Optimize CompositePreCompiler

Author: SergeiPavlov

Orm/Xtensive.Orm/Orm/Providers/DomainHandler.cs

@@ -1,6 +1,6 @@
-// Copyright (C) 2003-2010 Xtensive LLC.
-// All rights reserved.
-// For conditions of distribution and use, see license.
+// Copyright (C) 2003-2021 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
 // Created by: Dmitri Maximov
 // Created:    2008.05.19
 
@@ -20,6 +20,8 @@ namespace Xtensive.Orm.Providers
   /// </summary>
   public abstract class DomainHandler : DomainBoundHandler
   {
+    private static readonly OrderingCorrector OrderingCorrector = new OrderingCorrector(ResolveOrderingDescriptor);
+
     private Dictionary<Type, IMemberCompilerProvider> memberCompilerProviders;
 
     /// <summary>
@@ -94,13 +96,12 @@ protected virtual IPreCompiler CreatePreCompiler(CompilerConfiguration configura
       var skipTakeCorrector = new SkipTakeCorrector(
         providerInfo.Supports(ProviderFeatures.NativeTake),
         providerInfo.Supports(ProviderFeatures.NativeSkip));
-      return new CompositePreCompiler(
+      return new CompositePreCompiler(configuration.Tags,
         applyCorrector,
         skipTakeCorrector,
-        new RedundantColumnOptimizer(),
-        new OrderingCorrector(ResolveOrderingDescriptor)) {
-          Tags = configuration.Tags
-      };
+        RedundantColumnOptimizer.Instance,
+        OrderingCorrector
+        );
     }
 
     /// <summary>

Orm/Xtensive.Orm/Orm/Rse/Compilation/CompositePreCompiler.cs

@@ -1,6 +1,6 @@
-// Copyright (C) 2003-2010 Xtensive LLC.
-// All rights reserved.
-// For conditions of distribution and use, see license.
+// Copyright (C) 2003-2021 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
 // Created by: Alexis Kochetov
 // Created:    2009.03.30
 
@@ -12,29 +12,31 @@ namespace Xtensive.Orm.Rse.Compilation
 {
   public sealed class CompositePreCompiler : IPreCompiler
   {
-    public List<IPreCompiler> Items { get; private set; }
-    public IReadOnlyList<string> Tags { get; init; }
+    public IReadOnlyList<IPreCompiler> items { get; }
+    public IReadOnlyList<string> tags { get; }
 
     public CompilableProvider Process(CompilableProvider rootProvider)
     {
       var provider = rootProvider;
-      if (Tags != null) {
-        foreach (var tag in Tags) {
+      if (tags != null) {
+        foreach (var tag in tags) {
           provider = new TagProvider(provider, tag);
         }
       }
 
-      foreach (var item in Items)
+      foreach (var item in items) {
         provider = item.Process(provider);
+      }
       return provider;
     }
 
 
     // Constructors
 
-    public CompositePreCompiler(params IPreCompiler[] preCompilers)
+    public CompositePreCompiler(IReadOnlyList<string> tags, params IPreCompiler[] preCompilers)
     {
-      Items = preCompilers.ToList();
+      this.tags = tags;
+      items = preCompilers;
     }
   }
 }

Orm/Xtensive.Orm/Orm/Rse/Transformation/RedundantColumnOptimizer.cs

@@ -16,6 +16,7 @@ namespace Xtensive.Orm.Rse.Transformation
   [Serializable]
   public class RedundantColumnOptimizer: IPreCompiler
   {
+    public static RedundantColumnOptimizer Instance { get; } = new RedundantColumnOptimizer();
 
     /// <inheritdoc/>
     CompilableProvider IPreCompiler.Process(CompilableProvider rootProvider)