apr_skiplist.h revision 266733
1266733Speter/* Licensed to the Apache Software Foundation (ASF) under one or more 2266733Speter * contributor license agreements. See the NOTICE file distributed with 3266733Speter * this work for additional information regarding copyright ownership. 4266733Speter * The ASF licenses this file to You under the Apache License, Version 2.0 5266733Speter * (the "License"); you may not use this file except in compliance with 6266733Speter * the License. You may obtain a copy of the License at 7266733Speter * 8266733Speter * http://www.apache.org/licenses/LICENSE-2.0 9266733Speter * 10266733Speter * Unless required by applicable law or agreed to in writing, software 11266733Speter * distributed under the License is distributed on an "AS IS" BASIS, 12266733Speter * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13266733Speter * See the License for the specific language governing permissions and 14266733Speter * limitations under the License. 15266733Speter */ 16266733Speter 17266733Speter#ifndef APR_SKIPLIST_H 18266733Speter#define APR_SKIPLIST_H 19266733Speter/** 20266733Speter * @file apr_skiplist.h 21266733Speter * @brief APR skip list implementation 22266733Speter */ 23266733Speter 24266733Speter#include "apr.h" 25266733Speter#include "apr_portable.h" 26266733Speter#include <stdlib.h> 27266733Speter 28266733Speter#ifdef __cplusplus 29266733Speterextern "C" { 30266733Speter#endif /* __cplusplus */ 31266733Speter 32266733Speter/** 33266733Speter * @defgroup apr_skiplist Skip list implementation 34266733Speter * Refer to http://en.wikipedia.org/wiki/Skip_list for information 35266733Speter * about the purpose of and ideas behind skip lists. 36266733Speter * @ingroup APR 37266733Speter * @{ 38266733Speter */ 39266733Speter 40266733Speter/** 41266733Speter * apr_skiplist_compare is the function type that must be implemented 42266733Speter * per object type that is used in a skip list for comparisons to maintain 43266733Speter * order 44266733Speter * */ 45266733Spetertypedef int (*apr_skiplist_compare) (void *, void *); 46266733Speter 47266733Speter/** 48266733Speter * apr_skiplist_freefunc is the function type that must be implemented 49266733Speter * to handle elements as they are removed from a skip list. 50266733Speter */ 51266733Spetertypedef void (*apr_skiplist_freefunc) (void *); 52266733Speter 53266733Speter/** Opaque structure used to represent the skip list */ 54266733Speterstruct apr_skiplist; 55266733Speter/** Opaque structure used to represent the skip list */ 56266733Spetertypedef struct apr_skiplist apr_skiplist; 57266733Speter 58266733Speter/** 59266733Speter * Opaque structure used to represent abstract nodes in the skip list 60266733Speter * (an abstraction above the raw elements which are collected in the 61266733Speter * skip list). 62266733Speter */ 63266733Speterstruct apr_skiplistnode; 64266733Speter/** Opaque structure */ 65266733Spetertypedef struct apr_skiplistnode apr_skiplistnode; 66266733Speter 67266733Speter/** 68266733Speter * Allocate memory using the same mechanism as the skip list. 69266733Speter * @param sl The skip list 70266733Speter * @param size The amount to allocate 71266733Speter * @remark If a pool was provided to apr_skiplist_init(), memory will 72266733Speter * be allocated from the pool or from a free list maintained with 73266733Speter * the skip list. Otherwise, memory will be allocated using the 74266733Speter * C standard library heap functions. 75266733Speter */ 76266733SpeterAPR_DECLARE(void *) apr_skiplist_alloc(apr_skiplist *sl, size_t size); 77266733Speter 78266733Speter/** 79266733Speter * Free memory using the same mechanism as the skip list. 80266733Speter * @param sl The skip list 81266733Speter * @param mem The object to free 82266733Speter * @remark If a pool was provided to apr_skiplist_init(), memory will 83266733Speter * be added to a free list maintained with the skip list and be available 84266733Speter * to operations on the skip list or to other calls to apr_skiplist_alloc(). 85266733Speter * Otherwise, memory will be freed using the C standard library heap 86266733Speter * functions. 87266733Speter */ 88266733SpeterAPR_DECLARE(void) apr_skiplist_free(apr_skiplist *sl, void *mem); 89266733Speter 90266733Speter/** 91266733Speter * Allocate a new skip list 92266733Speter * @param sl The pointer in which to return the newly created skip list 93266733Speter * @param p The pool from which to allocate the skip list (optional). 94266733Speter * @remark Unlike most APR functions, a pool is optional. If no pool 95266733Speter * is provided, the C standard library heap functions will be used instead. 96266733Speter */ 97266733SpeterAPR_DECLARE(apr_status_t) apr_skiplist_init(apr_skiplist **sl, apr_pool_t *p); 98266733Speter 99266733Speter/** 100266733Speter * Set the comparison functions to be used for searching the skip list. 101266733Speter * @param sl The skip list 102266733Speter * @param XXX1 FIXME 103266733Speter * @param XXX2 FIXME 104266733Speter * 105266733Speter * @remark If existing comparison functions are being replaced, the index 106266733Speter * will be replaced during this call. That is a potentially expensive 107266733Speter * operation. 108266733Speter */ 109266733SpeterAPR_DECLARE(void) apr_skiplist_set_compare(apr_skiplist *sl, apr_skiplist_compare XXX1, 110266733Speter apr_skiplist_compare XXX2); 111266733Speter 112266733Speter/** 113266733Speter * Set the indexing functions to the specified comparison functions and 114266733Speter * rebuild the index. 115266733Speter * @param sl The skip list 116266733Speter * @param XXX1 FIXME 117266733Speter * @param XXX2 FIXME 118266733Speter * 119266733Speter * @remark If an index already exists, it will not be replaced and the 120266733Speter * comparison functions will not be changed. 121266733Speter */ 122266733SpeterAPR_DECLARE(void) apr_skiplist_add_index(apr_skiplist *sl, apr_skiplist_compare XXX1, 123266733Speter apr_skiplist_compare XXX2); 124266733Speter 125266733Speter/** 126266733Speter * Return the list maintained by the skip list abstraction. 127266733Speter * @param sl The skip list 128266733Speter */ 129266733SpeterAPR_DECLARE(apr_skiplistnode *) apr_skiplist_getlist(apr_skiplist *sl); 130266733Speter 131266733Speter/** 132266733Speter * Return the next matching element in the skip list using the specified 133266733Speter * comparison function. 134266733Speter * @param sl The skip list 135266733Speter * @param data The value to search for 136266733Speter * @param iter A pointer to the returned skip list node representing the element 137266733Speter * found 138266733Speter * @param func The comparison function to use 139266733Speter */ 140266733SpeterAPR_DECLARE(void *) apr_skiplist_find_compare(apr_skiplist *sl, 141266733Speter void *data, 142266733Speter apr_skiplistnode **iter, 143266733Speter apr_skiplist_compare func); 144266733Speter 145266733Speter/** 146266733Speter * Return the next matching element in the skip list using the current comparison 147266733Speter * function. 148266733Speter * @param sl The skip list 149266733Speter * @param data The value to search for 150266733Speter * @param iter A pointer to the returned skip list node representing the element 151266733Speter * found 152266733Speter */ 153266733SpeterAPR_DECLARE(void *) apr_skiplist_find(apr_skiplist *sl, void *data, apr_skiplistnode **iter); 154266733Speter 155266733Speter/** 156266733Speter * Return the next element in the skip list. 157266733Speter * @param sl The skip list 158266733Speter * @param iter On entry, a pointer to the skip list node to start with; on return, 159266733Speter * a pointer to the skip list node representing the element returned 160266733Speter * @remark If iter points to a NULL value on entry, NULL will be returned. 161266733Speter */ 162266733SpeterAPR_DECLARE(void *) apr_skiplist_next(apr_skiplist *sl, apr_skiplistnode **iter); 163266733Speter 164266733Speter/** 165266733Speter * Return the previous element in the skip list. 166266733Speter * @param sl The skip list 167266733Speter * @param iter On entry, a pointer to the skip list node to start with; on return, 168266733Speter * a pointer to the skip list node representing the element returned 169266733Speter * @remark If iter points to a NULL value on entry, NULL will be returned. 170266733Speter */ 171266733SpeterAPR_DECLARE(void *) apr_skiplist_previous(apr_skiplist *sl, apr_skiplistnode **iter); 172266733Speter 173266733Speter/** 174266733Speter * Insert an element into the skip list using the specified comparison function. 175266733Speter * @param sl The skip list 176266733Speter * @param data The element to insert 177266733Speter * @param comp The comparison function to use for placement into the skip list 178266733Speter */ 179266733SpeterAPR_DECLARE(apr_skiplistnode *) apr_skiplist_insert_compare(apr_skiplist *sl, 180266733Speter void *data, apr_skiplist_compare comp); 181266733Speter 182266733Speter/** 183266733Speter * Insert an element into the skip list using the existing comparison function. 184266733Speter * @param sl The skip list 185266733Speter * @param data The element to insert 186266733Speter * @remark If no comparison function has been set for the skip list, the element 187266733Speter * will not be inserted and NULL will be returned. 188266733Speter */ 189266733SpeterAPR_DECLARE(apr_skiplistnode *) apr_skiplist_insert(apr_skiplist* sl, void *data); 190266733Speter 191266733Speter/** 192266733Speter * Remove an element from the skip list using the specified comparison function for 193266733Speter * locating the element. 194266733Speter * @param sl The skip list 195266733Speter * @param data The element to remove 196266733Speter * @param myfree A function to be called for each removed element 197266733Speter * @param comp The comparison function to use for placement into the skip list 198266733Speter * @remark If the element is not found, 0 will be returned. Otherwise, the heightXXX 199266733Speter * will be returned. 200266733Speter */ 201266733SpeterAPR_DECLARE(int) apr_skiplist_remove_compare(apr_skiplist *sl, void *data, 202266733Speter apr_skiplist_freefunc myfree, apr_skiplist_compare comp); 203266733Speter 204266733Speter/** 205266733Speter * Remove an element from the skip list using the existing comparison function for 206266733Speter * locating the element. 207266733Speter * @param sl The skip list 208266733Speter * @param data The element to remove 209266733Speter * @param myfree A function to be called for each removed element 210266733Speter * @remark If the element is not found, 0 will be returned. Otherwise, the heightXXX 211266733Speter * will be returned. 212266733Speter * @remark If no comparison function has been set for the skip list, the element 213266733Speter * will not be removed and 0 will be returned. 214266733Speter */ 215266733SpeterAPR_DECLARE(int) apr_skiplist_remove(apr_skiplist *sl, void *data, apr_skiplist_freefunc myfree); 216266733Speter 217266733Speter/** 218266733Speter * Remove all elements from the skip list. 219266733Speter * @param sl The skip list 220266733Speter * @param myfree A function to be called for each removed element 221266733Speter */ 222266733SpeterAPR_DECLARE(void) apr_skiplist_remove_all(apr_skiplist *sl, apr_skiplist_freefunc myfree); 223266733Speter 224266733Speter/** 225266733Speter * Remove each element from the skip list. 226266733Speter * @param sl The skip list 227266733Speter * @param myfree A function to be called for each removed element 228266733Speter */ 229266733SpeterAPR_DECLARE(void) apr_skiplist_destroy(apr_skiplist *sl, apr_skiplist_freefunc myfree); 230266733Speter 231266733Speter/** 232266733Speter * Return the first element in the skip list, leaving the element in the skip list. 233266733Speter * @param sl The skip list 234266733Speter * @param myfree A function to be called for the removed element 235266733Speter * @remark NULL will be returned if there are no elements 236266733Speter */ 237266733SpeterAPR_DECLARE(void *) apr_skiplist_pop(apr_skiplist *sl, apr_skiplist_freefunc myfree); 238266733Speter 239266733Speter/** 240266733Speter * Return the first element in the skip list, leaving the element in the skip list. 241266733Speter * @param sl The skip list 242266733Speter * @remark NULL will be returned if there are no elements 243266733Speter */ 244266733SpeterAPR_DECLARE(void *) apr_skiplist_peek(apr_skiplist *sl); 245266733Speter 246266733Speter/** 247266733Speter * Merge two skip lists. XXX SEMANTICS 248266733Speter * @param sl1 One of two skip lists to be merged 249266733Speter * @param sl2 The other of two skip lists to be merged 250266733Speter */ 251266733SpeterAPR_DECLARE(apr_skiplist *) apr_skiplist_merge(apr_skiplist *sl1, apr_skiplist *sl2); 252266733Speter 253266733Speter/** @} */ 254266733Speter 255266733Speter#ifdef __cplusplus 256266733Speter} 257266733Speter#endif 258266733Speter 259266733Speter#endif /* ! APR_SKIPLIST_H */ 260