Implement const version of Maybe<T&>::map().

d54b005b · Kenton Varda · bacdc241 · d54b005b
Commit d54b005b authored Nov 10, 2017 by Kenton Varda
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common.h c++/src/kj/common.h +10 -0

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--- a/c++/src/kj/common.h
+++ b/c++/src/kj/common.h
@@ -1222,6 +1222,16 @@ public:
    }
  }

+  template <typename Func>
+  auto map(Func&& f) const -> Maybe<decltype(f(instance<const T&>()))> {
+    if (ptr == nullptr) {
+      return nullptr;
+    } else {
+      const T& ref = *ptr;
+      return f(ref);
+    }
+  }
+
 private:
  T* ptr;