Improved FieldExpressionCollections traversal

Author: alex-kulakov

Orm/Xtensive.Orm/Orm/Linq/Expressions/EntityExpression.cs

@@ -26,7 +26,7 @@ public List<PersistentFieldExpression> Fields
       get => fields;
       private set {
         fields = value;
-        foreach (var fieldExpression in fields.OfType<FieldExpression>()) {
+        foreach (var fieldExpression in fields.OfAnyFieldExpression()) {
           fieldExpression.Owner = this;
         }
       }
@@ -137,7 +137,7 @@ public static void Fill(EntityExpression entityExpression, int offset)
         _ = entityExpression.Remap(offset, new Dictionary<Expression, Expression>());
       }
       var typeInfo = entityExpression.PersistentType;
-      foreach (var nestedField in typeInfo.Fields.Except(entityExpression.Fields.OfType<FieldExpression>().Select(field => field.Field))) {
+      foreach (var nestedField in typeInfo.Fields.Except(entityExpression.Fields.OfAnyFieldExpression().Select(field => field.Field))) {
         var nestedFieldExpression = BuildNestedFieldExpression(nestedField, offset);
         if (nestedFieldExpression is FieldExpression fieldExpression) {
           fieldExpression.Owner = entityExpression;

Orm/Xtensive.Orm/Orm/Linq/Expressions/ParameterizedExpressionExtensions.cs

@@ -0,0 +1,44 @@
+// Copyright (C) 2009-2020 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:    2009.05.05
+
+using System.Linq;
+using System.Collections.Generic;
+
+namespace Xtensive.Orm.Linq.Expressions
+{
+  internal static class ParameterizedExpressionExtensions
+  {
+    /// <summary>
+    /// Gets instances of any implementation of <see cref="FieldExpression"/>
+    /// </summary>
+    /// <param name="fields">Sequence of expressions.</param>
+    /// <returns>Filtered results.</returns>
+    public static IEnumerable<FieldExpression> OfAnyFieldExpression(this IEnumerable<PersistentFieldExpression> fields)
+    {
+      // Faster that .OfType<FieldExpression>()
+      return fields
+        .Where(static f => f.ExtendedType is ExtendedExpressionType.Field
+            or ExtendedExpressionType.EntityField
+            or ExtendedExpressionType.EntitySet
+            or ExtendedExpressionType.StructureField)
+        .Cast<FieldExpression>();
+    }
+
+    /// <summary>
+    /// Gets instances of only <see cref="FieldExpression"/> type.
+    /// </summary>
+    /// <param name="fields">Sequence of expressions.</param>
+    /// <returns>Filtered results.</returns>
+    public static IEnumerable<FieldExpression> OfExactlyFieldExpression(this IEnumerable<PersistentFieldExpression> fields)
+    {
+      // A lot faster than fields.OfType<FieldExpression>().Where(static f => f.ExtendedType is ExtendedExpressionType.Field)
+      // because contains less casts and more basic comparisons
+      return fields
+        .Where(static f => f.ExtendedType is ExtendedExpressionType.Field)
+        .Cast<FieldExpression>();
+    }
+  }
+}

Orm/Xtensive.Orm/Orm/Linq/Expressions/StructureExpression.cs

@@ -29,7 +29,7 @@ public List<PersistentFieldExpression> Fields
       get => fields;
       private set {
         fields = value;
-        foreach (var fieldExpression in fields.OfType<FieldExpression>()) {
+        foreach (var fieldExpression in fields.OfAnyFieldExpression()) {
           fieldExpression.Owner = this;
         }
       }

Orm/Xtensive.Orm/Orm/Linq/Expressions/StructureFieldExpression.cs

@@ -26,7 +26,7 @@ public List<PersistentFieldExpression> Fields
       get => fields;
       private set {
         fields = value;
-        foreach (var fieldExpression in fields.OfType<FieldExpression>()) {
+        foreach (var fieldExpression in fields.OfAnyFieldExpression()) {
           fieldExpression.Owner = this;
         }
       }

Orm/Xtensive.Orm/Orm/Linq/Materialization/ExpressionMaterializer.cs

@@ -247,10 +247,9 @@ protected override Expression VisitStructureFieldExpression(StructureFieldExpres
         var typeInfo = expression.PersistentType;
         var tuplePrototype = typeInfo.TuplePrototype;
         var mappingInfo = expression.Fields
-          .OfType<FieldExpression>()
-          .Where(f => f.ExtendedType == ExtendedExpressionType.Field)
-          .OrderBy(f => f.Field.MappingInfo.Offset)
-          .Select(f => new Pair<int>(f.Field.MappingInfo.Offset, f.Mapping.Offset))
+          .OfExactlyFieldExpression()
+          .OrderBy(static f => f.Field.MappingInfo.Offset)
+          .Select(static f => new Pair<int>(f.Field.MappingInfo.Offset, f.Mapping.Offset))
           .Distinct()
           .ToArray();
 
@@ -296,10 +295,9 @@ protected override Expression VisitStructureExpression(StructureExpression expre
       var typeInfo = expression.PersistentType;
       var tuplePrototype = typeInfo.TuplePrototype;
       var mappingInfo = expression.Fields
-        .OfType<FieldExpression>()
-        .Where(f => f.ExtendedType == ExtendedExpressionType.Field)
-        .OrderBy(f => f.Field.MappingInfo.Offset)
-        .Select(f => new Pair<int>(f.Field.MappingInfo.Offset, f.Mapping.Offset))
+        .OfExactlyFieldExpression()
+        .OrderBy(static f => f.Field.MappingInfo.Offset)
+        .Select(static f => new Pair<int>(f.Field.MappingInfo.Offset, f.Mapping.Offset))
         .Distinct()
         .ToArray();
 
@@ -361,10 +359,9 @@ private Expression CreateEntity(IEntityExpression expression, Expression tupleEx
       var typeIdIndex = typeIdField == null ? -1 : typeIdField.Mapping.Offset;
 
       var mappingInfo = expression.Fields
-        .OfType<FieldExpression>()
-        .Where(f => f.ExtendedType == ExtendedExpressionType.Field)
-        .OrderBy(f => f.Field.MappingInfo.Offset)
-        .Select(f => new Pair<int>(f.Field.MappingInfo.Offset, f.Mapping.Offset))
+        .OfExactlyFieldExpression()
+        .OrderBy(static f => f.Field.MappingInfo.Offset)
+        .Select(static f => new Pair<int>(f.Field.MappingInfo.Offset, f.Mapping.Offset))
         .Distinct()
         .ToArray();