Zhe Wang | 8ae3b11 | 2019-06-18 13:23:54 +0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2017 Amlogic Corporation. |
| 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 | /** |
| 19 | @file dictionary.h |
| 20 | @author N. Devillard |
| 21 | @brief Implements a dictionary for string variables. |
| 22 | |
| 23 | This module implements a simple dictionary object, i.e. a list |
| 24 | of string/string associations. This object is useful to store e.g. |
| 25 | informations retrieved from a configuration file (ini files). |
| 26 | */ |
| 27 | /*--------------------------------------------------------------------------*/ |
| 28 | |
| 29 | #ifndef _DICTIONARY_H_ |
| 30 | #define _DICTIONARY_H_ |
| 31 | |
| 32 | /*--------------------------------------------------------------------------- |
| 33 | Includes |
| 34 | ---------------------------------------------------------------------------*/ |
| 35 | |
| 36 | #include <stdio.h> |
| 37 | #include <stdlib.h> |
| 38 | #include <string.h> |
| 39 | #include <unistd.h> |
| 40 | |
| 41 | #ifdef __cplusplus |
| 42 | extern "C" { |
| 43 | #endif |
| 44 | |
| 45 | /*--------------------------------------------------------------------------- |
| 46 | New types |
| 47 | ---------------------------------------------------------------------------*/ |
| 48 | |
| 49 | |
| 50 | /*-------------------------------------------------------------------------*/ |
| 51 | /** |
| 52 | @brief Dictionary object |
| 53 | |
| 54 | This object contains a list of string/string associations. Each |
| 55 | association is identified by a unique string key. Looking up values |
| 56 | in the dictionary is speeded up by the use of a (hopefully collision-free) |
| 57 | hash function. |
| 58 | */ |
| 59 | /*-------------------------------------------------------------------------*/ |
| 60 | typedef struct _dictionary_ { |
| 61 | int n; /** Number of entries in dictionary */ |
| 62 | ssize_t size; /** Storage size */ |
| 63 | char ** val; /** List of string values */ |
| 64 | char ** key; /** List of string keys */ |
| 65 | unsigned * hash; /** List of hash values for keys */ |
| 66 | } dictionary; |
| 67 | |
| 68 | |
| 69 | /*--------------------------------------------------------------------------- |
| 70 | Function prototypes |
| 71 | ---------------------------------------------------------------------------*/ |
| 72 | |
| 73 | /*-------------------------------------------------------------------------*/ |
| 74 | /** |
| 75 | @brief Compute the hash key for a string. |
| 76 | @param key Character string to use for key. |
| 77 | @return 1 unsigned int on at least 32 bits. |
| 78 | |
| 79 | This hash function has been taken from an Article in Dr Dobbs Journal. |
| 80 | This is normally a collision-free function, distributing keys evenly. |
| 81 | The key is stored anyway in the struct so that collision can be avoided |
| 82 | by comparing the key itself in last resort. |
| 83 | */ |
| 84 | /*--------------------------------------------------------------------------*/ |
| 85 | unsigned dictionary_hash(const char *key); |
| 86 | |
| 87 | /*-------------------------------------------------------------------------*/ |
| 88 | /** |
| 89 | @brief Create a new dictionary object. |
| 90 | @param size Optional initial size of the dictionary. |
| 91 | @return 1 newly allocated dictionary objet. |
| 92 | |
| 93 | This function allocates a new dictionary object of given size and returns |
| 94 | it. If you do not know in advance (roughly) the number of entries in the |
| 95 | dictionary, give size=0. |
| 96 | */ |
| 97 | /*--------------------------------------------------------------------------*/ |
| 98 | dictionary *dictionary_new(size_t size); |
| 99 | |
| 100 | /*-------------------------------------------------------------------------*/ |
| 101 | /** |
| 102 | @brief Delete a dictionary object |
| 103 | @param d dictionary object to deallocate. |
| 104 | @return void |
| 105 | |
| 106 | Deallocate a dictionary object and all memory associated to it. |
| 107 | */ |
| 108 | /*--------------------------------------------------------------------------*/ |
| 109 | void dictionary_del(dictionary *vd); |
| 110 | |
| 111 | /*-------------------------------------------------------------------------*/ |
| 112 | /** |
| 113 | @brief Get a value from a dictionary. |
| 114 | @param d dictionary object to search. |
| 115 | @param key Key to look for in the dictionary. |
| 116 | @param def Default value to return if key not found. |
| 117 | @return 1 pointer to internally allocated character string. |
| 118 | |
| 119 | This function locates a key in a dictionary and returns a pointer to its |
| 120 | value, or the passed 'def' pointer if no such key can be found in |
| 121 | dictionary. The returned character pointer points to data internal to the |
| 122 | dictionary object, you should not try to free it or modify it. |
| 123 | */ |
| 124 | /*--------------------------------------------------------------------------*/ |
| 125 | const char *dictionary_get(const dictionary *d, const char *key, const char *def); |
| 126 | |
| 127 | |
| 128 | /*-------------------------------------------------------------------------*/ |
| 129 | /** |
| 130 | @brief Set a value in a dictionary. |
| 131 | @param d dictionary object to modify. |
| 132 | @param key Key to modify or add. |
| 133 | @param val Value to add. |
| 134 | @return int 0 if Ok, anything else otherwise |
| 135 | |
| 136 | If the given key is found in the dictionary, the associated value is |
| 137 | replaced by the provided one. If the key cannot be found in the |
| 138 | dictionary, it is added to it. |
| 139 | |
| 140 | It is Ok to provide a NULL value for val, but NULL values for the dictionary |
| 141 | or the key are considered as errors: the function will return immediately |
| 142 | in such a case. |
| 143 | |
| 144 | Notice that if you dictionary_set a variable to NULL, a call to |
| 145 | dictionary_get will return a NULL value: the variable will be found, and |
| 146 | its value (NULL) is returned. In other words, setting the variable |
| 147 | content to NULL is equivalent to deleting the variable from the |
| 148 | dictionary. It is not possible (in this implementation) to have a key in |
| 149 | the dictionary without value. |
| 150 | |
| 151 | This function returns non-zero in case of failure. |
| 152 | */ |
| 153 | /*--------------------------------------------------------------------------*/ |
| 154 | int dictionary_set(dictionary *vd, const char *key, const char *val); |
| 155 | |
| 156 | /*-------------------------------------------------------------------------*/ |
| 157 | /** |
| 158 | @brief Delete a key in a dictionary |
| 159 | @param d dictionary object to modify. |
| 160 | @param key Key to remove. |
| 161 | @return void |
| 162 | |
| 163 | This function deletes a key in a dictionary. Nothing is done if the |
| 164 | key cannot be found. |
| 165 | */ |
| 166 | /*--------------------------------------------------------------------------*/ |
| 167 | void dictionary_unset(dictionary *d, const char *key); |
| 168 | |
| 169 | |
| 170 | /*-------------------------------------------------------------------------*/ |
| 171 | /** |
| 172 | @brief Dump a dictionary to an opened file pointer. |
| 173 | @param d Dictionary to dump |
| 174 | @param f Opened file pointer. |
| 175 | @return void |
| 176 | |
| 177 | Dumps a dictionary onto an opened file pointer. Key pairs are printed out |
| 178 | as @c [Key]=[Value], one per line. It is Ok to provide stdout or stderr as |
| 179 | output file pointers. |
| 180 | */ |
| 181 | /*--------------------------------------------------------------------------*/ |
| 182 | void dictionary_dump(const dictionary *d, FILE *out); |
| 183 | |
| 184 | #ifdef __cplusplus |
| 185 | } |
| 186 | #endif |
| 187 | |
| 188 | #endif |