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/* A type-safe hash map that retains the insertion order of keys.
Copyright (C) 2019-2020 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 GCC_ORDERED_HASH_MAP_H
#define GCC_ORDERED_HASH_MAP_H
/* Notes:
- The keys must be PODs, since vec<> uses assignment to populate slots
without properly initializing them.
- doesn't have GTY support.
- supports removal, but retains order of original insertion.
(Removal might be better handled by using a doubly-linked list
of nodes, holding the values). */
template<typename KeyId, typename Value,
typename Traits>
class ordered_hash_map
{
typedef typename Traits::key_type Key;
public:
ordered_hash_map () {}
ordered_hash_map (const ordered_hash_map &other)
: m_map (other.m_map),
m_keys (other.m_keys.length ()),
m_key_index (other.m_key_index)
{
unsigned i;
Key key;
FOR_EACH_VEC_ELT (other.m_keys, i, key)
m_keys.quick_push (key);
}
/* 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)
{
bool existed = m_map.put (k, v);
if (!existed)
{
bool key_present;
int &slot = m_key_index.get_or_insert (k, &key_present);
if (!key_present)
{
slot = m_keys.length ();
m_keys.safe_push (k);
}
}
return existed;
}
/* If the passed in key is in the map return its value otherwise NULL. */
Value *get (const Key &k)
{
return m_map.get (k);
}
/* Removing a key removes it from the map, but retains the insertion
order. */
void remove (const Key &k)
{
m_map.remove (k);
}
size_t elements () const { return m_map.elements (); }
class iterator
{
public:
explicit iterator (const ordered_hash_map &map, unsigned idx) :
m_ordered_hash_map (map), m_idx (idx) {}
iterator &operator++ ()
{
/* Increment m_idx until we find a non-deleted element, or go beyond
the end. */
while (1)
{
++m_idx;
if (valid_index_p ())
break;
}
return *this;
}
/* Can't use std::pair here, because GCC before 4.3 don't handle
std::pair where template parameters are references well.
See PR86739. */
struct reference_pair {
const Key &first;
Value &second;
reference_pair (const Key &key, Value &value)
: first (key), second (value) {}
template <typename K, typename V>
operator std::pair<K, V> () const { return std::pair<K, V> (first, second); }
};
reference_pair operator* ()
{
const Key &k = m_ordered_hash_map.m_keys[m_idx];
Value *slot
= const_cast<ordered_hash_map &> (m_ordered_hash_map).get (k);
gcc_assert (slot);
return reference_pair (k, *slot);
}
bool
operator != (const iterator &other) const
{
return m_idx != other.m_idx;
}
/* Treat one-beyond-the-end as valid, for handling the "end" case. */
bool valid_index_p () const
{
if (m_idx > m_ordered_hash_map.m_keys.length ())
return false;
if (m_idx == m_ordered_hash_map.m_keys.length ())
return true;
const Key &k = m_ordered_hash_map.m_keys[m_idx];
Value *slot
= const_cast<ordered_hash_map &> (m_ordered_hash_map).get (k);
return slot != NULL;
}
const ordered_hash_map &m_ordered_hash_map;
unsigned m_idx;
};
/* Standard iterator retrieval methods. */
iterator begin () const
{
iterator i = iterator (*this, 0);
while (!i.valid_index_p () && i != end ())
++i;
return i;
}
iterator end () const { return iterator (*this, m_keys.length ()); }
private:
/* The assignment operator is not yet implemented; prevent erroneous
usage of unsafe compiler-generated one. */
void operator= (const ordered_hash_map &);
/* The underlying map. */
hash_map<KeyId, Value, Traits> m_map;
/* The ordering of the keys. */
auto_vec<Key> m_keys;
/* For each key that's ever been in the map, its index within m_keys. */
hash_map<KeyId, int> m_key_index;
};
/* Two-argument form. */
template<typename Key, typename Value,
typename Traits = simple_hashmap_traits<default_hash_traits<Key>,
Value> >
class ordered_hash_map;
#endif /* GCC_ORDERED_HASH_MAP_H */
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