/*-------------------------------------------------------------------------*/
/**
@file dictionary.c
@author N. Devillard
@brief Implements a dictionary for string variables.
This module implements a simple dictionary object, i.e. a list
of string/string associations. This object is useful to store e.g.
informations retrieved from a configuration file (ini files).
*/
/*--------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------
Includes
---------------------------------------------------------------------------*/
#include "dictionary.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/** Maximum value size for integers and doubles. */
#define MAXVALSZ 1024
/** Minimal allocated number of entries in a dictionary */
#define DICTMINSZ 128
/** Invalid key token */
#define DICT_INVALID_KEY ((char*)-1)
/*---------------------------------------------------------------------------
Private functions
---------------------------------------------------------------------------*/
/* Doubles the allocated size associated to a pointer */
/* 'size' is the current allocated size. */
static void * mem_double(void * ptr, int size)
{
void * newptr ;
newptr = calloc(2*size, 1);
if (newptr==NULL) {
return NULL ;
}
memcpy(newptr, ptr, size);
free(ptr);
return newptr ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Duplicate a string
@param s String to duplicate
@return Pointer to a newly allocated string, to be freed with free()
This is a replacement for strdup(). This implementation is provided
for systems that do not have it.
*/
/*--------------------------------------------------------------------------*/
static char * xstrdup(const char * s)
{
char * t ;
if (!s)
return NULL ;
t = (char*)malloc(strlen(s)+1) ;
if (t) {
strcpy(t,s);
}
return t ;
}
/*---------------------------------------------------------------------------
Function codes
---------------------------------------------------------------------------*/
/*-------------------------------------------------------------------------*/
/**
@brief Compute the hash key for a string.
@param key Character string to use for key.
@return 1 unsigned int on at least 32 bits.
This hash function has been taken from an Article in Dr Dobbs Journal.
This is normally a collision-free function, distributing keys evenly.
The key is stored anyway in the struct so that collision can be avoided
by comparing the key itself in last resort.
*/
/*--------------------------------------------------------------------------*/
unsigned dictionary_hash(const char * key)
{
int len ;
unsigned hash ;
int i ;
len = strlen(key);
for (hash=0, i=0 ; i<len ; i++) {
hash += (unsigned)key[i] ;
hash += (hash<<10);
hash ^= (hash>>6) ;
}
hash += (hash <<3);
hash ^= (hash >>11);
hash += (hash <<15);
return hash ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Create a new dictionary object.
@param size Optional initial size of the dictionary.
@return 1 newly allocated dictionary objet.
This function allocates a new dictionary object of given size and returns
it. If you do not know in advance (roughly) the number of entries in the
dictionary, give size=0.
*/
/*--------------------------------------------------------------------------*/
dictionary * dictionary_new(int size)
{
dictionary * d ;
/* If no size was specified, allocate space for DICTMINSZ */
if (size<DICTMINSZ) size=DICTMINSZ ;
if (!(d = (dictionary *)calloc(1, sizeof(dictionary)))) {
return NULL;
}
d->size = size ;
d->val = (char **)calloc(size, sizeof(char*));
d->key = (char **)calloc(size, sizeof(char*));
d->hash = (unsigned int *)calloc(size, sizeof(unsigned));
return d ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Delete a dictionary object
@param d dictionary object to deallocate.
@return void
Deallocate a dictionary object and all memory associated to it.
*/
/*--------------------------------------------------------------------------*/
void dictionary_del(dictionary * d)
{
int i ;
if (d==NULL) return ;
for (i=0 ; i<d->size ; i++) {
if (d->key[i]!=NULL)
free(d->key[i]);
if (d->val[i]!=NULL)
free(d->val[i]);
}
free(d->val);
free(d->key);
free(d->hash);
free(d);
return ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Get a value from a dictionary.
@param d dictionary object to search.
@param key Key to look for in the dictionary.
@param def Default value to return if key not found.
@return 1 pointer to internally allocated character string.
This function locates a key in a dictionary and returns a pointer to its
value, or the passed 'def' pointer if no such key can be found in
dictionary. The returned character pointer points to data internal to the
dictionary object, you should not try to free it or modify it.
*/
/*--------------------------------------------------------------------------*/
char * dictionary_get(dictionary * d, const char * key, char * def)
{
unsigned hash ;
int i ;
hash = dictionary_hash(key);
for (i=0 ; i<d->size ; i++) {
if (d->key[i]==NULL)
continue ;
/* Compare hash */
if (hash==d->hash[i]) {
/* Compare string, to avoid hash collisions */
if (!strcmp(key, d->key[i])) {
return d->val[i] ;
}
}
}
return def ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Set a value in a dictionary.
@param d dictionary object to modify.
@param key Key to modify or add.
@param val Value to add.
@return int 0 if Ok, anything else otherwise
If the given key is found in the dictionary, the associated value is
replaced by the provided one. If the key cannot be found in the
dictionary, it is added to it.
It is Ok to provide a NULL value for val, but NULL values for the dictionary
or the key are considered as errors: the function will return immediately
in such a case.
Notice that if you dictionary_set a variable to NULL, a call to
dictionary_get will return a NULL value: the variable will be found, and
its value (NULL) is returned. In other words, setting the variable
content to NULL is equivalent to deleting the variable from the
dictionary. It is not possible (in this implementation) to have a key in
the dictionary without value.
This function returns non-zero in case of failure.
*/
/*--------------------------------------------------------------------------*/
int dictionary_set(dictionary * d, const char * key, const char * val)
{
int i ;
unsigned hash ;
if (d==NULL || key==NULL) return -1 ;
/* Compute hash for this key */
hash = dictionary_hash(key) ;
/* Find if value is already in dictionary */
if (d->n>0) {
for (i=0 ; i<d->size ; i++) {
if (d->key[i]==NULL)
continue ;
if (hash==d->hash[i]) { /* Same hash value */
if (!strcmp(key, d->key[i])) { /* Same key */
/* Found a value: modify and return */
if (d->val[i]!=NULL)
free(d->val[i]);
d->val[i] = val ? xstrdup(val) : NULL ;
/* Value has been modified: return */
return 0 ;
}
}
}
}
/* Add a new value */
/* See if dictionary needs to grow */
if (d->n==d->size) {
/* Reached maximum size: reallocate dictionary */
d->val = (char **)mem_double(d->val, d->size * sizeof(char*)) ;
d->key = (char **)mem_double(d->key, d->size * sizeof(char*)) ;
d->hash = (unsigned int *)mem_double(d->hash, d->size * sizeof(unsigned)) ;
if ((d->val==NULL) || (d->key==NULL) || (d->hash==NULL)) {
/* Cannot grow dictionary */
return -1 ;
}
/* Double size */
d->size *= 2 ;
}
/* Insert key in the first empty slot. Start at d->n and wrap at
d->size. Because d->n < d->size this will necessarily
terminate. */
for (i=d->n ; d->key[i] ; ) {
if(++i == d->size) i = 0;
}
/* Copy key */
d->key[i] = xstrdup(key);
d->val[i] = val ? xstrdup(val) : NULL ;
d->hash[i] = hash;
d->n ++ ;
return 0 ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Delete a key in a dictionary
@param d dictionary object to modify.
@param key Key to remove.
@return void
This function deletes a key in a dictionary. Nothing is done if the
key cannot be found.
*/
/*--------------------------------------------------------------------------*/
void dictionary_unset(dictionary * d, const char * key)
{
unsigned hash ;
int i ;
if (key == NULL) {
return;
}
hash = dictionary_hash(key);
for (i=0 ; i<d->size ; i++) {
if (d->key[i]==NULL)
continue ;
/* Compare hash */
if (hash==d->hash[i]) {
/* Compare string, to avoid hash collisions */
if (!strcmp(key, d->key[i])) {
/* Found key */
break ;
}
}
}
if (i>=d->size)
/* Key not found */
return ;
free(d->key[i]);
d->key[i] = NULL ;
if (d->val[i]!=NULL) {
free(d->val[i]);
d->val[i] = NULL ;
}
d->hash[i] = 0 ;
d->n -- ;
return ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Dump a dictionary to an opened file pointer.
@param d Dictionary to dump
@param f Opened file pointer.
@return void
Dumps a dictionary onto an opened file pointer. Key pairs are printed out
as @c [Key]=[Value], one per line. It is Ok to provide stdout or stderr as
output file pointers.
*/
/*--------------------------------------------------------------------------*/
void dictionary_dump(dictionary * d, FILE * out)
{
int i ;
if (d==NULL || out==NULL) return ;
if (d->n<1) {
fprintf(out, "empty dictionary\n");
return ;
}
for (i=0 ; i<d->size ; i++) {
if (d->key[i]) {
fprintf(out, "%20s\t[%s]\n",
d->key[i],
d->val[i] ? d->val[i] : "UNDEF");
}
}
return ;
}
/* Test code */
#ifdef TESTDIC
#define NVALS 20000
int main(int argc, char *argv[])
{
dictionary * d ;
char * val ;
int i ;
char cval[90] ;
/* Allocate dictionary */
printf("allocating...\n");
d = dictionary_new(0);
/* Set values in dictionary */
printf("setting %d values...\n", NVALS);
for (i=0 ; i<NVALS ; i++) {
sprintf(cval, "%04d", i);
dictionary_set(d, cval, "salut");
}
printf("getting %d values...\n", NVALS);
for (i=0 ; i<NVALS ; i++) {
sprintf(cval, "%04d", i);
val = dictionary_get(d, cval, DICT_INVALID_KEY);
if (val==DICT_INVALID_KEY) {
printf("cannot get value for key [%s]\n", cval);
}
}
printf("unsetting %d values...\n", NVALS);
for (i=0 ; i<NVALS ; i++) {
sprintf(cval, "%04d", i);
dictionary_unset(d, cval);
}
if (d->n != 0) {
printf("error deleting values\n");
}
printf("deallocating...\n");
dictionary_del(d);
return 0 ;
}
#endif
/* vim: set ts=4 et sw=4 tw=75 */