tdelibs/kjs/lookup.cpp

/*
 *  This file is part of the KDE libraries
 *  Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
 *  Copyright (C) 2003 Apple Computer, Inc.
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

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

#include "lookup.h"

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

using namespace KJS;

static bool keysMatch(const UChar *c, unsigned len, const char *s)
{
  for (unsigned i = 0; i != len; i++, c++, s++)
    if (c->uc != (unsigned char)*s)
      return false;
  return *s == 0;
}

const HashEntry* Lookup::findEntry( const struct HashTable *table,
                              const UChar *c, unsigned int len )
{
#ifndef NDEBUG
  if (table->type != 2) {
    fprintf(stderr, "KJS: Unknown hash table version.\n");
    return 0;
  }
#endif

  int h = hash(c, len) % table->hashSize;
  const HashEntry *e = &table->entries[h];

  // empty bucket ?
  if (!e->soffset)
    return 0;

  while(1) {
    // compare strings
    if (keysMatch(c, len, &table->sbase[e->soffset]))
      return e;
    // try next bucket
    if(e->next < 0) break;

    e = &table->entries[e->next];
  }

  return 0;
}

const HashEntry* Lookup::findEntry( const struct HashTable *table,
                                const Identifier &s )
{
  return findEntry( table, s.data(), s.size() );
}

int Lookup::find(const struct HashTable *table,
		 const UChar *c, unsigned int len)
{
  const HashEntry *entry = findEntry( table, c, len );
  if (entry)
    return entry->value;
  return -1;
}

int Lookup::find(const struct HashTable *table, const Identifier &s)
{
  return find(table, s.data(), s.size());
}

unsigned int Lookup::hash(const UChar *c, unsigned int len)
{
  unsigned int val = 0;
  // ignoring higher byte
  for (unsigned int i = 0; i < len; i++, c++)
    val += c->low();

  return val;
}

unsigned int Lookup::hash(const Identifier &key)
{
  return hash(key.data(), key.size());
}

unsigned int Lookup::hash(const char *s)
{
  unsigned int val = 0;
  while (*s)
    val += *s++;

  return val;
}