etl/include/etl/const_map.h

///\file

/******************************************************************************
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Embedded Template Library.
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Copyright(c) 2025 John Wellbelove

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#ifndef ETL_CONST_MAP_INCLUDED
#define ETL_CONST_MAP_INCLUDED

#include "platform.h"

#include "algorithm.h"
#include "functional.h"
#include "nth_type.h"
#include "span.h"
#include "type_traits.h"

#include "private/comparator_is_transparent.h"

#if ETL_USING_CPP11

///\defgroup const_map const_map
///\ingroup containers

namespace etl
{
  template <typename TKey, typename TMapped, typename TKeyCompare>
  class iconst_map
  {
  public:

    using key_type        = TKey;
    using value_type      = ETL_OR_STD::pair<const TKey, TMapped>;
    using mapped_type     = TMapped;
    using key_compare     = TKeyCompare;
    using const_reference = const value_type&;
    using const_pointer   = const value_type*;
    using const_iterator  = const value_type*;
    using size_type       = size_t;

    //*********************************************************************
    /// How to compare elements and keys.
    //*********************************************************************
    class value_compare
    {
    public:

      // Compare two value types.
      ETL_CONSTEXPR14 bool operator()(const value_type& element1, const value_type& element2) const ETL_NOEXCEPT
      {
        return kcompare(element1.first, element2.first);
      }

      // Compare value type and key.
      ETL_CONSTEXPR14 bool operator()(const value_type& element, const key_type& key) const ETL_NOEXCEPT
      {
        return kcompare(element.first, key);
      }

      // Compare value types and key.
      // Enabled for transparent comparators.
      template <typename K, typename KC = TKeyCompare, etl::enable_if_t<comparator_is_transparent<KC>::value, int> = 0>
      ETL_CONSTEXPR14 bool operator()(const value_type& element, const K& key) const ETL_NOEXCEPT
      {
        return kcompare(element.first, key);
      }

      // Compare key and value type.
      ETL_CONSTEXPR14 bool operator()(const key_type& key, const value_type& element) const ETL_NOEXCEPT
      {
        return kcompare(key, element.first);
      }

      // Compare key and value type.
      // Enabled for transparent comparators.
      template <typename K, typename KC = TKeyCompare, etl::enable_if_t<comparator_is_transparent<KC>::value, int> = 0>
      ETL_CONSTEXPR14 bool operator()(const K& key, const value_type& element) const ETL_NOEXCEPT
      {
        return kcompare(key, element.first);
      }

      key_compare kcompare;
    };

    //*************************************************************************
    /// Check that the elements are valid for a map.
    /// The elements must be sorted and contain no duplicates.
    /// \return <b>true</b> if the elements are valid for the map.
    //*************************************************************************
    ETL_CONSTEXPR14 bool is_valid() const ETL_NOEXCEPT
    {
      return etl::is_unique_sorted(begin(), end(), vcompare);
    }

    //*************************************************************************
    ///\brief Returns a <code>const_iterator</code> to the beginning of the map.
    //*************************************************************************
    ETL_CONSTEXPR14 const_iterator begin() const ETL_NOEXCEPT
    {
      return element_list;
    }

    //*************************************************************************
    ///\brief Returns a <code>const_iterator</code> to the beginning of the map.
    //*************************************************************************
    ETL_CONSTEXPR14 const_iterator cbegin() const ETL_NOEXCEPT
    {
      return element_list;
    }

    //*************************************************************************
    ///\brief Returns a <code>const_iterator</code> to the end of the map.
    //*************************************************************************
    ETL_CONSTEXPR14 const_iterator end() const ETL_NOEXCEPT
    {
      return element_list_end;
    }

    //*************************************************************************
    ///\brief Returns a <code>const_iterator</code> to the end of the map.
    //*************************************************************************
    ETL_CONSTEXPR14 const_iterator cend() const ETL_NOEXCEPT
    {
      return element_list_end;
    }

    //*************************************************************************
    ///\brief Returns a <code>const_pointer</code> to the beginning of the map.
    //*************************************************************************
    ETL_CONSTEXPR14 const_pointer data() const ETL_NOEXCEPT
    {
      return element_list;
    }

    //*************************************************************************
    ///\brief Index operator.
    ///\param key The key of the element to return.
    ///\return A <code>const mapped_type&</code> to the mapped value at the
    /// index.
    /// Undefined behaviour if the key is not in the map.
    //*************************************************************************
    ETL_CONSTEXPR14 const mapped_type& operator[](const key_type& key) const ETL_NOEXCEPT
    {
      const_iterator itr = find(key);

      return itr->second;
    }

    //*************************************************************************
    ///\brief Key index operator.
    /// Enabled for transparent comparators.
    ///\param key The key of the element to return.
    ///\return A <code>const mapped_type&</code> to the mapped value at the key
    /// index.
    /// Undefined behaviour if the key is not in the map.
    //*************************************************************************
    template <typename K, typename KC = TKeyCompare, etl::enable_if_t<comparator_is_transparent<KC>::value, int> = 0>
    ETL_CONSTEXPR14 const mapped_type& operator[](const K& key) const ETL_NOEXCEPT
    {
      const_iterator itr = find(key);

      return itr->second;
    }

    //*************************************************************************
    ///\brief Gets the mapped value at the key index.
    ///\param key The key of the element to return.
    ///\return A <code>const mapped_type&</code> to the mapped value at the
    /// index.
    /// Undefined behaviour if the key is not in the map.
    //*************************************************************************
    ETL_CONSTEXPR14 const mapped_type& at(const key_type& key) const ETL_NOEXCEPT
    {
      const_iterator itr = find(key);

      return itr->second;
    }

    //*************************************************************************
    ///\brief Gets the mapped value at the key index.
    /// Enabled if the comparator is transparent.
    ///\param key The key of the element to return.
    ///\return A <code>const mapped_type&</code> to the mapped value at the
    /// index.
    /// Undefined behaviour if the key is not in the map.
    //*************************************************************************
    template <typename K, typename KC = TKeyCompare, etl::enable_if_t<comparator_is_transparent<KC>::value, int> = 0>
    ETL_CONSTEXPR14 const mapped_type& at(const K& key) const ETL_NOEXCEPT
    {
      const_iterator itr = find(key);

      return itr->second;
    }

    //*************************************************************************
    ///\brief Gets a const_iterator to the mapped value at the key index.
    ///\param key The key of the element to find.
    ///\return A <code>const_iterator</code> to the mapped value at the index,
    /// or end() if not found.
    //*************************************************************************
    ETL_CONSTEXPR14 const_iterator find(const key_type& key) const ETL_NOEXCEPT
    {
      const_iterator itr = lower_bound(key);

      if ((itr != end()) && (keys_are_equal(itr->first, key)))
      {
        return itr;
      }

      return end();
    }

    //*************************************************************************
    ///\brief Gets a const_iterator to the mapped value at the key index.
    /// Enabled if the comparator is transparent.
    ///\param key The key of the element to find.
    ///\return A <code>const_iterator</code> to the mapped value at the index,
    /// or end() if not found.
    //*************************************************************************
    template <typename K, typename KC = TKeyCompare, etl::enable_if_t<comparator_is_transparent<KC>::value, int> = 0>
    ETL_CONSTEXPR14 const_iterator find(const K& key) const ETL_NOEXCEPT
    {
      const_iterator itr = lower_bound(key);

      if ((itr != end()) && (keys_are_equal(itr->first, key)))
      {
        return itr;
      }

      return end();
    }

    //*************************************************************************
    ///\brief Checks if the map contains an element with key.
    ///\param key The key of the element to check.
    ///\return <b>true</b> if the map contains an element with key.
    //*************************************************************************
    ETL_CONSTEXPR14 bool contains(const key_type& key) const ETL_NOEXCEPT
    {
      return find(key) != end();
    }

    //*************************************************************************
    ///\brief Checks if the map contains an element with key.
    /// Enabled if the comparator is transparent.
    ///\param key The key of the element to check.
    ///\return <b>true</b> if the map contains an element with key.
    //*************************************************************************
    template <typename K, typename KC = TKeyCompare, etl::enable_if_t<comparator_is_transparent<KC>::value, int> = 0>
    ETL_CONSTEXPR14 bool contains(const K& key) const ETL_NOEXCEPT
    {
      return find(key) != end();
    }

    //*************************************************************************
    ///\brief Counts the numbeer elements with key.
    ///\param key The key of the element to count.
    ///\return 0 or 1
    //*************************************************************************
    ETL_CONSTEXPR14 size_type count(const key_type& key) const ETL_NOEXCEPT
    {
      return contains(key) ? 1 : 0;
    }

    //*************************************************************************
    ///\brief Counts the numbeer elements with key.
    /// Enabled if the comparator is transparent.
    ///\param key The key of the element to count.
    ///\return 0 or 1
    //*************************************************************************
    template <typename K, typename KC = TKeyCompare, etl::enable_if_t<comparator_is_transparent<KC>::value, int> = 0>
    ETL_CONSTEXPR14 size_type count(const K& key) const ETL_NOEXCEPT
    {
      return contains(key) ? 1 : 0;
    }

    //*************************************************************************
    ///\brief Returns a range containing all elements with the key.
    /// The range is defined by a pair of two iterators, one to the
    /// first element that is not less than the key and second to the first
    /// element greater than the key.
    ///\param key The key of the element
    ///\return etl::pair or std::pair containing a pair of iterators.
    //*************************************************************************
    ETL_CONSTEXPR14 ETL_OR_STD::pair<const_iterator, const_iterator> equal_range(const key_type& key) const ETL_NOEXCEPT
    {
      return etl::equal_range(begin(), end(), key, vcompare);
    }

    //*************************************************************************
    ///\brief Returns a range containing all elements with the key.
    /// The range is defined by a pair of two iterators, one to the
    /// first element that is not less than the key and second to the first
    /// element greater than the key.
    /// Enabled if the comparator is transparent.
    ///\param key The key of the element
    ///\return etl::pair or std::pair containing a pair of iterators.
    //*************************************************************************
    template <typename K, typename KC = TKeyCompare, etl::enable_if_t<comparator_is_transparent<KC>::value, int> = 0>
    ETL_CONSTEXPR14 ETL_OR_STD::pair<const_iterator, const_iterator> equal_range(const K& key) const ETL_NOEXCEPT
    {
      return etl::equal_range(begin(), end(), key, vcompare);
    }

    //*************************************************************************
    ///\brief Returns a const_iterator to the first element that is not less
    /// than the key.
    /// Returns a const_iterator to the first element that is not less than the
    /// key.
    ///\param key The key of the element
    ///\return const_iterator to the element or end()
    //*************************************************************************
    ETL_CONSTEXPR14 const_iterator lower_bound(const key_type& key) const ETL_NOEXCEPT
    {
      return etl::lower_bound(begin(), end(), key, vcompare);
    }

    //*************************************************************************
    ///\brief Returns a const_iterator to the first element that is not less
    /// than the key.
    /// Returns a const_iterator to the first element that is not less than the
    /// key. Enabled if the comparator is transparent.
    ///\param key The key of the element
    ///\return const_iterator to the element or end()
    //*************************************************************************
    template <typename K, typename KC = TKeyCompare, etl::enable_if_t<comparator_is_transparent<KC>::value, int> = 0>
    ETL_CONSTEXPR14 const_iterator lower_bound(const K& key) const ETL_NOEXCEPT
    {
      return etl::lower_bound(begin(), end(), key, vcompare);
    }

    //*************************************************************************
    ///\brief Returns a const_iterator to the first element that is greater than
    /// the key.
    /// Returns a const_iterator to the first element that is greater than the
    /// key.
    ///\param key The key of the element
    ///\return const_iterator to the element or end()
    //*************************************************************************
    ETL_CONSTEXPR14 const_iterator upper_bound(const key_type& key) const ETL_NOEXCEPT
    {
      return etl::upper_bound(begin(), end(), key, vcompare);
    }

    //*************************************************************************
    ///\brief Returns a const_iterator to the first element that is greater than
    /// the key.
    /// Returns a const_iterator to the first element that is greater than the
    /// key. Enabled if the comparator is transparent.
    ///\param key The key of the element
    ///\return const_iterator to the element or end()
    //*************************************************************************
    template <typename K, typename KC = TKeyCompare, etl::enable_if_t<comparator_is_transparent<KC>::value, int> = 0>
    ETL_CONSTEXPR14 const_iterator upper_bound(const K& key) const ETL_NOEXCEPT
    {
      return etl::upper_bound(begin(), end(), key, vcompare);
    }

    //*************************************************************************
    /// Checks if the map is empty.
    ///\return <b>true</b> if the map is empty.
    //*************************************************************************
    ETL_CONSTEXPR14 size_type empty() const ETL_NOEXCEPT
    {
      return size() == 0U;
    }

    //*************************************************************************
    /// Checks if the map is full.
    ///\return <b>true</b> if the map is full.
    //*************************************************************************
    ETL_CONSTEXPR14 size_type full() const ETL_NOEXCEPT
    {
      return (max_elements != 0) && (size() == max_elements);
    }

    //*************************************************************************
    /// Gets the size of the map.
    ///\return The size of the map.
    //*************************************************************************
    ETL_CONSTEXPR14 size_type size() const ETL_NOEXCEPT
    {
      return size_type(element_list_end - element_list);
    }

    //*************************************************************************
    /// Gets the maximum size of the map.
    ///\return The maximum size of the map.
    //*************************************************************************
    ETL_CONSTEXPR14 size_type max_size() const ETL_NOEXCEPT
    {
      return max_elements;
    }

    //*************************************************************************
    /// Gets the capacity of the map.
    /// This is always equal to max_size().
    ///\return The capacity of the map.
    //*************************************************************************
    ETL_CONSTEXPR14 size_type capacity() const ETL_NOEXCEPT
    {
      return max_elements;
    }

    //*************************************************************************
    /// How to compare two key elements.
    ///\return An instance of the key_compare type.
    //*************************************************************************
    ETL_CONSTEXPR14 key_compare key_comp() const ETL_NOEXCEPT
    {
      return vcompare.kcompare;
    }

    //*************************************************************************
    /// How to compare two value elements.
    ///\return An instance of the value_compare type.
    //*************************************************************************
    ETL_CONSTEXPR14 value_compare value_comp() const ETL_NOEXCEPT
    {
      return vcompare;
    }

  protected:

    //*************************************************************************
    /// Constructor
    //*************************************************************************
    template <typename... TElements>
    ETL_CONSTEXPR14 explicit iconst_map(const value_type* element_list_, size_type size_, size_type max_elements_) ETL_NOEXCEPT
      : element_list(element_list_)
      , element_list_end{element_list_ + size_}
      , max_elements(max_elements_)
    {
    }

  private:

    //*********************************************************************
    /// Check to see if the keys are equal.
    //*********************************************************************
    ETL_CONSTEXPR14 bool keys_are_equal(const key_type& key1, const key_type& key2) const ETL_NOEXCEPT
    {
      return !key_compare()(key1, key2) && !key_compare()(key2, key1);
    }

    //*********************************************************************
    /// Check to see if the keys are equal.
    /// Enabled if the comparator is transparent.
    //*********************************************************************
    template <typename K1, typename K2, typename KC = TKeyCompare, etl::enable_if_t<comparator_is_transparent<KC>::value, int> = 0>
    ETL_CONSTEXPR14 bool keys_are_equal(const K1& key1, const K2& key2) const ETL_NOEXCEPT
    {
      return !key_compare()(key1, key2) && !key_compare()(key2, key1);
    }

    value_compare vcompare;

    const value_type* element_list;
    const value_type* element_list_end;
    size_type         max_elements;
  };

  //*********************************************************************
  /// Map type designed for constexpr.
  //*********************************************************************
  template <typename TKey, typename TMapped, size_t Size, typename TKeyCompare = etl::less<TKey>>
  class const_map : public iconst_map<TKey, TMapped, TKeyCompare>
  {
  public:

    using base_t = iconst_map<TKey, TMapped, TKeyCompare>;

    using key_type        = typename base_t::key_type;
    using value_type      = typename base_t::value_type;
    using mapped_type     = typename base_t::mapped_type;
    using key_compare     = typename base_t::key_compare;
    using const_reference = typename base_t::const_reference;
    using const_pointer   = typename base_t::const_pointer;
    using const_iterator  = typename base_t::const_iterator;
    using size_type       = typename base_t::size_type;

    static_assert((etl::is_default_constructible<key_type>::value), "key_type must be default constructible");
    static_assert((etl::is_default_constructible<mapped_type>::value), "mapped_type must be default constructible");

    //*************************************************************************
    ///\brief Construct a const_map from a variadic list of elements.
    /// Static asserts if the elements are not of type <code>value_type</code>.
    /// Static asserts if the number of elements is greater than the capacity of
    /// the const_map.
    //*************************************************************************
    template <typename... TElements>
    ETL_CONSTEXPR14 explicit const_map(TElements&&... elements) ETL_NOEXCEPT
      : iconst_map<TKey, TMapped, TKeyCompare>(element_list, sizeof...(elements), Size)
      , element_list{etl::forward<TElements>(elements)...}
    {
      static_assert((etl::are_all_same<value_type, etl::decay_t<TElements>...>::value), "All elements must be value_type");
      static_assert(sizeof...(elements) <= Size, "Number of elements exceeds capacity");
    }

  private:

    value_type element_list[Size];
  };

    //*************************************************************************
    /// Template deduction guides.
    //*************************************************************************
  #if ETL_USING_CPP17
  template <typename... TElements>
  const_map(TElements...)
    -> const_map<typename etl::nth_type_t<0, TElements...>::first_type, typename etl::nth_type_t<0, TElements...>::second_type, sizeof...(TElements)>;
  #endif

  //*********************************************************************
  /// Map type designed for constexpr.
  //*********************************************************************
  template <typename TKey, typename TMapped, typename TKeyCompare = etl::less<TKey>>
  class const_map_ext : public iconst_map<TKey, TMapped, TKeyCompare>
  {
  public:

    using base_t = iconst_map<TKey, TMapped, TKeyCompare>;

    using key_type        = typename base_t::key_type;
    using value_type      = typename base_t::value_type;
    using mapped_type     = typename base_t::mapped_type;
    using key_compare     = typename base_t::key_compare;
    using const_reference = typename base_t::const_reference;
    using const_pointer   = typename base_t::const_pointer;
    using const_iterator  = typename base_t::const_iterator;
    using size_type       = typename base_t::size_type;

    static_assert((etl::is_default_constructible<key_type>::value), "key_type must be default constructible");
    static_assert((etl::is_default_constructible<mapped_type>::value), "mapped_type must be default constructible");

    //*************************************************************************
    ///\brief Default construct a const_map.
    //*************************************************************************
    ETL_CONSTEXPR14 const_map_ext() ETL_NOEXCEPT
      : iconst_map<TKey, TMapped, TKeyCompare>(nullptr, 0, 0)
    {
    }

    //*************************************************************************
    ///\brief Construct a const_map from a variadic list of elements.
    //*************************************************************************
    template <size_type Size>
    ETL_CONSTEXPR14 explicit const_map_ext(const etl::span<const value_type, Size>& sp) ETL_NOEXCEPT
      : iconst_map<TKey, TMapped, TKeyCompare>(sp.data(), Size, Size)
    {
    }

    //*************************************************************************
    ///\brief Construct a const_map from an array.
    //*************************************************************************
    template <size_type Size>
    ETL_CONSTEXPR14 explicit const_map_ext(const value_type (&begin_)[Size]) ETL_NOEXCEPT
      : iconst_map<TKey, TMapped, TKeyCompare>(begin_, Size, Size)
    {
    }
  };

    //*************************************************************************
    /// Template deduction guides.
    //*************************************************************************
  #if ETL_USING_CPP17
  template <typename TElements, size_t Size>
  const_map_ext(const etl::span<TElements, Size>&) -> const_map_ext<typename TElements::first_type, typename TElements::second_type>;

  template <typename TElements, size_t Size>
  const_map_ext(const TElements (&)[Size]) -> const_map_ext<typename TElements::first_type, typename TElements::second_type>;
  #endif

  //*************************************************************************
  /// Equality test.
  //*************************************************************************
  template <typename TKey, typename TMapped, typename TKeyCompare>
  ETL_CONSTEXPR14 bool operator==(const etl::iconst_map<TKey, TMapped, TKeyCompare>& lhs, const etl::iconst_map<TKey, TMapped, TKeyCompare>& rhs)
    ETL_NOEXCEPT
  {
    return (lhs.size() == rhs.size()) && etl::equal(lhs.begin(), lhs.end(), rhs.begin());
  }

  //*************************************************************************
  /// Inequality test.
  //*************************************************************************
  template <typename TKey, typename TMapped, typename TKeyCompare>
  ETL_CONSTEXPR14 bool operator!=(const etl::iconst_map<TKey, TMapped, TKeyCompare>& lhs, const etl::iconst_map<TKey, TMapped, TKeyCompare>& rhs)
    ETL_NOEXCEPT
  {
    return !(lhs == rhs);
  }

  //*************************************************************************
  /// Less-than.
  //*************************************************************************
  template <typename TKey, typename TMapped, typename TKeyCompare>
  ETL_CONSTEXPR14 bool operator<(const etl::iconst_map<TKey, TMapped, TKeyCompare>& lhs, const etl::iconst_map<TKey, TMapped, TKeyCompare>& rhs)
    ETL_NOEXCEPT
  {
    return etl::lexicographical_compare(lhs.begin(), lhs.end(), rhs.begin(), rhs.end(), lhs.value_comp());
  }

  //*************************************************************************
  /// Greater-than.
  //*************************************************************************
  template <typename TKey, typename TMapped, typename TKeyCompare>
  ETL_CONSTEXPR14 bool operator>(const etl::iconst_map<TKey, TMapped, TKeyCompare>& lhs, const etl::iconst_map<TKey, TMapped, TKeyCompare>& rhs)
    ETL_NOEXCEPT
  {
    return (rhs < lhs);
  }

  //*************************************************************************
  /// Less-than-equal.
  //*************************************************************************
  template <typename TKey, typename TMapped, typename TKeyCompare>
  ETL_CONSTEXPR14 bool operator<=(const etl::iconst_map<TKey, TMapped, TKeyCompare>& lhs, const etl::iconst_map<TKey, TMapped, TKeyCompare>& rhs)
    ETL_NOEXCEPT
  {
    return !(rhs < lhs);
  }

  //*************************************************************************
  /// Greater-than-equal.
  //*************************************************************************
  template <typename TKey, typename TMapped, typename TKeyCompare>
  ETL_CONSTEXPR14 bool operator>=(const etl::iconst_map<TKey, TMapped, TKeyCompare>& lhs, const etl::iconst_map<TKey, TMapped, TKeyCompare>& rhs)
    ETL_NOEXCEPT
  {
    return !(lhs < rhs);
  }
} // namespace etl

#endif
#endif