bitmask as a range, sparse enum handling in bitmask (#31)

Author: arturbac

include/simple_enum/core.hpp

@@ -6,7 +6,7 @@
 #include <concepts>
 #include <type_traits>
 
-#define SIMPLE_ENUM_NAME_VERSION "0.9.2"
+#define SIMPLE_ENUM_NAME_VERSION "0.9.3"
 
 namespace simple_enum::inline v0_9
   {

include/simple_enum/enum_bitfield.h

@@ -4,11 +4,12 @@
 #pragma once
 
 #include <simple_enum/enum_index.hpp>
+#include <optional>
 #include "detail/static_call_operator_prolog.h"
 
 namespace simple_enum::inline v0_9
   {
-template<enum_concept enum_type_t>
+template<enum_concept enumeration>
 struct enum_bitfield_t;
 
 namespace detail
@@ -30,29 +31,23 @@ namespace detail
       return uint64_t{};
     }
 
-  template<enum_concept enum_type_t>
-  using select_storage_for_enum_t = decltype(select_storage_type<enum_size_v<enum_type_t>>());
+  template<enum_concept enumeration>
+  using select_storage_for_enum_t = decltype(select_storage_type<enum_size_v<enumeration>>());
+
+  constexpr bool test_bit(auto bits, size_t ix) noexcept { return ((bits >> ix) & 1u) != 0; }
 
   ///@brief A proxy object to get/set a specific bit in the parent bitfield.
-  template<typename parent_type, enum_concept enum_type_t>
+  template<typename parent_type, enum_concept enumeration>
   struct bit_proxy_t
     {
-    using storage_t = typename enum_bitfield_t<enum_type_t>::storage_t;
+    using storage_t = typename enum_bitfield_t<enumeration>::storage_t;
 
     parent_type & parent_;
-    enum_type_t value_;
-
-    [[nodiscard]]
-    static constexpr auto get_offset(enum_type_t const value) noexcept -> std::size_t
-      {
-      // enum_size_v/select_storage_for_enum_t would not compile for invalid enum so testing for expected is redudant
-      // here
-      return *enum_index(value);
-      }
+    enumeration value_;
 
     constexpr auto operator=(std::same_as<bool> auto const bit_value) noexcept -> bit_proxy_t &
       {
-      auto const offset = get_offset(value_);
+      auto const offset = *enum_index(value_);
       auto const mask = storage_t(1) << offset;
 
       if(bit_value)
@@ -66,7 +61,8 @@ namespace detail
     [[nodiscard]]
     constexpr operator bool() const noexcept
       {
-      return ((parent_.bits_ >> get_offset(value_)) & 1u) != 0;
+      return test_bit(parent_.bits_, *enum_index(value_));
+      // return ((parent_.bits_ >> *enum_index(value_)) & 1u) != 0;
       }
     };
 
@@ -85,14 +81,118 @@ namespace detail
 
   template<std::unsigned_integral T, std::size_t N>
   inline constexpr T bitmask_v = bitmask_t<T, N>::value;
+
+  template<enum_concept enumeration>
+  struct enum_mask_impl_t
+    {
+    using mask_type = select_storage_for_enum_t<enumeration>;
+    static constexpr size_t size{enum_size_v<enumeration>};
+
+    template<size_t N>
+    static consteval auto op(mask_type init) noexcept -> mask_type
+      {
+      if constexpr(N != 0)
+        {
+        if constexpr(is_valid_enumeration_index_v<enumeration>(N - 1))
+          init |= mask_type(mask_type(1u) << (N - 1));
+        init |= op<N - 1>(init);
+        }
+      return init;
+      }
+
+    static constexpr mask_type value{op<size>(0)};
+    };
+
+  template<enum_concept enumeration>
+  inline constexpr auto enum_mask_v = enum_mask_impl_t<enumeration>::value;
+
+  template<enum_concept enum_type_t>
+  struct enum_bitfield_traits_t
+    {
+    using storage_t = detail::select_storage_for_enum_t<enum_type_t>;
+    // mask with eanbled bits of all valid mapped enumerations indexes, it does not enable indexes for holes in enum
+    static constexpr storage_t bits_mask{detail::enum_mask_v<enum_type_t>};
+    };
+
+  template<enum_concept enumeration>
+  struct enum_bitfield_iterator_t
+    {
+    using traits_type = detail::enum_bitfield_traits_t<enumeration>;
+    using storage_t = traits_type::storage_t;
+    static constexpr storage_t bits_mask{traits_type::bits_mask};
+
+    using iterator_category = std::forward_iterator_tag;
+    using value_type = enumeration;
+    using difference_type = std::ptrdiff_t;
+    using pointer = enumeration const *;
+    using reference = enumeration const &;
+
+    storage_t bits_{};
+    std::optional<enumeration> current_{};
+
+    constexpr enum_bitfield_iterator_t() noexcept = default;
+
+    constexpr explicit enum_bitfield_iterator_t(storage_t bits) noexcept : bits_{bits}, current_{}
+      {
+      // move to first
+      static constexpr size_t size{enum_size_v<enumeration>};
+      for(size_t ix{}; ix != size; ++ix)
+        if(test_bit(bits_, ix))  // no need to test if it is valid as mask will always maintain that
+          {
+          current_ = *emum_index_to_enumeration<enumeration>(ix);
+          break;
+          }
+      }
+
+    constexpr auto operator*() const noexcept -> reference { return *current_; }
+
+    constexpr auto operator->() const noexcept -> pointer { return current_->value(); }
+
+    constexpr auto operator++() noexcept -> enum_bitfield_iterator_t &
+      {
+      if(current_)
+        {
+        static constexpr size_t size{enum_size_v<enumeration>};
+        size_t ix{*enum_index(*current_)};
+        current_.reset();
+        for(++ix; ix != size; ++ix)
+          if(test_bit(bits_, ix))  // no need to test if it is valid as mask will always maintain that
+            {
+            current_ = *emum_index_to_enumeration<enumeration>(ix);
+            break;
+            }
+        }
+      return *this;
+      }
+
+    constexpr auto operator++(int) noexcept -> enum_bitfield_iterator_t
+      {
+      enum_bitfield_iterator_t tmp{*this};
+      ++(*this);
+      return tmp;
+      }
+
+    constexpr auto operator==(enum_bitfield_iterator_t const & other) const noexcept -> bool = default;
+    };
   }  // namespace detail
 
+enum struct enum_bitfield_full_e
+  {
+  };
+
 /// @brief A template struct providing a bitfield with enum indexing.
-template<enum_concept enum_type_t>
+template<enum_concept enumeration>
 struct enum_bitfield_t
   {
-  using storage_t = detail::select_storage_for_enum_t<enum_type_t>;
-  static constexpr storage_t bits_mask{detail::bitmask_v<storage_t, enum_size_v<enum_type_t>>};
+  using traits_type = detail::enum_bitfield_traits_t<enumeration>;
+  using storage_t = traits_type::storage_t;
+  static constexpr storage_t bits_mask{traits_type::bits_mask};
+  using iterator = detail::enum_bitfield_iterator_t<enumeration>;
+
+  struct sentinel_t
+    {
+    constexpr auto operator==(iterator const & it) const noexcept { return not it.current_.has_value(); }
+    };
 
   storage_t bits_{0};
 
@@ -102,31 +202,38 @@ struct enum_bitfield_t
 
   explicit constexpr enum_bitfield_t(std::same_as<storage_t> auto bits) noexcept : bits_{bits} {}
 
-  template<std::same_as<enum_type_t>... Args>
+  // constructs will full bits enabled
+  explicit constexpr enum_bitfield_t(enum_bitfield_full_e) noexcept : bits_{bits_mask} {}
+
+  template<std::same_as<enumeration>... Args>
   constexpr explicit enum_bitfield_t(Args &&... args) noexcept
     {
     set_values(std::forward<Args>(args)...);
     }
 
+  constexpr auto begin() const noexcept -> iterator { return iterator{bits_}; }
+
+  constexpr auto end() const noexcept -> sentinel_t { return sentinel_t{}; }
+
   /**
    * @brief Accesses a bit corresponding to an index of enumeration value.
    * @returns A proxy object to manipulate the bit.
    */
   template<typename Self>
   [[nodiscard]]
-  constexpr auto operator[](this Self && self, enum_type_t const value) noexcept
+  constexpr auto operator[](this Self && self, enumeration const value) noexcept
     {
     return detail::bit_proxy_t{self, value};
     }
 
-  template<std::same_as<enum_type_t>... Args>
-  constexpr void set_values(enum_type_t const & arg, Args &&... args) noexcept
+  template<std::same_as<enumeration>... Args>
+  constexpr void set_values(enumeration const & arg, Args &&... args) noexcept
     {
     detail::bit_proxy_t{*this, arg} = true;
     set_values(std::forward<Args>(args)...);
     }
 
-  constexpr void set_values(enum_type_t const & arg) noexcept { detail::bit_proxy_t{*this, arg} = true; }
+  constexpr void set_values(enumeration const & arg) noexcept { detail::bit_proxy_t{*this, arg} = true; }
 
   [[nodiscard]]
   constexpr auto operator==(enum_bitfield_t const &) const noexcept -> bool
@@ -175,11 +282,11 @@ struct enum_bitfield_t
     }
   };
 
-template<enum_concept enum_type_t>
-enum_bitfield_t(enum_type_t const & arg) -> enum_bitfield_t<enum_type_t>;
+template<enum_concept enumeration>
+enum_bitfield_t(enumeration const & arg) -> enum_bitfield_t<enumeration>;
 
-template<enum_concept enum_type_t, typename... Args>
-enum_bitfield_t(enum_type_t const & arg, Args &&... args) -> enum_bitfield_t<enum_type_t>;
+template<enum_concept enumeration, typename... Args>
+enum_bitfield_t(enumeration const & arg, Args &&... args) -> enum_bitfield_t<enumeration>;
 
   }  // namespace simple_enum::inline v0_9
 

include/simple_enum/enum_index.hpp

@@ -79,6 +79,28 @@ consteval auto consteval_enum_index() -> std::size_t
   return enum_index(value).or_else([](auto &&) { throw; });
   }
 
+/// @brief enumeration value for 0 - based index
+template<enum_concept enum_type>
+struct emum_index_to_enumeration_t
+  {
+  [[nodiscard]]
+  static_call_operator constexpr auto operator()(std::size_t index) static_call_operator_const noexcept
+    -> cxx23::expected<enum_type, enum_index_error>
+    {
+    using enum_meta_info = detail::enum_meta_info_t<enum_type>;
+    auto const requested_value{enum_meta_info::first_index() + std::underlying_type_t<enum_type>(index)};
+
+    if(requested_value <= enum_meta_info::last_index()) [[likely]]
+      return static_cast<enum_type>(requested_value);
+    else
+      return cxx23::unexpected{enum_index_error::out_of_range};
+    }
+  };
+
+/// @brief enumeration value for 0 - based index
+template<enum_concept enum_type>
+inline constexpr emum_index_to_enumeration_t<enum_type> emum_index_to_enumeration;
+
 /// @brief Provides compile time information of length of enumeration (including holes).
 template<enum_concept enum_type>
 struct enum_size_t
@@ -90,6 +112,51 @@ struct enum_size_t
 template<enum_concept enum_type>
 inline constexpr std::size_t enum_size_v = enum_size_t<enum_type>::value;
 
+namespace detail
+  {
+  [[nodiscard]]
+  constexpr bool isdigit(char src) noexcept
+    {
+    unsigned c{static_cast<unsigned>(src)};
+    return c >= 48u && c <= 57u;
+    }
+  }  // namespace detail
+
+template<enum_concept enum_type>
+struct is_valid_enumeration_index_t
+  {
+  static_call_operator constexpr auto operator()(size_t index) static_call_operator_const noexcept -> bool
+    {
+    using enum_meta_info = detail::enum_meta_info_t<enum_type>;
+
+    if(index < enum_meta_info::size())
+      {
+      detail::meta_name const & res{enum_meta_info::meta_data[index]};
+      return res.is_valid;
+      }
+    else
+      return false;
+    }
+  };
+
+template<enum_concept enum_type>
+inline constexpr is_valid_enumeration_index_t<enum_type> is_valid_enumeration_index_v;
+
+struct is_valid_enumeration_value_t
+  {
+  template<enum_concept enum_type>
+  static_call_operator constexpr auto operator()(enum_type value) static_call_operator_const noexcept -> bool
+    {
+    using enum_meta_info = detail::enum_meta_info_t<enum_type>;
+    auto const requested_value{simple_enum::detail::to_underlying(value)};
+    if(requested_value >= enum_meta_info::first_index())
+      return is_valid_enumeration_index_t<enum_type>{}(size_t(requested_value - enum_meta_info::first_index()));
+    else
+      return false;
+    }
+  };
+
+inline constexpr is_valid_enumeration_value_t is_valid_enumeration_value_v;
   }  // namespace simple_enum::inline v0_9
 
 #include "detail/static_call_operator_epilog.h"