X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=unittests%2FSupport%2FYAMLIOTest.cpp;h=e7affa1698dcc7989ca59bdf23549f9164fac76d;hb=21577c0682a8c0a3073cf970eeb3fd8dde2bcb21;hp=ffabbcfe055d1bd452946fef9f573f6a5791d221;hpb=08e66be96d6b019e574d7d0801d198cd9c584f21;p=oota-llvm.git

diff --git a/unittests/Support/YAMLIOTest.cpp b/unittests/Support/YAMLIOTest.cpp
index ffabbcfe055..e7affa1698d 100644
--- a/unittests/Support/YAMLIOTest.cpp
+++ b/unittests/Support/YAMLIOTest.cpp
@@ -46,6 +46,9 @@ typedef std::vector<FooBar> FooBarSequence;
 
 LLVM_YAML_IS_SEQUENCE_VECTOR(FooBar)
 
+struct FooBarContainer {
+  FooBarSequence fbs;
+};
 
 namespace llvm {
 namespace yaml {
@@ -56,6 +59,12 @@ namespace yaml {
       io.mapRequired("bar",    fb.bar);
     }
   };
+
+  template <> struct MappingTraits<FooBarContainer> {
+    static void mapping(IO &io, FooBarContainer &fb) {
+      io.mapRequired("fbs", fb.fbs);
+    }
+  };
 }
 }
 
@@ -84,6 +93,13 @@ TEST(YAMLIO, TestMapRead) {
   }
 }
 
+TEST(YAMLIO, TestMalformedMapRead) {
+  FooBar doc;
+  Input yin("{foo: 3; bar: 5}", nullptr, suppressErrorMessages);
+  yin >> doc;
+  EXPECT_TRUE(!!yin.error());
+}
+
 //
 // Test the reading of a yaml sequence of mappings
 //
@@ -102,6 +118,83 @@ TEST(YAMLIO, TestSequenceMapRead) {
   EXPECT_EQ(map2.bar, 9);
 }
 
+//
+// Test the reading of a map containing a yaml sequence of mappings
+//
+TEST(YAMLIO, TestContainerSequenceMapRead) {
+  {
+    FooBarContainer cont;
+    Input yin2("---\nfbs:\n - foo: 3\n   bar: 5\n - foo: 7\n   bar: 9\n...\n");
+    yin2 >> cont;
+
+    EXPECT_FALSE(yin2.error());
+    EXPECT_EQ(cont.fbs.size(), 2UL);
+    EXPECT_EQ(cont.fbs[0].foo, 3);
+    EXPECT_EQ(cont.fbs[0].bar, 5);
+    EXPECT_EQ(cont.fbs[1].foo, 7);
+    EXPECT_EQ(cont.fbs[1].bar, 9);
+  }
+
+  {
+    FooBarContainer cont;
+    Input yin("---\nfbs:\n...\n");
+    yin >> cont;
+    // Okay: Empty node represents an empty array.
+    EXPECT_FALSE(yin.error());
+    EXPECT_EQ(cont.fbs.size(), 0UL);
+  }
+
+  {
+    FooBarContainer cont;
+    Input yin("---\nfbs: !!null null\n...\n");
+    yin >> cont;
+    // Okay: null represents an empty array.
+    EXPECT_FALSE(yin.error());
+    EXPECT_EQ(cont.fbs.size(), 0UL);
+  }
+
+  {
+    FooBarContainer cont;
+    Input yin("---\nfbs: ~\n...\n");
+    yin >> cont;
+    // Okay: null represents an empty array.
+    EXPECT_FALSE(yin.error());
+    EXPECT_EQ(cont.fbs.size(), 0UL);
+  }
+
+  {
+    FooBarContainer cont;
+    Input yin("---\nfbs: null\n...\n");
+    yin >> cont;
+    // Okay: null represents an empty array.
+    EXPECT_FALSE(yin.error());
+    EXPECT_EQ(cont.fbs.size(), 0UL);
+  }
+}
+
+//
+// Test the reading of a map containing a malformed yaml sequence
+//
+TEST(YAMLIO, TestMalformedContainerSequenceMapRead) {
+  {
+    FooBarContainer cont;
+    Input yin("---\nfbs:\n   foo: 3\n   bar: 5\n...\n", nullptr,
+              suppressErrorMessages);
+    yin >> cont;
+    // Error: fbs is not a sequence.
+    EXPECT_TRUE(!!yin.error());
+    EXPECT_EQ(cont.fbs.size(), 0UL);
+  }
+
+  {
+    FooBarContainer cont;
+    Input yin("---\nfbs: 'scalar'\n...\n", nullptr, suppressErrorMessages);
+    yin >> cont;
+    // This should be an error.
+    EXPECT_TRUE(!!yin.error());
+    EXPECT_EQ(cont.fbs.size(), 0UL);
+  }
+}
 
 //
 // Test writing then reading back a sequence of mappings
@@ -686,6 +779,146 @@ TEST(YAMLIO, TestReadWriteMyCustomType) {
 }
 
 
+//===----------------------------------------------------------------------===//
+//  Test BlockScalarTraits
+//===----------------------------------------------------------------------===//
+
+struct MultilineStringType {
+  std::string str;
+};
+
+struct MultilineStringTypeMap {
+  MultilineStringType name;
+  MultilineStringType description;
+  MultilineStringType ingredients;
+  MultilineStringType recipes;
+  MultilineStringType warningLabels;
+  MultilineStringType documentation;
+  int price;
+};
+
+namespace llvm {
+namespace yaml {
+  template <>
+  struct MappingTraits<MultilineStringTypeMap> {
+    static void mapping(IO &io, MultilineStringTypeMap& s) {
+      io.mapRequired("name", s.name);
+      io.mapRequired("description", s.description);
+      io.mapRequired("ingredients", s.ingredients);
+      io.mapRequired("recipes", s.recipes);
+      io.mapRequired("warningLabels", s.warningLabels);
+      io.mapRequired("documentation", s.documentation);
+      io.mapRequired("price", s.price);
+     }
+  };
+
+  // MultilineStringType is formatted as a yaml block literal scalar. A value of
+  // "Hello\nWorld" would be represented in yaml as
+  //  |
+  //    Hello
+  //    World
+  template <>
+  struct BlockScalarTraits<MultilineStringType> {
+    static void output(const MultilineStringType &value, void *ctxt,
+                       llvm::raw_ostream &out) {
+      out << value.str;
+    }
+    static StringRef input(StringRef scalar, void *ctxt,
+                           MultilineStringType &value) {
+      value.str = scalar.str();
+      return StringRef();
+    }
+  };
+}
+}
+
+LLVM_YAML_IS_DOCUMENT_LIST_VECTOR(MultilineStringType)
+
+//
+// Test writing then reading back custom values
+//
+TEST(YAMLIO, TestReadWriteMultilineStringType) {
+  std::string intermediate;
+  {
+    MultilineStringTypeMap map;
+    map.name.str = "An Item";
+    map.description.str = "Hello\nWorld";
+    map.ingredients.str = "SubItem 1\nSub Item 2\n\nSub Item 3\n";
+    map.recipes.str = "\n\nTest 1\n\n\n";
+    map.warningLabels.str = "";
+    map.documentation.str = "\n\n";
+    map.price = 350;
+
+    llvm::raw_string_ostream ostr(intermediate);
+    Output yout(ostr);
+    yout << map;
+  }
+  {
+    Input yin(intermediate);
+    MultilineStringTypeMap map2;
+    yin >> map2;
+
+    EXPECT_FALSE(yin.error());
+    EXPECT_EQ(map2.name.str, "An Item\n");
+    EXPECT_EQ(map2.description.str, "Hello\nWorld\n");
+    EXPECT_EQ(map2.ingredients.str, "SubItem 1\nSub Item 2\n\nSub Item 3\n");
+    EXPECT_EQ(map2.recipes.str, "\n\nTest 1\n");
+    EXPECT_TRUE(map2.warningLabels.str.empty());
+    EXPECT_TRUE(map2.documentation.str.empty());
+    EXPECT_EQ(map2.price, 350);
+  }
+}
+
+//
+// Test writing then reading back custom values
+//
+TEST(YAMLIO, TestReadWriteBlockScalarDocuments) {
+  std::string intermediate;
+  {
+    std::vector<MultilineStringType> documents;
+    MultilineStringType doc;
+    doc.str = "Hello\nWorld";
+    documents.push_back(doc);
+
+    llvm::raw_string_ostream ostr(intermediate);
+    Output yout(ostr);
+    yout << documents;
+
+    // Verify that the block scalar header was written out on the same line
+    // as the document marker.
+    EXPECT_NE(llvm::StringRef::npos, llvm::StringRef(ostr.str()).find("--- |"));
+  }
+  {
+    Input yin(intermediate);
+    std::vector<MultilineStringType> documents2;
+    yin >> documents2;
+
+    EXPECT_FALSE(yin.error());
+    EXPECT_EQ(documents2.size(), size_t(1));
+    EXPECT_EQ(documents2[0].str, "Hello\nWorld\n");
+  }
+}
+
+TEST(YAMLIO, TestReadWriteBlockScalarValue) {
+  std::string intermediate;
+  {
+    MultilineStringType doc;
+    doc.str = "Just a block\nscalar doc";
+
+    llvm::raw_string_ostream ostr(intermediate);
+    Output yout(ostr);
+    yout << doc;
+  }
+  {
+    Input yin(intermediate);
+    MultilineStringType doc;
+    yin >> doc;
+
+    EXPECT_FALSE(yin.error());
+    EXPECT_EQ(doc.str, "Just a block\nscalar doc\n");
+  }
+}
+
 //===----------------------------------------------------------------------===//
 //  Test flow sequences
 //===----------------------------------------------------------------------===//
@@ -736,6 +969,26 @@ namespace yaml {
 }
 }
 
+typedef std::vector<MyNumber> MyNumberFlowSequence;
+
+LLVM_YAML_IS_SEQUENCE_VECTOR(MyNumberFlowSequence)
+
+struct NameAndNumbersFlow {
+  llvm::StringRef                    name;
+  std::vector<MyNumberFlowSequence>  sequenceOfNumbers;
+};
+
+namespace llvm {
+namespace yaml {
+  template <>
+  struct MappingTraits<NameAndNumbersFlow> {
+    static void mapping(IO &io, NameAndNumbersFlow& nn) {
+      io.mapRequired("name",     nn.name);
+      io.mapRequired("sequenceOfNumbers",  nn.sequenceOfNumbers);
+    }
+  };
+}
+}
 
 //
 // Test writing then reading back custom values
@@ -783,6 +1036,51 @@ TEST(YAMLIO, TestReadWriteMyFlowSequence) {
 }
 
 
+//
+// Test writing then reading back a sequence of flow sequences.
+//
+TEST(YAMLIO, TestReadWriteSequenceOfMyFlowSequence) {
+  std::string intermediate;
+  {
+    NameAndNumbersFlow map;
+    map.name  = "hello";
+    MyNumberFlowSequence single = { 0 };
+    MyNumberFlowSequence numbers = { 12, 1, -512 };
+    map.sequenceOfNumbers.push_back(single);
+    map.sequenceOfNumbers.push_back(numbers);
+    map.sequenceOfNumbers.push_back(MyNumberFlowSequence());
+
+    llvm::raw_string_ostream ostr(intermediate);
+    Output yout(ostr);
+    yout << map;
+
+    // Verify sequences were written in flow style
+    // and that the parent sequence used '-'.
+    ostr.flush();
+    llvm::StringRef flowOut(intermediate);
+    EXPECT_NE(llvm::StringRef::npos, flowOut.find("- [ 0 ]"));
+    EXPECT_NE(llvm::StringRef::npos, flowOut.find("- [ 12, 1, -512 ]"));
+    EXPECT_NE(llvm::StringRef::npos, flowOut.find("- [  ]"));
+  }
+
+  {
+    Input yin(intermediate);
+    NameAndNumbersFlow map2;
+    yin >> map2;
+
+    EXPECT_FALSE(yin.error());
+    EXPECT_TRUE(map2.name.equals("hello"));
+    EXPECT_EQ(map2.sequenceOfNumbers.size(), 3UL);
+    EXPECT_EQ(map2.sequenceOfNumbers[0].size(), 1UL);
+    EXPECT_EQ(0,    map2.sequenceOfNumbers[0][0]);
+    EXPECT_EQ(map2.sequenceOfNumbers[1].size(), 3UL);
+    EXPECT_EQ(12,   map2.sequenceOfNumbers[1][0]);
+    EXPECT_EQ(1,    map2.sequenceOfNumbers[1][1]);
+    EXPECT_EQ(-512, map2.sequenceOfNumbers[1][2]);
+    EXPECT_TRUE(map2.sequenceOfNumbers[2].empty());
+  }
+}
+
 //===----------------------------------------------------------------------===//
 //  Test normalizing/denormalizing
 //===----------------------------------------------------------------------===//
@@ -1204,11 +1502,96 @@ TEST(YAMLIO, TestValidatingInput) {
   std::vector<MyValidation> docList;
   Input yin("--- \nvalue:  3.0\n"
             "--- \nvalue:  -1.0\n...\n",
-            NULL, suppressErrorMessages);
+            nullptr, suppressErrorMessages);
   yin >> docList;
   EXPECT_TRUE(!!yin.error());
 }
 
+//===----------------------------------------------------------------------===//
+//  Test flow mapping
+//===----------------------------------------------------------------------===//
+
+struct FlowFooBar {
+  int foo;
+  int bar;
+
+  FlowFooBar() : foo(0), bar(0) {}
+  FlowFooBar(int foo, int bar) : foo(foo), bar(bar) {}
+};
+
+typedef std::vector<FlowFooBar> FlowFooBarSequence;
+
+LLVM_YAML_IS_SEQUENCE_VECTOR(FlowFooBar)
+
+struct FlowFooBarDoc {
+  FlowFooBar attribute;
+  FlowFooBarSequence seq;
+};
+
+namespace llvm {
+namespace yaml {
+  template <>
+  struct MappingTraits<FlowFooBar> {
+    static void mapping(IO &io, FlowFooBar &fb) {
+      io.mapRequired("foo", fb.foo);
+      io.mapRequired("bar", fb.bar);
+    }
+
+    static const bool flow = true;
+  };
+
+  template <>
+  struct MappingTraits<FlowFooBarDoc> {
+    static void mapping(IO &io, FlowFooBarDoc &fb) {
+      io.mapRequired("attribute", fb.attribute);
+      io.mapRequired("seq", fb.seq);
+    }
+  };
+}
+}
+
+//
+// Test writing then reading back custom mappings
+//
+TEST(YAMLIO, TestReadWriteMyFlowMapping) {
+  std::string intermediate;
+  {
+    FlowFooBarDoc doc;
+    doc.attribute = FlowFooBar(42, 907);
+    doc.seq.push_back(FlowFooBar(1, 2));
+    doc.seq.push_back(FlowFooBar(0, 0));
+    doc.seq.push_back(FlowFooBar(-1, 1024));
+
+    llvm::raw_string_ostream ostr(intermediate);
+    Output yout(ostr);
+    yout << doc;
+
+    // Verify that mappings were written in flow style
+    ostr.flush();
+    llvm::StringRef flowOut(intermediate);
+    EXPECT_NE(llvm::StringRef::npos, flowOut.find("{ foo: 42, bar: 907 }"));
+    EXPECT_NE(llvm::StringRef::npos, flowOut.find("- { foo: 1, bar: 2 }"));
+    EXPECT_NE(llvm::StringRef::npos, flowOut.find("- { foo: 0, bar: 0 }"));
+    EXPECT_NE(llvm::StringRef::npos, flowOut.find("- { foo: -1, bar: 1024 }"));
+  }
+
+  {
+    Input yin(intermediate);
+    FlowFooBarDoc doc2;
+    yin >> doc2;
+
+    EXPECT_FALSE(yin.error());
+    EXPECT_EQ(doc2.attribute.foo, 42);
+    EXPECT_EQ(doc2.attribute.bar, 907);
+    EXPECT_EQ(doc2.seq.size(), 3UL);
+    EXPECT_EQ(doc2.seq[0].foo, 1);
+    EXPECT_EQ(doc2.seq[0].bar, 2);
+    EXPECT_EQ(doc2.seq[1].foo, 0);
+    EXPECT_EQ(doc2.seq[1].bar, 0);
+    EXPECT_EQ(doc2.seq[2].foo, -1);
+    EXPECT_EQ(doc2.seq[2].bar, 1024);
+  }
+}
 
 //===----------------------------------------------------------------------===//
 //  Test error handling
@@ -1224,7 +1607,7 @@ TEST(YAMLIO, TestColorsReadError) {
             "c2:  purple\n"
             "c3:  green\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> map;
   EXPECT_TRUE(!!yin.error());
@@ -1241,7 +1624,7 @@ TEST(YAMLIO, TestFlagsReadError) {
             "f2:  [ round, hollow ]\n"
             "f3:  []\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> map;
 
@@ -1260,7 +1643,7 @@ TEST(YAMLIO, TestReadBuiltInTypesUint8Error) {
             "- 0\n"
             "- 257\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1279,7 +1662,7 @@ TEST(YAMLIO, TestReadBuiltInTypesUint16Error) {
             "- 0\n"
             "- 66000\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1298,7 +1681,7 @@ TEST(YAMLIO, TestReadBuiltInTypesUint32Error) {
             "- 0\n"
             "- 5000000000\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1317,7 +1700,7 @@ TEST(YAMLIO, TestReadBuiltInTypesUint64Error) {
             "- 0\n"
             "- 19446744073709551615\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1337,7 +1720,7 @@ TEST(YAMLIO, TestReadBuiltInTypesint8OverError) {
             "- 127\n"
             "- 128\n"
            "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1355,7 +1738,7 @@ TEST(YAMLIO, TestReadBuiltInTypesint8UnderError) {
             "- 127\n"
             "- -129\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1375,7 +1758,7 @@ TEST(YAMLIO, TestReadBuiltInTypesint16UnderError) {
             "- -32768\n"
             "- -32769\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1394,7 +1777,7 @@ TEST(YAMLIO, TestReadBuiltInTypesint16OverError) {
             "- -32768\n"
             "- 32768\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1414,7 +1797,7 @@ TEST(YAMLIO, TestReadBuiltInTypesint32UnderError) {
             "- -2147483648\n"
             "- -2147483649\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1432,7 +1815,7 @@ TEST(YAMLIO, TestReadBuiltInTypesint32OverError) {
             "- -2147483648\n"
             "- 2147483649\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1452,7 +1835,7 @@ TEST(YAMLIO, TestReadBuiltInTypesint64UnderError) {
             "- 9223372036854775807\n"
             "- -9223372036854775809\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1470,7 +1853,7 @@ TEST(YAMLIO, TestReadBuiltInTypesint64OverError) {
             "- 9223372036854775807\n"
             "- 9223372036854775809\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1489,7 +1872,7 @@ TEST(YAMLIO, TestReadBuiltInTypesFloatError) {
             "- -123.456\n"
             "- 1.2.3\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1508,7 +1891,7 @@ TEST(YAMLIO, TestReadBuiltInTypesDoubleError) {
             "- -123.456\n"
             "- 1.2.3\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1526,7 +1909,7 @@ TEST(YAMLIO, TestReadBuiltInTypesHex8Error) {
             "- 0xFE\n"
             "- 0x123\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1545,7 +1928,7 @@ TEST(YAMLIO, TestReadBuiltInTypesHex16Error) {
             "- 0xFEFF\n"
             "- 0x12345\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1563,7 +1946,7 @@ TEST(YAMLIO, TestReadBuiltInTypesHex32Error) {
             "- 0xFEFF0000\n"
             "- 0x1234556789\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1581,7 +1964,7 @@ TEST(YAMLIO, TestReadBuiltInTypesHex64Error) {
             "- 0xFFEEDDCCBBAA9988\n"
             "- 0x12345567890ABCDEF0\n"
             "...\n",
-            /*Ctxt=*/NULL,
+            /*Ctxt=*/nullptr,
             suppressErrorMessages);
   yin >> seq;
 
@@ -1593,13 +1976,13 @@ TEST(YAMLIO, TestMalformedMapFailsGracefully) {
   {
     // We pass the suppressErrorMessages handler to handle the error
     // message generated in the constructor of Input.
-    Input yin("{foo:3, bar: 5}", /*Ctxt=*/NULL, suppressErrorMessages);
+    Input yin("{foo:3, bar: 5}", /*Ctxt=*/nullptr, suppressErrorMessages);
     yin >> doc;
     EXPECT_TRUE(!!yin.error());
   }
 
   {
-    Input yin("---\nfoo:3\nbar: 5\n...\n", /*Ctxt=*/NULL, suppressErrorMessages);
+    Input yin("---\nfoo:3\nbar: 5\n...\n", /*Ctxt=*/nullptr, suppressErrorMessages);
     yin >> doc;
     EXPECT_TRUE(!!yin.error());
   }
@@ -1685,9 +2068,129 @@ TEST(YAMLIO, TestEmptyStringSucceedsForMapWithOptionalFields) {
 
 TEST(YAMLIO, TestEmptyStringSucceedsForSequence) {
   std::vector<uint8_t> seq;
-  Input yin("", /*Ctxt=*/NULL, suppressErrorMessages);
+  Input yin("", /*Ctxt=*/nullptr, suppressErrorMessages);
   yin >> seq;
 
   EXPECT_FALSE(yin.error());
   EXPECT_TRUE(seq.empty());
 }
+
+struct FlowMap {
+  llvm::StringRef str1, str2, str3;
+  FlowMap(llvm::StringRef str1, llvm::StringRef str2, llvm::StringRef str3)
+    : str1(str1), str2(str2), str3(str3) {}
+};
+
+struct FlowSeq {
+  llvm::StringRef str;
+  FlowSeq(llvm::StringRef S) : str(S) {}
+  FlowSeq() = default;
+};
+
+namespace llvm {
+namespace yaml {
+  template <>
+  struct MappingTraits<FlowMap> {
+    static void mapping(IO &io, FlowMap &fm) {
+      io.mapRequired("str1", fm.str1);
+      io.mapRequired("str2", fm.str2);
+      io.mapRequired("str3", fm.str3);
+    }
+
+    static const bool flow = true;
+  };
+
+template <>
+struct ScalarTraits<FlowSeq> {
+  static void output(const FlowSeq &value, void*, llvm::raw_ostream &out) {
+    out << value.str;
+  }
+  static StringRef input(StringRef scalar, void*, FlowSeq &value) {
+    value.str = scalar;
+    return "";
+  }
+
+  static bool mustQuote(StringRef S) { return false; }
+};
+}
+}
+
+LLVM_YAML_IS_FLOW_SEQUENCE_VECTOR(FlowSeq)
+
+TEST(YAMLIO, TestWrapFlow) {
+  std::string out;
+  llvm::raw_string_ostream ostr(out);
+  FlowMap Map("This is str1", "This is str2", "This is str3");
+  std::vector<FlowSeq> Seq;
+  Seq.emplace_back("This is str1");
+  Seq.emplace_back("This is str2");
+  Seq.emplace_back("This is str3");
+
+  {
+    // 20 is just bellow the total length of the first mapping field.
+    // We should wreap at every element.
+    Output yout(ostr, nullptr, 15);
+
+    yout << Map;
+    ostr.flush();
+    EXPECT_EQ(out,
+              "---\n"
+              "{ str1: This is str1, \n"
+              "  str2: This is str2, \n"
+              "  str3: This is str3 }\n"
+              "...\n");
+    out.clear();
+
+    yout << Seq;
+    ostr.flush();
+    EXPECT_EQ(out,
+              "---\n"
+              "[ This is str1, \n"
+              "  This is str2, \n"
+              "  This is str3 ]\n"
+              "...\n");
+    out.clear();
+  }
+  {
+    // 25 will allow the second field to be output on the first line.
+    Output yout(ostr, nullptr, 25);
+
+    yout << Map;
+    ostr.flush();
+    EXPECT_EQ(out,
+              "---\n"
+              "{ str1: This is str1, str2: This is str2, \n"
+              "  str3: This is str3 }\n"
+              "...\n");
+    out.clear();
+
+    yout << Seq;
+    ostr.flush();
+    EXPECT_EQ(out,
+              "---\n"
+              "[ This is str1, This is str2, \n"
+              "  This is str3 ]\n"
+              "...\n");
+    out.clear();
+  }
+  {
+    // 0 means no wrapping.
+    Output yout(ostr, nullptr, 0);
+
+    yout << Map;
+    ostr.flush();
+    EXPECT_EQ(out,
+              "---\n"
+              "{ str1: This is str1, str2: This is str2, str3: This is str3 }\n"
+              "...\n");
+    out.clear();
+
+    yout << Seq;
+    ostr.flush();
+    EXPECT_EQ(out,
+              "---\n"
+              "[ This is str1, This is str2, This is str3 ]\n"
+              "...\n");
+    out.clear();
+  }
+}