Generator core update

rt/include/typon/generator.hpp

@@ -13,11 +13,44 @@ namespace typon {
  * https://github.com/feabhas/coroutines-blog
  */
 template <typename T> class Generator {
-  class Promise {
+
+public:
+  using value_type = T;
+  class promise_type;
+
+  explicit Generator(std::coroutine_handle<promise_type> coroutine) noexcept
+      : _coroutine(coroutine) {}
+
+  Generator(const Generator &) = delete;
+  Generator &operator=(const Generator &) = delete;
+
+  Generator(Generator &&other) noexcept
+      : _coroutine(std::exchange(other._coroutine, nullptr)) {}
+
+  Generator &operator=(Generator other) {
+    std::swap(_coroutine, other._coroutine);
+    return *this;
+  }
+
+  ~Generator() {
+    if (_coroutine) {
+      _coroutine.destroy();
+    }
+  }
+
+  Task<Generator> async_self() {
+    co_return std::move(*this);
+  }
+
+  auto operator co_await() && noexcept {
+    return std::move(async_self().operator co_await());
+  }
+
+  class promise_type {
   public:
     using value_type = std::optional<T>;
 
-    Promise() = default;
+    promise_type() = default;
     std::suspend_always initial_suspend() { return {}; }
     std::suspend_always final_suspend() noexcept {
       final = true;
@@ -38,7 +71,10 @@ template <typename T> class Generator {
 
     void return_void() { this->value = std::nullopt; }
 
-    inline Generator get_return_object();
+    inline Generator<T> get_return_object() noexcept {
+      return Generator{
+          std::coroutine_handle<promise_type>::from_promise(*this)};
+    }
 
     value_type get_value() { return std::move(value); }
 
@@ -52,24 +88,12 @@ template <typename T> class Generator {
     bool final = false;
   };
 
-public:
-  using value_type = T;
-  using promise_type = Promise;
-
-  explicit Generator(std::coroutine_handle<Promise> handle) : handle(handle) {}
-
-  ~Generator() {
-    if (handle) {
-      handle.destroy();
-    }
-  }
-
-  Promise::value_type next() {
-    if (handle) {
-      if (!handle.promise().finished()) {
-        handle.resume();
+  promise_type::value_type next() {
+    if (_coroutine) {
+      if (!_coroutine.promise().finished()) {
+        _coroutine.resume();
       }
-      return handle.promise().get_value();
+      return _coroutine.promise().get_value();
     } else {
       return {};
     }
@@ -79,7 +103,7 @@ public:
 
   class iterator {
   public:
-    using value_type = Promise::value_type;
+    using value_type = promise_type::value_type;
     using difference_type = std::ptrdiff_t;
     using iterator_category = std::input_iterator_tag;
 
@@ -88,34 +112,34 @@ public:
 
     value_type operator*() const {
       if (generator) {
-        return generator->handle.promise().get_value();
+        return generator->_coroutine.promise().get_value();
       }
       return {};
     }
 
     value_type operator->() const {
       if (generator) {
-        return generator->handle.promise().get_value();
+        return generator->_coroutine.promise().get_value();
       }
       return {};
     }
 
     iterator &operator++() {
-      if (generator && generator->handle) {
-        generator->handle.resume();
+      if (generator && generator->_coroutine) {
+        generator->_coroutine.resume();
       }
       return *this;
     }
 
     iterator &operator++(int) {
-      if (generator && generator->handle) {
-        generator->handle.resume();
+      if (generator && generator->_coroutine) {
+        generator->_coroutine.resume();
       }
       return *this;
     }
 
     bool operator==(const end_iterator &) const {
-      return generator ? generator->handle.promise().finished() : true;
+      return !generator || generator->_coroutine.promise().finished();
     }
 
   private:
@@ -133,14 +157,9 @@ public:
 
 private:
   end_iterator end_sentinel{};
-  std::coroutine_handle<Promise> handle;
+  std::coroutine_handle<promise_type> _coroutine;
 };
 
-template <typename T>
-inline Generator<T> Generator<T>::Promise::get_return_object() {
-  return Generator{std::coroutine_handle<Promise>::from_promise(*this)};
-}
-
 } // namespace typon
 
 #endif // TYPON_GENERATOR_HPP