app: preallocate layouts storage

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

diff --git a/src/result.hpp b/src/result.hpp
index fe9956b..b740a0c 100644 (file)
--- a/src/result.hpp
+++ b/src/result.hpp
@@ -6,33 +6,60 @@
 #define TMCAGLWM_RESULT_HPP
 
 #include <experimental/optional>
+#include <functional>
 
 namespace wm {
 
-    using std::experimental::optional;
-    using std::experimental::nullopt;
+using std::experimental::optional;
+using std::experimental::nullopt;
 
-    // We only ever return a string as an error - so just parametrize
-    // this over result type T
-    template<typename T>
-    struct result {
-        char const *e;
-        optional<T> t;
+// We only ever return a string as an error - so just parametrize
+// this over result type T
+template <typename T>
+struct result {
+   char const *e;
+   optional<T> t;
 
-        bool is_ok() const { return this->t != nullopt; }
-        bool is_err() const { return this->e != nullptr; }
+   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();
+   }
 
-        char const *unwrap_err() { return this->e; }
-    };
+   operator T() {
+      return this->unwrap();
+   }
 
-    template<typename T>
-    struct result<T> Err(char const *e) { return result<T>{e, nullopt}; }
+   char const *unwrap_err() { return this->e; }
 
-    template<typename T>
-    struct result<T> Ok(T t) { return result<T>{nullptr, t}; }
+   optional<T> ok() const { return this->t; }
+   optional<char const *> err() const { return optional<char const *>(this->e); }
 
-} // namespace wm
+   result<T> map_err(std::function<char const *(char const *)> f);
+};
 
-#endif //TMCAGLWM_RESULT_HPP
+template <typename T>
+struct result<T> Err(char const *e) {
+   return result<T>{e, nullopt};
+}
+
+template <typename T>
+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