ladybird/AK/HashMap.h
Lenny Maiorani e6f907a155 AK: Simplify constructors and conversions from nullptr_t
Problem:
- Many constructors are defined as `{}` rather than using the ` =
  default` compiler-provided constructor.
- Some types provide an implicit conversion operator from `nullptr_t`
  instead of requiring the caller to default construct. This violates
  the C++ Core Guidelines suggestion to declare single-argument
  constructors explicit
  (https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#c46-by-default-declare-single-argument-constructors-explicit).

Solution:
- Change default constructors to use the compiler-provided default
  constructor.
- Remove implicit conversion operators from `nullptr_t` and change
  usage to enforce type consistency without conversion.
2021-01-12 09:11:45 +01:00

161 lines
4.9 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER OR CONTRIBUTORS 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
#include <AK/HashTable.h>
#include <AK/Optional.h>
#include <AK/StdLibExtras.h>
#include <AK/Vector.h>
// NOTE: We can't include <initializer_list> during the toolchain bootstrap,
// since it's part of libstdc++, and libstdc++ depends on LibC.
// For this reason, we don't support HashMap(initializer_list) in LibC.
#ifndef SERENITY_LIBC_BUILD
# include <initializer_list>
#endif
namespace AK {
template<typename K, typename V, typename KeyTraits>
class HashMap {
private:
struct Entry {
K key;
V value;
};
struct EntryTraits {
static unsigned hash(const Entry& entry) { return KeyTraits::hash(entry.key); }
static bool equals(const Entry& a, const Entry& b) { return KeyTraits::equals(a.key, b.key); }
};
public:
HashMap() = default;
#ifndef SERENITY_LIBC_BUILD
HashMap(std::initializer_list<Entry> list)
{
ensure_capacity(list.size());
for (auto& item : list)
set(item.key, item.value);
}
#endif
bool is_empty() const
{
return m_table.is_empty();
}
size_t size() const { return m_table.size(); }
size_t capacity() const { return m_table.capacity(); }
void clear() { m_table.clear(); }
HashSetResult set(const K& key, const V& value) { return m_table.set({ key, value }); }
HashSetResult set(const K& key, V&& value) { return m_table.set({ key, move(value) }); }
bool remove(const K& key)
{
auto it = find(key);
if (it != end()) {
m_table.remove(it);
return true;
}
return false;
}
void remove_one_randomly() { m_table.remove(m_table.begin()); }
using HashTableType = HashTable<Entry, EntryTraits>;
using IteratorType = typename HashTableType::Iterator;
using ConstIteratorType = typename HashTableType::ConstIterator;
IteratorType begin() { return m_table.begin(); }
IteratorType end() { return m_table.end(); }
IteratorType find(const K& key)
{
return m_table.find(KeyTraits::hash(key), [&](auto& entry) { return KeyTraits::equals(key, entry.key); });
}
template<typename Finder>
IteratorType find(unsigned hash, Finder finder)
{
return m_table.find(hash, finder);
}
ConstIteratorType begin() const { return m_table.begin(); }
ConstIteratorType end() const { return m_table.end(); }
ConstIteratorType find(const K& key) const
{
return m_table.find(KeyTraits::hash(key), [&](auto& entry) { return KeyTraits::equals(key, entry.key); });
}
template<typename Finder>
ConstIteratorType find(unsigned hash, Finder finder) const
{
return m_table.find(hash, finder);
}
void ensure_capacity(size_t capacity) { m_table.ensure_capacity(capacity); }
Optional<typename Traits<V>::PeekType> get(const K& key) const
{
auto it = find(key);
if (it == end())
return {};
return (*it).value;
}
bool contains(const K& key) const
{
return find(key) != end();
}
void remove(IteratorType it)
{
m_table.remove(it);
}
V& ensure(const K& key)
{
auto it = find(key);
if (it == end())
set(key, V());
return find(key)->value;
}
Vector<K> keys() const
{
Vector<K> list;
list.ensure_capacity(size());
for (auto& it : *this)
list.unchecked_append(it.key);
return list;
}
private:
HashTableType m_table;
};
}
using AK::HashMap;