hash.c

/*
    Copyright (c) 1991-2002, The Numerical ALgorithms Group Ltd.
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are
    met:

        - Redistributions of source code must retain the above copyright
          notice, this list of conditions and the following disclaimer.

        - Redistributions in binary form must reproduce the above copyright
          notice, this list of conditions and the following disclaimer in
          the documentation and/or other materials provided with the
          distribution.

        - Neither the name of The Numerical ALgorithms Group Ltd. nor the
          names of its contributors may be used to endorse or promote products
          derived from this software without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
    IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
    TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
    PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
    OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
    EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
    PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
    PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
    LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
    NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/


#include "openaxiom-c-macros.h"
#define _HASH_C
#include "debug.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "halloc.h"
#include "hash.h"

/* initialize a hash table */

void
hash_init(HashTable *table, int size, EqualFunction equal, 
          HashcodeFunction hash_code)
{
    int i;

    table->table =
        (HashEntry **) halloc(size * sizeof(HashEntry *), "HashEntry");
    for (i = 0; i < size; i++)
        table->table[i] = NULL;
    table->size = size;
    table->equal = equal;
    table->hash_code = hash_code;
    table->num_entries = 0;
}

void
free_hash(HashTable* table, FreeFunction free_fun)
{
  if (table) {
    int i;

    for (i = 0; i < table->size; i++) {
      HashEntry *e, *next;

      for (e = table->table[i]; e != NULL;) {
        next = e->next;
        (*free_fun) ((char*) e->data);
        (*e).data=0;
        free(e);
        e = next;
      }
    }
    free(table->table);
  }
}

/* insert an entry into a hash table */

void
hash_insert(HashTable* table, char* data, const char *key)
{
    HashEntry *entry = (HashEntry *) halloc(sizeof(HashEntry), "HashEntry");
    int code;

    entry->data = data;
    entry->key = key;
    code = (*table->hash_code) (key, table->size) % table->size;
#ifdef DEBUG
    fprintf(stderr, "Hash value = %d\n", code);
#endif
    entry->next = table->table[code];
    table->table[code] = entry;
    table->num_entries++;
}

char *
hash_find(HashTable* table, const char *key)
{
    HashEntry *entry;
    int code = table->hash_code(key, table->size) % table->size;

    for (entry = table->table[code]; entry != NULL; entry = entry->next)
        if ((*table->equal) (entry->key, key))
            return entry->data;
    return NULL;
}

char *
hash_replace(HashTable* table, char* data, const char* key)
{
    HashEntry *entry;
    int code = table->hash_code(key, table->size) % table->size;

    for (entry = table->table[code]; entry != NULL; entry = entry->next)
        if ((*table->equal) (entry->key, key)) {
            entry->data = data;
            return entry->data;
        }
    return NULL;
}

void
hash_delete(HashTable* table, const char* key)
{
    HashEntry **entry;
    int code = table->hash_code(key, table->size) % table->size;

    for (entry = &table->table[code]; *entry != NULL; entry = &((*entry)->next))
        if ((*table->equal) ((*entry)->key, key)) {
            *entry = (*entry)->next;
            table->num_entries--;
            return;
        }
}

void
hash_map(HashTable* table, MappableFunction func)
{
    int i;
    HashEntry *e;

    if (table == NULL)
        return;
    for (i = 0; i < table->size; i++)
        for (e = table->table[i]; e != NULL; e = e->next)
            (*func) (e->data);
}

HashEntry *
hash_copy_entry(HashEntry *e)
{
    HashEntry *ne;

    if (e == NULL)
        return e;
    ne = (HashEntry *) halloc(sizeof(HashEntry), "HashEntry");
    ne->data = e->data;
    ne->key = e->key;
    ne->next = hash_copy_entry(e->next);
    return ne;
}

/* copy a hash table */
HashTable *
hash_copy_table(HashTable* table)
{
    HashTable *nt = (HashTable *) halloc(sizeof(HashTable), "copy hash table");
    int i;

    nt->size = table->size;
    nt->num_entries = table->num_entries;
    nt->equal = table->equal;
    nt->hash_code = table->hash_code;
    nt->table = (HashEntry **) halloc(nt->size * sizeof(HashEntry *),
                                      "copy table");
    for (i = 0; i < table->size; i++)
        nt->table[i] = hash_copy_entry(table->table[i]);
    return nt;
}

/* hash code function for strings */
int
string_hash(const char* s, int size)
{
    int c = 0;
    const char *p =s;


    while (*p)
        c += *p++;
    return c % size;
}

/* test strings for equality */

int
string_equal(const char* s1, const char* s2)
{
    return (strcmp(s1, s2) == 0);
}

/* make a fresh copy of the given string */
char *
alloc_string(const char* str)
{
    char * result;
    result = halloc(strlen(str)+1,"alloc_string");
    strcpy(result,str);
    return (result);
}