From 8c89c7ddb2690e391521420253724a4ab1fb237b Mon Sep 17 00:00:00 2001
From: Mike Curtiss <mcurtiss@fb.com>
Date: Wed, 27 Feb 2013 19:53:14 -0800
Subject: [PATCH] folly::make_optional
Summary:
Helper method for creating a folly::Optional<T> by just passing
in a T reference. Analogous to boost::make_optional.
Test Plan: Added test case
Reviewed By: tjackson@fb.com
FB internal diff: D721762
---
folly/Optional.h | 8 +++++++-
folly/test/OptionalTest.cpp | 37 ++++++++++++++++++++++++++++++++++++-
2 files changed, 43 insertions(+), 2 deletions(-)
diff --git a/folly/Optional.h b/folly/Optional.h
index 5b574f5b..b168b59a 100644
--- a/folly/Optional.h
+++ b/folly/Optional.h
@@ -268,6 +268,12 @@ void swap(Optional<T>& a, Optional<T>& b) {
}
}
-}// namespace folly
+template<class T,
+ class Opt = Optional<typename std::decay<T>::type>>
+Opt make_optional(T&& v) {
+ return Opt(std::forward<T>(v));
+}
+
+} // namespace folly
#endif//FOLLY_OPTIONAL_H_
diff --git a/folly/test/OptionalTest.cpp b/folly/test/OptionalTest.cpp
index 0e240a01..4eb56417 100644
--- a/folly/test/OptionalTest.cpp
+++ b/folly/test/OptionalTest.cpp
@@ -1,5 +1,5 @@
/*
- * Copyright 2012 Facebook, Inc.
+ * Copyright 2013 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -274,3 +274,38 @@ TEST(Optional, Pointee) {
x = none;
EXPECT_FALSE(get_pointer(x));
}
+
+TEST(Optional, MakeOptional) {
+ // const L-value version
+ const std::string s("abc");
+ auto optStr = make_optional(s);
+ ASSERT_TRUE(optStr.hasValue());
+ EXPECT_EQ(*optStr, "abc");
+ *optStr = "cde";
+ EXPECT_EQ(s, "abc");
+ EXPECT_EQ(*optStr, "cde");
+
+ // L-value version
+ std::string s2("abc");
+ auto optStr2 = make_optional(s2);
+ ASSERT_TRUE(optStr2.hasValue());
+ EXPECT_EQ(*optStr2, "abc");
+ *optStr2 = "cde";
+ // it's vital to check that s2 wasn't clobbered
+ EXPECT_EQ(s2, "abc");
+
+ // L-value reference version
+ std::string& s3(s2);
+ auto optStr3 = make_optional(s3);
+ ASSERT_TRUE(optStr3.hasValue());
+ EXPECT_EQ(*optStr3, "abc");
+ *optStr3 = "cde";
+ EXPECT_EQ(s3, "abc");
+
+ // R-value ref version
+ unique_ptr<int> pInt(new int(3));
+ auto optIntPtr = make_optional(std::move(pInt));
+ EXPECT_TRUE(pInt.get() == nullptr);
+ ASSERT_TRUE(optIntPtr.hasValue());
+ EXPECT_EQ(**optIntPtr, 3);
+}
--
2.34.1