apr_skiplist.h
Go to the documentation of this file.00001 /* Licensed to the Apache Software Foundation (ASF) under one or more 00002 * contributor license agreements. See the NOTICE file distributed with 00003 * this work for additional information regarding copyright ownership. 00004 * The ASF licenses this file to You under the Apache License, Version 2.0 00005 * (the "License"); you may not use this file except in compliance with 00006 * the License. You may obtain a copy of the License at 00007 * 00008 * http://www.apache.org/licenses/LICENSE-2.0 00009 * 00010 * Unless required by applicable law or agreed to in writing, software 00011 * distributed under the License is distributed on an "AS IS" BASIS, 00012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 00013 * See the License for the specific language governing permissions and 00014 * limitations under the License. 00015 */ 00016 00017 #ifndef APR_SKIPLIST_H 00018 #define APR_SKIPLIST_H 00019 /** 00020 * @file apr_skiplist.h 00021 * @brief APR skip list implementation 00022 */ 00023 00024 #include "apr.h" 00025 #include "apr_portable.h" 00026 #include <stdlib.h> 00027 00028 #ifdef __cplusplus 00029 extern "C" { 00030 #endif /* __cplusplus */ 00031 00032 /** 00033 * @defgroup apr_skiplist Skip list implementation 00034 * Refer to http://en.wikipedia.org/wiki/Skip_list for information 00035 * about the purpose of and ideas behind skip lists. 00036 * @ingroup APR 00037 * @{ 00038 */ 00039 00040 /** 00041 * apr_skiplist_compare is the function type that must be implemented 00042 * per object type that is used in a skip list for comparisons to maintain 00043 * order 00044 * */ 00045 typedef int (*apr_skiplist_compare) (void *, void *); 00046 00047 /** 00048 * apr_skiplist_freefunc is the function type that must be implemented 00049 * to handle elements as they are removed from a skip list. 00050 */ 00051 typedef void (*apr_skiplist_freefunc) (void *); 00052 00053 /** Opaque structure used to represent the skip list */ 00054 struct apr_skiplist; 00055 /** Opaque structure used to represent the skip list */ 00056 typedef struct apr_skiplist apr_skiplist; 00057 00058 /** 00059 * Opaque structure used to represent abstract nodes in the skip list 00060 * (an abstraction above the raw elements which are collected in the 00061 * skip list). 00062 */ 00063 struct apr_skiplistnode; 00064 /** Opaque structure */ 00065 typedef struct apr_skiplistnode apr_skiplistnode; 00066 00067 /** 00068 * Allocate memory using the same mechanism as the skip list. 00069 * @param sl The skip list 00070 * @param size The amount to allocate 00071 * @remark If a pool was provided to apr_skiplist_init(), memory will 00072 * be allocated from the pool or from a free list maintained with 00073 * the skip list. Otherwise, memory will be allocated using the 00074 * C standard library heap functions. 00075 */ 00076 APR_DECLARE(void *) apr_skiplist_alloc(apr_skiplist *sl, size_t size); 00077 00078 /** 00079 * Free memory using the same mechanism as the skip list. 00080 * @param sl The skip list 00081 * @param mem The object to free 00082 * @remark If a pool was provided to apr_skiplist_init(), memory will 00083 * be added to a free list maintained with the skip list and be available 00084 * to operations on the skip list or to other calls to apr_skiplist_alloc(). 00085 * Otherwise, memory will be freed using the C standard library heap 00086 * functions. 00087 */ 00088 APR_DECLARE(void) apr_skiplist_free(apr_skiplist *sl, void *mem); 00089 00090 /** 00091 * Allocate a new skip list 00092 * @param sl The pointer in which to return the newly created skip list 00093 * @param p The pool from which to allocate the skip list (optional). 00094 * @remark Unlike most APR functions, a pool is optional. If no pool 00095 * is provided, the C standard library heap functions will be used instead. 00096 */ 00097 APR_DECLARE(apr_status_t) apr_skiplist_init(apr_skiplist **sl, apr_pool_t *p); 00098 00099 /** 00100 * Set the comparison functions to be used for searching the skip list. 00101 * @param sl The skip list 00102 * @param XXX1 FIXME 00103 * @param XXX2 FIXME 00104 * 00105 * @remark If existing comparison functions are being replaced, the index 00106 * will be replaced during this call. That is a potentially expensive 00107 * operation. 00108 */ 00109 APR_DECLARE(void) apr_skiplist_set_compare(apr_skiplist *sl, apr_skiplist_compare XXX1, 00110 apr_skiplist_compare XXX2); 00111 00112 /** 00113 * Set the indexing functions to the specified comparison functions and 00114 * rebuild the index. 00115 * @param sl The skip list 00116 * @param XXX1 FIXME 00117 * @param XXX2 FIXME 00118 * 00119 * @remark If an index already exists, it will not be replaced and the 00120 * comparison functions will not be changed. 00121 */ 00122 APR_DECLARE(void) apr_skiplist_add_index(apr_skiplist *sl, apr_skiplist_compare XXX1, 00123 apr_skiplist_compare XXX2); 00124 00125 /** 00126 * Return the list maintained by the skip list abstraction. 00127 * @param sl The skip list 00128 */ 00129 APR_DECLARE(apr_skiplistnode *) apr_skiplist_getlist(apr_skiplist *sl); 00130 00131 /** 00132 * Return the next matching element in the skip list using the specified 00133 * comparison function. 00134 * @param sl The skip list 00135 * @param data The value to search for 00136 * @param iter A pointer to the returned skip list node representing the element 00137 * found 00138 * @param func The comparison function to use 00139 */ 00140 APR_DECLARE(void *) apr_skiplist_find_compare(apr_skiplist *sl, 00141 void *data, 00142 apr_skiplistnode **iter, 00143 apr_skiplist_compare func); 00144 00145 /** 00146 * Return the next matching element in the skip list using the current comparison 00147 * function. 00148 * @param sl The skip list 00149 * @param data The value to search for 00150 * @param iter A pointer to the returned skip list node representing the element 00151 * found 00152 */ 00153 APR_DECLARE(void *) apr_skiplist_find(apr_skiplist *sl, void *data, apr_skiplistnode **iter); 00154 00155 /** 00156 * Return the next element in the skip list. 00157 * @param sl The skip list 00158 * @param iter On entry, a pointer to the skip list node to start with; on return, 00159 * a pointer to the skip list node representing the element returned 00160 * @remark If iter points to a NULL value on entry, NULL will be returned. 00161 */ 00162 APR_DECLARE(void *) apr_skiplist_next(apr_skiplist *sl, apr_skiplistnode **iter); 00163 00164 /** 00165 * Return the previous element in the skip list. 00166 * @param sl The skip list 00167 * @param iter On entry, a pointer to the skip list node to start with; on return, 00168 * a pointer to the skip list node representing the element returned 00169 * @remark If iter points to a NULL value on entry, NULL will be returned. 00170 */ 00171 APR_DECLARE(void *) apr_skiplist_previous(apr_skiplist *sl, apr_skiplistnode **iter); 00172 00173 /** 00174 * Insert an element into the skip list using the specified comparison function. 00175 * @param sl The skip list 00176 * @param data The element to insert 00177 * @param comp The comparison function to use for placement into the skip list 00178 */ 00179 APR_DECLARE(apr_skiplistnode *) apr_skiplist_insert_compare(apr_skiplist *sl, 00180 void *data, apr_skiplist_compare comp); 00181 00182 /** 00183 * Insert an element into the skip list using the existing comparison function. 00184 * @param sl The skip list 00185 * @param data The element to insert 00186 * @remark If no comparison function has been set for the skip list, the element 00187 * will not be inserted and NULL will be returned. 00188 */ 00189 APR_DECLARE(apr_skiplistnode *) apr_skiplist_insert(apr_skiplist* sl, void *data); 00190 00191 /** 00192 * Remove an element from the skip list using the specified comparison function for 00193 * locating the element. 00194 * @param sl The skip list 00195 * @param data The element to remove 00196 * @param myfree A function to be called for each removed element 00197 * @param comp The comparison function to use for placement into the skip list 00198 * @remark If the element is not found, 0 will be returned. Otherwise, the heightXXX 00199 * will be returned. 00200 */ 00201 APR_DECLARE(int) apr_skiplist_remove_compare(apr_skiplist *sl, void *data, 00202 apr_skiplist_freefunc myfree, apr_skiplist_compare comp); 00203 00204 /** 00205 * Remove an element from the skip list using the existing comparison function for 00206 * locating the element. 00207 * @param sl The skip list 00208 * @param data The element to remove 00209 * @param myfree A function to be called for each removed element 00210 * @remark If the element is not found, 0 will be returned. Otherwise, the heightXXX 00211 * will be returned. 00212 * @remark If no comparison function has been set for the skip list, the element 00213 * will not be removed and 0 will be returned. 00214 */ 00215 APR_DECLARE(int) apr_skiplist_remove(apr_skiplist *sl, void *data, apr_skiplist_freefunc myfree); 00216 00217 /** 00218 * Remove all elements from the skip list. 00219 * @param sl The skip list 00220 * @param myfree A function to be called for each removed element 00221 */ 00222 APR_DECLARE(void) apr_skiplist_remove_all(apr_skiplist *sl, apr_skiplist_freefunc myfree); 00223 00224 /** 00225 * Remove each element from the skip list. 00226 * @param sl The skip list 00227 * @param myfree A function to be called for each removed element 00228 */ 00229 APR_DECLARE(void) apr_skiplist_destroy(apr_skiplist *sl, apr_skiplist_freefunc myfree); 00230 00231 /** 00232 * Return the first element in the skip list, leaving the element in the skip list. 00233 * @param sl The skip list 00234 * @param myfree A function to be called for the removed element 00235 * @remark NULL will be returned if there are no elements 00236 */ 00237 APR_DECLARE(void *) apr_skiplist_pop(apr_skiplist *sl, apr_skiplist_freefunc myfree); 00238 00239 /** 00240 * Return the first element in the skip list, leaving the element in the skip list. 00241 * @param sl The skip list 00242 * @remark NULL will be returned if there are no elements 00243 */ 00244 APR_DECLARE(void *) apr_skiplist_peek(apr_skiplist *sl); 00245 00246 /** 00247 * Merge two skip lists. XXX SEMANTICS 00248 * @param sl1 One of two skip lists to be merged 00249 * @param sl2 The other of two skip lists to be merged 00250 */ 00251 APR_DECLARE(apr_skiplist *) apr_skiplist_merge(apr_skiplist *sl1, apr_skiplist *sl2); 00252 00253 /** @} */ 00254 00255 #ifdef __cplusplus 00256 } 00257 #endif 00258 00259 #endif /* ! APR_SKIPLIST_H */
