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/* A type-safe hash set.
Copyright (C) 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 hash_set_h
#define hash_set_h
#include "hash-table.h"
/* implement default behavior for traits when types allow it. */
struct default_hashset_traits
{
/* Hashes the passed in key. */
template<typename T>
static hashval_t
hash (T *p)
{
return uintptr_t(p) >> 3;
}
template<typename T> static hashval_t hash(const T &v) { return v; }
/* Return true if the two keys passed as arguments are equal. */
template<typename T>
static bool
equal (const T &a, const T &b)
{
return a == b;
}
/* Called to dispose of the key before marking the entry as deleted. */
template<typename T> static void remove (T &v) { v.~T (); }
/* Mark the passed in entry as being deleted. */
template<typename T>
static void
mark_deleted (T *&e)
{
e = reinterpret_cast<void *> (1);
}
/* Mark the passed in entry as being empty. */
template<typename T>
static void
mark_empty (T *&e)
{
e = NULL;
}
/* Return true if the passed in entry is marked as deleted. */
template<typename T>
static bool
is_deleted (T *e)
{
return e == reinterpret_cast<void *> (1);
}
/* Return true if the passed in entry is marked as empty. */
template<typename T> static bool is_empty (T *e) { return e == NULL; }
};
template<typename Key, typename Traits = default_hashset_traits>
class hash_set
{
struct hash_entry
{
Key m_key;
typedef hash_entry value_type;
typedef Key compare_type;
typedef int store_values_directly;
static hashval_t hash (const hash_entry &e)
{
return Traits::hash (e.m_key);
}
static bool equal (const hash_entry &a, const Key &b)
{
return Traits::equal (a.m_key, b);
}
static void remove (hash_entry &e) { Traits::remove (e.m_key); }
static void
mark_deleted (hash_entry &e)
{
Traits::mark_deleted (e.m_key);
}
static bool is_deleted (const hash_entry &e)
{
return Traits::is_deleted (e.m_key);
}
static void
mark_empty (hash_entry &e)
{
Traits::mark_empty (e.m_key);
}
static bool
is_empty (const hash_entry &e)
{
return Traits::is_empty (e.m_key);
}
};
public:
explicit hash_set (size_t n = 13) : m_table (n) {}
/* If key k isn't already in the map add it to the map, and
return false. Otherwise return true. */
bool add (const Key &k)
{
hash_entry *e = m_table.find_slot_with_hash (k, Traits::hash (k),
INSERT);
bool existed = !hash_entry::is_empty (*e);
if (!existed)
e->m_key = k;
return existed;
}
/* if the passed in key is in the map return its value otherwise NULL. */
bool contains (const Key &k)
{
hash_entry &e = m_table.find_with_hash (k, Traits::hash (k));
return !Traits::is_empty (e.m_key);
}
/* Call the call back on each pair of key and value with the passed in
arg. */
template<typename Arg, bool (*f)(const Key &, Arg)>
void traverse (Arg a) const
{
for (typename hash_table<hash_entry>::iterator iter = m_table.begin ();
iter != m_table.end (); ++iter)
f ((*iter).m_key, a);
}
private:
hash_table<hash_entry> m_table;
};
#endif
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