+struct OptionalTest {
+ std::vector<int> Numbers;
+};
+
+struct OptionalTestSeq {
+ std::vector<OptionalTest> Tests;
+};
+
+LLVM_YAML_IS_SEQUENCE_VECTOR(OptionalTest);
+namespace llvm {
+namespace yaml {
+ template <>
+ struct MappingTraits<OptionalTest> {
+ static void mapping(IO& IO, OptionalTest &OT) {
+ IO.mapOptional("Numbers", OT.Numbers);
+ }
+ };
+
+ template <>
+ struct MappingTraits<OptionalTestSeq> {
+ static void mapping(IO &IO, OptionalTestSeq &OTS) {
+ IO.mapOptional("Tests", OTS.Tests);
+ }
+ };
+}
+}
+
+TEST(YAMLIO, SequenceElideTest) {
+ // Test that writing out a purely optional structure with its fields set to
+ // default followed by other data is properly read back in.
+ OptionalTestSeq Seq;
+ OptionalTest One, Two, Three, Four;
+ int N[] = {1, 2, 3};
+ Three.Numbers.assign(N, N + 3);
+ Seq.Tests.push_back(One);
+ Seq.Tests.push_back(Two);
+ Seq.Tests.push_back(Three);
+ Seq.Tests.push_back(Four);
+
+ std::string intermediate;
+ {
+ llvm::raw_string_ostream ostr(intermediate);
+ Output yout(ostr);
+ yout << Seq;
+ }
+
+ Input yin(intermediate);
+ OptionalTestSeq Seq2;
+ yin >> Seq2;
+
+ EXPECT_FALSE(yin.error());
+
+ EXPECT_EQ(4UL, Seq2.Tests.size());
+
+ EXPECT_TRUE(Seq2.Tests[0].Numbers.empty());
+ EXPECT_TRUE(Seq2.Tests[1].Numbers.empty());
+
+ EXPECT_EQ(1, Seq2.Tests[2].Numbers[0]);
+ EXPECT_EQ(2, Seq2.Tests[2].Numbers[1]);
+ EXPECT_EQ(3, Seq2.Tests[2].Numbers[2]);
+
+ EXPECT_TRUE(Seq2.Tests[3].Numbers.empty());
+}