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/* Set operations on pointers
Copyright (C) 2004-2014 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC 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 General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#ifndef POINTER_SET_H
#define POINTER_SET_H
/* A pointer set is represented as a simple open-addressing hash
table. Simplifications: The hash code is based on the value of the
pointer, not what it points to. The number of buckets is always a
power of 2. Null pointers are a reserved value. Deletion is not
supported (yet). There is no mechanism for user control of hash
function, equality comparison, initial size, or resizing policy. */
struct pointer_set_t
{
size_t log_slots;
size_t n_slots; /* n_slots = 2^log_slots */
size_t n_elements;
const void **slots;
};
struct pointer_set_t *pointer_set_create (void);
void pointer_set_destroy (struct pointer_set_t *pset);
int pointer_set_contains (const struct pointer_set_t *pset, const void *p);
int pointer_set_insert (struct pointer_set_t *pset, const void *p);
void pointer_set_traverse (const struct pointer_set_t *,
bool (*) (const void *, void *),
void *);
bool pointer_set_lookup (const pointer_set_t *, const void *, size_t *);
/* A pointer map is represented the same way as a pointer_set, so
the hash code is based on the address of the key, rather than
its contents. Null keys are a reserved value. Deletion is not
supported (yet). There is no mechanism for user control of hash
function, equality comparison, initial size, or resizing policy. */
template <typename T>
class pointer_map : protected pointer_set_t
{
T *values;
public:
pointer_map ();
~pointer_map ();
T *contains (const void *p);
T *insert (const void *p, bool *existed_p = NULL);
void traverse (bool (*fn) (const void *, T *, void *), void *data);
};
/* Allocate an empty pointer map. */
template <typename T>
pointer_map<T>::pointer_map (void)
{
n_elements = 0;
log_slots = 8;
n_slots = (size_t) 1 << log_slots;
slots = XCNEWVEC (const void *, n_slots);
values = XNEWVEC (T, n_slots);
}
/* Reclaims all memory associated with PMAP. */
template <typename T>
pointer_map<T>::~pointer_map (void)
{
XDELETEVEC (slots);
XDELETEVEC (values);
}
/* Returns a pointer to the value to which P maps, if PMAP contains P. P
must be nonnull. Return NULL if PMAP does not contain P.
Collisions are resolved by linear probing. */
template <typename T>
T *
pointer_map<T>::contains (const void *p)
{
size_t n;
if (!pointer_set_lookup (this, p, &n))
return NULL;
return &values[n];
}
/* Inserts P into PMAP if it wasn't already there. Returns a pointer
to the value. P must be nonnull. */
template <typename T>
T *
pointer_map<T>::insert (const void *p, bool *existed_p)
{
size_t n;
/* For simplicity, expand the map even if P is already there. This can be
superfluous but can happen at most once. */
/* ??? Fugly that we have to inline that here. */
if (n_elements > n_slots / 4)
{
size_t old_n_slots = n_slots;
const void **old_keys = slots;
T *old_values = values;
log_slots = log_slots + 1;
n_slots = n_slots * 2;
slots = XCNEWVEC (const void *, n_slots);
values = XNEWVEC (T, n_slots);
for (size_t i = 0; i < old_n_slots; ++i)
if (old_keys[i])
{
const void *key = old_keys[i];
pointer_set_lookup (this, key, &n);
slots[n] = key;
values[n] = old_values[i];
}
XDELETEVEC (old_keys);
XDELETEVEC (old_values);
}
if (!pointer_set_lookup (this, p, &n))
{
++n_elements;
slots[n] = p;
if (existed_p)
*existed_p = false;
}
else if (existed_p)
*existed_p = true;
return &values[n];
}
/* Pass each pointer in PMAP to the function in FN, together with the pointer
to the value and the fixed parameter DATA. If FN returns false, the
iteration stops. */
template <class T>
void
pointer_map<T>::traverse (bool (*fn) (const void *, T *, void *), void *data)
{
for (size_t i = 0; i < n_slots; ++i)
if (slots[i] && !fn (slots[i], &values[i], data))
break;
}
struct pointer_map_t;
pointer_map_t *pointer_map_create (void);
void pointer_map_destroy (pointer_map_t *pmap);
void **pointer_map_contains (const pointer_map_t *pmap, const void *p);
void **pointer_map_insert (pointer_map_t *pmap, const void *p);
void pointer_map_traverse (const pointer_map_t *,
bool (*) (const void *, void **, void *), void *);
#endif /* POINTER_SET_H */
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