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 377d5a2..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 {
 
@@ -22,9 +23,23 @@ struct result {
    bool is_ok() const { return this->t != nullopt; }
    bool is_err() const { return this->e != nullptr; }
 
-   T unwrap() { return this->t.value(); }
+   T unwrap() {
+      if (this->e != nullptr) {
+         throw std::logic_error(this->e);
+      }
+      return this->t.value();
+   }
+
+   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>
@@ -37,6 +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