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#include <ctype.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "util.h"
typedef int T;
struct hash_item {
struct hash_item *next;
char * key;
T data;
};
struct hash_tab {
struct hash_item *table[251]; // fit for your needs...
};
static unsigned long
hash_key(const unsigned char *str)
{
unsigned long hash = 5381;
unsigned int c;
while ( (c = *str++) != '\0' )
hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
return hash;
}
void
hash_init(struct hash_tab *ht)
{
for ( size_t i = 0; i != NELEM(ht->table); ++i )
ht->table[i] = NULL;
}
static struct hash_item *
hash_add(struct hash_item *next, const char *key, T data)
{
struct hash_item *new_item;
char * new_key;
new_key = strdup(key); // strdup: not standard but commonly used...
new_item = malloc(sizeof(*new_item));
if ( new_key == NULL || new_item == NULL ) {
free(new_key);
free(new_item);
ERROR("out of memory");
return NULL;
}
new_item->next = next;
new_item->key = new_key;
new_item->data = data;
return new_item;
}
T *
hash_lookup(struct hash_tab *ht, const char *key, T data, int create)
{
unsigned long h;
struct hash_item *item;
h = hash_key((const unsigned char *) key) % NELEM(ht->table);
for ( item = ht->table[h]; item; item = item->next )
if ( strcmp(key, item->key) == 0 )
return &item->data;
// not found! create?
if ( create ) {
item = hash_add(ht->table[h], key, data);
if ( item != NULL )
ht->table[h] = item;
else
ERROR("can't create item");
}
return item ? &item->data : NULL;
}
bool
hash_delete(struct hash_tab *ht, const char *key)
{
unsigned long h;
struct hash_item *prev, *p;
h = hash_key((const unsigned char *) key) % NELEM(ht->table);
prev = NULL;
for ( p = ht->table[h]; p; p = p->next ) {
if ( strcmp(key, p->key) == 0 ) {
if ( prev == NULL )
ht->table[h] = p->next;
else
prev->next = p->next;
free(p->key);
free(p);
return true; // successfully removed!
}
prev = p;
}
return false;
}
void
hash_apply(struct hash_tab *ht, void (*visit)(const char *key, T data, void *cl), void *cl)
{
struct hash_item *item;
for ( size_t i = 0; i != NELEM(ht->table); ++i )
for ( item = ht->table[i]; item; item = item->next )
visit(item->key, item->data, cl);
}
void
hash_free(struct hash_tab *ht)
{
struct hash_item *p, *next;
for ( size_t i = 0; i != NELEM(ht->table); ++i ) {
for ( p = ht->table[i]; p; p = next ) {
next = p->next;
free(p->key);
free(p);
}
ht->table[i] = NULL;
}
}
int
getword(FILE *fp, char *buf, int size, int first(int), int rest(int))
{
int i = 0, c;
c = getc(fp);
for ( ; c != EOF; c = getc(fp) )
if ( first(c) ) {
if ( i < size - 1 )
buf[i++] = c;
c = getc(fp);
break;
}
for ( ; c != EOF && rest(c); c = getc(fp) )
if ( i < size - 1 )
buf[i++] = c;
if ( i < size )
buf[i] = 0;
else
buf[size - 1] = 0;
if ( c != EOF )
ungetc(c, fp);
return c > 0;
}
int
first(int c)
{
return isalpha(c);
}
int
rest(int c)
{
return isalpha(c) || c == '_';
}
void
print(const char *key, T data, void *cl)
{
fprintf(cl, "%s: %d\n", key, data);
}
int
main()
{
struct hash_tab ht[1];
char word[100];
hash_init(ht);
while ( getword(stdin, word, sizeof word, first, rest) ) {
int *p = hash_lookup(ht, word, 0, 1);
if ( p != NULL )
++(*p);
}
hash_delete(ht, "new_item");
hash_apply(ht, print, stdout);
hash_free(ht);
}
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