draconisplusplus/include/matchit.hpp

/*
 *  Copyright (c) 2021-2022 Bowen Fu
 *  Distributed Under The Apache-2.0 License
 */

#pragma once

#include <algorithm>
#include <any>
#include <array>
#include <cassert>
#include <cstdint>
#include <optional>
#include <stdexcept>
#include <tuple>
#include <type_traits>
#include <utility>
#include <variant>

#include "src/util/defs.hpp"

// NOLINTBEGIN(readability-identifier-*, cppcoreguidelines-special-member-functions)
namespace matchit {
  namespace impl {
    template <typename Value, bool byRef>
    class ValueType {
     public:
      using ValueT = Value;
    };

    template <typename Value>
    class ValueType<Value, true> {
     public:
      using ValueT = Value&&;
    };

    template <typename Value, typename... Patterns>
    constexpr fn matchPatterns(Value&& value, const Patterns&... patterns);

    template <typename Value, bool byRef>
    class MatchHelper {
     private:
      using ValueT = typename ValueType<Value, byRef>::ValueT;
      ValueT mValue;
      using ValueRefT = ValueT&&;

     public:
      template <typename V>
      constexpr explicit MatchHelper(V&& value)
        : mValue { std::forward<V>(value) } {}

      template <typename... PatternPair>
      constexpr fn operator()(const PatternPair&... patterns) {
        return matchPatterns(std::forward<ValueRefT>(mValue), patterns...);
      }

      MatchHelper(const MatchHelper&) = delete;
      MatchHelper(MatchHelper&&)      = delete;
    };

    template <typename Value>
    constexpr fn match(Value&& value) {
      return MatchHelper<Value, true> { std::forward<Value>(value) };
    }

    template <typename First, typename... Values>
    constexpr fn match(First&& first, Values&&... values) {
      auto result = std::forward_as_tuple(std::forward<First>(first), std::forward<Values>(values)...);
      return MatchHelper<decltype(result), false> { std::forward<decltype(result)>(result) };
    }

    template <typename T>
    class Nullary : public T {
     public:
      using T::operator();
    };

    template <typename T>
    constexpr fn nullary(const T& t) {
      return Nullary<T> { t };
    }

    template <typename T>
    class Id;
    template <typename T>
    constexpr fn expr(Id<T>& id) {
      return nullary([&] { return *id; });
    }

    template <typename T>
    constexpr fn expr(const T& v) {
      return nullary([&] { return v; });
    }

    template <typename T>
    constexpr fn toNullary(T&& v) {
      if constexpr (std::is_invocable_v<std::decay_t<T>>)
        return std::forward<T>(v);
      else
        return expr(std::forward<T>(v));
    }

    // for constant
    template <typename T>
    class EvalTraits {
     public:
      template <typename... Args>
      constexpr static fn evalImpl(const T& v, const Args&... /*unused*/) -> decltype(auto) {
        return v;
      }
    };

    template <typename T>
    class EvalTraits<Nullary<T>> {
     public:
      constexpr static fn evalImpl(const Nullary<T>& e) -> decltype(auto) {
        return e();
      }
    };

    // Only allowed in nullary
    template <typename T>
    class EvalTraits<Id<T>> {
     public:
      constexpr static fn evalImpl(const Id<T>& id) -> decltype(auto) {
        return *id;
      }
    };

    template <typename Pred>
    class Meet;

    // Unary is an alias of Meet.
    template <typename T>
    using Unary = Meet<T>;

    template <typename T>
    class EvalTraits<Unary<T>> {
     public:
      template <typename Arg>
      constexpr static fn evalImpl(const Unary<T>& e, const Arg& arg) -> decltype(auto) {
        return e(arg);
      }
    };

    class Wildcard;
    template <>
    class EvalTraits<Wildcard> {
     public:
      template <typename Arg>
      constexpr static fn evalImpl(const Wildcard& /*unused*/, const Arg& arg) -> decltype(auto) {
        return arg;
      }
    };

    template <typename T, typename... Args>
    constexpr fn evaluate_(const T& t, const Args&... args) -> decltype(auto) {
      return EvalTraits<T>::evalImpl(t, args...);
    }

    template <typename T>
    class IsNullaryOrId : public std::false_type {};

    template <typename T>
    class IsNullaryOrId<Id<T>> : public std::true_type {};

    template <typename T>
    class IsNullaryOrId<Nullary<T>> : public std::true_type {};

    template <typename T>
    constexpr bool isNullaryOrIdV = IsNullaryOrId<std::decay_t<T>>::value;

#define UN_OP_FOR_NULLARY(op)                        \
  template <typename T>                              \
  constexpr fn operator op(T const& t)               \
    requires isNullaryOrIdV<T>                       \
  {                                                  \
    return nullary([&] { return op evaluate_(t); }); \
  }

#define BIN_OP_FOR_NULLARY(op)                                    \
  template <typename T, typename U>                               \
  constexpr fn operator op(T const& t, U const& u)                \
    requires isNullaryOrIdV<T> || isNullaryOrIdV<U>               \
  {                                                               \
    return nullary([&] { return evaluate_(t) op evaluate_(u); }); \
  }

    // ADL will find these operators.
    UN_OP_FOR_NULLARY(!)
    UN_OP_FOR_NULLARY(-)

#undef UN_OP_FOR_NULLARY

    BIN_OP_FOR_NULLARY(+)
    BIN_OP_FOR_NULLARY(-)
    BIN_OP_FOR_NULLARY(*)
    BIN_OP_FOR_NULLARY(/)
    BIN_OP_FOR_NULLARY(%)
    BIN_OP_FOR_NULLARY(<)
    BIN_OP_FOR_NULLARY(<=)
    BIN_OP_FOR_NULLARY(==)
    BIN_OP_FOR_NULLARY(!=)
    BIN_OP_FOR_NULLARY(>=)
    BIN_OP_FOR_NULLARY(>)
    BIN_OP_FOR_NULLARY(||)
    BIN_OP_FOR_NULLARY(&&)
    BIN_OP_FOR_NULLARY(^)

#undef BIN_OP_FOR_NULLARY

    // Unary
    template <typename T>
    class IsUnaryOrWildcard : public std::false_type {};

    template <>
    class IsUnaryOrWildcard<Wildcard> : public std::true_type {};

    template <typename T>
    class IsUnaryOrWildcard<Unary<T>> : public std::true_type {};

    template <typename T>
    constexpr bool isUnaryOrWildcardV = IsUnaryOrWildcard<std::decay_t<T>>::value;

    // unary is an alias of meet.
    template <typename T>
    constexpr fn unary(T&& t) {
      return meet(std::forward<T>(t));
    }

#define UN_OP_FOR_UNARY(op)                                                   \
  template <typename T>                                                       \
  constexpr fn operator op(T const& t)                                        \
    requires isUnaryOrWildcardV<T>                                            \
  {                                                                           \
    return unary([&](auto&& arg) constexpr { return op evaluate_(t, arg); }); \
  }

#define BIN_OP_FOR_UNARY(op)                                                                    \
  template <typename T, typename U>                                                             \
  constexpr fn operator op(T const& t, U const& u)                                              \
    requires isUnaryOrWildcardV<T> || isUnaryOrWildcardV<U>                                     \
  {                                                                                             \
    return unary([&](auto&& arg) constexpr { return evaluate_(t, arg) op evaluate_(u, arg); }); \
  }

    UN_OP_FOR_UNARY(!)
    UN_OP_FOR_UNARY(-)

#undef UN_OP_FOR_UNARY

    BIN_OP_FOR_UNARY(+)
    BIN_OP_FOR_UNARY(-)
    BIN_OP_FOR_UNARY(*)
    BIN_OP_FOR_UNARY(/)
    BIN_OP_FOR_UNARY(%)
    BIN_OP_FOR_UNARY(<)
    BIN_OP_FOR_UNARY(<=)
    BIN_OP_FOR_UNARY(==)
    BIN_OP_FOR_UNARY(!=)
    BIN_OP_FOR_UNARY(>=)
    BIN_OP_FOR_UNARY(>)
    BIN_OP_FOR_UNARY(||)
    BIN_OP_FOR_UNARY(&&)
    BIN_OP_FOR_UNARY(^)

#undef BIN_OP_FOR_UNARY

    template <typename I, typename S = I>
    class Subrange {
      I mBegin;
      S mEnd;

     public:
      constexpr Subrange(const I begin, const S end)
        : mBegin { begin }, mEnd { end } {}

      constexpr Subrange(const Subrange& other)
        : mBegin { other.begin() }, mEnd { other.end() } {}

      fn operator=(const Subrange& other)->Subrange& {
        if (this == &other)
          return *this;

        mBegin = other.begin();
        mEnd   = other.end();

        return *this;
      }

      [[nodiscard]] fn size() const -> size_t {
        return static_cast<size_t>(std::distance(mBegin, mEnd));
      }

      [[nodiscard]] fn begin() const {
        return mBegin;
      }

      [[nodiscard]] fn end() const {
        return mEnd;
      }
    };

    template <typename I, typename S>
    constexpr fn makeSubrange(I begin, S end) {
      return Subrange<I, S> { begin, end };
    }

    template <typename RangeType>
    class IterUnderlyingType {
     public:
      using beginT = decltype(std::begin(std::declval<RangeType&>()));
      using endT   = decltype(std::end(std::declval<RangeType&>()));
    };

    // force array iterators fallback to pointers.
    template <typename ElemT, size_t size>
    class IterUnderlyingType<std::array<ElemT, size>> {
     public:
      using beginT = decltype(&*std::begin(std::declval<std::array<ElemT, size>&>()));
      using endT   = beginT;
    };

    // force array iterators fallback to pointers.
    template <typename ElemT, size_t size>
    class IterUnderlyingType<const std::array<ElemT, size>> {
     public:
      using beginT = decltype(&*std::begin(std::declval<const std::array<ElemT, size>&>()));
      using endT   = beginT;
    };

    template <typename RangeType>
    using SubrangeT =
      Subrange<typename IterUnderlyingType<RangeType>::beginT, typename IterUnderlyingType<RangeType>::endT>;

    template <typename I, typename S>
    fn operator==(const Subrange<I, S>& lhs, const Subrange<I, S>& rhs)->bool {
      using std::operator==;
      return lhs.size() == rhs.size() && std::equal(lhs.begin(), lhs.end(), rhs.begin());
    }

    template <typename K1, typename V1, typename K2, typename V2>
    constexpr fn operator==(const std::pair<K1, V1>& t, const std::pair<K2, V2>& u) {
      return t.first == u.first && t.second == u.second;
    }

    template <typename T, typename... Ts>
    class WithinTypes {
     public:
      constexpr static bool value = (std::is_same_v<T, Ts> || ...);
    };

    template <typename T, typename Tuple>
    class PrependUnique;

    template <typename T, typename... Ts>
    class PrependUnique<T, std::tuple<Ts...>> {
      constexpr static bool unique = !WithinTypes<T, Ts...>::value;

     public:
      using type = std::conditional_t<unique, std::tuple<T, Ts...>, std::tuple<Ts...>>;
    };

    template <typename T, typename Tuple>
    using PrependUniqueT = typename PrependUnique<T, Tuple>::type;

    template <typename Tuple>
    class Unique;

    template <typename... Ts>
    using UniqueT = typename Unique<std::tuple<Ts...>>::type;

    template <>
    class Unique<std::tuple<>> {
     public:
      using type = std::tuple<>;
    };

    template <typename T, typename... Ts>
    class Unique<std::tuple<T, Ts...>> {
     public:
      using type = PrependUniqueT<T, UniqueT<Ts...>>;
    };

    static_assert(std::is_same_v<std::tuple<int32_t>, UniqueT<int32_t, int32_t>>);
    static_assert(std::is_same_v<std::tuple<std::tuple<>, int32_t>, UniqueT<int32_t, std::tuple<>, int32_t>>);

    using std::get;

    namespace detail {
      template <std::size_t start, class Tuple, std::size_t... I>
      constexpr fn subtupleImpl(Tuple&& t, std::index_sequence<I...> /*unused*/) -> decltype(auto) {
        return std::forward_as_tuple(get<start + I>(std::forward<Tuple>(t))...);
      }
    } // namespace detail

    // [start, end)
    template <std::size_t start, std::size_t end, class Tuple>
    constexpr fn subtuple(Tuple&& t) -> decltype(auto) {
      constexpr size_t tupleSize = std::tuple_size_v<std::remove_reference_t<Tuple>>;
      static_assert(start <= end);
      static_assert(end <= tupleSize);
      return detail::subtupleImpl<start>(std::forward<Tuple>(t), std::make_index_sequence<end - start> {});
    }

    template <std::size_t start, class Tuple>
    constexpr fn drop(Tuple&& t) -> decltype(auto) {
      constexpr size_t tupleSize = std::tuple_size_v<std::remove_reference_t<Tuple>>;
      static_assert(start <= tupleSize);
      return subtuple<start, tupleSize>(std::forward<Tuple>(t));
    }

    template <std::size_t len, class Tuple>
    constexpr fn take(Tuple&& t) -> decltype(auto) {
      constexpr size_t tupleSize = std::tuple_size_v<std::remove_reference_t<Tuple>>;
      static_assert(len <= tupleSize);
      return subtuple<0, len>(std::forward<Tuple>(t));
    }

    template <class F, class Tuple>
    constexpr fn apply_(F&& f, Tuple&& t) -> decltype(auto) {
      return std::apply(std::forward<F>(f), drop<0>(std::forward<Tuple>(t)));
    }

    // as constexpr
    template <class F, class... Args>
    constexpr fn invoke_(F&& f, Args&&... args) noexcept(std::is_nothrow_invocable_v<F, Args...>) -> std::invoke_result_t<F, Args...> {
      return std::apply(std::forward<F>(f), std::forward_as_tuple(std::forward<Args>(args)...));
    }

    template <class T>
    struct decayArray {
     private:
      using U = std::remove_reference_t<T>;

     public:
      using type = std::conditional_t<std::is_array_v<U>, std::remove_extent_t<U>*, T>;
    };

    template <class T>
    using decayArrayT = typename decayArray<T>::type;

    static_assert(std::is_same_v<decayArrayT<int32_t*>, int32_t*>);
    static_assert(std::is_same_v<decayArrayT<const int32_t*>, const int32_t*>);
    static_assert(std::is_same_v<decayArrayT<const int32_t&>, const int32_t&>);

    template <typename T>
    struct AddConstToPointer {
      using type =
        std::conditional_t<!std::is_pointer_v<T>, T, std::add_pointer_t<std::add_const_t<std::remove_pointer_t<T>>>>;
    };

    template <typename T>
    using AddConstToPointerT = typename AddConstToPointer<T>::type;

    static_assert(std::is_same_v<AddConstToPointerT<void*>, const void*>);
    static_assert(std::is_same_v<AddConstToPointerT<int32_t>, int32_t>);

    template <typename Pattern>
    using InternalPatternT = std::remove_reference_t<AddConstToPointerT<decayArrayT<Pattern>>>;

    template <typename Pattern>
    class PatternTraits;

    template <typename... PatternPairs>
    class PatternPairsRetType {
     public:
      using RetType = std::common_type_t<typename PatternPairs::RetType...>;
    };

    enum class IdProcess : uint8_t {
      kCANCEL,
      kCONFIRM,
    };

    template <typename Pattern>
    constexpr void processId(const Pattern& pattern, int32_t depth, IdProcess idProcess) {
      PatternTraits<Pattern>::processIdImpl(pattern, depth, idProcess);
    }

    template <typename Tuple>
    class Variant;

    template <typename T, typename... Ts>
    class Variant<std::tuple<T, Ts...>> {
     public:
      using type = std::variant<std::monostate, T, Ts...>;
    };

    template <typename... Ts>
    using UniqVariant = typename Variant<UniqueT<Ts...>>::type;

    template <typename... Ts>
    class Context {
      using ElementT   = UniqVariant<Ts...>;
      using ContainerT = std::array<ElementT, sizeof...(Ts)>;
      ContainerT mMemHolder;
      size_t     mSize = 0;

     public:
      template <typename T>
      constexpr fn emplace_back(T&& t) -> void {
        mMemHolder[mSize] = std::forward<T>(t);
        ++mSize;
      }
      constexpr fn back() -> ElementT& {
        return mMemHolder[mSize - 1];
      }
    };

    template <>
    class Context<> {};

    template <typename T>
    class ContextTrait;

    template <typename... Ts>
    class ContextTrait<std::tuple<Ts...>> {
     public:
      using ContextT = Context<Ts...>;
    };

    template <typename Value, typename Pattern, typename ConctextT>
    constexpr fn matchPattern(Value&& value, const Pattern& pattern, int32_t depth, ConctextT& context) {
      const auto result  = PatternTraits<Pattern>::matchPatternImpl(std::forward<Value>(value), pattern, depth, context);
      const auto process = result ? IdProcess::kCONFIRM : IdProcess::kCANCEL;
      processId(pattern, depth, process);
      return result;
    }

    template <typename Pattern, typename Func>
    class PatternPair {
     public:
      using RetType  = std::invoke_result_t<Func>;
      using PatternT = Pattern;

      constexpr PatternPair(const Pattern& pattern, const Func& func)
        : mPattern { pattern }, mHandler { func } {}

      template <typename Value, typename ContextT>
      constexpr fn matchValue(Value&& value, ContextT& context) const -> bool {
        return matchPattern(std::forward<Value>(value), mPattern, /*depth*/ 0, context);
      }

      constexpr fn execute() const {
        return mHandler();
      }

     private:
      Pattern                                                               mPattern;
      std::conditional_t<std::is_function_v<Func>, const Func&, const Func> mHandler;
    };

    template <typename Pattern, typename Pred>
    class PostCheck;

    template <typename Pred>
    class When {
     public:
      Pred mPred;
    };

    template <typename Pred>
    constexpr fn when(Pred&& pred) {
      auto p = toNullary(std::forward<Pred>(pred));
      return When<decltype(p)> { p };
    }

    template <typename Pattern>
    class PatternHelper {
     public:
      constexpr explicit PatternHelper(const Pattern& pattern)
        : mPattern { pattern } {}

      template <typename Func>
      constexpr fn operator=(Func&& func) { // NOLINT(misc-unconventional-assign-operator, cppcoreguidelines-c-copy-assignment-signature)
        auto f = toNullary(std::forward<Func>(func));
        return PatternPair<Pattern, decltype(f)> { mPattern, f };
      }

      template <typename Pred>
      constexpr fn operator|(const When<Pred>& w) {
        return PatternHelper<PostCheck<Pattern, Pred>>(PostCheck(mPattern, w.mPred));
      }

     private:
      Pattern mPattern;
    };

    template <typename... Patterns>
    class Ds;

    template <typename... Patterns>
    constexpr fn ds(const Patterns&... patterns) -> Ds<Patterns...>;

    template <typename Pattern>
    class OooBinder;

    class PatternPipable {
     public:
      template <typename Pattern>
      // ReSharper disable once CppDFAUnreachableFunctionCall
      constexpr fn operator|(const Pattern& p) const->PatternHelper<Pattern> {
        return PatternHelper<Pattern> { p };
      }

      template <typename T>
      constexpr fn operator|(const T* p) const->PatternHelper<const T*> {
        return PatternHelper<const T*> { p };
      }

      template <typename Pattern>
      constexpr fn operator|(const OooBinder<Pattern>& p) const->PatternHelper<Pattern> {
        return operator|(ds(p));
      }
    };

    constexpr PatternPipable is {};

    template <typename Pattern>
    class PatternTraits {
     public:
      template <typename Value>
      using AppResultTuple = std::tuple<>;

      constexpr static int nbIdV = 0;

      template <typename Value, typename ContextT>
      constexpr static fn matchPatternImpl(Value&& value, const Pattern& pattern, int32_t /* depth */, ContextT& /*context*/) -> bool {
        return pattern == std::forward<Value>(value);
      }
      constexpr static void processIdImpl(const Pattern& /*unused*/, int32_t /*depth*/, IdProcess /*unused*/) {}
    };

    class Wildcard {};

    constexpr Wildcard _;

    template <>
    class PatternTraits<Wildcard> {
      using Pattern = Wildcard;

     public:
      template <typename Value>
      using AppResultTuple = std::tuple<>;

      constexpr static int nbIdV = 0;

      template <typename Value, typename ContextT>
      constexpr static fn matchPatternImpl(Value&& /*unused*/, const Pattern& /*unused*/, int32_t /*unused*/, ContextT& /*unused*/) -> bool {
        return true;
      }
      constexpr static fn processIdImpl(const Pattern& /*unused*/, int32_t /*depth*/, IdProcess /*unused*/) -> void {}
    };

    template <typename... Patterns>
    class Or {
     public:
      constexpr explicit Or(const Patterns&... patterns)
        : mPatterns { patterns... } {}
      constexpr fn patterns() const -> const std::tuple<InternalPatternT<Patterns>...>& {
        return mPatterns;
      }

     private:
      std::tuple<InternalPatternT<Patterns>...> mPatterns;
    };

    template <typename... Patterns>
    constexpr fn or_(const Patterns&... patterns) -> Or<Patterns...> {
      return Or<Patterns...> { patterns... };
    }

    template <typename... Patterns>
    class PatternTraits<Or<Patterns...>> {
     public:
      template <typename Value>
      using AppResultTuple =
        decltype(std::tuple_cat(typename PatternTraits<Patterns>::template AppResultTuple<Value> {}...));

      constexpr static int nbIdV = (PatternTraits<Patterns>::nbIdV + ... + 0);

      template <typename Value, typename ContextT>
      constexpr static fn matchPatternImpl(Value&& value, const Or<Patterns...>& orPat, int32_t depth, ContextT& context) -> bool {
        constexpr uint64_t patSize = sizeof...(Patterns);
        return std::apply(
                 [&value, depth, &context](const auto&... patterns) {
                   return (matchPattern(value, patterns, depth + 1, context) || ...);
                 },
                 take<patSize - 1>(orPat.patterns())
               ) ||
          matchPattern(std::forward<Value>(value), get<patSize - 1>(orPat.patterns()), depth + 1, context);
      }
      constexpr static void processIdImpl(const Or<Patterns...>& orPat, int32_t depth, IdProcess idProcess) {
        return std::apply(
          [depth, idProcess](const Patterns&... patterns) { return (processId(patterns, depth, idProcess), ...); },
          orPat.patterns()
        );
      }
    };

    template <typename Pred>
    class Meet : public Pred {
     public:
      using Pred::operator();
    };

    template <typename Pred>
    constexpr fn meet(const Pred& pred) -> Meet<Pred> {
      return Meet<Pred> { pred };
    }

    template <typename Pred>
    class PatternTraits<Meet<Pred>> {
     public:
      template <typename Value>
      using AppResultTuple = std::tuple<>;

      constexpr static int nbIdV = 0;

      template <typename Value, typename ContextT>
      constexpr static fn matchPatternImpl(Value&& value, const Meet<Pred>& meetPat, int32_t /* depth */, ContextT& /*unused*/) -> bool {
        return meetPat(std::forward<Value>(value));
      }

      constexpr static fn processIdImpl(const Meet<Pred>& /*unused*/, int32_t /*depth*/, IdProcess /*unused*/) -> void {}
    };

    template <typename Unary, typename Pattern>
    class App {
     public:
      constexpr App(Unary&& unary, const Pattern& pattern) : mUnary { std::move(unary) }, mPattern { pattern } {}

      [[nodiscard]] constexpr fn unary() const -> const Unary& {
        return mUnary;
      }
      [[nodiscard]] constexpr fn pattern() const -> const InternalPatternT<Pattern>& {
        return mPattern;
      }

     private:
      std::decay_t<Unary>       mUnary;
      InternalPatternT<Pattern> mPattern;
    };

    template <typename Unary, typename Pattern>
    constexpr fn app(Unary&& unary, const Pattern& pattern) -> App<Unary, Pattern> {
      return { std::forward<Unary>(unary), pattern };
    }

    constexpr int y = 1;
    static_assert(std::holds_alternative<const int32_t*>(std::variant<std::monostate, const int32_t*> { &y }));

    template <typename Unary, typename Pattern>
    class PatternTraits<App<Unary, Pattern>> {
     public:
      template <typename Value>
      using AppResult = std::invoke_result_t<Unary, Value>;
      // We store value for scalar types in Id and they can not be moved. So to
      // support constexpr.
      template <typename Value>
      using AppResultCurTuple = std::conditional_t<
        std::is_lvalue_reference_v<AppResult<Value>> || std::is_scalar_v<AppResult<Value>>,
        std::tuple<>,
        std::tuple<std::decay_t<AppResult<Value>>>>;

      template <typename Value>
      using AppResultTuple = decltype(std::tuple_cat(
        std::declval<AppResultCurTuple<Value>>(),
        std::declval<typename PatternTraits<Pattern>::template AppResultTuple<AppResult<Value>>>()
      ));

      constexpr static int nbIdV = PatternTraits<Pattern>::nbIdV;

      template <typename Value, typename ContextT>
      constexpr static fn matchPatternImpl(Value&& value, const App<Unary, Pattern>& appPat, const int32_t depth, ContextT& context) -> bool {
        if constexpr (std::is_same_v<AppResultCurTuple<Value>, std::tuple<>>) {
          return matchPattern(
            std::forward<AppResult<Value>>(invoke_(appPat.unary(), std::forward<Value>(value))), appPat.pattern(), depth + 1, context
          );
        } else {
          context.emplace_back(invoke_(appPat.unary(), std::forward<Value>(value)));
          decltype(auto) result = get<std::decay_t<AppResult<Value>>>(context.back());
          return matchPattern(std::forward<decltype(result)>(result), appPat.pattern(), depth + 1, context);
        }
      }

      constexpr static fn processIdImpl(const App<Unary, Pattern>& appPat, int32_t depth, IdProcess idProcess) -> void {
        return processId(appPat.pattern(), depth, idProcess);
      }
    };

    template <typename... Patterns>
    class And {
     public:
      constexpr explicit And(const Patterns&... patterns)
        : mPatterns { patterns... } {}

      constexpr fn patterns() const -> const std::tuple<InternalPatternT<Patterns>...>& {
        return mPatterns;
      }

     private:
      std::tuple<InternalPatternT<Patterns>...> mPatterns;
    };

    template <typename... Patterns>
    constexpr fn and_(const Patterns&... patterns) -> And<Patterns...> {
      return { patterns... };
    }

    template <typename Tuple>
    class NbIdInTuple;

    template <typename... Patterns>
    class NbIdInTuple<std::tuple<Patterns...>> {
     public:
      constexpr static int nbIdV = (PatternTraits<std::decay_t<Patterns>>::nbIdV + ... + 0);
    };

    template <typename... Patterns>
    class PatternTraits<And<Patterns...>> {
     public:
      template <typename Value>
      using AppResultTuple =
        decltype(std::tuple_cat(std::declval<typename PatternTraits<Patterns>::template AppResultTuple<Value>>()...));

      constexpr static int nbIdV = (PatternTraits<Patterns>::nbIdV + ... + 0);

      template <typename Value, typename ContextT>
      constexpr static fn matchPatternImpl(Value&& value, const And<Patterns...>& andPat, int32_t depth, ContextT& context) -> bool {
        constexpr uint64_t patSize    = sizeof...(Patterns);
        const auto         exceptLast = std::apply(
          [&value, depth, &context](const auto&... patterns) {
            return (matchPattern(value, patterns, depth + 1, context) && ...);
          },
          take<patSize - 1>(andPat.patterns())
        );

        // No Id in patterns except the last one.
        if constexpr (NbIdInTuple<std::decay_t<decltype(take<patSize - 1>(andPat.patterns()))>>::nbIdV == 0) {
          return exceptLast &&
            matchPattern(std::forward<Value>(value), get<patSize - 1>(andPat.patterns()), depth + 1, context);
        } else {
          return exceptLast && matchPattern(value, get<patSize - 1>(andPat.patterns()), depth + 1, context);
        }
      }
      constexpr static void processIdImpl(const And<Patterns...>& andPat, int32_t depth, IdProcess idProcess) {
        return std::apply(
          [depth, idProcess](const Patterns&... patterns) { return (processId(patterns, depth, idProcess), ...); },
          andPat.patterns()
        );
      }
    };

    template <typename Pattern>
    class Not {
     public:
      explicit Not(const Pattern& pattern)
        : mPattern { pattern } {}
      [[nodiscard]] constexpr fn pattern() const -> const InternalPatternT<Pattern>& {
        return mPattern;
      }

     private:
      InternalPatternT<Pattern> mPattern;
    };

    template <typename Pattern>
    constexpr fn not_(const Pattern& pattern) -> Not<Pattern> {
      return { pattern };
    }

    template <typename Pattern>
    class PatternTraits<Not<Pattern>> {
     public:
      template <typename Value>
      using AppResultTuple = typename PatternTraits<Pattern>::template AppResultTuple<Value>;

      constexpr static int nbIdV = PatternTraits<Pattern>::nbIdV;

      template <typename Value, typename ContextT>
      constexpr static fn matchPatternImpl(Value&& value, const Not<Pattern>& notPat, const int32_t depth, ContextT& context) -> bool {
        return !matchPattern(std::forward<Value>(value), notPat.pattern(), depth + 1, context);
      }

      constexpr static void processIdImpl(const Not<Pattern>& notPat, int32_t depth, IdProcess idProcess) {
        processId(notPat.pattern(), depth, idProcess);
      }
    };

    template <typename Ptr, typename Value, typename = std::void_t<>>
    struct StorePointer : std::false_type {};

    template <typename Type>
    using ValueVariant = std::conditional_t<
      std::is_lvalue_reference_v<Type>,
      UniqVariant<std::remove_reference_t<Type>*>,
      std::conditional_t<
        std::is_rvalue_reference_v<Type>,
        UniqVariant<std::remove_reference_t<Type>, std::remove_reference_t<Type>*>,
        std::conditional_t<
          std::is_abstract_v<std::remove_reference_t<Type>>,
          UniqVariant<std::remove_reference_t<Type>*, const std::remove_reference_t<Type>*>,
          UniqVariant<
            std::remove_reference_t<Type>,
            std::remove_reference_t<Type>*,
            const std::remove_reference_t<Type>*>>>>;

    template <typename Type, typename Value>
    struct StorePointer<Type, Value, std::void_t<decltype(std::declval<ValueVariant<Type>&>() = &std::declval<Value>())>>
      : std::is_reference<Value> {};

    static_assert(!StorePointer<char, char>::value);
    static_assert(StorePointer<char, char&>::value);
    static_assert(StorePointer<const char, const char&>::value);
    static_assert(StorePointer<const char, char&>::value);
    static_assert(StorePointer<const std::tuple<int32_t&, int32_t&>, const std::tuple<int32_t&, int32_t&>&>::value);

    template <typename... Ts>
    class Overload : public Ts... {
     public:
      using Ts::operator()...;
    };

    template <typename... Ts>
    constexpr fn overload(Ts&&... ts) -> Overload<Ts...> {
      return { std::forward<Ts>(ts)... };
    }

    template <typename Pattern>
    class OooBinder;

    class Ooo;

    template <typename Type>
    class IdTraits {
     public:
      constexpr static fn equal(const Type& lhs, const Type& rhs) -> bool {
        return lhs == rhs;
      }
    };

    template <typename Type>
    class IdBlockBase {
      int32_t mDepth {};

     private:
      ValueVariant<Type> mVariant {};

     public:
      constexpr IdBlockBase() = default;

      [[nodiscard]] constexpr fn variant() -> ValueVariant<Type>& {
        return mVariant;
      }

      constexpr void reset(const int32_t depth) {
        if (mDepth - depth >= 0) {
          mVariant = {};
          mDepth   = depth;
        }
      }

      constexpr void confirm(const int32_t depth) {
        if (mDepth > depth || mDepth == 0) {
          assert(depth == mDepth - 1 || depth == mDepth || mDepth == 0);
          mDepth = depth;
        }
      }
    };

    constexpr IdBlockBase<int> dummy;

    template <typename Type>
    class IdBlock : public IdBlockBase<Type> {
     public:
      [[nodiscard]] constexpr fn hasValue() const -> bool {
        return std::visit(
          overload(
            [](const Type&) { return true; },
            [](const Type*) { return true; },
            [](const std::monostate&) { return false; }
          ),
          IdBlockBase<Type>::mVariant
        );
      }

      [[nodiscard]] constexpr fn get() const -> decltype(auto) {
        return std::visit(
          overload(
            [](const Type& v) -> Type { return v; },
            [](const Type* p) -> const Type& { return *p; },
            [](Type* p) -> const Type& { return *p; },
            [](const std::monostate&) -> const Type& { throw std::logic_error("invalid state!"); }
          ),
          IdBlockBase<Type>::mVariant
        );
      }
    };

    template <typename Type>
    class IdBlock<const Type&> : public IdBlock<Type> {};

    template <typename Type>
    class IdBlock<Type&> : public IdBlockBase<Type&> {
     public:
      [[nodiscard]] constexpr fn hasValue() const -> bool {
        return std::visit(
          overload([](Type*) { return true; }, [](const std::monostate&) { return false; }),
          IdBlockBase<Type&>::mVariant
        );
      }

      [[nodiscard]] constexpr fn get() -> decltype(auto) {
        return std::visit(
          overload(
            [](Type* v) -> Type& {
              if (v == nullptr) {
                throw std::logic_error("Trying to dereference a nullptr!");
              }
              return *v;
            },
            [](std::monostate&) -> Type& { throw std::logic_error("Invalid state!"); }
          ),
          IdBlockBase<Type&>::mVariant
        );
      }
    };

    template <typename Type>
    class IdBlock<Type&&> : public IdBlockBase<Type&&> {
     public:
      [[nodiscard]] constexpr fn hasValue() const -> bool {
        return std::visit(
          overload(
            [](const Type&) { return true; }, [](Type*) { return true; }, [](const std::monostate&) { return false; }
          ),
          IdBlockBase<Type&&>::mVariant
        );
      }

      [[nodiscard]] constexpr fn get() -> decltype(auto) {
        return std::visit(
          overload(
            [](Type& v) -> Type& { return v; },
            [](Type* v) -> Type& {
              if (v == nullptr) {
                throw std::logic_error("Trying to dereference a nullptr!");
              }
              return *v;
            },
            [](std::monostate&) -> Type& { throw std::logic_error("Invalid state!"); }
          ),
          IdBlockBase<Type&&>::mVariant
        );
      }
    };

    template <typename Type>
    class IdUtil {
     public:
      template <typename Value>
      constexpr static fn bindValue(ValueVariant<Type>& v, Value&& value, std::false_type /* StorePointer */) {
        // for constexpr
        v = ValueVariant<Type> { std::forward<Value>(value) };
      }

      template <typename Value>
      constexpr static fn bindValue(ValueVariant<Type>& v, Value&& value, std::true_type /* StorePointer */) {
        v = ValueVariant<Type> { &std::forward<Value>(value) };
      }
    };

    template <typename Type>
    class Id {
     private:
      using BlockT   = IdBlock<Type>;
      using BlockVT  = std::variant<BlockT, BlockT*>;
      BlockVT mBlock = BlockT {};

      [[nodiscard]] constexpr fn internalValue() const -> decltype(auto) {
        return block().get();
      }

     public:
      constexpr Id() = default;

      constexpr Id(const Id& id) : mBlock(BlockVT { &id.block() }) {}

      // non-const to inform users not to mark Id as const.
      template <typename Pattern>
      constexpr fn at(Pattern&& pattern) -> decltype(auto) {
        return and_(std::forward<Pattern>(pattern), *this);
      }

      // non-const to inform users not to mark Id as const.
      constexpr fn at(const Ooo& /*unused*/) -> OooBinder<Type> {
        return OooBinder<Type> { *this };
      }

      [[nodiscard]] constexpr fn block() const -> BlockT& {
        return std::visit(
          overload([](BlockT& v) -> BlockT& { return v; }, [](BlockT* p) -> BlockT& { return *p; }),
          mBlock
        );
      }

      template <typename Value>
      constexpr fn matchValue(Value&& v) const -> bool {
        if (hasValue())
          return IdTraits<std::decay_t<Type>>::equal(internalValue(), v);

        IdUtil<Type>::bindValue(block().variant(), std::forward<Value>(v), StorePointer<Type, Value> {});
        return true;
      }

      constexpr fn reset(int32_t depth) const -> void {
        return block().reset(depth);
      }

      constexpr fn confirm(int32_t depth) const -> void {
        return block().confirm(depth);
      }

      [[nodiscard]] constexpr fn hasValue() const -> bool {
        return block().hasValue();
      }

      // non-const to inform users not to mark Id as const.
      [[nodiscard]] constexpr fn get() -> decltype(auto) {
        return block().get();
      }

      // non-const to inform users not to mark Id as const.
      [[nodiscard]] constexpr fn operator*()->decltype(auto) {
        return get();
      }
    };

    template <typename Type>
    class PatternTraits<Id<Type>> {
     public:
      template <typename Value>
      using AppResultTuple = std::tuple<>;

      constexpr static bool nbIdV = true;

      template <typename Value, typename ContextT>
      constexpr static fn matchPatternImpl(Value&& value, const Id<Type>& idPat, int32_t /* depth */, ContextT& /*unused*/) -> bool {
        return idPat.matchValue(std::forward<Value>(value));
      }

      constexpr static fn processIdImpl(const Id<Type>& idPat, int32_t depth, const IdProcess idProcess) -> void {
        switch (idProcess) {
          case IdProcess::kCANCEL:  idPat.reset(depth); break;
          case IdProcess::kCONFIRM: idPat.confirm(depth); break;
        }
      }
    };

    template <typename... Patterns>
    class Ds {
     public:
      constexpr explicit Ds(const Patterns&... patterns)
        : mPatterns { patterns... } {}

      [[nodiscard]] constexpr fn patterns() const -> const auto& {
        return mPatterns;
      }

      using Type = std::tuple<InternalPatternT<Patterns>...>;

     private:
      Type mPatterns;
    };

    template <typename... Patterns>
    constexpr fn ds(const Patterns&... patterns) -> Ds<Patterns...> {
      return Ds<Patterns...> { patterns... };
    }

    template <typename T>
    class OooBinder {
      Id<T> mId;

     public:
      explicit OooBinder(const Id<T>& id)
        : mId { id } {}

      [[nodiscard]] constexpr fn binder() const -> decltype(auto) {
        return mId;
      }
    };

    class Ooo {
     public:
      template <typename T>
      constexpr fn operator()(Id<T> id) const->OooBinder<T> {
        return OooBinder<T> { id };
      }
    };

    constexpr Ooo ooo;

    template <>
    class PatternTraits<Ooo> {
     public:
      template <typename Value>
      using AppResultTuple = std::tuple<>;

      constexpr static bool nbIdV = false;

      template <typename Value, typename ContextT>
      constexpr static fn matchPatternImpl(Value&& /*unused*/, Ooo /*unused*/, int32_t /*depth*/, ContextT& /*unused*/) -> bool {
        return true;
      }

      constexpr static fn processIdImpl(Ooo /*unused*/, int32_t /*depth*/, IdProcess /*unused*/) -> void {}
    };

    template <typename Pattern>
    class PatternTraits<OooBinder<Pattern>> {
     public:
      template <typename Value>
      using AppResultTuple = typename PatternTraits<Pattern>::template AppResultTuple<Value>;

      constexpr static bool nbIdV = PatternTraits<Pattern>::nbIdV;

      template <typename Value, typename ContextT>
      constexpr static fn matchPatternImpl(Value&& value, const OooBinder<Pattern>& oooBinderPat, const int32_t depth, ContextT& context) {
        return matchPattern(std::forward<Value>(value), oooBinderPat.binder(), depth + 1, context);
      }

      constexpr static fn processIdImpl(const OooBinder<Pattern>& oooBinderPat, int32_t depth, IdProcess idProcess) -> void {
        processId(oooBinderPat.binder(), depth, idProcess);
      }
    };

    template <typename T>
    class IsOoo : public std::false_type {};

    template <>
    class IsOoo<Ooo> : public std::true_type {};

    template <typename T>
    class IsOooBinder : public std::false_type {};

    template <typename T>
    class IsOooBinder<OooBinder<T>> : public std::true_type {};

    template <typename T>
    constexpr bool isOooBinderV = IsOooBinder<std::decay_t<T>>::value;

    template <typename T>
    constexpr bool isOooOrBinderV = IsOoo<std::decay_t<T>>::value || isOooBinderV<T>;

    template <typename... Patterns>
    constexpr size_t nbOooOrBinderV = ((isOooOrBinderV<Patterns> ? 1 : 0) + ... + 0);

    static_assert(nbOooOrBinderV<int32_t&, const Ooo&, const char*, Wildcard, const Ooo> == 2);

    template <typename Tuple, std::size_t... I>
    constexpr fn findOooIdxImpl(std::index_sequence<I...> /*unused*/) -> std::size_t {
      return ((isOooOrBinderV<decltype(get<I>(std::declval<Tuple>()))> ? I : 0) + ...);
    }

    template <typename Tuple>
    constexpr fn findOooIdx() -> std::size_t {
      return findOooIdxImpl<Tuple>(std::make_index_sequence<std::tuple_size_v<std::remove_reference_t<Tuple>>> {});
    }

    static_assert(isOooOrBinderV<Ooo>);
    static_assert(isOooOrBinderV<OooBinder<int32_t>>);
    static_assert(findOooIdx<std::tuple<int32_t, OooBinder<int32_t>, const char*>>() == 1);
    static_assert(findOooIdx<std::tuple<int32_t, Ooo, const char*>>() == 1);

    using std::get;

    template <std::size_t valueStartIdx, std::size_t patternStartIdx, std::size_t... I, typename ValueTuple, typename PatternTuple, typename ContextT>
    constexpr fn matchPatternMultipleImpl(ValueTuple&& valueTuple, PatternTuple&& patternTuple, const int32_t depth, ContextT& context, std::index_sequence<I...> /*unused*/) -> decltype(auto) {
      const fn func = [&]<typename T>(T&& value, auto&& pattern) { return matchPattern(std::forward<T>(value), pattern, depth + 1, context); };

      static_cast<void>(func);

      return (func(get<I + valueStartIdx>(std::forward<ValueTuple>(valueTuple)), std::get<I + patternStartIdx>(patternTuple)) && ...);
    }

    template <std::size_t valueStartIdx, std::size_t patternStartIdx, std::size_t size, typename ValueTuple, typename PatternTuple, typename ContextT>
    constexpr fn matchPatternMultiple(ValueTuple&& valueTuple, PatternTuple&& patternTuple, int32_t depth, ContextT& context) -> decltype(auto) {
      return matchPatternMultipleImpl<valueStartIdx, patternStartIdx>(
        std::forward<ValueTuple>(valueTuple), std::forward<PatternTuple>(patternTuple), depth, context, std::make_index_sequence<size> {}
      );
    }

    template <std::size_t patternStartIdx, std::size_t... I, typename RangeBegin, typename PatternTuple, typename ContextT>
    constexpr fn matchPatternRangeImpl(RangeBegin&& rangeBegin, PatternTuple&& patternTuple, const int32_t depth, ContextT& context, std::index_sequence<I...> /*unused*/) -> decltype(auto) {
      const fn func = [&]<typename T>(T&& value, auto&& pattern) { return matchPattern(std::forward<T>(value), pattern, depth + 1, context); };

      static_cast<void>(func);

      auto it = rangeBegin;

      bool result = true;

      ((result = result && func(*it, std::get<I + patternStartIdx>(patternTuple)), ++it), ...);

      return result;
    }

    template <std::size_t patternStartIdx, std::size_t size, typename ValueRangeBegin, typename PatternTuple, typename ContextT>
    constexpr fn matchPatternRange(
      ValueRangeBegin&& valueRangeBegin,
      PatternTuple&&    patternTuple,
      int32_t           depth,
      ContextT&         context
    ) {
      return matchPatternRangeImpl<patternStartIdx>(
        std::forward<ValueRangeBegin>(valueRangeBegin), std::forward<PatternTuple>(patternTuple), depth, context, std::make_index_sequence<size> {}
      );
    }

    template <std::size_t start, typename Indices, typename Tuple>
    class IndexedTypes;

    template <typename Tuple, std::size_t start, std::size_t... I>
    class IndexedTypes<start, std::index_sequence<I...>, Tuple> {
     public:
      using type = std::tuple<std::decay_t<decltype(std::get<start + I>(std::declval<Tuple>()))>...>;
    };

    template <std::size_t start, std::size_t end, class Tuple>
    class SubTypes {
      constexpr static size_t tupleSize = std::tuple_size_v<std::remove_reference_t<Tuple>>;
      static_assert(start <= end);
      static_assert(end <= tupleSize);

      using Indices = std::make_index_sequence<end - start>;

     public:
      using type = typename IndexedTypes<start, Indices, Tuple>::type;
    };

    template <std::size_t start, std::size_t end, class Tuple>
    using SubTypesT = typename SubTypes<start, end, Tuple>::type;

    static_assert(std::is_same_v<std::tuple<std::nullptr_t>, SubTypesT<3, 4, std::tuple<char, bool, int32_t, std::nullptr_t>>>);
    static_assert(std::is_same_v<std::tuple<char>, SubTypesT<0, 1, std::tuple<char, bool, int32_t, std::nullptr_t>>>);
    static_assert(std::is_same_v<std::tuple<>, SubTypesT<1, 1, std::tuple<char, bool, int32_t, std::nullptr_t>>>);
    static_assert(std::is_same_v<std::tuple<int32_t, std::nullptr_t>, SubTypesT<2, 4, std::tuple<char, bool, int32_t, std::nullptr_t>>>);

    template <typename ValueTuple>
    class IsArray : public std::false_type {};

    template <typename T, size_t s>
    class IsArray<std::array<T, s>> : public std::true_type {};

    template <typename ValueTuple>
    constexpr bool isArrayV = IsArray<std::decay_t<ValueTuple>>::value;

    template <typename Value, typename = std::void_t<>>
    struct IsTupleLike : std::false_type {};

    template <typename Value>
    struct IsTupleLike<Value, std::void_t<decltype(std::tuple_size<Value>::value)>> : std::true_type {};

    template <typename ValueTuple>
    constexpr bool isTupleLikeV = IsTupleLike<std::decay_t<ValueTuple>>::value;

    static_assert(isTupleLikeV<std::pair<int32_t, char>>);
    static_assert(!isTupleLikeV<bool>);

    template <typename Value, typename = std::void_t<>>
    struct IsRange : std::false_type {};

    template <typename Value>
    struct IsRange<Value, std::void_t<decltype(std::begin(std::declval<Value>())), decltype(std::end(std::declval<Value>()))>>
      : std::true_type {};

    template <typename ValueTuple>
    constexpr bool isRangeV = IsRange<std::decay_t<ValueTuple>>::value;

    static_assert(!isRangeV<std::pair<int32_t, char>>);
    static_assert(isRangeV<const std::array<int32_t, 5>>);

    template <typename... Patterns>
    class PatternTraits<Ds<Patterns...>> {
      constexpr static size_t nbOooOrBinder = nbOooOrBinderV<Patterns...>;
      static_assert(nbOooOrBinder == 0 || nbOooOrBinder == 1);

     public:
      template <typename PsTuple, typename VsTuple>
      class PairPV;

      template <typename... Ps, typename... Vs>
      class PairPV<std::tuple<Ps...>, std::tuple<Vs...>> {
       public:
        using type = decltype(std::tuple_cat(std::declval<typename PatternTraits<Ps>::template AppResultTuple<Vs>>()...));
      };

      template <std::size_t nbOoos, typename ValueTuple>
      class AppResultForTupleHelper;

      template <typename... Values>
      class AppResultForTupleHelper<0, std::tuple<Values...>> {
       public:
        using type = decltype(std::tuple_cat(std::declval<typename PatternTraits<Patterns>::template AppResultTuple<Values>>()...));
      };

      template <typename... Values>
      class AppResultForTupleHelper<1, std::tuple<Values...>> {
        constexpr static size_t idxOoo = findOooIdx<typename Ds<Patterns...>::Type>();
        using Ps0                      = SubTypesT<0, idxOoo, std::tuple<Patterns...>>;
        using Vs0                      = SubTypesT<0, idxOoo, std::tuple<Values...>>;
        constexpr static bool isBinder = isOooBinderV<std::tuple_element_t<idxOoo, std::tuple<Patterns...>>>;
        // <0, ...int32_t> to workaround compile failure for std::tuple<>.
        using ElemT                          = std::tuple_element_t<0, std::tuple<std::remove_reference_t<Values>..., int32_t>>;
        constexpr static int64_t diff        = static_cast<int64_t>(sizeof...(Values) - sizeof...(Patterns));
        constexpr static size_t  clippedDiff = static_cast<size_t>(diff > 0 ? diff : 0);
        using OooResultTuple =
          std::conditional_t<isBinder, std::tuple<SubrangeT<std::array<ElemT, clippedDiff>>>, std::tuple<>>;
        using FirstHalfTuple             = typename PairPV<Ps0, Vs0>::type;
        using Ps1                        = SubTypesT<idxOoo + 1, sizeof...(Patterns), std::tuple<Patterns...>>;
        constexpr static size_t vs1Start = static_cast<size_t>(static_cast<int64_t>(idxOoo) + 1 + diff);
        using Vs1                        = SubTypesT<vs1Start, sizeof...(Values), std::tuple<Values...>>;
        using SecondHalfTuple            = typename PairPV<Ps1, Vs1>::type;

       public:
        using type = decltype(std::tuple_cat(
          std::declval<FirstHalfTuple>(),
          std::declval<OooResultTuple>(),
          std::declval<SecondHalfTuple>()
        ));
      };

      template <typename Tuple>
      using AppResultForTuple = typename AppResultForTupleHelper<nbOooOrBinder, decltype(drop<0>(std::declval<Tuple>()))>::type;

      template <typename RangeType>
      using RangeTuple = std::conditional_t<nbOooOrBinder == 1, std::tuple<SubrangeT<RangeType>>, std::tuple<>>;

      template <typename RangeType>
      using AppResultForRangeType = decltype(std::tuple_cat(
        std::declval<RangeTuple<RangeType>>(),
        std::declval<typename PatternTraits<Patterns>::template AppResultTuple<decltype(*std::begin(std::declval<RangeType>()))>>()...
      ));

      template <typename Value, typename = std::void_t<>>
      class AppResultHelper;

      template <typename Value>
      class AppResultHelper<Value, std::enable_if_t<isTupleLikeV<Value>>> {
       public:
        using type = AppResultForTuple<Value>;
      };

      template <typename RangeType>
      class AppResultHelper<RangeType, std::enable_if_t<!isTupleLikeV<RangeType> && isRangeV<RangeType>>> {
       public:
        using type = AppResultForRangeType<RangeType>;
      };

      template <typename Value>
      using AppResultTuple = typename AppResultHelper<Value>::type;

      constexpr static size_t nbIdV = (PatternTraits<Patterns>::nbIdV + ... + 0);

      template <typename ValueTuple, typename ContextT>
      constexpr static fn matchPatternImpl(ValueTuple&& valueTuple, const Ds<Patterns...>& dsPat, int32_t depth, ContextT& context)
        -> bool
        requires(isTupleLikeV<ValueTuple>)
      {
        if constexpr (nbOooOrBinder == 0) {
          return std::apply(
            [&valueTuple, depth, &context](const auto&... patterns) {
              return apply_(
                [depth, &context, &patterns...]<typename... T>(T&&... values) constexpr {
                  static_assert(sizeof...(patterns) == sizeof...(values));
                  return (matchPattern(std::forward<T>(values), patterns, depth + 1, context) && ...);
                },
                valueTuple
              );
            },
            dsPat.patterns()
          );
        } else if constexpr (nbOooOrBinder == 1) {
          constexpr size_t idxOoo   = findOooIdx<typename Ds<Patterns...>::Type>();
          constexpr bool   isBinder = isOooBinderV<std::tuple_element_t<idxOoo, std::tuple<Patterns...>>>;
          constexpr bool   isArray  = isArrayV<ValueTuple>;
          auto             result   = matchPatternMultiple<0, 0, idxOoo>(std::forward<ValueTuple>(valueTuple), dsPat.patterns(), depth, context);
          constexpr size_t valLen   = std::tuple_size_v<std::decay_t<ValueTuple>>;
          constexpr size_t patLen   = sizeof...(Patterns);

          if constexpr (isArray) {
            if constexpr (isBinder) {
              const size_t rangeSize = static_cast<long>(valLen - (patLen - 1));
              context.emplace_back(makeSubrange(&valueTuple[idxOoo], &valueTuple[idxOoo] + rangeSize));
              using type = decltype(makeSubrange(&valueTuple[idxOoo], &valueTuple[idxOoo] + rangeSize));
              result     = result &&
                matchPattern(std::get<type>(context.back()), std::get<idxOoo>(dsPat.patterns()), depth, context);
            }
          } else {
            static_assert(!isBinder);
          }

          return result && matchPatternMultiple<valLen - patLen + idxOoo + 1, idxOoo + 1, patLen - idxOoo - 1>(std::forward<ValueTuple>(valueTuple), dsPat.patterns(), depth, context);
        }

        return false;
      }

      template <typename ValueRange, typename ContextT>
      constexpr static fn matchPatternImpl(ValueRange&& valueRange, const Ds<Patterns...>& dsPat, int32_t depth, ContextT& context)
        -> bool
        requires(!isTupleLikeV<ValueRange> && isRangeV<ValueRange>)
      {
        static_assert(nbOooOrBinder == 0 || nbOooOrBinder == 1);
        constexpr size_t nbPat = sizeof...(Patterns);

        if constexpr (nbOooOrBinder == 0) {
          // size mismatch for dynamic array is not an error;
          if (std::forward<ValueRange>(valueRange).size() != nbPat)
            return false;

          return matchPatternRange<0, nbPat>(std::begin(std::forward<ValueRange>(valueRange)), dsPat.patterns(), depth, context);
        } else if constexpr (nbOooOrBinder == 1) {
          if (std::forward<ValueRange>(valueRange).size() < nbPat - 1)
            return false;

          constexpr auto   idxOoo   = findOooIdx<typename Ds<Patterns...>::Type>();
          constexpr auto   isBinder = isOooBinderV<std::tuple_element_t<idxOoo, std::tuple<Patterns...>>>;
          auto             result   = matchPatternRange<0, idxOoo>(std::begin(std::forward<ValueRange>(valueRange)), dsPat.patterns(), depth, context);
          const size_t     valLen   = std::forward<ValueRange>(valueRange).size();
          constexpr size_t patLen   = sizeof...(Patterns);
          const auto       beginOoo = std::next(std::begin(std::forward<ValueRange>(valueRange)), idxOoo);

          if constexpr (isBinder) {
            const size_t rangeSize = static_cast<long>(valLen - (patLen - 1));
            const auto   end       = std::next(beginOoo, rangeSize);
            context.emplace_back(makeSubrange(beginOoo, end));
            using type = decltype(makeSubrange(beginOoo, end));
            result     = result &&
              matchPattern(std::get<type>(context.back()), std::get<idxOoo>(dsPat.patterns()), depth, context);
          }

          const auto beginAfterOoo = std::next(beginOoo, static_cast<long>(valLen - patLen + 1));
          return result &&
            matchPatternRange<idxOoo + 1, patLen - idxOoo - 1>(beginAfterOoo, dsPat.patterns(), depth, context);
        }

        return false;
      }

      constexpr static fn processIdImpl(const Ds<Patterns...>& dsPat, int32_t depth, IdProcess idProcess) -> void {
        return std::apply(
          [depth, idProcess](auto&&... patterns) { return (processId(patterns, depth, idProcess), ...); },
          dsPat.patterns()
        );
      }
    };

    static_assert(std::is_same_v<PatternTraits<Ds<OooBinder<SubrangeT<const std::array<int32_t, 2>>>>>::AppResultTuple<const std::array<int32_t, 2>>, std::tuple<matchit::impl::Subrange<const int32_t*>>>);
    static_assert(std::is_same_v<PatternTraits<Ds<OooBinder<Subrange<int32_t*>>, matchit::impl::Id<int32_t>>>::AppResultTuple<const std::array<int32_t, 3>>, std::tuple<matchit::impl::Subrange<const int32_t*>>>);
    static_assert(std::is_same_v<PatternTraits<Ds<OooBinder<Subrange<int32_t*>>, matchit::impl::Id<int32_t>>>::AppResultTuple<std::array<int32_t, 3>>, std::tuple<matchit::impl::Subrange<int32_t*>>>);

    template <typename Pattern, typename Pred>
    class PostCheck {
     public:
      constexpr explicit PostCheck(const Pattern& pattern, const Pred& pred)
        : mPattern { pattern }, mPred { pred } {}
      [[nodiscard]] constexpr fn check() const -> bool {
        return mPred();
      }

      constexpr fn pattern() const -> const Pattern& {
        return mPattern;
      }

     private:
      Pattern mPattern;
      Pred    mPred;
    };

    template <typename Pattern, typename Pred>
    class PatternTraits<PostCheck<Pattern, Pred>> {
     public:
      template <typename Value>
      using AppResultTuple = typename PatternTraits<Pattern>::template AppResultTuple<Value>;

      template <typename Value, typename ContextT>
      constexpr static fn matchPatternImpl(
        Value&&                         value,
        const PostCheck<Pattern, Pred>& postCheck,
        const int32_t                   depth,
        ContextT&                       context
      ) -> bool {
        return matchPattern(std::forward<Value>(value), postCheck.pattern(), depth + 1, context) && postCheck.check();
      }

      constexpr static fn processIdImpl(const PostCheck<Pattern, Pred>& postCheck, int32_t depth, IdProcess idProcess) -> void {
        processId(postCheck.pattern(), depth, idProcess);
      }
    };

    static_assert(std::is_same_v<PatternTraits<Wildcard>::AppResultTuple<int32_t>, std::tuple<>>);
    static_assert(std::is_same_v<PatternTraits<int32_t>::AppResultTuple<int32_t>, std::tuple<>>);
    constexpr fn x = [](auto&& t) { return t; };
    static_assert(std::is_same_v<PatternTraits<App<decltype(x), Wildcard>>::AppResultTuple<std::array<int32_t, 3>>, std::tuple<std::array<int32_t, 3>>>);

    static_assert(PatternTraits<And<App<decltype(x), Wildcard>>>::nbIdV == 0);
    static_assert(PatternTraits<And<App<decltype(x), Id<int32_t>>>>::nbIdV == 1);
    static_assert(PatternTraits<And<Id<int32_t>, Id<float>>>::nbIdV == 2);
    static_assert(PatternTraits<Or<Id<int32_t>, Id<float>>>::nbIdV == 2);
    static_assert(PatternTraits<Or<Wildcard, float>>::nbIdV == 0);

    template <typename Value, typename... PatternPairs>
    constexpr fn matchPatterns(Value&& value, const PatternPairs&... patterns) {
      using RetType   = typename PatternPairsRetType<PatternPairs...>::RetType;
      using TypeTuple = decltype(std::tuple_cat(
        std::declval<typename PatternTraits<typename PatternPairs::PatternT>::template AppResultTuple<Value>>()...
      ));

      // expression, has return value.
      if constexpr (!std::is_same_v<RetType, void>) {
        constexpr fn func = [](const auto& pattern, auto&& val, RetType& result) constexpr -> bool {
          if (auto context = typename ContextTrait<TypeTuple>::ContextT {};
              pattern.matchValue(std::forward<Value>(val), context)) {
            result = pattern.execute();
            processId(pattern, 0, IdProcess::kCANCEL);
            return true;
          }
          return false;
        };

        RetType result {};

        const bool matched = (func(patterns, std::forward<Value>(value), result) || ...);

        if (!matched)
          throw std::logic_error { "Error: no patterns got matched!" };

        static_cast<void>(matched);
        return result;
      } else {
        const fn func = [](const auto& pattern, auto&& val) -> bool {
          if (auto context = typename ContextTrait<TypeTuple>::ContextT {};
              pattern.matchValue(std::forward<Value>(val), context)) {
            pattern.execute();
            processId(pattern, 0, IdProcess::kCANCEL);
            return true;
          }
          return false;
        };
        const bool matched = (func(patterns, std::forward<Value>(value)) || ...);
        static_cast<void>(matched);
      }
    }

    template <typename T>
    constexpr fn cast = [](auto&& input) { return static_cast<T>(input); };

    constexpr fn deref = [](auto&& x) -> decltype(*x)& { return *x; };
    constexpr fn some  = [](const auto pat) { return and_(app(cast<bool>, true), app(deref, pat)); };

    constexpr fn none = app(cast<bool>, false);

    template <typename Value, typename Variant, typename = std::void_t<>>
    struct ViaGetIf : std::false_type {};

    using std::get_if;

    template <typename T, typename Variant>
    struct ViaGetIf<T, Variant, std::void_t<decltype(get_if<T>(std::declval<const Variant*>()))>> : std::true_type {};

    template <typename T, typename Variant>
    constexpr bool viaGetIfV = ViaGetIf<T, Variant>::value;

    static_assert(viaGetIfV<int, std::variant<int, bool>>);

    template <typename T>
    class AsPointer {
      static_assert(!std::is_reference_v<T>);

     public:
      template <typename Variant>
      constexpr fn operator()(Variant&& v) const
        requires(viaGetIfV<T, std::decay_t<Variant>>)
      {
        return get_if<T>(std::addressof(std::forward<Variant>(v)));
      }

      // template to disable implicit cast to std::any
      template <typename A>
      constexpr fn operator()(A&& a) const
        requires(std::is_same_v<std::decay_t<A>, std::any>)
      {
        return std::any_cast<T>(std::addressof(std::forward<A>(a)));
      }

      // cast to base class
      template <typename D>
      constexpr fn operator()(const D& d) const->decltype(static_cast<const T*>(std::addressof(d)))
        requires(!viaGetIfV<T, D> && std::is_base_of_v<T, D>)
      {
        return static_cast<const T*>(std::addressof(d));
      }

      // No way to handle rvalue to save copy in this class. Need to define some in another way to handle this.
      // cast to base class
      template <typename D>
      constexpr fn operator()(D& d) const->decltype(static_cast<T*>(std::addressof(d)))
        requires(!viaGetIfV<T, D> && std::is_base_of_v<T, D>)
      {
        return static_cast<T*>(std::addressof(d));
      }

      // cast to derived class
      template <typename B>
      constexpr fn operator()(const B& b) const->decltype(dynamic_cast<const T*>(std::addressof(b)))
        requires(!viaGetIfV<T, B> && std::is_base_of_v<B, T>)
      {
        return dynamic_cast<const T*>(std::addressof(b));
      }

      // cast to derived class
      template <typename B>
      constexpr fn operator()(B& b) const->decltype(dynamic_cast<T*>(std::addressof(b)))
        requires(!viaGetIfV<T, B> && std::is_base_of_v<B, T>)
      {
        return dynamic_cast<T*>(std::addressof(b));
      }

      constexpr fn operator()(const T& b) const {
        return std::addressof(b);
      }

      constexpr fn operator()(T& b) const {
        return std::addressof(b);
      }
    };

    static_assert(std::is_invocable_v<AsPointer<int>, int>);
    static_assert(std::is_invocable_v<AsPointer<std::tuple<int>>, std::tuple<int>>);

    template <typename T>
    constexpr AsPointer<T> asPointer;

    template <typename T>
    constexpr fn as = [](const auto pat) { return app(asPointer<T>, some(pat)); };

    template <typename Value, typename Pattern>
    constexpr fn matched(Value&& v, Pattern&& p) {
      return match(std::forward<Value>(v))(
        is | std::forward<Pattern>(p) = [] { return true; }, is | _ = [] { return false; }
      );
    }

    constexpr fn dsVia = [](auto... members) {
      return [members...](auto... pats) { return and_(app(members, pats)...); };
    };

    template <typename T>
    constexpr fn asDsVia = [](auto... members) { return [members...](auto... pats) { return as<T>(and_(app(members, pats)...)); }; };

    constexpr fn in = [](const auto& first, const auto& last) {
      return meet([=](auto&& v) { return first <= v && v <= last; });
    };
  } // namespace impl

  using impl::_;
  using impl::and_;
  using impl::app;
  using impl::as;
  using impl::asDsVia;
  using impl::ds;
  using impl::dsVia;
  using impl::expr;
  using impl::Id;
  using impl::in;
  using impl::is;
  using impl::match;
  using impl::matched;
  using impl::meet;
  using impl::none;
  using impl::not_;
  using impl::ooo;
  using impl::or_;
  using impl::some;
  using impl::Subrange;
  using impl::SubrangeT;
  using impl::when;
} // namespace matchit
// NOLINTEND(readability-identifier-*, cppcoreguidelines-special-member-functions)