1 files changed, 98 insertions, 0 deletions
diff --git a/src/utils/scopeguard.hpp b/src/utils/scopeguard.hpp
new file mode 100644
index 0000000..e697fc3
--- /dev/null
+++ b/src/utils/scopeguard.hpp
@@ -0,0 +1,98 @@
+#pragma once
+
+#include <functional>
+#include <memory>
+#include <vector>
+
+/**
+ * A class to be used to make sure some functions are called when the scope
+ * is left, because they will be called in the ScopeGuard's destructor.  It
+ * can for example be used to delete some pointer whenever any exception is
+ * called.  Example:
+
+ * {
+ *  ScopeGuard scope;
+ *  int* number = new int(2);
+ *  scope.add_callback([number]() { delete number; });
+ *  // Do some other stuff with the number. But these stuff might throw an exception:
+ *  throw std::runtime_error("Some error not caught here, but in our caller");
+ *  return true;
+ * }
+
+ * In this example, our pointer will always be deleted, even when the
+ * exception is thrown.  If we want the functions to be called only when the
+ * scope is left because of an unexpected exception, we can use
+ * ScopeGuard::disable();
+ */
+
+namespace utils
+{
+
+class ScopeGuard
+{
+public:
+  /**
+   * The constructor can take a callback. But additional callbacks can be
+   * added later with add_callback()
+   */
+  explicit ScopeGuard(std::function<void()>&& func):
+    enabled(true)
+  {
+    this->add_callback(std::move(func));
+  }
+
+  ScopeGuard(const ScopeGuard&) = delete;
+  ScopeGuard& operator=(ScopeGuard&&) = delete;
+  ScopeGuard(ScopeGuard&&) = delete;
+  ScopeGuard& operator=(const ScopeGuard&) = delete;
+
+  /**
+   * default constructor, the scope guard is enabled but empty, use
+   * add_callback()
+   */
+  explicit ScopeGuard():
+    enabled(true)
+  {
+  }
+  /**
+   * Call all callbacks in the desctructor, unless it has been disabled.
+   */
+  ~ScopeGuard()
+  {
+    if (this->enabled)
+      for (auto& func: this->callbacks)
+        func();
+  }
+  /**
+   * Add a callback to be called in our destructor, one scope guard can be
+   * used for more than one task, if needed.
+   */
+  void add_callback(std::function<void()>&& func)
+  {
+    this->callbacks.emplace_back(std::move(func));
+  }
+  /**
+   * Disable that scope guard, nothing will be done when the scope is
+   * exited.
+   */
+  void disable()
+  {
+    this->enabled = false;
+  }
+
+private:
+  bool enabled;
+  std::vector<std::function<void()>> callbacks;
+
+};
+
+template<typename F>
+auto make_scope_guard(F f)
+{
+  static struct Empty {} empty;
+  auto deleter = [f = std::move(f)](Empty*) { f(); };
+  return std::unique_ptr<Empty, decltype(deleter)>{&empty, std::move(deleter)};
+}
+
+}
+