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/* A type-safe hash map.
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_map_h
#define hash_map_h
#include "hash-table.h"
/* implement default behavior for traits when types allow it. */
struct default_hashmap_traits
{
/* Hashes the passed in key. */
template<typename T>
static hashval_t
hash (T *p)
{
return uintptr_t(p) >> 3;
}
/* The right thing to do here would be using is_integral to only allow
template arguments of integer type, but reimplementing that is a pain, so
we'll just promote everything to [u]int64_t and truncate to hashval_t. */
static hashval_t hash (uint64_t v) { return v; }
static hashval_t hash (int64_t v) { return v; }
/* Return true if the two keys passed as arguments are equal. */
template<typename T>
static bool
equal_keys (const T &a, const T &b)
{
return a == b;
}
/* Called to dispose of the key and value 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)
{
mark_key_deleted (e.m_key);
}
/* Mark the passed in entry as being empty. */
template<typename T>
static void
mark_empty (T &e)
{
mark_key_empty (e.m_key);
}
/* Return true if the passed in entry is marked as deleted. */
template<typename T>
static bool
is_deleted (T &e)
{
return e.m_key == (void *)1;
}
/* Return true if the passed in entry is marked as empty. */
template<typename T> static bool is_empty (T &e) { return e.m_key == NULL; }
private:
template<typename T>
static void
mark_key_deleted (T *&k)
{
k = reinterpret_cast<T *> (1);
}
template<typename T>
static void
mark_key_empty (T *&k)
{
k = static_cast<T *> (0);
}
};
template<typename Key, typename Value,
typename Traits = default_hashmap_traits>
class hash_map
{
struct hash_entry
{
Key m_key;
Value m_value;
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_keys (a.m_key, b);
}
static void remove (hash_entry &e) { Traits::remove (e); }
static void mark_deleted (hash_entry &e) { Traits::mark_deleted (e); }
static bool is_deleted (const hash_entry &e)
{
return Traits::is_deleted (e);
}
static void mark_empty (hash_entry &e) { Traits::mark_empty (e); }
static bool is_empty (const hash_entry &e) { return Traits::is_empty (e); }
};
public:
explicit hash_map (size_t n = 13) : m_table (n) {}
/* If key k isn't already in the map add key k with value v to the map, and
return false. Otherwise set the value of the entry for key k to be v and
return true. */
bool put (const Key &k, const Value &v)
{
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;
e->m_value = v;
return existed;
}
/* if the passed in key is in the map return its value otherwise NULL. */
Value *get (const Key &k)
{
hash_entry &e = m_table.find_with_hash (k, Traits::hash (k));
return Traits::is_empty (e) ? NULL : &e.m_value;
}
/* Return a reference to the value for the passed in key, creating the entry
if it doesn't already exist. If existed is not NULL then it is set to false
if the key was not previously in the map, and true otherwise. */
Value &get_or_insert (const Key &k, bool *existed = NULL)
{
hash_entry *e = m_table.find_slot_with_hash (k, Traits::hash (k),
INSERT);
bool ins = Traits::is_empty (*e);
if (ins)
e->m_key = k;
if (existed != NULL)
*existed = !ins;
return e->m_value;
}
void remove (const Key &k)
{
m_table.remove_elt_with_hash (k, Traits::hash (k));
}
/* Call the call back on each pair of key and value with the passed in
arg. */
template<typename Arg, bool (*f)(const Key &, const Value &, 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, (*iter).m_value, a);
}
template<typename Arg, bool (*f)(const Key &, Value *, Arg)>
void traverse (Arg a) const
{
for (typename hash_table<hash_entry>::iterator iter = m_table.begin ();
iter != m_table.end (); ++iter)
if (!f ((*iter).m_key, &(*iter).m_value, a))
break;
}
private:
hash_table<hash_entry> m_table;
};
#endif
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