Mega Top 1/os2_top1.zip/os2_top1/APPS/TEKST/TXI2IPF1/SOURCE.ZIP/gen/String_XClass_VHMap.cc

C/C++ Source or Header | 1993-02-04 | 5.9 KB | 226 lines

///////////////////////////////////////////////////////////////////////////////
// $Id: String_XClass_VHMap.cc,v 1.1.1.1 1993/02/04 15:18:32 ak Exp $
///////////////////////////////////////////////////////////////////////////////
// $Log: String_XClass_VHMap.cc,v $
// Revision 1.1.1.1  1993/02/04  15:18:32  ak
// Please Edit this file to contain the RCS log information
// to be associated with this file (please remove these lines)
//
// Revision 1.1  1993/02/04  15:18:29  ak
// Initial revision
//
///////////////////////////////////////////////////////////////////////////////

static char *rcsid = "$Id: String_XClass_VHMap.cc,v 1.1.1.1 1993/02/04 15:18:32 ak Exp $";

// This may look like C code, but it is really -*- C++ -*-
/*
Copyright (C) 1988 Free Software Foundation
    written by Doug Lea ([e-mail])

This file is part of the GNU C++ Library.  This library is free
software; you can redistribute it and/or modify it under the terms of
the GNU Library 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 Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free Software
Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#ifdef __GNUG__
#pragma implementation
#endif
#include "info.h"

/* codes for status fields */

#define EMPTYCELL   0
#define VALIDCELL   1
#define DELETEDCELL 2


StringXClassVHMap::StringXClassVHMap(XClass& dflt, unsigned int sz)
     :StringXClassMap(dflt)
{
  tab = new String[size = sz];
  cont = new XClass[size];
  status = new char[size];
  for (unsigned int i = 0; i < size; ++i) status[i] = EMPTYCELL;
}

StringXClassVHMap::StringXClassVHMap(StringXClassVHMap& a) : StringXClassMap(a.def)
{
  tab = new String[size = a.size];
  cont = new XClass[size];
  status = new char[size];
  for (unsigned int i = 0; i < size; ++i) status[i] = EMPTYCELL;
  count = 0;
  for (Pix p = a.first(); p; a.next(p)) (*this)[a.key(p)] = a.contents(p);
}


/*
 * hashing method: double hash based on high bits of hash fct,
 * followed by linear probe. Can't do too much better if table
 * sizes not constrained to be prime.
*/


static inline unsigned int doublehashinc(unsigned int h, unsigned int s)
{
  unsigned int dh =  ((h / s) % s);
  return (dh > 1)? dh : 1;
}

Pix StringXClassVHMap::seek(String& key)
{
  unsigned int hashval = StringHASH(key);
  unsigned int h = hashval % size;
  for (unsigned int i = 0; i <= size; ++i)
  {
    if (status[h] == EMPTYCELL)
      return 0;
    else if (status[h] == VALIDCELL && StringEQ(key, tab[h]))
      return Pix(&tab[h]);
    if (i == 0)
      h = (h + doublehashinc(hashval, size)) % size;
    else if (++h >= size)
      h -= size;
  }
  return 0;
}


XClass& StringXClassVHMap::operator [](String& item)
{
  if (size <= count + 1)
    resize();

  unsigned int bestspot = size;
  unsigned int hashval = StringHASH(item);
  unsigned int h = hashval % size;
  for (unsigned int i = 0; i <= size; ++i)
  {
    if (status[h] == EMPTYCELL)
    {
      ++count;
      if (bestspot >= size) bestspot = h;
      tab[bestspot] = item;
      status[bestspot] = VALIDCELL;
      cont[bestspot] = def;
      return cont[bestspot];
    }
    else if (status[h] == DELETEDCELL)
    {
      if (bestspot >= size) bestspot = h;
    }
    else if (StringEQ(tab[h],item))
      return cont[h];

    if (i == 0)
      h = (h + doublehashinc(hashval, size)) % size;
    else if (++h >= size)
      h -= size;
  }

  ++count;
  status[bestspot] = VALIDCELL;
  tab[bestspot] = item;
  cont[bestspot] = def;
  return cont[bestspot];
}


void StringXClassVHMap::del(String& key)
{
  unsigned int hashval = StringHASH(key);
  unsigned int h = hashval % size;
  for (unsigned int i = 0; i <= size; ++i)
  {
    if (status[h] == EMPTYCELL)
      return;
    else if (status[h] == VALIDCELL && StringEQ(key, tab[h]))
    {
      status[h] = DELETEDCELL;
      --count;
      return;
    }
    if (i == 0)
      h = (h + doublehashinc(hashval, size)) % size;
    else if (++h >= size)
      h -= size;
  }
}


void StringXClassVHMap::clear()
{
  for (unsigned int i = 0; i < size; ++i) status[i] = EMPTYCELL;
  count = 0;
}

void StringXClassVHMap::resize(unsigned int newsize)
{
  if (newsize <= count)
  {
    newsize = DEFAULT_INITIAL_CAPACITY;
    while (newsize <= count) newsize <<= 1;
  }
  String* oldtab = tab;
  XClass* oldcont = cont;
  char* oldstatus = status;
  unsigned int oldsize = size;
  tab = new String[size = newsize];
  cont = new XClass[size];
  status = new char[size];
  for (unsigned int i = 0; i < size; ++i) status[i] = EMPTYCELL;
  count = 0;
  for (i = 0; i < oldsize; ++i)
    if (oldstatus[i] == VALIDCELL)
      (*this)[oldtab[i]] = oldcont[i];
  delete [] oldtab;
  delete [] oldcont;
  delete oldstatus;
}

Pix StringXClassVHMap::first()
{
  for (unsigned int pos = 0; pos < size; ++pos)
    if (status[pos] == VALIDCELL) return Pix(&tab[pos]);
  return 0;
}

void StringXClassVHMap::next(Pix& i)
{
  if (i == 0) return;
  unsigned int pos = ((unsigned)i - (unsigned)tab) / sizeof(String) + 1;
  for (; pos < size; ++pos)
    if (status[pos] == VALIDCELL)
    {
      i = Pix(&tab[pos]);
      return;
    }
  i = 0;
}


int StringXClassVHMap::OK()
{
  int v = tab != 0;
  v &= status != 0;
  int n = 0;
  for (unsigned int i = 0; i < size; ++i)
  {
    if (status[i] == VALIDCELL) ++n;
    else if (status[i] != DELETEDCELL && status[i] != EMPTYCELL)
      v = 0;
  }
  v &= n == count;
  if (!v) error("invariant failure");
  return v;
}