Added TaskMutex header.

source/mijin/async/task_mutex.hpp

@@ -0,0 +1,63 @@
+
+#pragma once
+
+#ifndef MIJIN_ASYNC_TASK_MUTEX_HPP_INCLUDED
+#define MIJIN_ASYNC_TASK_MUTEX_HPP_INCLUDED 1
+
+#include "./coroutine.hpp"
+
+namespace mijin
+{
+class [[nodiscard]] TaskMutexLock
+{
+private:
+    class TaskMutex* mutex_;
+
+public:
+    explicit TaskMutexLock(class TaskMutex* mutex) noexcept : mutex_(mutex) {}
+    TaskMutexLock(const TaskMutexLock&) = delete;
+    TaskMutexLock(TaskMutexLock&& other) noexcept : mutex_(std::exchange(other.mutex_, nullptr)) {}
+
+    TaskMutexLock& operator=(const TaskMutexLock&) = delete;
+    inline TaskMutexLock& operator=(TaskMutexLock&& other) noexcept;
+    inline ~TaskMutexLock() noexcept;
+};
+
+class TaskMutex
+{
+private:
+    bool locked_ = false;
+public:
+    Task<TaskMutexLock> c_lock()
+    {
+        while (locked_)
+        {
+            co_await c_suspend();
+        }
+        locked_ = true;
+        co_return TaskMutexLock(this);
+    }
+
+    friend class TaskMutexLock;
+};
+
+TaskMutexLock::~TaskMutexLock() noexcept
+{
+    if (mutex_)
+    {
+        mutex_->locked_ = false;
+    }
+}
+
+TaskMutexLock& TaskMutexLock::operator=(TaskMutexLock&& other) noexcept
+{
+    if (mutex_)
+    {
+        mutex_->locked_ = false;
+    }
+    mutex_ = std::exchange(other.mutex_, nullptr);
+    return *this;
+}
+}
+
+#endif // MIJIN_ASYNC_TASK_MUTEX_HPP_INCLUDED