result: return nullopt if error is actuall nullptr

[staging/windowmanager.git] / src / result.hpp

diff --git a/src/result.hpp b/src/result.hpp
index e22fde9..5701f24 100644 (file)
--- a/src/result.hpp
+++ b/src/result.hpp
@@ -6,6 +6,7 @@
 #define TMCAGLWM_RESULT_HPP
 
 #include <experimental/optional>
+#include <functional>
 
 namespace wm {
 
@@ -29,11 +30,16 @@ struct result {
       return this->t.value();
    }
 
-   operator T() {
-      return this->unwrap();
-   }
+   operator T() { return this->unwrap(); }
 
    char const *unwrap_err() { return this->e; }
+
+   optional<T> const &ok() const { return this->t; }
+   optional<char const *> err() const {
+      return this->e ? optional<char const *>(this->e) : nullopt;
+   }
+
+   result<T> map_err(std::function<char const *(char const *)> f);
 };
 
 template <typename T>
@@ -46,6 +52,14 @@ struct result<T> Ok(T t) {
    return result<T>{nullptr, t};
 }
 
+template <typename T>
+result<T> result<T>::map_err(std::function<char const *(char const *)> f) {
+   if (this->is_err()) {
+      return Err<T>(f(this->e));
+   }
+   return *this;
+}
+
 }  // namespace wm
 
 #endif  // TMCAGLWM_RESULT_HPP