Add OpenAI serialization helper methods. (#5697)

* Add a System.Net.ServerSentEvents polyfill.

* Move model mapping helpers to standalone class.

* Skeleton implementation of OpenAI serialization methods.

* Add unit testing.

* Also normalize escaped line endings.

* Fix unix test failures

* Exclude System.Net.Sse from code coverage

* Improve test coverage.

* Remove msbuild artifact

* Fix merge conflicts.

* Address feedback.

* Address feedback.

* Address feedback.

* Add function result name inference.

eng/MSBuild/Shared.props

@@ -14,6 +14,10 @@
   <ItemGroup Condition="'$(InjectSharedRentedSpan)' == 'true'">
     <Compile Include="$(MSBuildThisFileDirectory)\..\..\src\Shared\RentedSpan\*.cs" LinkBase="Shared\RentedSpan" />
   </ItemGroup>
+
+  <ItemGroup Condition="'$(InjectSharedServerSentEvents)' == 'true'">
+    <Compile Include="$(MSBuildThisFileDirectory)\..\..\src\Shared\ServerSentEvents\*.cs" LinkBase="Shared\ServerSentEvents" />
+  </ItemGroup>
 
   <ItemGroup Condition="'$(InjectSharedNumericExtensions)' == 'true'">
     <Compile Include="$(MSBuildThisFileDirectory)\..\..\src\Shared\NumericExtensions\*.cs" LinkBase="Shared\NumericExtensions" />

src/Libraries/Microsoft.Extensions.AI.OpenAI/JsonModelHelpers.cs

@@ -0,0 +1,31 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.ClientModel.Primitives;
+
+namespace Microsoft.Extensions.AI;
+
+/// <summary>
+/// Defines a set of helper methods for working with <see cref="IJsonModel{T}"/> types.
+/// </summary>
+internal static class JsonModelHelpers
+{
+    public static BinaryData Serialize<TModel>(TModel value)
+        where TModel : IJsonModel<TModel>
+    {
+        return value.Write(ModelReaderWriterOptions.Json);
+    }
+
+    public static TModel Deserialize<TModel>(BinaryData data)
+        where TModel : IJsonModel<TModel>, new()
+    {
+        return JsonModelDeserializationWitness<TModel>.Value.Create(data, ModelReaderWriterOptions.Json);
+    }
+
+    private sealed class JsonModelDeserializationWitness<TModel>
+        where TModel : IJsonModel<TModel>, new()
+    {
+        public static readonly IJsonModel<TModel> Value = new TModel();
+    }
+}

src/Libraries/Microsoft.Extensions.AI.OpenAI/Microsoft.Extensions.AI.OpenAI.csproj

@@ -18,11 +18,15 @@
     <NoWarn>$(NoWarn);CA1063;CA1508;CA2227;SA1316;S1121;S3358;EA0002;OPENAI002</NoWarn>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <DisableNETStandardCompatErrors>true</DisableNETStandardCompatErrors>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
   <PropertyGroup>
     <InjectSharedEmptyCollections>true</InjectSharedEmptyCollections>
     <InjectStringHashOnLegacy>true</InjectStringHashOnLegacy>
+    <InjectSharedServerSentEvents>true</InjectSharedServerSentEvents>
+    <InjectRequiredMemberOnLegacy>true</InjectRequiredMemberOnLegacy>
+    <InjectCompilerFeatureRequiredOnLegacy>true</InjectCompilerFeatureRequiredOnLegacy>
   </PropertyGroup>
 
   <ItemGroup>