ah-dry.H

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/*
                          Aleph_w
 
  Data structures & Algorithms
  version 2.0.0b
  https://github.com/lrleon/Aleph-w
 
  This file is part of Aleph-w library
 
  Copyright (c) 2002-2026 Leandro Rabindranath Leon
 
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
 
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
 
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
*/
 
#ifndef AH_DRY_H
#define AH_DRY_H
 
#include "ahFunctional.H"
#include <ah-concepts.H>
#include <type_traits>
#include <utility>
#include <vector>
#include <ah-errors.H>
 
namespace Aleph {
template <class>
class Array;
}
 
template <class Container>
struct GenericTraverse
{
private:
  template <class Operation>
  static constexpr bool traverse_is_noexcept() noexcept
  {
    return noexcept(std::declval<Operation &>()(std::declval<typename Container::Item_Type &>()));
  }
 
public:
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, typename Aleph::concepts_detail::traverse_arg<Container, Operation>::type>
  bool traverse(Operation &operation) noexcept(traverse_is_noexcept<Operation>())
  {
    for (typename Container::Iterator it(*static_cast<Container *>(this)); it.has_curr(); it.next())
      if (not operation(it.get_curr()))
        return false;
    return true;
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, typename Aleph::concepts_detail::traverse_arg<Container, Operation>::type>
  bool traverse(Operation &operation) const noexcept(traverse_is_noexcept<Operation>())
  {
    return const_cast<GenericTraverse *>(this)->traverse<Operation>(operation);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, typename Aleph::concepts_detail::traverse_arg<Container, Operation>::type>
  bool traverse(Operation &&operation) const noexcept(traverse_is_noexcept<Operation>())
  {
    return traverse<Operation>(operation);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, typename Aleph::concepts_detail::traverse_arg<Container, Operation>::type>
  bool traverse(Operation &&operation) noexcept(traverse_is_noexcept<Operation>())
  {
    return traverse<Operation>(operation);
  }
};
 
template <class Container, class Operation>
bool traverse(const Container &c, Operation &op) noexcept(noexcept(c.traverse(op)))
{
  return c.traverse(op);
}
 
template <class Container, class Operation>
bool traverse(const Container &c, Operation &&op) noexcept(noexcept(c.traverse(op)))
{
  return c.traverse(op);
}
 
template <class Container, typename Type>
class LocateFunctions
{
  Container *me() noexcept
  {
    return static_cast<Container *>(this);
  }
 
  const Container *const_me() const noexcept
  {
    return static_cast<const Container *>(this);
  }
 
  LocateFunctions<Container, Type> *base() const
  {
    return const_cast<LocateFunctions *>(this);
  }
 
  template <class Operation>
  static constexpr bool operation_is_noexcept() noexcept
  {
    return noexcept(std::declval<Operation &>()(std::declval<Type &>()));
  }
 
public:
  auto get_it() const
  {
    return typename Container::Iterator(*const_me());
  }
 
  // auto get_it()
  // {
  //   return typename Container::Iterator(*me());
  // }
 
  auto get_it(const size_t pos) const
  {
    auto ret = typename Container::Iterator(*const_me());
    for (size_t i = 0; i < pos; ++i)
      ret.next();
    return ret;
  }
 
  auto get_itor() const
  {
    return get_it();
  }
 
  Type &nth_ne(const size_t n) noexcept
  {
    Type *ptr = nullptr;
    size_t i = 0;
    me()->traverse([&ptr, &i, &n](Type &item)
      {
        if (i++ < n)
          return true;
        ptr = &item;
        return false;
      });
    return *ptr;
  }
 
  const Type &nth_ne(const size_t n) const noexcept
  {
    return base()->nth_ne(n);
  }
 
  Type &nth(const size_t n)
  {
    Type *ptr = nullptr;
    size_t i = 0;
    me()->traverse([&ptr, &i, &n](Type &item)
      {
        if (i++ < n)
          return true;
        ptr = &item;
        return false;
      });
 
    ah_out_of_range_error_if(i != n + 1) << "index out of range";
 
    return *ptr;
  }
 
  const Type &nth(const size_t n) const
  {
    return base()->nth(n);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, Type &>
  Type *find_ptr(Operation &operation) noexcept(operation_is_noexcept<Operation>())
  {
    Type *ptr = nullptr;
    me()->traverse([&ptr, &operation](Type &item)
      {
        if (operation(item))
          {
            ptr = &item;
            return false;
          }
        return true;
      });
    return ptr;
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, Type &>
  const Type *find_ptr(Operation &operation) const noexcept(operation_is_noexcept<Operation>())
  {
    return base()->find_ptr(operation);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, Type &>
  const Type *find_ptr(Operation &&operation) const noexcept(operation_is_noexcept<Operation>())
  {
    return find_ptr<Operation>(operation);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, Type &>
  Type *find_ptr(Operation &&operation) noexcept(operation_is_noexcept<Operation>())
  {
    return find_ptr<Operation>(operation);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, const Type &>
  size_t find_index(Operation &operation) const noexcept(operation_is_noexcept<Operation>())
  {
    size_t i = 0;
    const_me()->traverse([&i, &operation](const Type &item)
      {
        if (operation(item))
          return false;
        ++i;
        return true;
      });
    return i;
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, const Type &>
  size_t find_index(Operation &&operation) const noexcept(operation_is_noexcept<Operation>())
  {
    return find_index<Operation>(operation);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, Type &>
  std::tuple<bool, Type> find_item(Operation &operation) noexcept(operation_is_noexcept<Operation>())
  {
    using TT = std::tuple<bool, Type>;
    auto ptr = find_ptr(operation);
    return ptr ? TT(true, *ptr) : TT(false, Type());
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, Type &>
  std::tuple<bool, Type> find_item(Operation &operation) const
    noexcept(operation_is_noexcept<Operation>())
  {
    using TT = std::tuple<bool, Type>;
    auto ptr = find_ptr(operation);
    return ptr ? TT(true, *ptr) : TT(false, Type());
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, Type &>
  std::tuple<bool, Type> find_item(Operation &&operation) noexcept(operation_is_noexcept<Operation>())
  {
    return find_item<Operation>(operation);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, Type &>
  std::tuple<bool, Type> find_item(Operation &&operation) const
    noexcept(operation_is_noexcept<Operation>())
  {
    return find_item<Operation>(operation);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, Type &>
  bool contains_if(Operation &&operation) const noexcept(operation_is_noexcept<Operation>())
  {
    return find_ptr(operation) != nullptr;
  }
 
  bool contains(const Type &item) const
  {
    return contains_if([&item](const Type &x)
      {
        return x == item;
      });
  }
};
 
template <class Container, typename T>
struct SpecialCtors
{
  SpecialCtors() = default;
 
  SpecialCtors(const SpecialCtors &) = default;
 
  SpecialCtors(SpecialCtors &&) noexcept {}
 
  SpecialCtors &operator = (const SpecialCtors &) = default;
 
  SpecialCtors &operator = (SpecialCtors &&) noexcept
  {
    return *this;
  }
 
  SpecialCtors(const Aleph::DynList<T> &l)
  {
    l.for_each([this](const T &item)
      {
        static_cast<Container *>(this)->append(item);
      });
  }
 
  template <class It>
  SpecialCtors(It b, It e)
  {
    for (It it = b; it != e; ++it)
      static_cast<Container *>(this)->append(*it);
  }
 
  SpecialCtors(std::initializer_list<T> l)
  {
    for (const auto &item : l)
      static_cast<Container *>(this)->append(item);
  }
};
 
template <class Container, typename T>
class FunctionalMethods
{
  Container *me()
  {
    return static_cast<Container *>(this);
  }
 
  FunctionalMethods<Container, T> *base() const noexcept
  {
    return const_cast<FunctionalMethods<Container, T> *>(this);
  }
 
  const Container *const_me() const noexcept
  {
    return static_cast<const Container *>(this);
  }
 
public:
  template <typename... Args>
  void emplace(Args &&...args)
  {
    (void) me()->append(T(std::forward<Args>(args)...));
  }
 
  template <typename... Args>
  void emplace_end(Args &&...args)
  {
    (void) me()->append(T(std::forward<Args>(args)...));
  }
 
  template <typename... Args>
  void emplace_ins(Args &&...args)
  {
    (void) me()->insert(T(std::forward<Args>(args)...));
  }
 
private:
  static void nninsert(size_t &) {}
  static void nnappend(size_t &) {}
 
  template <typename... Args>
  void nninsert(size_t &n, const T &item, Args &...args)
  {
    (void) me()->insert(item);
    ++n;
    nninsert(n, args...);
  }
 
  template <typename... Args>
  void nnappend(size_t &n, const T &item, Args &...args)
  {
    (void) me()->append(item);
    ++n;
    nnappend(n, args...);
  }
 
public:
  template <typename... Args>
  size_t ninsert(Args... args)
  {
    size_t n = 0;
    nninsert(n, args...);
    return n;
  }
 
  template <typename... Args>
  size_t nappend(Args... args)
  {
    size_t n = 0;
    nnappend(n, args...);
    return n;
  }
 
  template <class Operation>
    requires Aleph::CallableWith<Operation &, const T &>
  void for_each(Operation &operation)
  {
    me()->traverse([&operation](const T &item)
      {
        operation(item);
        return true;
      });
  }
 
  template <class Operation>
    requires Aleph::CallableWith<Operation &, const T &>
  void for_each(Operation &operation) const
  {
    base()->for_each(operation);
  }
 
  template <class Operation>
    requires Aleph::CallableWith<Operation &, const T &>
  void for_each(Operation &&operation) const
  {
    for_each<Operation>(operation);
  }
 
  template <class Operation>
    requires Aleph::CallableWith<Operation &, const T &>
  void for_each(Operation &&operation)
  {
    for_each<Operation>(operation);
  }
 
  template <class Operation>
    requires Aleph::CallableWith<Operation &, const T &>
  void each(Operation &operation)
  {
    for_each(operation);
  }
 
  template <class Operation>
    requires Aleph::CallableWith<Operation &, const T &>
  void each(Operation &operation) const
  {
    for_each(operation);
  }
 
  template <class Operation>
    requires Aleph::CallableWith<Operation &, const T &>
  void each(Operation &&operation) const
  {
    for_each<Operation>(operation);
  }
 
  template <class Operation>
    requires Aleph::CallableWith<Operation &, const T &>
  void each(Operation &&operation)
  {
    for_each<Operation>(operation);
  }
 
  template <class Operation>
  void each(size_t pos, const size_t slice, Operation &operation) const
  {
    if (slice == 0)
      return;
    auto it = const_me()->get_it(pos);
    while (true)
      {
        operation(it.get_curr());
        for (size_t k = 0; k < slice; ++k)
          {
            it.next();
            if (not it.has_curr())
              return;
          }
      }
  }
 
  template <class Operation>
  void each(const size_t pos, const size_t slice, Operation &&operation) const
  {
    each<Operation>(pos, slice, operation);
  }
 
  template <class Operation>
    requires Aleph::CallableWith<Operation &, T &>
  void mutable_for_each(Operation &operation)
  {
    me()->traverse([&operation](T &item)
      {
        operation(item);
        return true;
      });
  }
 
  template <class Operation>
    requires Aleph::CallableWith<Operation &, T &>
  void mutable_for_each(Operation &&operation)
  {
    mutable_for_each<Operation>(operation);
  }
 
  template <class Operation>
    requires requires(const typename Aleph::concepts_detail::defer<Container, Operation>::type &c, Operation &op) { { c.traverse(op) } -> std::convertible_to<bool>; }
  bool all(Operation &operation) const
  {
    return const_me()->traverse(operation);
  }
 
  template <class Operation>
    requires requires(const typename Aleph::concepts_detail::defer<Container, Operation>::type &c, Operation &op) { { c.traverse(op) } -> std::convertible_to<bool>; }
  bool all(Operation &&operation) const
  {
    return all<Operation>(operation);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, const T &>
  bool exists(Operation &op) const
  {
    return not const_me()->traverse([&op](const T &i)
      {
        return not op(i);
      });
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, const T &>
  bool exists(Operation &&op) const
  {
    return exists<Operation>(op);
  }
 
  template <typename __T = T, class Operation = Aleph::Dft_Map_Op<T, __T>>
    requires requires(Aleph::DynList<__T> &l, Operation &op, const T &item) { l.append(op(item)); }
  Aleph::DynList<__T> maps(Operation &op) const
  {
    Aleph::DynList<__T> ret_val;
    const_me()->for_each([&ret_val, &op](const T &item)
      {
        ret_val.append(op(item));
      });
    return ret_val;
  }
 
  template <typename __T = T, class Operation = Aleph::Dft_Map_Op<__T, __T>>
    requires requires(Aleph::DynList<__T> &l, Operation &op, const T &item) { l.append(op(item)); }
  Aleph::DynList<__T> maps(Operation &&op) const
  {
    return maps<__T, Operation>(op);
  }
 
  template <typename __T = T, class Prop, class Operation>
    requires Aleph::PredicateWith<Prop &, const T &> and
             requires(Aleph::DynList<__T> &l, Operation &op, const T &item) { l.append(op(item)); }
  Aleph::DynList<__T> maps_if(Prop prop, Operation &op) const
  {
    Aleph::DynList<__T> ret_val;
    const_me()->for_each([&ret_val, &prop, &op](const T &item)
      {
        if (prop(item))
          ret_val.append(op(item));
      });
    return ret_val;
  }
 
  template <typename __T = T, class Prop, class Operation>
    requires Aleph::PredicateWith<Prop &, const T &> and
             requires(Aleph::DynList<__T> &l, Operation &op, const T &item) { l.append(op(item)); }
  Aleph::DynList<__T> maps_if(Prop prop, Operation &&op) const
  {
    return maps_if<__T, Prop, Operation>(prop, op);
  }
 
  template <typename __T = T, class Operation = Aleph::Dft_Map_Op<T, __T>>
    requires requires(Aleph::DynList<__T> &l, Operation &op, const T &item) { l.append(op(item)); }
  Aleph::DynList<__T> map(Operation &op) const
  {
    return maps<__T, Operation>(op);
  }
 
  template <typename __T = T, class Operation = Aleph::Dft_Map_Op<__T, __T>>
    requires requires(Aleph::DynList<__T> &l, Operation &op, const T &item) { l.append(op(item)); }
  Aleph::DynList<__T> map(Operation &&op) const
  {
    return maps<__T, Operation>(op);
  }
 
  template <typename __T = T, class Prop, class Operation>
    requires Aleph::PredicateWith<Prop &, const T &> and
             requires(Aleph::DynList<__T> &l, Operation &op, const T &item) { l.append(op(item)); }
  Aleph::DynList<__T> map_if(Prop prop, Operation &op) const
  {
    return maps_if<__T, Prop, Operation>(prop, op);
  }
 
  template <typename __T = T, class Prop, class Operation>
    requires Aleph::PredicateWith<Prop &, const T &> and
             requires(Aleph::DynList<__T> &l, Operation &op, const T &item) { l.append(op(item)); }
  Aleph::DynList<__T> map_if(Prop prop, Operation &&op) const
  {
    return maps_if<__T, Prop, Operation>(prop, op);
  }
 
  Aleph::DynList<T> to_dynlist() const
  {
    return maps([](auto &item)
      {
        return item;
      });
  }
 
  std::vector<T> to_vector() const
  {
    std::vector<T> ret;
    if constexpr (requires { const_me()->size(); })
      ret.reserve(const_me()->size());
    const_me()->for_each([&ret](const T &item)
      {
        ret.push_back(item);
      });
    return ret;
  }
 
  template <typename __T = T, class Op = Aleph::Dft_Fold_Op<__T, T>>
    requires requires(__T &acc, Op &op, const T &item) { acc = op(acc, item); }
  __T foldl(const __T &init, Op &op) const
  {
    __T ret_val = init;
    const_me()->for_each([&ret_val, &op](const T &item)
      {
        ret_val = op(ret_val, item);
      });
    return ret_val;
  }
 
  template <typename __T = T, class Op = Aleph::Dft_Fold_Op<__T, T>>
    requires requires(__T &acc, Op &op, const T &item) { acc = op(acc, item); }
  __T foldl(const __T &init, Op &&op = Op()) const
  {
    return foldl<__T, Op>(init, op);
  }
 
  template <typename __T = T, class Op = Aleph::Dft_Fold_Op<__T, T>>
    requires requires(__T &acc, Op &op, const T &item) { acc = op(acc, item); }
  __T fold_left(const __T &init, Op &op) const
  {
    return const_me()->template foldl<__T>(init, op);
  }
 
  template <typename __T = T, class Op = Aleph::Dft_Fold_Op<__T, T>>
    requires requires(__T &acc, Op &op, const T &item) { acc = op(acc, item); }
  __T fold_left(const __T &init, Op &&op = Op()) const
  {
    return const_me()->template foldl<__T>(init, op);
  }
 
  template <class Operation>
    requires requires(T &acc, Operation &op, const T &item) { acc = op(acc, item); }
  T fold(const T &init, Operation &operation) const
  {
    auto ret_val = init;
    const_me()->for_each([&ret_val, &operation](const T &item)
      {
        ret_val = operation(ret_val, item);
      });
    return ret_val;
  }
 
  template <class Operation>
    requires requires(T &acc, Operation &op, const T &item) { acc = op(acc, item); }
  T fold(const T &init, Operation &&operation) const
  {
    return fold<Operation>(init, operation);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, const T &>
  Aleph::DynList<T> filter(Operation &operation) const
  {
    Aleph::DynList<T> ret_val;
    const_me()->for_each([&ret_val, &operation](const T &item)
      {
        if (operation(item))
          ret_val.append(item);
      });
    return ret_val;
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, const T &>
  Aleph::DynList<T> filter(Operation &&operation) const
  {
    return filter<Operation>(operation);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, const T &>
  Aleph::DynList<const T *> ptr_filter(Operation &operation) const
  {
    Aleph::DynList<const T *> ret_val;
    const_me()->for_each([&ret_val, &operation](const T &item)
      {
        if (operation(item))
          ret_val.append(&item);
      });
    return ret_val;
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, const T &>
  Aleph::DynList<const T *> ptr_filter(Operation &&operation) const
  {
    return ptr_filter<Operation>(operation);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, const T &>
  Aleph::DynList<std::tuple<T, size_t>> pfilter(Operation &operation) const
  {
    using TT = std::tuple<T, size_t>;
    Aleph::DynList<TT> ret_val;
    size_t i = 0;
    const_me()->for_each([&ret_val, &operation, &i](const T &item)
      {
        if (operation(item))
          ret_val.append(TT(item, i));
        ++i;
      });
    return ret_val;
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, const T &>
  Aleph::DynList<std::tuple<T, size_t>> pfilter(Operation &&operation) const
  {
    return pfilter<Operation>(operation);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, const T &>
  std::pair<Aleph::DynList<T>, Aleph::DynList<T>> partition(Operation &op) const
  {
    std::pair<Aleph::DynList<T>, Aleph::DynList<T>> ret_val;
    const_me()->for_each([&ret_val, &op](const T &item)
      {
        if (op(item))
          ret_val.first.append(item);
        else
          ret_val.second.append(item);
      });
    return ret_val;
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, const T &>
  std::pair<Aleph::DynList<T>, Aleph::DynList<T>> partition(Operation &&op) const
  {
    return partition<Operation>(op);
  }
 
  std::pair<Aleph::DynList<T>, Aleph::DynList<T>> partition(size_t n) const
  {
    size_t i = 0;
    std::pair<Aleph::DynList<T>, Aleph::DynList<T>> ret_val;
    const_me()->for_each([&ret_val, &i, n](const T &item)
      {
        if (i++ < n)
          ret_val.first.append(item);
        else
          ret_val.second.append(item);
      });
    return ret_val;
  }
 
  std::pair<Aleph::DynList<T>, Aleph::DynList<T>> split_half() const
  {
    size_t i = 0;
    std::pair<Aleph::DynList<T>, Aleph::DynList<T>> ret_val;
    const_me()->for_each([&ret_val, &i](const T &item)
      {
        if (i % 2 == 0)
          ret_val.first.append(item);
        else
          ret_val.second.append(item);
        i++;
      });
    return ret_val;
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, const T &>
  std::tuple<Aleph::DynList<T>, Aleph::DynList<T>> tpartition(Operation &op) const
  {
    Aleph::DynList<T> r1, r2;
    const_me()->for_each([&r1, &r2, &op](const T &item)
      {
        if (op(item))
          r1.append(item);
        else
          r2.append(item);
      });
    return std::tuple<Aleph::DynList<T>, Aleph::DynList<T>>(r1, r2);
  }
 
  template <class Operation>
    requires Aleph::PredicateWith<Operation &, const T &>
  std::tuple<Aleph::DynList<T>, Aleph::DynList<T>> tpartition(Operation &&op) const
  {
    return tpartition<Operation>(op);
  }
 
  [[nodiscard]] size_t length() const noexcept
  {
    size_t count = 0;
    const_me()->for_each([&count](const T &)
      {
        ++count;
      });
    return count;
  }
 
  Aleph::DynList<T> rev() const
  {
    Aleph::DynList<T> ret;
    const_me()->for_each([&ret](const T &i)
      {
        ret.insert(i);
      });
    return ret;
  }
 
  Aleph::DynList<T> take(const size_t n) const
  {
    size_t i = 0;
    Aleph::DynList<T> ret;
    const_me()->traverse([&i, &ret, n](const T &item)
      {
        if (i++ >= n)
          return false;
        ret.append(item);
        return true;
      });
    return ret;
  }
 
  Aleph::DynList<T> take(size_t i, const size_t j, const size_t step = 1) const
  {
    Aleph::DynList<T> ret;
    if (step == 0)
      return ret;
    for (auto it = const_me()->get_it(i); i <= j and it.has_curr(); it.next_ne(), i += step)
      ret.append(it.get_curr());
    return ret;
  }
 
  Aleph::DynList<T> drop(const size_t n) const
  {
    size_t i = 0;
    Aleph::DynList<T> ret;
    const_me()->traverse([&i, &ret, n](const T &item)
      {
        if (i++ >= n)
          ret.append(item);
        return true;
      });
    return ret;
  }
 
  void mutable_drop(const size_t n)
  {
    for (size_t i = 0; i < n; ++i)
      me()->remove();
  }
};
 
template <class Container, typename T>
struct GenericItems
{
  Aleph::DynList<T> items() const
  {
    return static_cast<const Container *>(this)->Container::template maps<T>([](const T &key)
      {
        return key;
      });
  }
 
  Aleph::DynList<T> keys() const
  {
    return items();
  }
};
 
template <class Container, typename T>
using GenericKeys = GenericItems<Container, T>;
 
template <class Container>
class EqualSequenceMethod
{
  const Container *const_me() const noexcept
  {
    return static_cast<const Container *>(this);
  }
 
public:
  bool equal_to(const Container &r) const
  {
    if (const_me() == &r)
      return true;
 
    if (const_me()->size() != r.size())
      return false;
 
    auto it1 = const_me()->get_it();
    auto it2 = r.get_it();
 
    while (it1.has_curr())
      {
        if (not(it1.get_curr() == it2.get_curr()))
          return false;
 
        it1.next();
        it2.next();
      }
 
    return true;
  }
 
  bool operator == (const Container &r) const
  {
    return equal_to(r);
  }
 
  bool operator != (const Container &r) const
  {
    return not equal_to(r);
  }
};
 
template <class Container>
class EqualToMethod
{
  const Container *const_me() const
  {
    return static_cast<const Container *>(this);
  }
 
public:
  bool equal_to(const Container &r) const noexcept
  {
    if (const_me() == &r)  // Use const_me() to get correct pointer in case of multiple inheritance
      return true;
 
    if (const_me()->size() != r.size())
      return false;
 
    return const_me()->all([&r](const typename Container::Key_Type &k)
      {
        return r.search(k) != nullptr;
      });
  }
 
  bool operator == (const Container &r) const noexcept
  {
    return equal_to(r);
  }
 
  bool operator != (const Container &r) const noexcept
  {
    return not equal_to(r);
  }
};
 
template <class Container, typename Key, typename Data>
class MapSequencesMethods
{
  const Container *const_me() const
  {
    return static_cast<const Container *>(this);
  }
 
  Container *me()
  {
    return static_cast<Container *>(this);
  }
 
public:
  template <template <typename> class C = Aleph::DynList>
  C<Key> keys() const
  {
    C<Key> ret_val;
    const_me()->for_each([&ret_val](const Key &p)
      {
        ret_val.append(p.first);
      });
    return ret_val;
  }
 
  template <template <typename> class C = Aleph::DynList>
  C<Data> values() const
  {
    C<Data> ret_val;
    const_me()->for_each([&ret_val](const std::pair<Key, Data> &p)
      {
        ret_val.append(p.second);
      });
    return ret_val;
  }
 
  template <template <typename> class C = Aleph::DynList>
  C<Data *> values_ptr() const
  {
    C<Data *> ret_val;
    const_me()->for_each([&ret_val](std::pair<Key, Data> &p)
      {
        ret_val.append(&p.second);
      });
    return ret_val;
  }
 
  template <template <typename> class C = Aleph::DynList>
  C<std::pair<Key, Data>> items() const
  {
    C<std::pair<Key, Data>> ret;
    const_me()->for_each([&ret](std::pair<Key, Data> &p)
      {
        ret.append(p);
      });
    return ret;
  }
 
  template <template <typename> class C = Aleph::DynList>
  C<std::pair<Key, Data *>> items_ptr() const
  {
    C<std::pair<Key, Data *>> ret_val;
    const_me()->for_each([&ret_val](std::pair<Key, Data> &p)
      {
        ret_val.append(std::pair<Key, Data *>(p.first, &p.second));
      });
    return ret_val;
  }
 
  Data &operator () (const Key &key)
  {
    // CRTP: `find` lives on the derived `Container`, not on this base.
    // Casting via `me()` is required for AppleClang (which performs the
    // member lookup eagerly at template definition time) and is the
    // correct pattern regardless of compiler leniency.
    return me()->find(key);
  }
 
  const Data &operator () (const Key &key) const
  {
    return const_me()->find(key);
  }
};
#endif  // AH_DRY_H