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