maphash.c

/******************************************************************************
 * $Id$
 *
 * Project:  MapServer
 * Purpose:  Implement hashTableObj class.
 * Author:   Sean Gillies, sgillies@frii.com
 *
 ******************************************************************************
 * Copyright (c) 1996-2005 Regents of the University of Minnesota.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies of this Software or works derived from this Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 ****************************************************************************/

#include <ctype.h>

#include "mapserver.h"
#include "maphash.h"



static unsigned hash(const char *key)
{
  unsigned hashval;

  for(hashval=0; *key!='\0'; key++)
    hashval = tolower(*key) + 31 * hashval;

  return(hashval % MS_HASHSIZE);
}

hashTableObj *msCreateHashTable()
{
  int i;
  hashTableObj *table;

  table = (hashTableObj *) msSmallMalloc(sizeof(hashTableObj));
  table->items = (struct hashObj **) msSmallMalloc(sizeof(struct hashObj *)*MS_HASHSIZE);

  for (i=0; i<MS_HASHSIZE; i++)
    table->items[i] = NULL;
  table->numitems = 0;

  return table;
}

int initHashTable( hashTableObj *table )
{
  int i;

  table->items = (struct hashObj **) malloc(sizeof(struct hashObj *)*MS_HASHSIZE);
  MS_CHECK_ALLOC(table->items, sizeof(struct hashObj *)*MS_HASHSIZE, MS_FAILURE);

  for (i=0; i<MS_HASHSIZE; i++)
    table->items[i] = NULL;
  table->numitems = 0;
  return MS_SUCCESS;
}

void msFreeHashTable( hashTableObj *table )
{
  if( table != NULL ) {
    msFreeHashItems(table);
    free(table);
    table = NULL;
  }
}

int msHashIsEmpty( hashTableObj *table )
{
  if (table->numitems == 0 )
    return MS_TRUE;
  else
    return MS_FALSE;
}


void msFreeHashItems( hashTableObj *table )
{
  int i;
  struct hashObj *tp=NULL;
  struct hashObj *prev_tp=NULL;

  if (table) {
    if(table->items) {
      for (i=0; i<MS_HASHSIZE; i++) {
        if (table->items[i] != NULL) {
          for (tp=table->items[i]; tp!=NULL; prev_tp=tp,tp=tp->next,free(prev_tp)) {
            msFree(tp->key);
            msFree(tp->data);
          }
        }
      }
      free(table->items);
      table->items = NULL;
    } else {
      msSetError(MS_HASHERR, "No items allocated.", "msFreeHashItems()");
    }
  } else {
    msSetError(MS_HASHERR, "Can't free NULL table", "msFreeHashItems()");
  }
}

struct hashObj *msInsertHashTable(hashTableObj *table,
                                  const char *key, const char *value) {
  struct hashObj *tp;
  unsigned hashval;

  if (!table || !key || !value) {
    msSetError(MS_HASHERR, "Invalid hash table or key",
               "msInsertHashTable");
    return NULL;
  }

  for (tp=table->items[hash(key)]; tp!=NULL; tp=tp->next)
    if(strcasecmp(key, tp->key) == 0)
      break;

  if (tp == NULL) { /* not found */
    tp = (struct hashObj *) malloc(sizeof(*tp));
    MS_CHECK_ALLOC(tp, sizeof(*tp), NULL);
    tp->key = msStrdup(key);
    hashval = hash(key);
    tp->next = table->items[hashval];
    table->items[hashval] = tp;
    table->numitems++;
  } else {
    free(tp->data);
  }

  if ((tp->data = msStrdup(value)) == NULL)
    return NULL;

  return tp;
}

char *msLookupHashTable(hashTableObj *table, const char *key)
{
  struct hashObj *tp;

  if (!table || !key) {
    return(NULL);
  }

  for (tp=table->items[hash(key)]; tp!=NULL; tp=tp->next)
    if (strcasecmp(key, tp->key) == 0)
      return(tp->data);

  return NULL;
}

int msRemoveHashTable(hashTableObj *table, const char *key)
{
  struct hashObj *tp;
  struct hashObj *prev_tp=NULL;
  int status = MS_FAILURE;

  if (!table || !key) {
    msSetError(MS_HASHERR, "No hash table", "msRemoveHashTable");
    return MS_FAILURE;
  }

  tp=table->items[hash(key)];
  if (!tp) {
    msSetError(MS_HASHERR, "No such hash entry", "msRemoveHashTable");
    return MS_FAILURE;
  }

  prev_tp = NULL;
  while (tp != NULL) {
    if (strcasecmp(key, tp->key) == 0) {
      status = MS_SUCCESS;
      if (prev_tp) {
        prev_tp->next = tp->next;
        free(tp);
        break;
      } else {
        table->items[hash(key)] = tp->next;
        free(tp);
        break;
      }
    }
    prev_tp = tp;
    tp = tp->next;
  }

  if (status == MS_SUCCESS)
    table->numitems--;

  return status;
}

const char *msFirstKeyFromHashTable( hashTableObj *table )
{
  int hash_index;

  if (!table) {
    msSetError(MS_HASHERR, "No hash table", "msFirstKeyFromHashTable");
    return NULL;
  }

  for (hash_index = 0; hash_index < MS_HASHSIZE; hash_index++ ) {
    if (table->items[hash_index] != NULL )
      return table->items[hash_index]->key;
  }

  return NULL;
}

const char *msNextKeyFromHashTable( hashTableObj *table, const char *lastKey )
{
  int hash_index;
  struct hashObj *link;

  if (!table) {
    msSetError(MS_HASHERR, "No hash table", "msNextKeyFromHashTable");
    return NULL;
  }

  if ( lastKey == NULL )
    return msFirstKeyFromHashTable( table );

  hash_index = hash(lastKey);
  for ( link = table->items[hash_index];
        link != NULL && strcasecmp(lastKey,link->key) != 0;
        link = link->next ) {}

  if ( link != NULL && link->next != NULL )
    return link->next->key;

  while ( ++hash_index < MS_HASHSIZE ) {
    if ( table->items[hash_index] != NULL )
      return table->items[hash_index]->key;
  }

  return NULL;
}