feat update

include/sled/exec/just.h

@@ -0,0 +1,68 @@
+#pragma once
+#ifndef SLED_EXEC_JUST_H
+#define SLED_EXEC_JUST_H
+
+#include <iostream>
+#include <utility>
+
+namespace sled {
+
+struct immovable {
+    immovable() = default;
+    immovable(immovable &&) = delete;
+};
+
+template<typename S, typename R>
+using connect_result_t = decltype(connect(std::declval<S>(), std::declval<R>()));
+
+template<typename T>
+using sender_result_t = typename T::result_t;
+
+template<typename R, typename T>
+struct just_operation : immovable {
+    R receiver;
+    T value;
+
+    friend void start(just_operation &self) { set_value(self.receiver, self.value); }
+};
+
+template<typename T>
+struct just_sender {
+    using result_t = T;
+    T value;
+
+    template<typename R>
+    just_operation<R, T> connect(R receiver)
+    {
+        return {{}, receiver, this->value};
+    }
+};
+
+template<typename T>
+just_sender<T>
+just(T t)
+{
+    return {t};
+}
+
+struct cout_receiver {
+    template<typename T>
+    friend void set_value(cout_receiver self, T &&val)
+    {
+        std::cout << "Result: " << val << std::endl;
+    }
+
+    friend void set_error(cout_receiver self, std::exception_ptr e)
+    {
+        try {
+            std::rethrow_exception(e);
+        } catch (const std::exception &e) {
+            std::cout << "Error: " << e.what() << std::endl;
+        }
+    }
+
+    friend void set_stopped(cout_receiver self) { std::cout << "Stopped" << std::endl; }
+};
+
+}// namespace sled
+#endif// SLED_EXEC_JUST_H