commit 189d18256ddd9e38987b0a52363eca3d110aae29
author Dominik Laskowski <domlaskowski@google.com> Fri May 03 17:30:26 2024 -0400
committer Dominik Laskowski <domlaskowski@google.com> Tue May 14 16:48:11 2024 -0400
tree a862feb0278b95a1ef0c54652e9cf8d3699fc4c1
parent a7873cc66b57db38e688d9d4e95883683110846f

FTL: Add Optional<T>::ok_or and FTL_TRY

Optional<T>::ok_or maps to Expected<T, E> where nullopt becomes E.

FTL_TRY unwraps T for Expected<T, E> or does an early out on error.

Bug: 185536303
Test: ftl_test
Change-Id: Ia03f7e3d8773878db1c493b62772ab2c2b7a4fed

libs/ftl/expected_test.cpp

diff --git a/libs/ftl/expected_test.cpp b/libs/ftl/expected_test.cpp
index 8cb07e4..9b7f017 100644
--- a/libs/ftl/expected_test.cpp
+++ b/libs/ftl/expected_test.cpp
@@ -15,8 +15,11 @@
  */
 
 #include <ftl/expected.h>
+#include <ftl/optional.h>
+#include <ftl/unit.h>
 #include <gtest/gtest.h>
 
+#include <cctype>
 #include <string>
 #include <system_error>
 
@@ -74,4 +77,42 @@
   }
 }
 
+namespace {
+
+IntExp increment(IntExp exp) {
+  const int i = FTL_TRY(exp);
+  return IntExp(i + 1);
+}
+
+StringExp repeat(StringExp exp) {
+  const std::string str = FTL_TRY(exp);
+  return StringExp(str + str);
+}
+
+void uppercase(char& c, ftl::Optional<char> opt) {
+  c = std::toupper(FTL_TRY(std::move(opt).ok_or(ftl::Unit())));
+}
+
+}  // namespace
+
+// Keep in sync with example usage in header file.
+TEST(Expected, Try) {
+  EXPECT_EQ(IntExp(100), increment(IntExp(99)));
+  EXPECT_TRUE(repeat(ftl::Unexpected(std::errc::value_too_large)).has_error([](std::errc e) {
+    return e == std::errc::value_too_large;
+  }));
+
+  EXPECT_EQ(StringExp("haha"s), repeat(StringExp("ha"s)));
+  EXPECT_TRUE(repeat(ftl::Unexpected(std::errc::bad_message)).has_error([](std::errc e) {
+    return e == std::errc::bad_message;
+  }));
+
+  char c = '?';
+  uppercase(c, std::nullopt);
+  EXPECT_EQ(c, '?');
+
+  uppercase(c, 'a');
+  EXPECT_EQ(c, 'A');
+}
+
 }  // namespace android::test