Optimize capturing lambdas in DependencyContextExtensions and DependencyContextJsonReader

src/libraries/Microsoft.Extensions.DependencyModel/src/DependencyContextExtensions.cs

@@ -17,30 +17,30 @@ public static IEnumerable<string> GetDefaultNativeAssets(this DependencyContext
         {
             ThrowHelper.ThrowIfNull(self);
 
-            return self.RuntimeLibraries.SelectMany(library => library.GetDefaultNativeAssets(self));
+            return LinqHelpers.SelectMany(self.RuntimeLibraries, static (library, context) => library.GetDefaultNativeAssets(context), self);
         }
 
         public static IEnumerable<RuntimeFile> GetDefaultNativeRuntimeFileAssets(this DependencyContext self)
         {
             ThrowHelper.ThrowIfNull(self);
 
-            return self.RuntimeLibraries.SelectMany(library => library.GetDefaultNativeRuntimeFileAssets(self));
+            return LinqHelpers.SelectMany(self.RuntimeLibraries, static (library, context) => library.GetDefaultNativeRuntimeFileAssets(context), self);
         }
 
         public static IEnumerable<string> GetRuntimeNativeAssets(this DependencyContext self, string runtimeIdentifier)
         {
             ThrowHelper.ThrowIfNull(self);
             ThrowHelper.ThrowIfNull(runtimeIdentifier);
 
-            return self.RuntimeLibraries.SelectMany(library => library.GetRuntimeNativeAssets(self, runtimeIdentifier));
+            return LinqHelpers.SelectMany(self.RuntimeLibraries, static (library, context, id) => library.GetRuntimeNativeAssets(context, id), self, runtimeIdentifier);
         }
 
         public static IEnumerable<RuntimeFile> GetRuntimeNativeRuntimeFileAssets(this DependencyContext self, string runtimeIdentifier)
         {
             ThrowHelper.ThrowIfNull(self);
             ThrowHelper.ThrowIfNull(runtimeIdentifier);
 
-            return self.RuntimeLibraries.SelectMany(library => library.GetRuntimeNativeRuntimeFileAssets(self, runtimeIdentifier));
+            return LinqHelpers.SelectMany(self.RuntimeLibraries, static (library, context, id) => library.GetRuntimeNativeRuntimeFileAssets(context, id), self, runtimeIdentifier);
         }
 
         public static IEnumerable<string> GetDefaultNativeAssets(this RuntimeLibrary self, DependencyContext context)
@@ -79,15 +79,15 @@ public static IEnumerable<AssemblyName> GetDefaultAssemblyNames(this DependencyC
         {
             ThrowHelper.ThrowIfNull(self);
 
-            return self.RuntimeLibraries.SelectMany(library => library.GetDefaultAssemblyNames(self));
+            return LinqHelpers.SelectMany(self.RuntimeLibraries, static (library, context) => library.GetDefaultAssemblyNames(context), self);
         }
 
         public static IEnumerable<AssemblyName> GetRuntimeAssemblyNames(this DependencyContext self, string runtimeIdentifier)
         {
             ThrowHelper.ThrowIfNull(self);
             ThrowHelper.ThrowIfNull(runtimeIdentifier);
 
-            return self.RuntimeLibraries.SelectMany(library => library.GetRuntimeAssemblyNames(self, runtimeIdentifier));
+            return LinqHelpers.SelectMany(self.RuntimeLibraries, static (library, context, id) => library.GetRuntimeAssemblyNames(context, id), self, runtimeIdentifier);
         }
 
         public static IEnumerable<AssemblyName> GetDefaultAssemblyNames(this RuntimeLibrary self, DependencyContext context)

src/libraries/Microsoft.Extensions.DependencyModel/src/DependencyContextJsonReader.cs

@@ -741,9 +741,18 @@ private IEnumerable<Library> CreateLibraries(IEnumerable<TargetLibrary>? librari
             {
                 return Enumerable.Empty<Library>();
             }
-            return libraries
-                .Select(property => CreateLibrary(property, runtime, libraryStubs))
-                .Where(library => library != null)!;
+
+            return CreateLibrariesNotNull(libraries, runtime, libraryStubs);
+
+            IEnumerable<Library> CreateLibrariesNotNull(IEnumerable<TargetLibrary> libraries, bool runtime, Dictionary<string, LibraryStub>? libraryStubs)
+            {
+                foreach (TargetLibrary library in libraries)
+                {
+                    Library? createdLibrary = CreateLibrary(library, runtime, libraryStubs);
+                    if (createdLibrary is not null)
+                        yield return createdLibrary;
+                }
+            }
         }
 
         private Library? CreateLibrary(TargetLibrary targetLibrary, bool runtime, Dictionary<string, LibraryStub>? libraryStubs)

src/libraries/Microsoft.Extensions.DependencyModel/src/LinqHelpers.cs

@@ -0,0 +1,38 @@
+// 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.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Microsoft.Extensions.DependencyModel
+{
+    internal static class LinqHelpers
+    {
+        public static IEnumerable<TResult> SelectMany<TSource, TResult, TParam1>(IEnumerable<TSource> src,
+            Func<TSource, TParam1, IEnumerable<TResult>> func, TParam1 param1)
+        {
+            foreach (TSource? elem in src)
+            {
+                foreach (TResult? subElem in func(elem, param1))
+                {
+                    yield return subElem;
+                }
+            }
+        }
+
+        public static IEnumerable<TResult> SelectMany<TSource, TResult, TParam1, TParam2>(IEnumerable<TSource> src,
+            Func<TSource, TParam1, TParam2, IEnumerable<TResult>> func, TParam1 param1, TParam2 param2)
+        {
+            foreach (TSource? elem in src)
+            {
+                foreach (TResult? subElem in func(elem, param1, param2))
+                {
+                    yield return subElem;
+                }
+            }
+        }
+    }
+}