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/*
* Copyright (c) 2020, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Forward.h>
#include <AK/HashMap.h>
#include <AK/OwnPtr.h>
#include <AK/Types.h>
namespace AK {
namespace Detail {
template<typename TypeA, typename Default>
struct SubstituteIfVoid {
using Type = TypeA;
};
template<typename Default>
struct SubstituteIfVoid<void, Default> {
using Type = Default;
};
template<typename DeclaredBaseType, typename DefaultBaseType, typename ValueType, typename MetadataT, typename ValueTraits>
class Trie {
using BaseType = typename SubstituteIfVoid<DeclaredBaseType, DefaultBaseType>::Type;
class ConstIterator {
public:
static ConstIterator end() { return {}; }
bool operator==(const ConstIterator& other) const { return m_current_node == other.m_current_node; }
const BaseType& operator*() const { return static_cast<const BaseType&>(*m_current_node); }
const BaseType* operator->() const { return static_cast<const BaseType*>(m_current_node); }
void operator++() { skip_to_next(); }
explicit ConstIterator(const Trie& node)
{
m_current_node = &node;
m_state.empend(false, node.m_children.begin(), node.m_children.end());
}
private:
void skip_to_next()
{
auto& current_state = m_state.last();
if (current_state.did_generate_root)
++current_state.it;
else
current_state.did_generate_root = true;
if (current_state.it == current_state.end)
return pop_and_get_next();
m_current_node = &*(*current_state.it).value;
m_state.empend(false, m_current_node->m_children.begin(), m_current_node->m_children.end());
}
void pop_and_get_next()
{
m_state.take_last();
if (m_state.is_empty()) {
m_current_node = nullptr;
return;
}
skip_to_next();
}
ConstIterator() = default;
struct State {
bool did_generate_root { false };
typename HashMap<ValueType, NonnullOwnPtr<Trie>, ValueTraits>::ConstIteratorType it;
typename HashMap<ValueType, NonnullOwnPtr<Trie>, ValueTraits>::ConstIteratorType end;
};
Vector<State> m_state;
const Trie* m_current_node { nullptr };
};
public:
using MetadataType = MetadataT;
Trie(ValueType value, Optional<MetadataType> metadata)
: m_value(move(value))
, m_metadata(move(metadata))
{
}
template<typename It>
BaseType& traverse_until_last_accessible_node(It& it, const It& end)
{
Trie* node = this;
for (; it < end; ++it) {
auto next_it = node->m_children.find(*it);
if (next_it == node->m_children.end())
return static_cast<BaseType&>(*node);
node = &*(*next_it).value;
}
return static_cast<BaseType&>(*node);
}
template<typename It>
const BaseType& traverse_until_last_accessible_node(It& it, const It& end) const { return const_cast<Trie*>(this)->traverse_until_last_accessible_node(it, end); }
template<typename It>
BaseType& traverse_until_last_accessible_node(const It& begin, const It& end)
{
auto it = begin;
return const_cast<Trie*>(this)->traverse_until_last_accessible_node(it, end);
}
template<typename It>
const BaseType& traverse_until_last_accessible_node(const It& begin, const It& end) const
{
auto it = begin;
return const_cast<Trie*>(this)->traverse_until_last_accessible_node(it, end);
}
Optional<MetadataType> metadata() const requires(!IsNullPointer<MetadataType>) { return m_metadata; }
void set_metadata(MetadataType metadata) requires(!IsNullPointer<MetadataType>) { m_metadata = move(metadata); }
const MetadataType& metadata_value() const requires(!IsNullPointer<MetadataType>) { return m_metadata.value(); }
const ValueType& value() const { return m_value; }
ValueType& value() { return m_value; }
Trie& ensure_child(ValueType value, Optional<MetadataType> metadata = {})
{
auto it = m_children.find(value);
if (it == m_children.end()) {
auto node = make<Trie>(value, move(metadata));
auto& node_ref = *node;
m_children.set(move(value), move(node));
return static_cast<BaseType&>(node_ref);
}
auto& node_ref = *it->value;
if (metadata.has_value())
node_ref.m_metadata = move(metadata);
return static_cast<BaseType&>(node_ref);
}
template<typename It, typename ProvideMetadataFunction>
BaseType& insert(
It& it, const It& end, MetadataType metadata, ProvideMetadataFunction provide_missing_metadata) requires(!IsNullPointer<MetadataType>)
{
Trie* last_root_node = &traverse_until_last_accessible_node(it, end);
for (; it != end; ++it)
last_root_node = static_cast<Trie*>(&last_root_node->ensure_child(*it, provide_missing_metadata(static_cast<BaseType&>(*last_root_node), it)));
last_root_node->set_metadata(move(metadata));
return static_cast<BaseType&>(*last_root_node);
}
template<typename It>
BaseType& insert(It& it, const It& end) requires(IsNullPointer<MetadataType>)
{
Trie* last_root_node = &traverse_until_last_accessible_node(it, end);
for (; it != end; ++it)
last_root_node = static_cast<Trie*>(&last_root_node->ensure_child(*it, {}));
return static_cast<BaseType&>(*last_root_node);
}
template<typename It, typename ProvideMetadataFunction>
BaseType& insert(
const It& begin, const It& end, MetadataType metadata, ProvideMetadataFunction provide_missing_metadata) requires(!IsNullPointer<MetadataType>)
{
auto it = begin;
return insert(it, end, move(metadata), move(provide_missing_metadata));
}
template<typename It>
BaseType& insert(const It& begin, const It& end) requires(IsNullPointer<MetadataType>)
{
auto it = begin;
return insert(it, end);
}
ConstIterator begin() const { return ConstIterator(*this); }
ConstIterator end() const { return ConstIterator::end(); }
[[nodiscard]] bool is_empty() const { return m_children.is_empty(); }
void clear() { m_children.clear(); }
BaseType deep_copy()
{
Trie root(m_value, m_metadata);
for (auto& it : m_children)
root.m_children.set(it.key, make<Trie>(it.value->deep_copy()));
return static_cast<BaseType&&>(move(root));
}
private:
ValueType m_value;
Optional<MetadataType> m_metadata;
HashMap<ValueType, NonnullOwnPtr<Trie>, ValueTraits> m_children;
};
template<typename BaseType, typename DefaultBaseType, typename ValueType, typename ValueTraits>
class Trie<BaseType, DefaultBaseType, ValueType, void, ValueTraits> : public Trie<BaseType, DefaultBaseType, ValueType, decltype(nullptr), ValueTraits> {
using Trie<BaseType, DefaultBaseType, ValueType, decltype(nullptr), ValueTraits>::Trie;
};
}
template<typename ValueType, typename MetadataT = void, typename ValueTraits = Traits<ValueType>, typename BaseT = void>
class Trie : public Detail::Trie<BaseT, Trie<ValueType, MetadataT, ValueTraits>, ValueType, MetadataT, ValueTraits> {
public:
using DetailTrie = Detail::Trie<BaseT, Trie<ValueType, MetadataT, ValueTraits>, ValueType, MetadataT, ValueTraits>;
using MetadataType = typename DetailTrie::MetadataType;
Trie(ValueType value, MetadataType metadata) requires(!IsVoid<MetadataType> && !IsNullPointer<MetadataType>)
: DetailTrie(move(value), move(metadata))
{
}
explicit Trie(ValueType value)
: DetailTrie(move(value), Optional<MetadataType> {})
{
}
};
}
using AK::Trie;
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