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