieldb;
|
|
* // ...
|
|
* };
|
|
* struct info {
|
|
* int some_other_field;
|
|
* struct foo my_foo;
|
|
* };
|
|
*
|
|
* static struct info *foo_to_info_allowing_null(struct foo *foo)
|
|
* {
|
|
* return ccan_container_of_or_null(foo, struct info, my_foo);
|
|
* }
|
|
*/
|
|
static inline char *container_of_or_null_(void *member_ptr, size_t offset)
|
|
{
|
|
return member_ptr ? (char *)member_ptr - offset : NULL;
|
|
}
|
|
#define ccan_container_of_or_null(member_ptr, containing_type, member) \
|
|
((containing_type *) \
|
|
ccan_container_of_or_null_(member_ptr, \
|
|
ccan_container_off(containing_type, member)) \
|
|
+ ccan_check_types_match(*(member_ptr), ((containing_type *)0)->member))
|
|
|
|
/**
|
|
* ccan_container_off - get offset to enclosing structure
|
|
* @containing_type: the type this member is within
|
|
* @member: the name of this member within the structure.
|
|
*
|
|
* Given a pointer to a member of a structure, this macro does
|
|
* typechecking and figures out the offset to the enclosing type.
|
|
*
|
|
* Example:
|
|
* struct foo {
|
|
* int fielda, fieldb;
|
|
* // ...
|
|
* };
|
|
* struct info {
|
|
* int some_other_field;
|
|
* struct foo my_foo;
|
|
* };
|
|
*
|
|
* static struct info *foo_to_info(struct foo *foo)
|
|
* {
|
|
* size_t off = ccan_container_off(struct info, my_foo);
|
|
* return (void *)((char *)foo - off);
|
|
* }
|
|
*/
|
|
#define ccan_container_off(containing_type, member) \
|
|
offsetof(containing_type, member)
|
|
|
|
/**
|
|
* ccan_container_of_var - get pointer to enclosing structure using a variable
|
|
* @member_ptr: pointer to the structure member
|
|
* @container_var: a pointer of same type as this member's container
|
|
* @member: the name of this member within the structure.
|
|
*
|
|
* Given a pointer to a member of a structure, this macro does pointer
|
|
* subtraction to return the pointer to the enclosing type.
|
|
*
|
|
* Example:
|
|
* static struct info *foo_to_i(struct foo *foo)
|
|
* {
|
|
* struct info *i = ccan_container_of_var(foo, i, my_foo);
|
|
* return i;
|
|
* }
|
|
*/
|
|
#if defined(HAVE_TYPEOF) && HAVE_TYPEOF
|
|
#define ccan_container_of_var(member_ptr, container_var, member) \
|
|
ccan_container_of(member_ptr, typeof(*container_var), member)
|
|
#else
|
|
#define ccan_container_of_var(member_ptr, container_var, member) \
|
|
((void *)((char *)(member_ptr) - \
|
|
ccan_container_off_var(container_var, member)))
|
|
#endif
|
|
|
|
/**
|
|
* ccan_container_off_var - get offset of a field in enclosing structure
|
|
* @container_var: a pointer to a container structure
|
|
* @member: the name of a member within the structure.
|
|
*
|
|
* Given (any) pointer to a structure and a its member name, this
|
|
* macro does pointer subtraction to return offset of member in a
|
|
* structure memory layout.
|
|
*
|
|
*/
|
|
#if defined(HAVE_TYPEOF) && HAVE_TYPEOF
|
|
#define ccan_container_off_var(var, member) \
|
|
ccan_container_off(typeof(*var), member)
|
|
#else
|
|
#define ccan_container_off_var(var, member) \
|
|
((const char *)&(var)->member - (const char *)(var))
|
|
#endif
|
|
|
|
#endif /* CCAN_CONTAINER_OF_H */
|