[mirror_edk2.git] / MdePkg / Include / Library / OrderedCollectionLib.h

/** @file\r
  An ordered collection library interface.\r
\r
  The library class provides a set of APIs to manage an ordered collection of\r
  items.\r
\r
  Copyright (C) 2014, Red Hat, Inc.\r
\r
  This program and the accompanying materials are licensed and made available\r
  under the terms and conditions of the BSD License that accompanies this\r
  distribution. The full text of the license may be found at\r
  http://opensource.org/licenses/bsd-license.php.\r
\r
  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT\r
  WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
**/\r
\r
#ifndef __ORDERED_COLLECTION_LIB__\r
#define __ORDERED_COLLECTION_LIB__\r
\r
#include <Base.h>\r
\r
//\r
// Opaque structure for a collection.\r
//\r
typedef struct ORDERED_COLLECTION ORDERED_COLLECTION;\r
\r
//\r
// Opaque structure for collection entries.\r
//\r
// Collection entries do not take ownership of the associated user structures,\r
// they only link them. This makes it easy to link the same user structure into\r
// several collections. If reference counting is required, the caller is\r
// responsible for implementing it, as part of the user structure.\r
//\r
// A pointer-to-ORDERED_COLLECTION_ENTRY is considered an "iterator". Multiple,\r
// simultaneous iterations are supported.\r
//\r
typedef struct ORDERED_COLLECTION_ENTRY ORDERED_COLLECTION_ENTRY;\r
\r
//\r
// Altering the key field of an in-collection user structure (ie. the portion\r
// of the user structure that ORDERED_COLLECTION_USER_COMPARE and\r
// ORDERED_COLLECTION_KEY_COMPARE, below, read) is not allowed in-place. The\r
// caller is responsible for bracketing the key change with the deletion and\r
// the reinsertion of the user structure, so that the changed key value is\r
// reflected in the collection.\r
//\r
\r
/**\r
  Comparator function type for two user structures.\r
\r
  @param[in] UserStruct1  Pointer to the first user structure.\r
\r
  @param[in] UserStruct2  Pointer to the second user structure.\r
\r
  @retval <0  If UserStruct1 compares less than UserStruct2.\r
\r
  @retval  0  If UserStruct1 compares equal to UserStruct2.\r
\r
  @retval >0  If UserStruct1 compares greater than UserStruct2.\r
**/\r
typedef\r
INTN\r
(EFIAPI *ORDERED_COLLECTION_USER_COMPARE)(\r
  IN CONST VOID *UserStruct1,\r
  IN CONST VOID *UserStruct2\r
  );\r
\r
/**\r
  Compare a standalone key against a user structure containing an embedded key.\r
\r
  @param[in] StandaloneKey  Pointer to the bare key.\r
\r
  @param[in] UserStruct     Pointer to the user structure with the embedded\r
                            key.\r
\r
  @retval <0  If StandaloneKey compares less than UserStruct's key.\r
\r
  @retval  0  If StandaloneKey compares equal to UserStruct's key.\r
\r
  @retval >0  If StandaloneKey compares greater than UserStruct's key.\r
**/\r
typedef\r
INTN\r
(EFIAPI *ORDERED_COLLECTION_KEY_COMPARE)(\r
  IN CONST VOID *StandaloneKey,\r
  IN CONST VOID *UserStruct\r
  );\r
\r
\r
//\r
// Some functions below are read-only, while others are read-write. If any\r
// write operation is expected to run concurrently with any other operation on\r
// the same collection, then the caller is responsible for implementing locking\r
// for the whole collection.\r
//\r
\r
/**\r
  Retrieve the user structure linked by the specified collection entry.\r
\r
  Read-only operation.\r
\r
  @param[in] Entry  Pointer to the collection entry whose associated user\r
                    structure we want to retrieve. The caller is responsible\r
                    for passing a non-NULL argument.\r
\r
  @return  Pointer to user structure linked by Entry.\r
**/\r
VOID *\r
EFIAPI\r
OrderedCollectionUserStruct (\r
  IN CONST ORDERED_COLLECTION_ENTRY *Entry\r
  );\r
\r
\r
/**\r
  Allocate and initialize the ORDERED_COLLECTION structure.\r
\r
  @param[in]  UserStructCompare  This caller-provided function will be used to\r
                                 order two user structures linked into the\r
                                 collection, during the insertion procedure.\r
\r
  @param[in]  KeyCompare         This caller-provided function will be used to\r
                                 order the standalone search key against user\r
                                 structures linked into the collection, during\r
                                 the lookup procedure.\r
\r
  @retval NULL  If allocation failed.\r
\r
  @return       Pointer to the allocated, initialized ORDERED_COLLECTION\r
                structure, otherwise.\r
**/\r
ORDERED_COLLECTION *\r
EFIAPI\r
OrderedCollectionInit (\r
  IN ORDERED_COLLECTION_USER_COMPARE UserStructCompare,\r
  IN ORDERED_COLLECTION_KEY_COMPARE  KeyCompare\r
  );\r
\r
\r
/**\r
  Check whether the collection is empty (has no entries).\r
\r
  Read-only operation.\r
\r
  @param[in] Collection  The collection to check for emptiness.\r
\r
  @retval TRUE   The collection is empty.\r
\r
  @retval FALSE  The collection is not empty.\r
**/\r
BOOLEAN\r
EFIAPI\r
OrderedCollectionIsEmpty (\r
  IN CONST ORDERED_COLLECTION *Collection\r
  );\r
\r
\r
/**\r
  Uninitialize and release an empty ORDERED_COLLECTION structure.\r
\r
  Read-write operation.\r
\r
  It is the caller's responsibility to delete all entries from the collection\r
  before calling this function.\r
\r
  @param[in] Collection  The empty collection to uninitialize and release.\r
**/\r
VOID\r
EFIAPI\r
OrderedCollectionUninit (\r
  IN ORDERED_COLLECTION *Collection\r
  );\r
\r
\r
/**\r
  Look up the collection entry that links the user structure that matches the\r
  specified standalone key.\r
\r
  Read-only operation.\r
\r
  @param[in] Collection     The collection to search for StandaloneKey.\r
\r
  @param[in] StandaloneKey  The key to locate among the user structures linked\r
                            into Collection. StandaloneKey will be passed to\r
                            ORDERED_COLLECTION_KEY_COMPARE.\r
\r
  @retval NULL  StandaloneKey could not be found.\r
\r
  @return       The collection entry that links to the user structure matching\r
                StandaloneKey, otherwise.\r
**/\r
ORDERED_COLLECTION_ENTRY *\r
EFIAPI\r
OrderedCollectionFind (\r
  IN CONST ORDERED_COLLECTION *Collection,\r
  IN CONST VOID               *StandaloneKey\r
  );\r
\r
\r
/**\r
  Find the collection entry of the minimum user structure stored in the\r
  collection.\r
\r
  Read-only operation.\r
\r
  @param[in] Collection  The collection to return the minimum entry of. The\r
                         user structure linked by the minimum entry compares\r
                         less than all other user structures in the collection.\r
\r
  @retval NULL  If Collection is empty.\r
\r
  @return       The collection entry that links the minimum user structure,\r
                otherwise.\r
**/\r
ORDERED_COLLECTION_ENTRY *\r
EFIAPI\r
OrderedCollectionMin (\r
  IN CONST ORDERED_COLLECTION *Collection\r
  );\r
\r
\r
/**\r
  Find the collection entry of the maximum user structure stored in the\r
  collection.\r
\r
  Read-only operation.\r
\r
  @param[in] Collection  The collection to return the maximum entry of. The\r
                         user structure linked by the maximum entry compares\r
                         greater than all other user structures in the\r
                         collection.\r
\r
  @retval NULL  If Collection is empty.\r
\r
  @return       The collection entry that links the maximum user structure,\r
                otherwise.\r
**/\r
ORDERED_COLLECTION_ENTRY *\r
EFIAPI\r
OrderedCollectionMax (\r
  IN CONST ORDERED_COLLECTION *Collection\r
  );\r
\r
\r
/**\r
  Get the collection entry of the least user structure that is greater than the\r
  one linked by Entry.\r
\r
  Read-only operation.\r
\r
  @param[in] Entry  The entry to get the successor entry of.\r
\r
  @retval NULL  If Entry is NULL, or Entry is the maximum entry of its\r
                containing collection (ie. Entry has no successor entry).\r
\r
  @return       The collection entry linking the least user structure that is\r
                greater than the one linked by Entry, otherwise.\r
**/\r
ORDERED_COLLECTION_ENTRY *\r
EFIAPI\r
OrderedCollectionNext (\r
  IN CONST ORDERED_COLLECTION_ENTRY *Entry\r
  );\r
\r
\r
/**\r
  Get the collection entry of the greatest user structure that is less than the\r
  one linked by Entry.\r
\r
  Read-only operation.\r
\r
  @param[in] Entry  The entry to get the predecessor entry of.\r
\r
  @retval NULL  If Entry is NULL, or Entry is the minimum entry of its\r
                containing collection (ie. Entry has no predecessor entry).\r
\r
  @return       The collection entry linking the greatest user structure that\r
                is less than the one linked by Entry, otherwise.\r
**/\r
ORDERED_COLLECTION_ENTRY *\r
EFIAPI\r
OrderedCollectionPrev (\r
  IN CONST ORDERED_COLLECTION_ENTRY *Entry\r
  );\r
\r
\r
/**\r
  Insert (link) a user structure into the collection, allocating a new\r
  collection entry.\r
\r
  Read-write operation.\r
\r
  @param[in,out] Collection  The collection to insert UserStruct into.\r
\r
  @param[out]    Entry       The meaning of this optional, output-only\r
                             parameter depends on the return value of the\r
                             function.\r
\r
                             When insertion is successful (RETURN_SUCCESS),\r
                             Entry is set on output to the new collection entry\r
                             that now links UserStruct.\r
\r
                             When insertion fails due to lack of memory\r
                             (RETURN_OUT_OF_RESOURCES), Entry is not changed.\r
\r
                             When insertion fails due to key collision (ie.\r
                             another user structure is already in the\r
                             collection that compares equal to UserStruct),\r
                             with return value RETURN_ALREADY_STARTED, then\r
                             Entry is set on output to the entry that links the\r
                             colliding user structure. This enables\r
                             "find-or-insert" in one function call, or helps\r
                             with later removal of the colliding element.\r
\r
  @param[in]     UserStruct  The user structure to link into the collection.\r
                             UserStruct is ordered against in-collection user\r
                             structures with the\r
                             ORDERED_COLLECTION_USER_COMPARE function.\r
\r
  @retval RETURN_SUCCESS           Insertion successful. A new collection entry\r
                                   has been allocated, linking UserStruct. The\r
                                   new collection entry is reported back in\r
                                   Entry (if the caller requested it).\r
\r
                                   Existing ORDERED_COLLECTION_ENTRY pointers\r
                                   into Collection remain valid. For example,\r
                                   on-going iterations in the caller can\r
                                   continue with OrderedCollectionNext() /\r
                                   OrderedCollectionPrev(), and they will\r
                                   return the new entry at some point if user\r
                                   structure order dictates it.\r
\r
  @retval RETURN_OUT_OF_RESOURCES  The function failed to allocate memory for\r
                                   the new collection entry. The collection has\r
                                   not been changed. Existing\r
                                   ORDERED_COLLECTION_ENTRY pointers into\r
                                   Collection remain valid.\r
\r
  @retval RETURN_ALREADY_STARTED   A user structure has been found in the\r
                                   collection that compares equal to\r
                                   UserStruct. The entry linking the colliding\r
                                   user structure is reported back in Entry (if\r
                                   the caller requested it). The collection has\r
                                   not been changed. Existing\r
                                   ORDERED_COLLECTION_ENTRY pointers into\r
                                   Collection remain valid.\r
**/\r
RETURN_STATUS\r
EFIAPI\r
OrderedCollectionInsert (\r
  IN OUT ORDERED_COLLECTION       *Collection,\r
  OUT    ORDERED_COLLECTION_ENTRY **Entry      OPTIONAL,\r
  IN     VOID                     *UserStruct\r
  );\r
\r
\r
/**\r
  Delete an entry from the collection, unlinking the associated user structure.\r
\r
  Read-write operation.\r
\r
  @param[in,out] Collection  The collection to delete Entry from.\r
\r
  @param[in]     Entry       The collection entry to delete from Collection.\r
                             The caller is responsible for ensuring that Entry\r
                             belongs to Collection, and that Entry is non-NULL\r
                             and valid. Entry is typically an earlier return\r
                             value, or output parameter, of:\r
\r
                             - OrderedCollectionFind(), for deleting an entry\r
                               by user structure key,\r
\r
                             - OrderedCollectionMin() / OrderedCollectionMax(),\r
                               for deleting the minimum / maximum entry,\r
\r
                             - OrderedCollectionNext() /\r
                               OrderedCollectionPrev(), for deleting an entry\r
                               found during an iteration,\r
\r
                             - OrderedCollectionInsert() with return value\r
                               RETURN_ALREADY_STARTED, for deleting an entry\r
                               whose linked user structure caused collision\r
                               during insertion.\r
\r
                             Existing ORDERED_COLLECTION_ENTRY pointers (ie.\r
                             iterators) *different* from Entry remain valid.\r
                             For example:\r
\r
                             - OrderedCollectionNext() /\r
                               OrderedCollectionPrev() iterations in the caller\r
                               can be continued from Entry, if\r
                               OrderedCollectionNext() or\r
                               OrderedCollectionPrev() is called on Entry\r
                               *before* OrderedCollectionDelete() is. That is,\r
                               fetch the successor / predecessor entry first,\r
                               then delete Entry.\r
\r
                             - On-going iterations in the caller that would\r
                               have otherwise returned Entry at some point, as\r
                               dictated by user structure order, will correctly\r
                               reflect the absence of Entry after\r
                               OrderedCollectionDelete() is called\r
                               mid-iteration.\r
\r
  @param[out]    UserStruct  If the caller provides this optional output-only\r
                             parameter, then on output it is set to the user\r
                             structure originally linked by Entry (which is now\r
                             freed).\r
\r
                             This is a convenience that may save the caller a\r
                             OrderedCollectionUserStruct() invocation before\r
                             calling OrderedCollectionDelete(), in order to\r
                             retrieve the user structure being unlinked.\r
**/\r
VOID\r
EFIAPI\r
OrderedCollectionDelete (\r
  IN OUT ORDERED_COLLECTION       *Collection,\r
  IN     ORDERED_COLLECTION_ENTRY *Entry,\r
  OUT    VOID                     **UserStruct OPTIONAL\r
  );\r
\r
#endif\r
Commit	Line	Data
250e4b0d KM	1	/** @file\r
	2	An ordered collection library interface.\r
	3	\r
	4	The library class provides a set of APIs to manage an ordered collection of\r
	5	items.\r
	6	\r
	7	Copyright (C) 2014, Red Hat, Inc.\r
	8	\r
	9	This program and the accompanying materials are licensed and made available\r
	10	under the terms and conditions of the BSD License that accompanies this\r
	11	distribution. The full text of the license may be found at\r
	12	http://opensource.org/licenses/bsd-license.php.\r
	13	\r
	14	THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT\r
	15	WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
	16	**/\r
	17	\r
	18	#ifndef __ORDERED_COLLECTION_LIB__\r
	19	#define __ORDERED_COLLECTION_LIB__\r
	20	\r
	21	#include <Base.h>\r
	22	\r
	23	//\r
	24	// Opaque structure for a collection.\r
	25	//\r
	26	typedef struct ORDERED_COLLECTION ORDERED_COLLECTION;\r
	27	\r
	28	//\r
	29	// Opaque structure for collection entries.\r
	30	//\r
	31	// Collection entries do not take ownership of the associated user structures,\r
	32	// they only link them. This makes it easy to link the same user structure into\r
	33	// several collections. If reference counting is required, the caller is\r
	34	// responsible for implementing it, as part of the user structure.\r
	35	//\r
	36	// A pointer-to-ORDERED_COLLECTION_ENTRY is considered an "iterator". Multiple,\r
	37	// simultaneous iterations are supported.\r
	38	//\r
	39	typedef struct ORDERED_COLLECTION_ENTRY ORDERED_COLLECTION_ENTRY;\r
	40	\r
	41	//\r
	42	// Altering the key field of an in-collection user structure (ie. the portion\r
	43	// of the user structure that ORDERED_COLLECTION_USER_COMPARE and\r
	44	// ORDERED_COLLECTION_KEY_COMPARE, below, read) is not allowed in-place. The\r
	45	// caller is responsible for bracketing the key change with the deletion and\r
	46	// the reinsertion of the user structure, so that the changed key value is\r
	47	// reflected in the collection.\r
	48	//\r
	49	\r
	50	/**\r
	51	Comparator function type for two user structures.\r
	52	\r
	53	@param[in] UserStruct1 Pointer to the first user structure.\r
	54	\r
	55	@param[in] UserStruct2 Pointer to the second user structure.\r
	56	\r
	57	@retval <0 If UserStruct1 compares less than UserStruct2.\r
	58	\r
	59	@retval 0 If UserStruct1 compares equal to UserStruct2.\r
	60	\r
	61	@retval >0 If UserStruct1 compares greater than UserStruct2.\r
	62	**/\r
	63	typedef\r
	64	INTN\r
65	(EFIAPI *ORDERED_COLLECTION_USER_COMPARE)(\r
66	IN CONST VOID *UserStruct1,\r
67	IN CONST VOID *UserStruct2\r
68	);\r
69	\r
70	/**\r
71	Compare a standalone key against a user structure containing an embedded key.\r
72	\r
73	@param[in] StandaloneKey Pointer to the bare key.\r
74	\r
75	@param[in] UserStruct Pointer to the user structure with the embedded\r
76	key.\r
77	\r
78	@retval <0 If StandaloneKey compares less than UserStruct's key.\r
79	\r
80	@retval 0 If StandaloneKey compares equal to UserStruct's key.\r
81	\r
82	@retval >0 If StandaloneKey compares greater than UserStruct's key.\r
83	**/\r
84	typedef\r
85	INTN\r
86	(EFIAPI *ORDERED_COLLECTION_KEY_COMPARE)(\r
87	IN CONST VOID *StandaloneKey,\r
88	IN CONST VOID *UserStruct\r
89	);\r
90	\r
91	\r
92	//\r
93	// Some functions below are read-only, while others are read-write. If any\r
94	// write operation is expected to run concurrently with any other operation on\r
95	// the same collection, then the caller is responsible for implementing locking\r
96	// for the whole collection.\r
97	//\r
98	\r
99	/**\r
100	Retrieve the user structure linked by the specified collection entry.\r
101	\r
102	Read-only operation.\r
103	\r
104	@param[in] Entry Pointer to the collection entry whose associated user\r
105	structure we want to retrieve. The caller is responsible\r
106	for passing a non-NULL argument.\r
107	\r
108	@return Pointer to user structure linked by Entry.\r
109	**/\r
110	VOID *\r
111	EFIAPI\r
112	OrderedCollectionUserStruct (\r
113	IN CONST ORDERED_COLLECTION_ENTRY *Entry\r
114	);\r
115	\r
116	\r
117	/**\r
118	Allocate and initialize the ORDERED_COLLECTION structure.\r
119	\r
120	@param[in] UserStructCompare This caller-provided function will be used to\r
121	order two user structures linked into the\r
122	collection, during the insertion procedure.\r
123	\r
124	@param[in] KeyCompare This caller-provided function will be used to\r
125	order the standalone search key against user\r
126	structures linked into the collection, during\r
127	the lookup procedure.\r
128	\r
129	@retval NULL If allocation failed.\r
130	\r
131	@return Pointer to the allocated, initialized ORDERED_COLLECTION\r
132	structure, otherwise.\r
133	**/\r
134	ORDERED_COLLECTION *\r
135	EFIAPI\r
136	OrderedCollectionInit (\r
137	IN ORDERED_COLLECTION_USER_COMPARE UserStructCompare,\r
138	IN ORDERED_COLLECTION_KEY_COMPARE KeyCompare\r
139	);\r
140	\r
141	\r
142	/**\r
143	Check whether the collection is empty (has no entries).\r
144	\r
145	Read-only operation.\r
146	\r
147	@param[in] Collection The collection to check for emptiness.\r
148	\r
149	@retval TRUE The collection is empty.\r
150	\r
151	@retval FALSE The collection is not empty.\r
152	**/\r
153	BOOLEAN\r
154	EFIAPI\r
155	OrderedCollectionIsEmpty (\r
156	IN CONST ORDERED_COLLECTION *Collection\r
157	);\r
158	\r
159	\r
160	/**\r
161	Uninitialize and release an empty ORDERED_COLLECTION structure.\r
162	\r
163	Read-write operation.\r
164	\r
165	It is the caller's responsibility to delete all entries from the collection\r
166	before calling this function.\r
167	\r
168	@param[in] Collection The empty collection to uninitialize and release.\r
169	**/\r
170	VOID\r
171	EFIAPI\r
172	OrderedCollectionUninit (\r
173	IN ORDERED_COLLECTION *Collection\r
174	);\r
175	\r
176	\r
177	/**\r
178	Look up the collection entry that links the user structure that matches the\r
179	specified standalone key.\r
180	\r
181	Read-only operation.\r
182	\r
183	@param[in] Collection The collection to search for StandaloneKey.\r
184	\r
185	@param[in] StandaloneKey The key to locate among the user structures linked\r
186	into Collection. StandaloneKey will be passed to\r
187	ORDERED_COLLECTION_KEY_COMPARE.\r
188	\r
189	@retval NULL StandaloneKey could not be found.\r
190	\r
191	@return The collection entry that links to the user structure matching\r
192	StandaloneKey, otherwise.\r
193	**/\r
194	ORDERED_COLLECTION_ENTRY *\r
195	EFIAPI\r
196	OrderedCollectionFind (\r
197	IN CONST ORDERED_COLLECTION *Collection,\r
198	IN CONST VOID *StandaloneKey\r
199	);\r
200	\r
201	\r
202	/**\r
203	Find the collection entry of the minimum user structure stored in the\r
204	collection.\r
205	\r
206	Read-only operation.\r
207	\r
208	@param[in] Collection The collection to return the minimum entry of. The\r
209	user structure linked by the minimum entry compares\r
210	less than all other user structures in the collection.\r
211	\r
212	@retval NULL If Collection is empty.\r
213	\r
214	@return The collection entry that links the minimum user structure,\r
215	otherwise.\r
216	**/\r
217	ORDERED_COLLECTION_ENTRY *\r
218	EFIAPI\r
219	OrderedCollectionMin (\r
220	IN CONST ORDERED_COLLECTION *Collection\r
221	);\r
222	\r
223	\r
224	/**\r
225	Find the collection entry of the maximum user structure stored in the\r
226	collection.\r
227	\r
228	Read-only operation.\r
229	\r
230	@param[in] Collection The collection to return the maximum entry of. The\r
231	user structure linked by the maximum entry compares\r
232	greater than all other user structures in the\r
233	collection.\r
234	\r
235	@retval NULL If Collection is empty.\r
236	\r
237	@return The collection entry that links the maximum user structure,\r
238	otherwise.\r
239	**/\r
240	ORDERED_COLLECTION_ENTRY *\r
241	EFIAPI\r
242	OrderedCollectionMax (\r
243	IN CONST ORDERED_COLLECTION *Collection\r
244	);\r
245	\r
246	\r
247	/**\r
248	Get the collection entry of the least user structure that is greater than the\r
249	one linked by Entry.\r
250	\r
251	Read-only operation.\r
252	\r
253	@param[in] Entry The entry to get the successor entry of.\r
254	\r
255	@retval NULL If Entry is NULL, or Entry is the maximum entry of its\r
256	containing collection (ie. Entry has no successor entry).\r
257	\r
258	@return The collection entry linking the least user structure that is\r
259	greater than the one linked by Entry, otherwise.\r
260	**/\r
261	ORDERED_COLLECTION_ENTRY *\r
262	EFIAPI\r
263	OrderedCollectionNext (\r
264	IN CONST ORDERED_COLLECTION_ENTRY *Entry\r
265	);\r
266	\r
267	\r
268	/**\r
269	Get the collection entry of the greatest user structure that is less than the\r
270	one linked by Entry.\r
271	\r
272	Read-only operation.\r
273	\r
274	@param[in] Entry The entry to get the predecessor entry of.\r
275	\r
276	@retval NULL If Entry is NULL, or Entry is the minimum entry of its\r
277	containing collection (ie. Entry has no predecessor entry).\r
278	\r
279	@return The collection entry linking the greatest user structure that\r
280	is less than the one linked by Entry, otherwise.\r
281	**/\r
282	ORDERED_COLLECTION_ENTRY *\r
283	EFIAPI\r
284	OrderedCollectionPrev (\r
285	IN CONST ORDERED_COLLECTION_ENTRY *Entry\r
286	);\r
287	\r
288	\r
289	/**\r
290	Insert (link) a user structure into the collection, allocating a new\r
291	collection entry.\r
292	\r
293	Read-write operation.\r
294	\r
295	@param[in,out] Collection The collection to insert UserStruct into.\r
296	\r
297	@param[out] Entry The meaning of this optional, output-only\r
298	parameter depends on the return value of the\r
299	function.\r
300	\r
301	When insertion is successful (RETURN_SUCCESS),\r
302	Entry is set on output to the new collection entry\r
303	that now links UserStruct.\r
304	\r
305	When insertion fails due to lack of memory\r
306	(RETURN_OUT_OF_RESOURCES), Entry is not changed.\r
307	\r
308	When insertion fails due to key collision (ie.\r
309	another user structure is already in the\r
310	collection that compares equal to UserStruct),\r
311	with return value RETURN_ALREADY_STARTED, then\r
312	Entry is set on output to the entry that links the\r
313	colliding user structure. This enables\r
314	"find-or-insert" in one function call, or helps\r
315	with later removal of the colliding element.\r
316	\r
317	@param[in] UserStruct The user structure to link into the collection.\r
318	UserStruct is ordered against in-collection user\r
319	structures with the\r
320	ORDERED_COLLECTION_USER_COMPARE function.\r
321	\r
322	@retval RETURN_SUCCESS Insertion successful. A new collection entry\r
323	has been allocated, linking UserStruct. The\r
324	new collection entry is reported back in\r
325	Entry (if the caller requested it).\r
326	\r
327	Existing ORDERED_COLLECTION_ENTRY pointers\r
328	into Collection remain valid. For example,\r
329	on-going iterations in the caller can\r
330	continue with OrderedCollectionNext() /\r
331	OrderedCollectionPrev(), and they will\r
332	return the new entry at some point if user\r
333	structure order dictates it.\r
334	\r
335	@retval RETURN_OUT_OF_RESOURCES The function failed to allocate memory for\r
336	the new collection entry. The collection has\r
337	not been changed. Existing\r
338	ORDERED_COLLECTION_ENTRY pointers into\r
339	Collection remain valid.\r
340	\r
341	@retval RETURN_ALREADY_STARTED A user structure has been found in the\r
342	collection that compares equal to\r
343	UserStruct. The entry linking the colliding\r
344	user structure is reported back in Entry (if\r
345	the caller requested it). The collection has\r
346	not been changed. Existing\r
347	ORDERED_COLLECTION_ENTRY pointers into\r
348	Collection remain valid.\r
349	**/\r
350	RETURN_STATUS\r
351	EFIAPI\r
352	OrderedCollectionInsert (\r
353	IN OUT ORDERED_COLLECTION *Collection,\r
354	OUT ORDERED_COLLECTION_ENTRY **Entry OPTIONAL,\r
355	IN VOID *UserStruct\r
356	);\r
357	\r
358	\r
359	/**\r
360	Delete an entry from the collection, unlinking the associated user structure.\r
361	\r
362	Read-write operation.\r
363	\r
364	@param[in,out] Collection The collection to delete Entry from.\r
365	\r
366	@param[in] Entry The collection entry to delete from Collection.\r
367	The caller is responsible for ensuring that Entry\r
368	belongs to Collection, and that Entry is non-NULL\r
369	and valid. Entry is typically an earlier return\r
370	value, or output parameter, of:\r
371	\r
372	- OrderedCollectionFind(), for deleting an entry\r
373	by user structure key,\r
374	\r
375	- OrderedCollectionMin() / OrderedCollectionMax(),\r
376	for deleting the minimum / maximum entry,\r
377	\r
378	- OrderedCollectionNext() /\r
379	OrderedCollectionPrev(), for deleting an entry\r
380	found during an iteration,\r
381	\r
382	- OrderedCollectionInsert() with return value\r
383	RETURN_ALREADY_STARTED, for deleting an entry\r
384	whose linked user structure caused collision\r
385	during insertion.\r
386	\r
387	Existing ORDERED_COLLECTION_ENTRY pointers (ie.\r
388	iterators) different from Entry remain valid.\r
389	For example:\r
390	\r
391	- OrderedCollectionNext() /\r
392	OrderedCollectionPrev() iterations in the caller\r
393	can be continued from Entry, if\r
394	OrderedCollectionNext() or\r
395	OrderedCollectionPrev() is called on Entry\r
396	before OrderedCollectionDelete() is. That is,\r
397	fetch the successor / predecessor entry first,\r
398	then delete Entry.\r
399	\r
400	- On-going iterations in the caller that would\r
401	have otherwise returned Entry at some point, as\r
402	dictated by user structure order, will correctly\r
403	reflect the absence of Entry after\r
404	OrderedCollectionDelete() is called\r
405	mid-iteration.\r
406	\r
407	@param[out] UserStruct If the caller provides this optional output-only\r
408	parameter, then on output it is set to the user\r
409	structure originally linked by Entry (which is now\r
410	freed).\r
411	\r
412	This is a convenience that may save the caller a\r
413	OrderedCollectionUserStruct() invocation before\r
414	calling OrderedCollectionDelete(), in order to\r
415	retrieve the user structure being unlinked.\r
416	**/\r
417	VOID\r
418	EFIAPI\r
419	OrderedCollectionDelete (\r
420	IN OUT ORDERED_COLLECTION *Collection,\r
421	IN ORDERED_COLLECTION_ENTRY *Entry,\r
422	OUT VOID **UserStruct OPTIONAL\r
423	);\r
424	\r
425	#endif\r