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/***************************************************************************
tagmap.h
Simple tag->object mapping functions.
****************************************************************************
Copyright Aaron Giles
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 'MAME' 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 AARON GILES ''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 AARON GILES 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.
***************************************************************************/
#pragma once
#ifndef __TAGMAP_H__
#define __TAGMAP_H__
#include "osdcore.h"
#include "astring.h"
//**************************************************************************
// CONSTANTS
//**************************************************************************
enum tagmap_error
{
TMERR_NONE,
TMERR_DUPLICATE
};
//**************************************************************************
// TYPE DEFINITIONS
//**************************************************************************
// generally used for small tables, though the hash size can be increased
// as necessary; good primes are: 53, 97, 193, 389, 769, 1543, 3079, 6151, etc
template<class _ElementType, int _HashSize = 53>
class tagmap_t
{
private:
// disable copying/assignment
tagmap_t(const tagmap_t &);
tagmap_t &operator=(const tagmap_t &);
public:
// an entry in the table
class entry_t
{
friend class tagmap_t<_ElementType, _HashSize>;
public:
// construction/destruction
entry_t(const char *tag, UINT32 fullhash, _ElementType object)
: m_next(NULL),
m_fullhash(fullhash),
m_tag(tag),
m_object(object) { }
// accessors
const astring &tag() const { return m_tag; }
_ElementType object() const { return m_object; }
// setters
void set_object(_ElementType object) { m_object = object; }
private:
// internal helpers
entry_t *next() const { return m_next; }
UINT32 fullhash() const { return m_fullhash; }
// internal state
entry_t * m_next;
UINT32 m_fullhash;
astring m_tag;
_ElementType m_object;
};
// construction/destruction
tagmap_t() { memset(m_table, 0, sizeof(m_table)); }
~tagmap_t() { reset(); }
// core hashing function
UINT32 hash(const char *string) const
{
UINT32 result = *string++;
for (UINT8 c = *string++; c != 0; c = *string++)
result = (result*33) ^ c;
return result;
}
// empty the list
void reset()
{
for (UINT32 hashindex = 0; hashindex < ARRAY_LENGTH(m_table); hashindex++)
while (m_table[hashindex] != NULL)
remove_common(&m_table[hashindex]);
}
// add/remove
tagmap_error add(const char *tag, _ElementType object, bool replace_if_duplicate = false) { return add_common(tag, object, replace_if_duplicate, false); }
tagmap_error add_unique_hash(const char *tag, _ElementType object, bool replace_if_duplicate = false) { return add_common(tag, object, replace_if_duplicate, true); }
// remove by tag
void remove(const char *tag)
{
UINT32 fullhash = hash(tag);
for (entry_t **entryptr = &m_table[fullhash % ARRAY_LENGTH(m_table)]; *entryptr != NULL; entryptr = &(*entryptr)->m_next)
if ((*entryptr)->fullhash() == fullhash && (*entryptr)->tag() == tag)
return remove_common(entryptr);
}
// remove by object
void remove(_ElementType object)
{
for (UINT32 hashindex = 0; hashindex < ARRAY_LENGTH(m_table); hashindex++)
for (entry_t **entryptr = &m_table[hashindex]; *entryptr != NULL; entryptr = &(*entryptr)->m_next)
if ((*entryptr)->object() == object)
return remove_common(entryptr);
}
// find by tag
_ElementType find(const char *tag) const { return find(tag, hash(tag)); }
// find by tag with precomputed hash
_ElementType find(const char *tag, UINT32 fullhash) const
{
for (entry_t *entry = m_table[fullhash % ARRAY_LENGTH(m_table)]; entry != NULL; entry = entry->next())
if (entry->fullhash() == fullhash && entry->tag() == tag)
return entry->object();
return _ElementType(NULL);
}
// find by tag without checking anything but the hash
_ElementType find_hash_only(const char *tag) const
{
UINT32 fullhash = hash(tag);
for (entry_t *entry = m_table[fullhash % ARRAY_LENGTH(m_table)]; entry != NULL; entry = entry->next())
if (entry->fullhash() == fullhash)
return entry->object();
return NULL;
}
// return first object in the table
entry_t *first() const { return next(NULL); }
// return next object in the table
entry_t *next(entry_t *after) const
{
// if there's another item in this hash bucket, just return it
if (after != NULL && after->next() != NULL)
return after->next();
// otherwise scan forward for the next bucket with an entry
UINT32 firstindex = (after != NULL) ? (after->fullhash() % ARRAY_LENGTH(m_table) + 1) : 0;
for (UINT32 hashindex = firstindex; hashindex < ARRAY_LENGTH(m_table); hashindex++)
if (m_table[hashindex] != NULL)
return m_table[hashindex];
// all out
return NULL;
}
private:
// internal helpers
tagmap_error add_common(const char *tag, _ElementType object, bool replace_if_duplicate, bool unique_hash);
// remove an entry given a pointer to its pointer
void remove_common(entry_t **entryptr)
{
entry_t *entry = *entryptr;
*entryptr = entry->next();
delete entry;
}
// internal state
entry_t * m_table[_HashSize];
};
//**************************************************************************
// IMPLEMENTATION
//**************************************************************************
//-------------------------------------------------
// add_common - core implementation of a tagmap
// addition
//-------------------------------------------------
template<class _ElementType, int _HashSize>
tagmap_error tagmap_t<_ElementType, _HashSize>::add_common(const char *tag, _ElementType object, bool replace_if_duplicate, bool unique_hash)
{
UINT32 fullhash = hash(tag);
UINT32 hashindex = fullhash % ARRAY_LENGTH(m_table);
// first make sure we don't have a duplicate
for (entry_t *entry = m_table[hashindex]; entry != NULL; entry = entry->next())
if (entry->fullhash() == fullhash)
if (unique_hash || entry->tag() == tag)
{
if (replace_if_duplicate)
entry->set_object(object);
return TMERR_DUPLICATE;
}
// now allocate a new entry and add to the head of the list
entry_t *entry = new entry_t(tag, fullhash, object);
entry->m_next = m_table[hashindex];
m_table[hashindex] = entry;
return TMERR_NONE;
}
#endif /* __TAGMAP_H__ */
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