Properly handle 32bits Unicode code points in escape sequences and url-encoded tags

YamlDotNet.Test/Core/ParserTests.cs

@@ -388,6 +388,28 @@ public void VerifyTokenWithMultiDocTag()
                 StreamEnd);
         }
 
+        [Fact]
+        public void VerifyTokenWithUrlEncodedTagContainingPlusSpaces()
+        {
+            AssertSequenceOfEventsFrom(Yaml.ParserForText("!(%20%20%20hello+you%20+) value"),
+                StreamStart,
+                DocumentStart(Implicit),
+                PlainScalar("value").T("!(   hello you  )"),
+                DocumentEnd(Implicit),
+                StreamEnd);
+        }
+
+        [Fact]
+        public void VerifyTokenWithUrlEncoded32BitsUnicodeTags()
+        {
+            AssertSequenceOfEventsFrom(Yaml.ParserForText("!hel%F4%8F%BF%BFlo%E2%99%A5+A%20 value"),
+                StreamStart,
+                DocumentStart(Implicit),
+                PlainScalar("value").T("!hel􏿿lo♥ A "),
+                DocumentEnd(Implicit),
+                StreamEnd);
+        }
+
         [Theory]
         [InlineData("|\n  b-carriage-return,b-line-feed\r\n  lll", "b-carriage-return,b-line-feed\nlll")]
         [InlineData("|\n  b-carriage-return\r  lll", "b-carriage-return\nlll")]

YamlDotNet.Test/RepresentationModel/YamlStreamTests.cs

@@ -174,6 +174,12 @@ public void FailBackreference()
             RoundtripTest("fail-backreference.yaml");
         }
 
+        [Fact]
+        public void Roundtrip32BitsUnicodeEscape()
+        {
+            RoundtripTest("unicode-32bits-escape.yaml");
+        }
+
         [Fact]
         public void AllAliasesMustBeResolved()
         {

YamlDotNet.Test/YamlDotNet.Test.csproj

@@ -140,6 +140,7 @@
     <EmbeddedResource Include="files\guid.yaml" />
     <EmbeddedResource Include="files\ordered-properties.yaml" />
     <EmbeddedResource Include="files\multi-doc-tag.yaml" />
+    <EmbeddedResource Include="files\unicode-32bits-escape.yaml" />
     <None Include="packages.config" />
   </ItemGroup>
   <ItemGroup>

YamlDotNet.Test/files/unicode-32bits-escape.yaml

@@ -0,0 +1,2 @@
+- hel􏿿lo♥
+- "hel\U0010fffflo\u2665"

YamlDotNet/Core/Emitter.cs

@@ -1160,12 +1160,25 @@ private void WriteDoubleQuotedScalar(string value, bool allowBreaks)
                             break;
 
                         default:
-                            var code = (short)character;
+                            var code = (ushort)character;
                             if (code <= 0xFF)
                             {
                                 Write('x');
                                 Write(code.ToString("X02", CultureInfo.InvariantCulture));
                             }
+                            else if (IsHighSurrogate(character))
+                            {
+                                if (index + 1 < value.Length && IsLowSurrogate(value[index + 1]))
+                                {
+                                    Write('U');
+                                    Write(char.ConvertToUtf32(character, value[index + 1]).ToString("X08", CultureInfo.InvariantCulture));
+                                    index++;
+                                }
+                                else
+                                {
+                                    throw new SyntaxErrorException("While writing a quoted scalar, found an orphaned high surrogate.");
+                                }
+                            }
                             else
                             {
                                 Write('u');
@@ -1342,6 +1355,16 @@ private static bool IsPrintable(char character)
                     (character >= '\xE000' && character <= '\xFFFD');
         }
 
+        private static bool IsHighSurrogate(char c)
+        {
+           return 0xD800 <= c && c <= 0xDBFF;
+        }
+
+        private static bool IsLowSurrogate(char c)
+        {
+            return 0xDC00 <= c && c <= 0xDFFF;
+        }
+
         #endregion
 
         /// <summary>

YamlDotNet/Core/Scanner.cs

@@ -1680,7 +1680,7 @@ private Token ScanFlowScalar(bool isSingleQuoted)
 
                         if (codeLength > 0)
                         {
-                            uint character = 0;
+                            int character = 0;
 
                             // Scan the character value.
 
@@ -1690,7 +1690,7 @@ private Token ScanFlowScalar(bool isSingleQuoted)
                                 {
                                     throw new SyntaxErrorException(start, cursor.Mark(), "While parsing a quoted scalar, did not find expected hexdecimal number.");
                                 }
-                                character = (uint)((character << 4) + analyzer.AsHex(k));
+                                character = ((character << 4) + analyzer.AsHex(k));
                             }
 
                             // Check the value and write the character.
@@ -1700,7 +1700,7 @@ private Token ScanFlowScalar(bool isSingleQuoted)
                                 throw new SyntaxErrorException(start, cursor.Mark(), "While parsing a quoted scalar, find invalid Unicode character escape code.");
                             }
 
-                            value.Append((char)character);
+                            value.Append(char.ConvertFromUtf32(character));
 
                             // Advance the pointer.
 
@@ -2145,6 +2145,11 @@ private string ScanTagUri(string head, Mark start)
                 {
                     tag.Append(ScanUriEscapes(start));
                 }
+                else if (analyzer.Check('+'))
+                {
+                    tag.Append(' ');
+                    Skip();
+                }
                 else
                 {
                     tag.Append(ReadCurrentCharacter());
@@ -2165,11 +2170,12 @@ private string ScanTagUri(string head, Mark start)
         /// Decode an URI-escape sequence corresponding to a single UTF-8 character.
         /// </summary>
 
-        private char ScanUriEscapes(Mark start)
+        private string ScanUriEscapes(Mark start)
         {
             // Decode the required number of characters.
 
-            var charBytes = new List<byte>();
+            byte[] charBytes = null;
+            int nextInsertionIndex = 0;
             int width = 0;
             do
             {
@@ -2197,6 +2203,8 @@ private char ScanUriEscapes(Mark start)
                     {
                         throw new SyntaxErrorException(start, cursor.Mark(), "While parsing a tag, find an incorrect leading UTF-8 octet.");
                     }
+
+                    charBytes = new byte[width];
                 }
                 else
                 {
@@ -2210,22 +2218,22 @@ private char ScanUriEscapes(Mark start)
 
                 // Copy the octet and move the pointers.
 
-                charBytes.Add((byte)octet);
+                charBytes[nextInsertionIndex++] = (byte)octet;
 
                 Skip();
                 Skip();
                 Skip();
             }
             while (--width > 0);
 
-            var characters = Encoding.UTF8.GetChars(charBytes.ToArray());
+            var result = Encoding.UTF8.GetString(charBytes, 0, nextInsertionIndex);
 
-            if (characters.Length != 1)
+            if (result.Length == 0 || result.Length > 2)
             {
                 throw new SyntaxErrorException(start, cursor.Mark(), "While parsing a tag, find an incorrect UTF-8 sequence.");
             }
 
-            return characters[0];
+            return result;
         }
 
         /// <summary>