From 67d26747cca6f8c563899857f820063221b77972 Mon Sep 17 00:00:00 2001
From: Susanne Pielawa <32822068+spielawa@users.noreply.github.com>
Date: Tue, 9 Jan 2018 17:54:53 +0100
Subject: [PATCH] Implement assignment operator for common::optional. (#800)

Implement assignment operator for common::optional.
---
 cartographer/common/optional.h       | 14 ++++++++++++++
 cartographer/common/optional_test.cc | 14 ++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/cartographer/common/optional.h b/cartographer/common/optional.h
index 1f6c8d9..58e0a92 100644
--- a/cartographer/common/optional.h
+++ b/cartographer/common/optional.h
@@ -45,6 +45,20 @@ class optional {
     return *value_;
   }
 
+  optional<T>& operator=(const T& other_value) {
+    this->value_ = common::make_unique<T>(other_value);
+    return *this;
+  }
+
+  optional<T>& operator=(const optional<T>& other) {
+    if (!other.has_value()) {
+      this->value_ = nullptr;
+    } else {
+      this->value_ = common::make_unique<T>(other.value());
+    }
+    return *this;
+  }
+
  private:
   std::unique_ptr<T> value_;
 };
diff --git a/cartographer/common/optional_test.cc b/cartographer/common/optional_test.cc
index f7dcc7c..fbf96c9 100644
--- a/cartographer/common/optional_test.cc
+++ b/cartographer/common/optional_test.cc
@@ -44,6 +44,20 @@ TEST(OptionalTest, CreateFromOtherOptional) {
   EXPECT_EQ(5, b.value());
 }
 
+TEST(OptionalTest, AssignmentOperator) {
+  optional<int> a(5);
+  optional<int> b(4);
+  optional<int> c;
+  a = b;
+  EXPECT_TRUE(a.has_value());
+  EXPECT_EQ(4, a.value());
+  a = c;
+  EXPECT_FALSE(a.has_value());
+  a = 3;
+  EXPECT_TRUE(a.has_value());
+  EXPECT_EQ(3, a.value());
+}
+
 }  // namespace
 }  // namespace common
 }  // namespace cartographer