ladybird/AK/Trie.h
2022-04-01 21:24:45 +01:00

277 lines
11 KiB
C++

/*
* Copyright (c) 2020, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Concepts.h>
#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;
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, It const& 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>
BaseType const& traverse_until_last_accessible_node(It& it, It const& end) const { return const_cast<Trie*>(this)->traverse_until_last_accessible_node(it, end); }
template<typename It>
BaseType& traverse_until_last_accessible_node(It const& begin, It const& end)
{
auto it = begin;
return const_cast<Trie*>(this)->traverse_until_last_accessible_node(it, end);
}
template<typename It>
BaseType const& traverse_until_last_accessible_node(It const& begin, It const& 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); }
MetadataType const& metadata_value() const requires(!IsNullPointer<MetadataType>) { return m_metadata.value(); }
MetadataType& metadata_value() requires(!IsNullPointer<MetadataType>) { return m_metadata.value(); }
ValueType const& value() const { return m_value; }
ValueType& value() { return m_value; }
ErrorOr<Trie*> ensure_child(ValueType value, Optional<MetadataType> metadata = {})
{
auto it = m_children.find(value);
if (it == m_children.end()) {
OwnPtr<Trie> node;
if constexpr (requires { { value->try_clone() } -> SpecializationOf<ErrorOr>; })
node = TRY(adopt_nonnull_own_or_enomem(new (nothrow) Trie(TRY(value->try_clone()), move(metadata))));
else
node = TRY(adopt_nonnull_own_or_enomem(new (nothrow) Trie(value, move(metadata))));
auto& node_ref = *node;
TRY(m_children.try_set(move(value), node.release_nonnull()));
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>
ErrorOr<BaseType*> insert(
It& it, It const& end, MetadataType metadata, ProvideMetadataFunction provide_missing_metadata) requires(!IsNullPointer<MetadataType>)
{
Trie* last_root_node = &traverse_until_last_accessible_node(it, end);
auto invoke_provide_missing_metadata = [&]<typename... Ts>(Ts&&... args) -> ErrorOr<Optional<MetadataType>> {
if constexpr (SameAs<MetadataType, decltype(provide_missing_metadata(forward<Ts>(args)...))>)
return Optional<MetadataType>(provide_missing_metadata(forward<Ts>(args)...));
else
return provide_missing_metadata(forward<Ts>(args)...);
};
for (; it != end; ++it) {
if constexpr (requires { { ValueType::ElementType::try_create(*it) } -> SpecializationOf<ErrorOr>; })
last_root_node = static_cast<Trie*>(TRY(last_root_node->ensure_child(TRY(ValueType::ElementType::try_create(*it)), TRY(invoke_provide_missing_metadata(static_cast<BaseType&>(*last_root_node), it)))));
else
last_root_node = static_cast<Trie*>(TRY(last_root_node->ensure_child(*it, TRY(invoke_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>
ErrorOr<BaseType*> insert(It& it, It const& end) requires(IsNullPointer<MetadataType>)
{
Trie* last_root_node = &traverse_until_last_accessible_node(it, end);
for (; it != end; ++it) {
if constexpr (requires { { ValueType::ElementType::try_create(*it) } -> SpecializationOf<ErrorOr>; })
last_root_node = static_cast<Trie*>(TRY(last_root_node->ensure_child(TRY(ValueType::ElementType::try_create(*it)), {})));
else
last_root_node = static_cast<Trie*>(TRY(last_root_node->ensure_child(*it, {})));
}
return static_cast<BaseType*>(last_root_node);
}
template<typename It, typename ProvideMetadataFunction>
ErrorOr<BaseType*> insert(
It const& begin, It const& 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>
ErrorOr<BaseType*> insert(It const& begin, It const& end) requires(IsNullPointer<MetadataType>)
{
auto it = begin;
return insert(it, end);
}
HashMap<ValueType, NonnullOwnPtr<Trie>, ValueTraits>& children() { return m_children; }
HashMap<ValueType, NonnullOwnPtr<Trie>, ValueTraits> const& children() const { return m_children; }
template<typename Fn>
ErrorOr<void> for_each_node_in_tree_order(Fn callback) const
{
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> state;
TRY(state.try_empend(false, m_children.begin(), m_children.end()));
auto invoke = [&](auto& current_node) -> ErrorOr<IterationDecision> {
if constexpr (VoidFunction<Fn, const BaseType&>) {
callback(static_cast<const BaseType&>(current_node));
return IterationDecision::Continue;
} else if constexpr (IsSpecializationOf<decltype(callback(declval<const BaseType&>())), ErrorOr>) {
return callback(static_cast<const BaseType&>(current_node));
} else if constexpr (IteratorFunction<Fn, const BaseType&>) {
return callback(static_cast<const BaseType&>(current_node));
} else {
static_assert(DependentFalse<Fn>, "Invalid iterator function type signature");
}
return IterationDecision::Continue;
};
for (auto* current_node = this; current_node != nullptr;) {
if (TRY(invoke(*current_node)) == IterationDecision::Break)
break;
TRY(skip_to_next_iterator(state, current_node));
}
return {};
}
[[nodiscard]] bool is_empty() const { return m_children.is_empty(); }
void clear() { m_children.clear(); }
ErrorOr<BaseType> deep_copy() requires(requires(ValueType value) { { value->try_clone() } -> SpecializationOf<ErrorOr>; })
{
Trie root(TRY(m_value->try_clone()), TRY(copy_metadata(m_metadata)));
for (auto& it : m_children)
TRY(root.m_children.try_set(TRY(it.key->try_clone()), TRY(adopt_nonnull_own_or_enomem(new (nothrow) Trie(TRY(it.value->deep_copy()))))));
return static_cast<BaseType&&>(move(root));
}
ErrorOr<BaseType> deep_copy()
{
Trie root(m_value, TRY(copy_metadata(m_metadata)));
for (auto& it : m_children)
TRY(root.m_children.try_set(it.key, TRY(adopt_nonnull_own_or_enomem(new (nothrow) Trie(TRY(it.value->deep_copy()))))));
return static_cast<BaseType&&>(move(root));
}
private:
static ErrorOr<Optional<MetadataType>> copy_metadata(Optional<MetadataType> const& metadata)
{
if (!metadata.has_value())
return Optional<MetadataType> {};
if constexpr (requires(MetadataType t) { { t.copy() } -> SpecializationOf<ErrorOr>; })
return Optional<MetadataType> { TRY(metadata->copy()) };
#ifndef KERNEL
else
return Optional<MetadataType> { MetadataType(metadata.value()) };
#endif
}
static ErrorOr<void> skip_to_next_iterator(auto& state, auto& current_node)
{
auto& current_state = 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_iterator(state, current_node);
current_node = &*(*current_state.it).value;
TRY(state.try_empend(false, current_node->m_children.begin(), current_node->m_children.end()));
return {};
}
static ErrorOr<void> pop_and_get_next_iterator(auto& state, auto& current_node)
{
state.take_last();
if (state.is_empty()) {
current_node = nullptr;
return {};
}
return skip_to_next_iterator(state, current_node);
}
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;