1 2 /*-------------------------------------------------------------------------*/ 3 /** 4 @file dictionary.h 5 @author N. Devillard 6 @brief Implements a dictionary for string variables. 7 8 This module implements a simple dictionary object, i.e. a list 9 of string/string associations. This object is useful to store e.g. 10 informations retrieved from a configuration file (ini files). 11 */ 12 /*--------------------------------------------------------------------------*/ 13 14 #ifndef _DICTIONARY_H_ 15 #define _DICTIONARY_H_ 16 17 /*--------------------------------------------------------------------------- 18 Includes 19 ---------------------------------------------------------------------------*/ 20 21 #include <stdio.h> 22 #include <stdlib.h> 23 #include <string.h> 24 #include <unistd.h> 25 26 #ifdef __cplusplus 27 extern "C" { 28 #endif 29 30 /*--------------------------------------------------------------------------- 31 New types 32 ---------------------------------------------------------------------------*/ 33 34 35 /*-------------------------------------------------------------------------*/ 36 /** 37 @brief Dictionary object 38 39 This object contains a list of string/string associations. Each 40 association is identified by a unique string key. Looking up values 41 in the dictionary is speeded up by the use of a (hopefully collision-free) 42 hash function. 43 */ 44 /*-------------------------------------------------------------------------*/ 45 typedef struct _dictionary_ { 46 int n ; /** Number of entries in dictionary */ 47 ssize_t size ; /** Storage size */ 48 char ** val ; /** List of string values */ 49 char ** key ; /** List of string keys */ 50 unsigned * hash ; /** List of hash values for keys */ 51 } dictionary ; 52 53 54 /*--------------------------------------------------------------------------- 55 Function prototypes 56 ---------------------------------------------------------------------------*/ 57 58 /*-------------------------------------------------------------------------*/ 59 /** 60 @brief Compute the hash key for a string. 61 @param key Character string to use for key. 62 @return 1 unsigned int on at least 32 bits. 63 64 This hash function has been taken from an Article in Dr Dobbs Journal. 65 This is normally a collision-free function, distributing keys evenly. 66 The key is stored anyway in the struct so that collision can be avoided 67 by comparing the key itself in last resort. 68 */ 69 /*--------------------------------------------------------------------------*/ 70 unsigned dictionary_hash(const char * key); 71 72 /*-------------------------------------------------------------------------*/ 73 /** 74 @brief Create a new dictionary object. 75 @param size Optional initial size of the dictionary. 76 @return 1 newly allocated dictionary objet. 77 78 This function allocates a new dictionary object of given size and returns 79 it. If you do not know in advance (roughly) the number of entries in the 80 dictionary, give size=0. 81 */ 82 /*--------------------------------------------------------------------------*/ 83 dictionary * dictionary_new(size_t size); 84 85 /*-------------------------------------------------------------------------*/ 86 /** 87 @brief Delete a dictionary object 88 @param d dictionary object to deallocate. 89 @return void 90 91 Deallocate a dictionary object and all memory associated to it. 92 */ 93 /*--------------------------------------------------------------------------*/ 94 void dictionary_del(dictionary * vd); 95 96 /*-------------------------------------------------------------------------*/ 97 /** 98 @brief Get a value from a dictionary. 99 @param d dictionary object to search. 100 @param key Key to look for in the dictionary. 101 @param def Default value to return if key not found. 102 @return 1 pointer to internally allocated character string. 103 104 This function locates a key in a dictionary and returns a pointer to its 105 value, or the passed 'def' pointer if no such key can be found in 106 dictionary. The returned character pointer points to data internal to the 107 dictionary object, you should not try to free it or modify it. 108 */ 109 /*--------------------------------------------------------------------------*/ 110 const char * dictionary_get(const dictionary * d, const char * key, const char * def); 111 112 113 /*-------------------------------------------------------------------------*/ 114 /** 115 @brief Set a value in a dictionary. 116 @param d dictionary object to modify. 117 @param key Key to modify or add. 118 @param val Value to add. 119 @return int 0 if Ok, anything else otherwise 120 121 If the given key is found in the dictionary, the associated value is 122 replaced by the provided one. If the key cannot be found in the 123 dictionary, it is added to it. 124 125 It is Ok to provide a NULL value for val, but NULL values for the dictionary 126 or the key are considered as errors: the function will return immediately 127 in such a case. 128 129 Notice that if you dictionary_set a variable to NULL, a call to 130 dictionary_get will return a NULL value: the variable will be found, and 131 its value (NULL) is returned. In other words, setting the variable 132 content to NULL is equivalent to deleting the variable from the 133 dictionary. It is not possible (in this implementation) to have a key in 134 the dictionary without value. 135 136 This function returns non-zero in case of failure. 137 */ 138 /*--------------------------------------------------------------------------*/ 139 int dictionary_set(dictionary * vd, const char * key, const char * val); 140 141 /*-------------------------------------------------------------------------*/ 142 /** 143 @brief Delete a key in a dictionary 144 @param d dictionary object to modify. 145 @param key Key to remove. 146 @return void 147 148 This function deletes a key in a dictionary. Nothing is done if the 149 key cannot be found. 150 */ 151 /*--------------------------------------------------------------------------*/ 152 void dictionary_unset(dictionary * d, const char * key); 153 154 155 /*-------------------------------------------------------------------------*/ 156 /** 157 @brief Dump a dictionary to an opened file pointer. 158 @param d Dictionary to dump 159 @param f Opened file pointer. 160 @return void 161 162 Dumps a dictionary onto an opened file pointer. Key pairs are printed out 163 as @c [Key]=[Value], one per line. It is Ok to provide stdout or stderr as 164 output file pointers. 165 */ 166 /*--------------------------------------------------------------------------*/ 167 void dictionary_dump(const dictionary * d, FILE * out); 168 169 #ifdef __cplusplus 170 } 171 #endif 172 173 #endif 174