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/*-------------------------------------------------------------------------*/
41typedef 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/*--------------------------------------------------------------------------*/
66unsigned 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/*--------------------------------------------------------------------------*/
79dictionary * 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/*--------------------------------------------------------------------------*/
90void 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/*--------------------------------------------------------------------------*/
106char * 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/*--------------------------------------------------------------------------*/
135int 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/*--------------------------------------------------------------------------*/
148void 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/*--------------------------------------------------------------------------*/
163void dictionary_dump(dictionary * d, FILE * out);
164
165#endif
166