Implement WriteStringValueSegment defined in Issue 67337

src/libraries/System.Text.Json/ref/System.Text.Json.cs

@@ -662,6 +662,8 @@ public void WriteStringValue(System.ReadOnlySpan<byte> utf8Value) { }
         public void WriteStringValue(System.ReadOnlySpan<char> value) { }
         public void WriteStringValue(string? value) { }
         public void WriteStringValue(System.Text.Json.JsonEncodedText value) { }
+        public void WriteStringValueSegment(System.ReadOnlySpan<byte> utf8Value, bool isFinalSegment) { }
+        public void WriteStringValueSegment(ReadOnlySpan<char> value, bool isFinalSegment) { }
     }
 }
 namespace System.Text.Json.Nodes

src/libraries/System.Text.Json/src/Resources/Strings.resx

@@ -751,5 +751,8 @@
   </data>
   <data name="NullabilityInfoContext_NotSupported" xml:space="preserve">
     <value>NullabilityInfoContext is not supported in the current application because 'System.Reflection.NullabilityInfoContext.IsSupported' is set to false. Set the MSBuild Property 'NullabilityInfoContextSupport' to true in order to enable it.</value>
+  </data>
+	<data name="CannotWriteWithinString" xml:space="preserve">
+    <value>The current JSON string must be finalized before a token of type '{0}' can be added.</value>
   </data>
 </root>

src/libraries/System.Text.Json/src/System/Text/Json/ThrowHelper.cs

@@ -598,6 +598,9 @@ private static string GetResourceString(ExceptionResource resource, int currentD
                 case ExceptionResource.CannotWriteValueAfterPrimitiveOrClose:
                     message = SR.Format(SR.CannotWriteValueAfterPrimitiveOrClose, tokenType);
                     break;
+                case ExceptionResource.CannotWriteWithinString:
+                    message = SR.Format(SR.CannotWriteWithinString, tokenType);
+                    break;
                 default:
                     Debug.Fail($"The ExceptionResource enum value: {resource} is not part of the switch. Add the appropriate case and exception message.");
                     break;
@@ -758,6 +761,7 @@ internal enum ExceptionResource
         ExpectedOneCompleteToken,
         NotEnoughData,
         InvalidLeadingZeroInNumber,
+        CannotWriteWithinString,
     }
 
     internal enum NumericType

src/libraries/System.Text.Json/src/System/Text/Json/Writer/Utf8JsonWriter.WriteProperties.Helpers.cs

@@ -36,6 +36,9 @@ private void ValidateWritingProperty()
         {
             if (!_options.SkipValidation)
             {
+                // Make sure a new property is not attempted within an unfinalized string.
+                ValidateNotWithinUnfinalizedString();
+
                 if (!_inObject || _tokenType == JsonTokenType.PropertyName)
                 {
                     Debug.Assert(_tokenType != JsonTokenType.StartObject);
@@ -49,6 +52,9 @@ private void ValidateWritingProperty(byte token)
         {
             if (!_options.SkipValidation)
             {
+                // Make sure a new property is not attempted within an unfinalized string.
+                ValidateNotWithinUnfinalizedString();
+
                 if (!_inObject || _tokenType == JsonTokenType.PropertyName)
                 {
                     Debug.Assert(_tokenType != JsonTokenType.StartObject);

src/libraries/System.Text.Json/src/System/Text/Json/Writer/Utf8JsonWriter.WriteValues.Comment.cs

@@ -61,6 +61,8 @@ public void WriteCommentValue(ReadOnlySpan<char> value)
 
         private void WriteCommentByOptions(ReadOnlySpan<char> value)
         {
+            ValidateWritingComment();
+
             if (_options.Indented)
             {
                 WriteCommentIndented(value);

src/libraries/System.Text.Json/src/System/Text/Json/Writer/Utf8JsonWriter.WriteValues.Helpers.cs

@@ -10,10 +10,29 @@ namespace System.Text.Json
 {
     public sealed partial class Utf8JsonWriter
     {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private void ValidateNotWithinUnfinalizedString()
+        {
+            if (_tokenType == StringSegmentSentinel)
+            {
+                ThrowHelper.ThrowInvalidOperationException(ExceptionResource.CannotWriteWithinString, currentDepth: default, maxDepth: _options.MaxDepth, token: default, _tokenType);
+            }
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private void ValidateWritingComment()
+        {
+            // Make sure a new comment is not attempted within an unfinalized string.
+            ValidateNotWithinUnfinalizedString();
+        }
+
         private void ValidateWritingValue()
         {
             Debug.Assert(!_options.SkipValidation);
 
+            // Make sure a new value is not attempted within an unfinalized string.
+            ValidateNotWithinUnfinalizedString();
+
             if (_inObject)
             {
                 if (_tokenType != JsonTokenType.PropertyName)