1 /* 2 * Copyright (C) 2007 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 /** 18 * Hash map. 19 */ 20 21 #ifndef __HASHMAP_H 22 #define __HASHMAP_H 23 24 #include <stdbool.h> 25 #include <stdlib.h> 26 27 #ifdef __cplusplus 28 extern "C" { 29 #endif 30 31 /** A hash map. */ 32 typedef struct Hashmap Hashmap; 33 34 /** 35 * Creates a new hash map. Returns NULL if memory allocation fails. 36 * 37 * @param initialCapacity number of expected entries 38 * @param hash function which hashes keys 39 * @param equals function which compares keys for equality 40 */ 41 Hashmap* hashmapCreate(size_t initialCapacity, 42 int (*hash)(void* key), bool (*equals)(void* keyA, void* keyB)); 43 44 /** 45 * Frees the hash map. Does not free the keys or values themselves. 46 */ 47 void hashmapFree(Hashmap* map); 48 49 /** 50 * Hashes the memory pointed to by key with the given size. Useful for 51 * implementing hash functions. 52 */ 53 int hashmapHash(void* key, size_t keySize); 54 55 /** 56 * Puts value for the given key in the map. Returns pre-existing value if 57 * any. 58 * 59 * If memory allocation fails, this function returns NULL, the map's size 60 * does not increase, and errno is set to ENOMEM. 61 */ 62 void* hashmapPut(Hashmap* map, void* key, void* value); 63 64 /** 65 * Gets a value from the map. Returns NULL if no entry for the given key is 66 * found or if the value itself is NULL. 67 */ 68 void* hashmapGet(Hashmap* map, void* key); 69 70 /** 71 * Returns true if the map contains an entry for the given key. 72 */ 73 bool hashmapContainsKey(Hashmap* map, void* key); 74 75 /** 76 * Gets the value for a key. If a value is not found, this function gets a 77 * value and creates an entry using the given callback. 78 * 79 * If memory allocation fails, the callback is not called, this function 80 * returns NULL, and errno is set to ENOMEM. 81 */ 82 void* hashmapMemoize(Hashmap* map, void* key, 83 void* (*initialValue)(void* key, void* context), void* context); 84 85 /** 86 * Removes an entry from the map. Returns the removed value or NULL if no 87 * entry was present. 88 */ 89 void* hashmapRemove(Hashmap* map, void* key); 90 91 /** 92 * Gets the number of entries in this map. 93 */ 94 size_t hashmapSize(Hashmap* map); 95 96 /** 97 * Invokes the given callback on each entry in the map. Stops iterating if 98 * the callback returns false. 99 */ 100 void hashmapForEach(Hashmap* map, 101 bool (*callback)(void* key, void* value, void* context), 102 void* context); 103 104 /** 105 * Concurrency support. 106 */ 107 108 /** 109 * Locks the hash map so only the current thread can access it. 110 */ 111 void hashmapLock(Hashmap* map); 112 113 /** 114 * Unlocks the hash map so other threads can access it. 115 */ 116 void hashmapUnlock(Hashmap* map); 117 118 /** 119 * Key utilities. 120 */ 121 122 /** 123 * Hashes int keys. 'key' is a pointer to int. 124 */ 125 int hashmapIntHash(void* key); 126 127 /** 128 * Compares two int keys for equality. 129 */ 130 bool hashmapIntEquals(void* keyA, void* keyB); 131 132 /** 133 * For debugging. 134 */ 135 136 /** 137 * Gets current capacity. 138 */ 139 size_t hashmapCurrentCapacity(Hashmap* map); 140 141 /** 142 * Counts the number of entry collisions. 143 */ 144 size_t hashmapCountCollisions(Hashmap* map); 145 146 #ifdef __cplusplus 147 } 148 #endif 149 150 #endif /* __HASHMAP_H */ 151
