Avoid unnecessary array copy before calling .Remap(); new() -> ValueTuple;

Orm/Xtensive.Orm.Tests/Rse/HeaderParseTest.cs

@@ -54,7 +54,7 @@ public void MainTest()
           ResetState(state);
 
           // Select Id, TypeId, Title
-          CompilableProvider rsTitle = rsMain.Select(0, 1, 2);
+          CompilableProvider rsTitle = rsMain.Select(new[] { 0, 1, 2 });
           UpdateCache(session, rsTitle.GetRecordSetReader(session, parameterContext));
           state = Session.Current.EntityStateCache[key, true];
           Assert.IsNotNull(state);
@@ -63,7 +63,7 @@ public void MainTest()
           ResetState(state);
 
           // Select Id, TypeId, Text
-          CompilableProvider rsText = rsMain.Select(0, 1, 3);
+          CompilableProvider rsText = rsMain.Select(new[] { 0, 1, 3 });
           UpdateCache(session, rsText.GetRecordSetReader(session, parameterContext));
           state = Session.Current.EntityStateCache[key, true];
           Assert.IsNotNull(state);

Orm/Xtensive.Orm.Tests/Storage/Providers/Sql/CharSupportTest.cs

@@ -66,7 +66,7 @@ public void SelectCharTest()
         var rs = GetRseQuery<MyEntity>();
         var parameterContext = new ParameterContext();
         var result = rs
-          .Select(rs.Header.IndexOf(charColumn))
+          .Select(new[] { rs.Header.IndexOf(charColumn) })
           .GetRecordSetReader(Session.Current, parameterContext)
           .ToEnumerable()
           .Select(i => i.GetValueOrDefault<char>(0))
@@ -88,7 +88,7 @@ public void CharParameterTest()
         var rs = GetRseQuery<MyEntity>();
         var parameterContext = new ParameterContext();
         var result = rs
-          .Select(rs.Header.IndexOf(charColumn))
+          .Select(new[] { rs.Header.IndexOf(charColumn) })
           .Filter(t => t.GetValueOrDefault<char>(0) == y)
           .GetRecordSetReader(Session.Current, parameterContext)
           .ToEnumerable()
@@ -108,7 +108,7 @@ public void CharConstantTest()
         var rs = GetRseQuery<MyEntity>();
         var parameterContext = new ParameterContext();
         var result = rs
-          .Select(rs.Header.IndexOf(charColumn))
+          .Select(new[] { rs.Header.IndexOf(charColumn) })
           .Filter(t => t.GetValueOrDefault<char>(0)=='Y')
           .GetRecordSetReader(Session.Current, parameterContext)
           .ToEnumerable()

Orm/Xtensive.Orm/Arithmetic/ArithmeticRules.cs

@@ -41,14 +41,8 @@ public bool Equals(ArithmeticRules other)
     }
 
     /// <inheritdoc/>
-    public override bool Equals(object obj)
-    {
-      if (obj==null)
-        return false;
-      if (obj is ArithmeticRules)
-        return Equals((ArithmeticRules)obj);
-      return false;
-    }
+    public override bool Equals(object obj) =>
+      obj is ArithmeticRules other && Equals(other);
 
     /// <inheritdoc/>
     public override int GetHashCode()

Orm/Xtensive.Orm/Caching/WeakestCache.cs

@@ -131,33 +131,24 @@ internal sealed class WeakEntryEqualityComparer : IEqualityComparer<object>
 
       public new bool Equals(object x, object y)
       {
-        TKey key;
-        var we = x as WeakEntry;
-        if (we!=null) {
+        if (x is WeakEntry we) {
           // x is WeakEntry
-          key = y as TKey;
-          if (key!=null)
+          if (y is TKey key)
             // x is WeakEntry, y is TKey
             return keyComparer.Equals(we.Key, key);
           else {
-            var we2 = y as WeakEntry;
-            if (we2==null)
-              return false;
-            // x is WeakEntry, y is WeakEntry
-            return keyComparer.Equals(we.Key, we2.Key);
+            return y is WeakEntry we2 && keyComparer.Equals(we.Key, we2.Key); // x is WeakEntry, y is WeakEntry
           }
         }
-        key = x as TKey;
-        if (key==null)
-          return false;
-        // x is TKey
-        we = y as WeakEntry;
-        if (we!=null)
-          // x is TKey, y is WeakEntry
-          return keyComparer.Equals(key, we.Key);
-        else
-          // x is TKey, y must be TKey
-          return keyComparer.Equals(key, y as TKey);
+        if (x is TKey keyX) {
+          if (y is WeakEntry weY)
+            // x is TKey, y is WeakEntry
+            return keyComparer.Equals(keyX, weY.Key);
+          else
+            // x is TKey, y must be TKey
+            return keyComparer.Equals(keyX, y as TKey);
+        }
+        return false;
       }
 
       public int GetHashCode(object obj)

Orm/Xtensive.Orm/Comparison/ComparisonRule.cs

@@ -83,12 +83,8 @@ public bool Equals(ComparisonRule other)
     }
 
     /// <inheritdoc/>
-    public override bool Equals(object obj)
-    {
-      if (obj is ComparisonRule)
-        return Equals((ComparisonRule)obj);
-      return false;
-    }
+    public override bool Equals(object obj) =>
+      obj is ComparisonRule other && Equals(other);
 
     /// <inheritdoc/>
     public override int GetHashCode()

Orm/Xtensive.Orm/Comparison/ComparisonRules.cs

@@ -193,12 +193,8 @@ public bool Equals(ComparisonRules other)
     #region Equals, GetHashCode
 
     /// <inheritdoc/>
-    public override bool Equals(object obj)
-    {
-      if (obj is ComparisonRules)
-        return Equals((ComparisonRules)obj);
-      return false;
-    }
+    public override bool Equals(object obj) =>
+      obj is ComparisonRules other && Equals(other);
 
     /// <inheritdoc/>
     public override int GetHashCode()

Orm/Xtensive.Orm/Conversion/Biconverter.cs

@@ -53,12 +53,8 @@ public bool Equals(Biconverter<TFrom, TTo> obj)
     }
 
     /// <inheritdoc/>
-    public override bool Equals(object obj)
-    {
-      if (obj.GetType()!=typeof (Biconverter<TFrom, TTo>))
-        return false;
-      return Equals((Biconverter<TFrom, TTo>) obj);
-    }
+    public override bool Equals(object obj) =>
+      obj is Biconverter<TFrom, TTo> other && Equals(other);
 
     /// <inheritdoc/>
     public override int GetHashCode()

Orm/Xtensive.Orm/Core/HasVersion{TValue,TVersion}.cs

@@ -57,12 +57,8 @@ public int CompareTo(HasVersion<TValue, TVersion> other)
     #region Equals, GetHashCode, ==, !=
 
     /// <inheritdoc/>
-    public override bool Equals(object obj)
-    {
-      if (obj.GetType()!=typeof (HasVersion<TValue, TVersion>))
-        return false;
-      return Equals((HasVersion<TValue, TVersion>) obj);
-    }
+    public override bool Equals(object obj) =>
+      obj is HasVersion<TValue, TVersion> other && Equals(other);
 
     /// <inheritdoc/>
     public override int GetHashCode()

Orm/Xtensive.Orm/Core/Pair{TFirst,TSecond}.cs

@@ -21,6 +21,9 @@ namespace Xtensive.Core
     IComparable<Pair<TFirst, TSecond>>,
     IEquatable<Pair<TFirst, TSecond>>
   {
+    private static readonly AdvancedComparerStruct<TFirst> FirstComparer = AdvancedComparerStruct<TFirst>.System;
+    private static readonly AdvancedComparerStruct<TSecond> SecondComparer = AdvancedComparerStruct<TSecond>.System;
+
     /// <summary>
     /// A first value.
     /// </summary>
@@ -33,33 +36,25 @@ namespace Xtensive.Core
     #region IComparable<...>, IEquatable<...> methods
 
     /// <inheritdoc/>
-    public bool Equals(Pair<TFirst, TSecond> other)
-    {
-      if (!AdvancedComparerStruct<TFirst>.System.Equals(First, other.First))
-        return false;
-      return AdvancedComparerStruct<TSecond>.System.Equals(Second, other.Second);
-    }
+    public bool Equals(Pair<TFirst, TSecond> other) =>
+      FirstComparer.Equals(First, other.First) && SecondComparer.Equals(Second, other.Second);
 
     /// <inheritdoc/>
     public int CompareTo(Pair<TFirst, TSecond> other)
     {
-      int result = AdvancedComparerStruct<TFirst>.System.Compare(First, other.First);
-      if (result != 0)
-        return result;
-      return AdvancedComparerStruct<TSecond>.System.Compare(Second, other.Second);
+      int result = FirstComparer.Compare(First, other.First);
+      return result != 0
+        ? result
+        : SecondComparer.Compare(Second, other.Second);
     }
 
     #endregion
 
     #region Equals, GetHashCode, ==, !=
 
     /// <inheritdoc/>
-    public override bool Equals(object obj)
-    {
-      if (obj.GetType() != typeof(Pair<TFirst, TSecond>))
-        return false;
-      return Equals((Pair<TFirst, TSecond>) obj);
-    }
+    public override bool Equals(object obj) =>
+      obj is Pair<TFirst, TSecond> other && Equals(other);
 
     /// <inheritdoc/>
     public override int GetHashCode()

Orm/Xtensive.Orm/Core/Pair{T}.cs

@@ -22,6 +22,8 @@ namespace Xtensive.Core
     IEquatable<Pair<T>>,
     IComparable<Pair<T>>
   {
+    private static readonly AdvancedComparerStruct<T> Comparer = AdvancedComparerStruct<T>.System;
+
     /// <summary>
     /// The first value.
     /// </summary>
@@ -35,33 +37,25 @@ namespace Xtensive.Core
     #region IComparable<...>, IEquatable<...> methods
 
     /// <inheritdoc/>
-    public bool Equals(Pair<T> other)
-    {
-      if (!AdvancedComparerStruct<T>.System.Equals(First, other.First))
-        return false;
-      return AdvancedComparerStruct<T>.System.Equals(Second, other.Second);
-    }
+    public bool Equals(Pair<T> other) =>
+      Comparer.Equals(First, other.First) && Comparer.Equals(Second, other.Second);
 
     /// <inheritdoc/>
     public int CompareTo(Pair<T> other)
     {
-      int result = AdvancedComparerStruct<T>.System.Compare(First, other.First);
-      if (result!=0)
-        return result;
-      return AdvancedComparerStruct<T>.System.Compare(Second, other.Second);
+      int result = Comparer.Compare(First, other.First);
+      return result != 0
+        ? result
+        : Comparer.Compare(Second, other.Second);
     }
 
     #endregion
 
     #region Equals, GetHashCode, ==, !=
 
     /// <inheritdoc/>
-    public override bool Equals(object obj)
-    {
-      if (obj.GetType()!=typeof (Pair<T>))
-        return false;
-      return Equals((Pair<T>) obj);
-    }
+    public override bool Equals(object obj) =>
+      obj is Pair<T> other && Equals(other);
 
     /// <inheritdoc/>
     public override int GetHashCode()
@@ -117,4 +111,4 @@ public Pair(T first, T second)
       Second = second;
     }
   }
-}
+}

Orm/Xtensive.Orm/Core/Segment.cs

@@ -62,14 +62,8 @@ public int CompareTo(Pair<T> other)
     #region Equals, GetHashCode
 
     /// <inheritdoc/>
-    public override bool Equals(object obj)
-    {
-      if (obj is Pair<T>) {
-        Pair<T> other = (Pair<T>)obj;
-        return Equals(other);
-      }
-      return false;
-    }
+    public override bool Equals(object obj) =>
+      obj is Pair<T> other && Equals(other);
 
     /// <inheritdoc/>
     public override int GetHashCode()

Orm/Xtensive.Orm/Linq/SerializableExpressions/Internals/SerializableExpressionToExpressionConverter.cs

@@ -148,16 +148,12 @@ private Expression VisitParameter(SerializableParameterExpression p)
     private Expression VisitMemberAccess(SerializableMemberExpression m)
     {
       var target = Visit(m.Expression);
-      var field = m.Member as FieldInfo;
-      if (field != null)
-        return Expression.Field(target, field);
-      var property = m.Member as PropertyInfo;
-      if (property != null)
-        return Expression.Property(target, property);
-      var method = m.Member as MethodInfo;
-      if (method != null)
-        return Expression.Property(target, method);
-      throw new ArgumentException();
+      return m.Member switch {
+        FieldInfo field => Expression.Field(target, field),
+        PropertyInfo property => Expression.Property(target, property),
+        MethodInfo method => Expression.Property(target, method),
+        _ => throw new ArgumentException()
+      };
     }
 
     private Expression VisitMethodCall(SerializableMethodCallExpression mc)

Orm/Xtensive.Orm/Modelling/Comparison/Comparer.cs

@@ -194,7 +194,7 @@ protected virtual Difference VisitNode(Node source, Node target)
           if ((difference.MovementInfo & recreated) != recreated) {
             var propertyAccessors = difference.PropertyChanges
               .Where(p => p.Value.Source != null && p.Value.Target != null)
-              .Select(p => new {Pair = p, NodeDifference = p.Value as NodeDifference})
+              .Select(p => (Pair: p, NodeDifference: p.Value as NodeDifference))
               .Where(a => a.NodeDifference != null && !a.NodeDifference.IsNameChanged)
               .Select(a => source.PropertyAccessors[a.Pair.Key])
               .ToList();

Orm/Xtensive.Orm/Modelling/Comparison/Upgrader.cs

@@ -657,12 +657,12 @@ protected static string GetPathWithoutName(Node node)
     /// <returns>A disposable deactivating the group.</returns>
     protected IDisposable OpenActionGroup(string comment)
     {
-      var oldActions = new {
+      var oldActions = (
         Context.PreConditions,
         Context.Actions,
         Context.Renames,
         Context.PostConditions
-      };
+      );
       Context.PreConditions = new GroupingNodeAction {
         Comment = PreConditionsGroupComment
       };

Orm/Xtensive.Orm/Orm/Building/Builders/DatabaseDependencyBuilder.cs

@@ -28,12 +28,8 @@ public bool Equals(DatabaseReference other)
         return string.Equals(TargetDatabase, other.TargetDatabase) && string.Equals(OwnerDatabase, other.OwnerDatabase);
       }
 
-      public override bool Equals(object obj)
-      {
-        if (ReferenceEquals(null, obj))
-          return false;
-        return obj is DatabaseReference && Equals((DatabaseReference) obj);
-      }
+      public override bool Equals(object obj) =>
+        obj is DatabaseReference other && Equals(other);
 
       public override int GetHashCode()
       {