Refactor enumerable : with xtd concepts and enumerable_generator

Author: gammasoft71

src/xtd.core/CMakeLists.txt

@@ -1727,7 +1727,6 @@ add_sources(
   "src/xtd/io/string_writer.cpp"
   "src/xtd/io/text_reader.cpp"
   "src/xtd/io/text_writer.cpp"
-  "src/xtd/linq/enumerable.cpp"
   "src/xtd/literals/byte.cpp"
   "src/xtd/literals/char32.cpp"
   "src/xtd/literals/double.cpp"

src/xtd.core/include/xtd/linq/enumerable.hpp

@@ -5,6 +5,7 @@
 #include "enumerable_.hpp" // contains xtd::linq::enumerable <type_t> class definition
 #include "../collections/generic/extensions/enumerable.hpp"
 #include "../collections/generic/enumerable_generator.hpp"
+#include "../nullopt.hpp"
 #include "from.hpp"
 
 /// @cond
@@ -170,3 +171,68 @@ auto xtd::linq::enumerable::average(source_t&& source) -> double {
   if (count == 0) xtd::helpers::throw_helper::throws(xtd::helpers::exception_case::invalid_operation);
   return average / count;
 }
+
+template<xtd::forward_iterable source_t>
+requires std::same_as<typename xtd::raw_type<source_t>::value_type, xtd::optional<xtd::decimal>>
+auto xtd::linq::enumerable::average(source_t&& source) -> xtd::optional<xtd::decimal> {
+  auto average = .0l;
+  auto count = 0;
+  for (auto item : source) {
+    if (!item) continue;
+    average += *item;
+    ++count;
+  }
+  return count == 0 ? xtd::nullopt : std::make_optional(average / count);
+}
+
+template<xtd::forward_iterable source_t>
+requires std::same_as<typename xtd::raw_type<source_t>::value_type, xtd::optional<double>>
+auto xtd::linq::enumerable::average(source_t&& source) -> xtd::optional<double> {
+  auto average = .0;
+  auto count = 0;
+  for (auto item : source) {
+    if (!item) continue;
+    average += *item;
+    ++count;
+  }
+  return count == 0 ? xtd::nullopt : std::make_optional(average / count);
+}
+
+template<xtd::forward_iterable source_t>
+requires std::same_as<typename xtd::raw_type<source_t>::value_type, xtd::optional<xtd::single>>
+auto xtd::linq::enumerable::average(source_t&& source) -> xtd::optional<xtd::single> {
+  auto average = .0f;
+  auto count = 0;
+  for (auto item : source) {
+    if (!item) continue;
+    average += *item;
+    ++count;
+  }
+  return count == 0 ? xtd::nullopt : std::make_optional(average / count);
+}
+
+template<xtd::forward_iterable source_t>
+requires std::same_as<typename xtd::raw_type<source_t>::value_type, xtd::optional<xtd::int32>>
+auto xtd::linq::enumerable::average(source_t&& source) -> xtd::optional<double> {
+  auto average = .0;
+  auto count = 0;
+  for (auto item : source) {
+    if (!item) continue;
+    average += *item;
+    ++count;
+  }
+  return count == 0 ? xtd::nullopt : std::make_optional(average / count);
+}
+
+template<xtd::forward_iterable source_t>
+requires std::same_as<typename xtd::raw_type<source_t>::value_type, xtd::optional<xtd::int64>>
+auto xtd::linq::enumerable::average(source_t&& source) -> xtd::optional<double> {
+  auto average = .0;
+  auto count = 0;
+  for (auto item : source) {
+    if (!item) continue;
+    average += *item;
+    ++count;
+  }
+  return count == 0 ? xtd::nullopt : std::make_optional(average / count);
+}

src/xtd.core/include/xtd/linq/enumerable_.hpp

@@ -276,24 +276,34 @@ namespace xtd {
       /// @brief Computes the average of a sequence of optional xtd::decimal values.
       /// @param source A sequence of optional xtd::decimal values to calculate the average of.
       /// @return The average of the sequence of values, or xtd::nullopt if the source sequence is empty or contains only values that are xtd::nullopt.
-      [[nodiscard]] static auto average(const ienumerable<xtd::optional<xtd::decimal >>& source) noexcept -> xtd::optional<xtd::decimal>;
+      template<xtd::forward_iterable source_t>
+      requires std::same_as<typename xtd::raw_type<source_t>::value_type, xtd::optional<xtd::decimal>>
+      [[nodiscard]] static auto average(source_t&& source) -> xtd::optional<xtd::decimal>;
       /// @brief Computes the average of a sequence of optional double values.
       /// @param source A sequence of optional double values to calculate the average of.
       /// @return The average of the sequence of values, or xtd::nullopt if the source sequence is empty or contains only values that are xtd::nullopt.
-      [[nodiscard]] static auto average(const ienumerable<xtd::optional<double >>& source) noexcept -> xtd::optional<double>;
+      template<xtd::forward_iterable source_t>
+      requires std::same_as<typename xtd::raw_type<source_t>::value_type, xtd::optional<double>>
+      [[nodiscard]] static auto average(source_t&& source) -> xtd::optional<double>;
       /// @brief Computes the average of a sequence of optional float values.
       /// @param source A sequence of optional float values to calculate the average of.
       /// @return The average of the sequence of values, or xtd::nullopt if the source sequence is empty or contains only values that are xtd::nullopt.
-      [[nodiscard]] static auto average(const ienumerable<xtd::optional<float >>& source) noexcept -> xtd::optional<float>;
+      template<xtd::forward_iterable source_t>
+      requires std::same_as<typename xtd::raw_type<source_t>::value_type, xtd::optional<xtd::single>>
+      [[nodiscard]] static auto average(source_t&& source) -> xtd::optional<xtd::single>;
       /// @brief Computes the average of a sequence of optional xtd::int32 values.
       /// @param source A sequence of optional xtd::int32 values to calculate the average of.
       /// @return The average of the sequence of values, or xtd::nullopt if the source sequence is empty or contains only values that are xtd::nullopt.
-      [[nodiscard]] static auto average(const ienumerable<xtd::optional<xtd::int32 >>& source) noexcept -> xtd::optional<double>;
+      template<xtd::forward_iterable source_t>
+      requires std::same_as<typename xtd::raw_type<source_t>::value_type, xtd::optional<xtd::int32>>
+      [[nodiscard]] static auto average(source_t&& source) -> xtd::optional<double>;
       /// @brief Computes the average of a sequence of optional xtd::int64 values.
       /// @param source A sequence of optional xtd::int64 values to calculate the average of.
       /// @return The average of the sequence of values, or xtd::nullopt if the source sequence is empty or contains only values that are xtd::nullopt.
-      [[nodiscard]] static auto average(const ienumerable<xtd::optional<xtd::int64 >>& source) noexcept -> xtd::optional<double>;
-      
+      template<xtd::forward_iterable source_t>
+      requires std::same_as<typename xtd::raw_type<source_t>::value_type, xtd::optional<xtd::int64>>
+      [[nodiscard]] static auto average(source_t&& source) -> xtd::optional<double>;
+
       /// @brief Casts the elements of an xtd::collections::generic::ienumerable to the specified type.
       /// @tparam result_t The type of the resulting value.
       /// @tparam source_t The type of the elements of source.