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NeXTSTEP 3.3 (Developer)…68k, x86, SPARC, PA-RISC]
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VHSet.ccP
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1995-02-06
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// This may look like C code, but it is really -*- C++ -*-
/*
Copyright (C) 1988 Free Software Foundation
written by Doug Lea (dl@rocky.oswego.edu)
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 "<T>.VHSet.h"
/* codes for status fields */
#define EMPTYCELL 0
#define VALIDCELL 1
#define DELETEDCELL 2
<T>VHSet::<T>VHSet(unsigned int sz)
{
tab = new <T>[size = sz];
status = new char[size];
for (unsigned int i = 0; i < size; ++i) status[i] = EMPTYCELL;
count = 0;
}
<T>VHSet::<T>VHSet(<T>VHSet& a)
{
tab = new <T>[size = a.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)) add(a(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 <T>VHSet::seek(<T&> key)
{
unsigned int hashval = <T>HASH(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 && <T>EQ(key, tab[h]))
return Pix(&tab[h]);
if (i == 0)
h = (h + doublehashinc(hashval, size)) % size;
else if (++h >= size)
h -= size;
}
return 0;
}
Pix <T>VHSet::add(<T&> item)
{
if (HASHTABLE_TOO_CROWDED(count, size))
resize();
unsigned int bestspot = size;
unsigned int hashval = <T>HASH(item);
unsigned int h = hashval % size;
for (unsigned int i = 0; i <= size; ++i)
{
if (status[h] == EMPTYCELL)
{
if (bestspot >= size) bestspot = h;
tab[bestspot] = item;
status[bestspot] = VALIDCELL;
++count;
return Pix(&tab[bestspot]);
}
else if (status[h] == DELETEDCELL)
{
if (bestspot >= size) bestspot = h;
}
else if (<T>EQ(tab[h],item))
return Pix(&tab[h]);
if (i == 0)
h = (h + doublehashinc(hashval, size)) % size;
else if (++h >= size)
h -= size;
}
tab[bestspot] = item;
status[bestspot] = VALIDCELL;
++count;
return Pix(&tab[bestspot]);
}
void <T>VHSet::del(<T&> key)
{
unsigned int hashval = <T>HASH(key);
unsigned int h = hashval % size;
for (unsigned int i = 0; i <= size; ++i)
{
if (status[h] == EMPTYCELL)
return;
else if (status[h] == VALIDCELL && <T>EQ(key, tab[h]))
{
status[h] = DELETEDCELL;
--count;
return;
}
if (i == 0)
h = (h + doublehashinc(hashval, size)) % size;
else if (++h >= size)
h -= size;
}
}
void <T>VHSet::clear()
{
for (unsigned int i = 0; i < size; ++i) status[i] = EMPTYCELL;
count = 0;
}
void <T>VHSet::resize(unsigned int newsize)
{
if (newsize <= count)
{
newsize = DEFAULT_INITIAL_CAPACITY;
while (HASHTABLE_TOO_CROWDED(count, newsize)) newsize <<= 1;
}
<T>* oldtab = tab;
char* oldstatus = status;
unsigned int oldsize = size;
tab = new <T>[size = newsize];
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) add(oldtab[i]);
delete [] oldtab;
delete oldstatus;
}
Pix <T>VHSet::first()
{
for (unsigned int pos = 0; pos < size; ++pos)
if (status[pos] == VALIDCELL) return Pix(&tab[pos]);
return 0;
}
void <T>VHSet::next(Pix& i)
{
if (i == 0) return;
unsigned int pos = ((unsigned)i - (unsigned)tab) / sizeof(<T>) + 1;
for (; pos < size; ++pos)
if (status[pos] == VALIDCELL)
{
i = Pix(&tab[pos]);
return;
}
i = 0;
}
int <T>VHSet:: operator == (<T>VHSet& b)
{
if (count != b.count)
return 0;
else
{
for (unsigned int i = 0; i < size; ++i)
if (status[i] == VALIDCELL && b.seek(tab[i]) == 0)
return 0;
for (i = 0; i < b.size; ++i)
if (b.status[i] == VALIDCELL && seek(b.tab[i]) == 0)
return 0;
return 1;
}
}
int <T>VHSet::operator <= (<T>VHSet& b)
{
if (count > b.count)
return 0;
else
{
for (unsigned int i = 0; i < size; ++i)
if (status[i] == VALIDCELL && b.seek(tab[i]) == 0)
return 0;
return 1;
}
}
void <T>VHSet::operator |= (<T>VHSet& b)
{
if (&b == this || b.count == 0)
return;
for (unsigned int i = 0; i < b.size; ++i)
if (b.status[i] == VALIDCELL) add(b.tab[i]);
}
void <T>VHSet::operator &= (<T>VHSet& b)
{
if (&b == this || count == 0)
return;
for (unsigned int i = 0; i < size; ++i)
{
if (status[i] == VALIDCELL && b.seek(tab[i]) == 0)
{
status[i] = DELETEDCELL;
--count;
}
}
}
void <T>VHSet::operator -= (<T>VHSet& b)
{
for (unsigned int i = 0; i < size; ++i)
{
if (status[i] == VALIDCELL && b.seek(tab[i]) != 0)
{
status[i] = DELETEDCELL;
--count;
}
}
}
int <T>VHSet::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;
}