2983: Add stream operators for result types

HarrievG · Jul 14, 2020 · 01445c2 · 01445c2
1 parent a8a9511
commit 01445c2
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diff --git a/lib/kdl/include/kdl/result.h b/lib/kdl/include/kdl/result.h
@@ -22,6 +22,7 @@
 #include "kdl/result_forward.h"
 
 #include <functional> // for std::ref
+#include <iosfwd> // users must include <ostream> to use stream operators
 #include <optional>
 #include <variant>
 
@@ -238,6 +239,11 @@ namespace kdl {
         friend bool operator!=(const result& lhs, const result& rhs) {
             return !(lhs == rhs);
         }
+
+        friend std::ostream& operator<<(std::ostream& str, const result& result_) {
+            std::visit([&](const auto& v){ str << v; }, result_.m_value);
+            return str;
+        }
     };
 
     /**
@@ -444,6 +450,11 @@ namespace kdl {
         friend bool operator!=(const result& lhs, const result& rhs) {
             return !(lhs == rhs);
         }
+
+        friend std::ostream& operator<<(std::ostream& str, const result& result_) {
+            std::visit([&](const auto& v){ str << v; }, result_.m_value);
+            return str;
+        }
     };
 
     /**
@@ -631,6 +642,13 @@ namespace kdl {
         friend bool operator!=(const result& lhs, const result& rhs) {
             return !(lhs == rhs);
         }
+
+        friend std::ostream& operator<<(std::ostream& str, const result& result_) {
+            if (result_.m_error.has_value()) {
+                std::visit([&](const auto& v){ str << v; }, result_.m_error.value());
+            }
+            return str;
+        }
     };
 
     /**
@@ -821,6 +839,13 @@ namespace kdl {
         friend bool operator!=(const result& lhs, const result& rhs) {
             return !(lhs == rhs);
         }
+
+        friend std::ostream& operator<<(std::ostream& str, const result& result_) {
+            if (result_.m_value.has_value()) {
+                std::visit([&](const auto& v){ str << v; }, result_.m_value.value());
+            }
+            return str;
+        }
     };
 
 

diff --git a/lib/kdl/test/src/result_test.cpp b/lib/kdl/test/src/result_test.cpp
@@ -22,6 +22,7 @@
 #include "kdl/overload.h"
 #include "kdl/result.h"
 
+#include <iostream>
 #include <string>
 
 namespace kdl {
@@ -36,6 +37,16 @@ namespace kdl {
         return true;
     }
 
+    inline std::ostream& operator<<(std::ostream& str, const Error1&) {
+        str << "Error1";
+        return str;
+    }
+
+    inline std::ostream& operator<<(std::ostream& str, const Error2&) {
+        str << "Error2";
+        return str;
+    }
+
     struct Counter {
         std::size_t copies = 0u;
         std::size_t moves = 0u;
@@ -62,6 +73,11 @@ namespace kdl {
             return *this;
         }
     };
+
+    inline std::ostream& operator<<(std::ostream& str, const Counter&) {
+        str << "Counter";
+        return str;
+    }
 
     /**
      * Tests construction of a successful result.