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