labm8/cpp: Add a Status.RaiseException() method.

This converts the error code into my best guess at the most
appropriate C++ exception class, and raises it. If status.ok(), no
error is raised.

Signed-off-by: format 2020.01.16 <github.com/ChrisCummins/format>

labm8/cpp/status.h

@@ -33,6 +33,7 @@
 #include "labm8/cpp/stringpiece.h"
 
 #include <iosfwd>
+#include <stdexcept>
 #include <string>
 
 namespace labm8 {
@@ -91,6 +92,35 @@ class Status {
   // Return a combination of the error code name and message.
   string ToString() const;
 
+  // Raise an error if !this->ok().
+  void RaiseException() const {
+    if (!ok()) {
+      switch (error_code()) {
+        case error::Code::CANCELLED:
+        case error::Code::UNKNOWN:
+        case error::Code::DEADLINE_EXCEEDED:
+        case error::Code::NOT_FOUND:
+        case error::Code::ALREADY_EXISTS:
+        case error::Code::PERMISSION_DENIED:
+        case error::Code::UNAUTHENTICATED:
+        case error::Code::RESOURCE_EXHAUSTED:
+        case error::Code::ABORTED:
+        case error::Code::INTERNAL:
+        case error::Code::UNAVAILABLE:
+        case error::Code::DATA_LOSS:
+          throw std::runtime_error(error_message());
+        case error::Code::INVALID_ARGUMENT:
+        case error::Code::FAILED_PRECONDITION:
+          throw std::invalid_argument(error_message());
+        case error::Code::OUT_OF_RANGE:
+          throw std::out_of_range(error_message());
+        case error::Code::UNIMPLEMENTED:
+        case error::Code::OK:
+          throw std::logic_error(error_message());
+      }
+    }
+  }
+
  private:
   error::Code error_code_;
   std::string error_message_;

labm8/cpp/statusor.h

@@ -152,7 +152,6 @@ class StatusOr {
 
   // Returns a reference to our current value, or raises an exception
   // if !this->ok().
-  template <typename Error = std::runtime_error>
   const T &ValueOrException() const;
 
  private:
@@ -253,11 +252,8 @@ inline const T &StatusOr<T>::ValueOrDie() const {
 }
 
 template <typename T>
-template <typename Error>
 inline const T &StatusOr<T>::ValueOrException() const {
-  if (!status_.ok()) {
-    throw Error(status_.ToString());
-  }
+  status_.RaiseException();
   return value_;
 }