No TupleDescriptor.FieldTypes array usage from outside the type

Author: alex-kulakov

Orm/Xtensive.Orm/Orm/EntitySetBase.cs

@@ -956,33 +956,23 @@ private static EntitySetTypeState BuildEntitySetTypeState(FieldInfo field, Entit
       var targetDescriptor = association.TargetType.Key.TupleDescriptor;
       var ownerFieldCount = ownerDescriptor.Count;
 
-      Type[] keyFieldTypes;
       IReadOnlyList<int> itemColumnOffsets;
       if (association.AuxiliaryType == null) {
-        itemColumnOffsets = Enumerable.Repeat(-1, ownerFieldCount).Concat(
-        association.UnderlyingIndex.ValueColumns
+        itemColumnOffsets = Enumerable.Repeat(-1, ownerFieldCount)
+          .Concat(association.UnderlyingIndex.ValueColumns
             .Where(ci => ci.IsPrimaryKey)
             .Select(ci => ci.Field.MappingInfo.Offset)).ToList();
-        var keyFieldCount = itemColumnOffsets.Count;
-        keyFieldTypes = new Type[keyFieldCount];
-        Array.Copy(ownerDescriptor.FieldTypes, keyFieldTypes, ownerFieldCount);
-        for (var index=ownerFieldCount; index<keyFieldCount; index++) {
-          keyFieldTypes[index] = targetDescriptor[itemColumnOffsets[index]];
-        }
       }
       else {
         var keyFieldCount = ownerDescriptor.Count + targetDescriptor.Count;
-        keyFieldTypes = new Type[keyFieldCount];
-        Array.Copy(ownerDescriptor.FieldTypes, keyFieldTypes, ownerFieldCount);
-        Array.Copy(targetDescriptor.FieldTypes, 0, keyFieldTypes, ownerFieldCount, targetDescriptor.Count);
         var offsetMap = new int[keyFieldCount];
-        for (var index=0; index < keyFieldCount; index++) {
+        for (var index = 0; index < keyFieldCount; index++) {
           offsetMap[index] = index - ownerFieldCount;
         }
         itemColumnOffsets = offsetMap;
-      }
 
-      var keyDescriptor = TupleDescriptor.Create(keyFieldTypes);
+      }
+      var keyDescriptor = ownerDescriptor.ConcatWith(targetDescriptor);
 
       Func<Tuple, Entity> itemCtor = null;
       if (association.AuxiliaryType != null) {

Orm/Xtensive.Orm/Tuples/Transform/ConcatTransform.cs

@@ -74,13 +74,8 @@ public ConcatTransform(bool isReadOnly, TupleDescriptor first, TupleDescriptor s
       ArgumentValidator.EnsureArgumentIsNotDefault(first, nameof(first));
       ArgumentValidator.EnsureArgumentIsNotDefault(second, nameof(second));
 
-      var (firstCount, secondCount) = (first.Count, second.Count);
-      var types = new Type[firstCount + secondCount];
-      Array.Copy(first.FieldTypes, types, firstCount);
-      Array.Copy(second.FieldTypes, 0, types, firstCount, secondCount);
-
       IsReadOnly = isReadOnly;
-      Descriptor = TupleDescriptor.Create(types);
+      Descriptor = first.ConcatWith(second);
       this.sources = (first, second);
     }
   }

Orm/Xtensive.Orm/Tuples/Transform/SegmentTransform.cs

@@ -79,9 +79,7 @@ public SegmentTransform(bool isReadOnly, TupleDescriptor sourceDescriptor, in Se
 
       IsReadOnly = isReadOnly;
 
-      var fields = new Type[segment.Length];
-      Array.Copy(sourceDescriptor.FieldTypes, segment.Offset, fields, 0, segment.Length);
-      Descriptor = TupleDescriptor.Create(fields);
+      Descriptor = sourceDescriptor.Segment(segment);
       this.segment = segment;
     }
   }

Orm/Xtensive.Orm/Tuples/TupleDescriptor.cs

@@ -34,9 +34,9 @@ namespace Xtensive.Tuples
     internal readonly PackedFieldDescriptor[] FieldDescriptors;
 
     [field: NonSerialized]
-    internal Type[] FieldTypes { get; }
+    private Type[] FieldTypes { get; }
 
-    #region IList members
+    #region IReadOnlyList members
 
     /// <inheritdoc/>
     public Type this[int fieldIndex]
@@ -69,6 +69,66 @@ IEnumerator IEnumerable.GetEnumerator()
 
     #endregion
 
+    /// <summary>
+    /// Creates tuple descriptor containing head of the current one.
+    /// </summary>
+    /// <param name="fieldCount">Head field count.</param>
+    /// <returns>
+    /// New tuple descriptor describing the specified set of fields.
+    /// </returns>
+    public TupleDescriptor Head(int fieldCount)
+    {
+      ArgumentValidator.EnsureArgumentIsInRange(fieldCount, 1, Count, nameof(fieldCount));
+      var fieldTypes = new Type[fieldCount];
+      Array.Copy(FieldTypes, 0, fieldTypes, 0, fieldCount);
+      return new TupleDescriptor(fieldTypes);
+    }
+
+    /// <summary>
+    /// Creates tuple descriptor containing tail of the current one.
+    /// </summary>
+    /// <param name="tailFieldCount">Tail field count.</param>
+    /// <returns>
+    /// New tuple descriptor describing the specified set of fields.
+    /// </returns>
+    public TupleDescriptor Tail(int tailFieldCount)
+    {
+      ArgumentValidator.EnsureArgumentIsInRange(tailFieldCount, 1, Count, nameof(tailFieldCount));
+      var fieldTypes = new Type[tailFieldCount];
+      Array.Copy(FieldTypes, Count - tailFieldCount, fieldTypes, 0, tailFieldCount);
+      return new TupleDescriptor(fieldTypes);
+    }
+
+    /// <summary>
+    /// Creates tuple descriptor containing segment of the current one
+    /// </summary>
+    /// <param name="segment">Offset and length of segment in form of Segment</param>
+    /// <returns>
+    /// New tuple descriptor describing the specified set of fields.
+    /// </returns>
+    public TupleDescriptor Segment(in Segment<int> segment)
+    {
+      var fields = new Type[segment.Length];
+      Array.Copy(FieldTypes, segment.Offset, fields, 0, segment.Length);
+
+      return new TupleDescriptor(fields);
+    }
+
+    /// <summary>
+    /// Concats fields of the current and the given descriptors to form new one.
+    /// </summary>
+    /// <param name="second">Tail fields descriptor.</param>
+    /// <returns>New tuple descriptor containing fields of the both given source descriptors.</returns>
+    public TupleDescriptor ConcatWith(in TupleDescriptor second)
+    {
+      var (firstCount, secondCount) = (Count, second.Count);
+      var types = new Type[firstCount + secondCount];
+      Array.Copy(FieldTypes, types, firstCount);
+      Array.Copy(second.FieldTypes, 0, types, firstCount, secondCount);
+
+      return new TupleDescriptor(types);
+    }
+
     #region IEquatable members, GetHashCode
 
     /// <inheritdoc/>
@@ -177,34 +237,6 @@ public static TupleDescriptor Create(Type[] fieldTypes)
       return new TupleDescriptor(fieldTypes);
     }
 
-    /// <summary>
-    /// Creates tuple descriptor containing head of the current one.
-    /// </summary>
-    /// <param name="fieldCount">Head field count.</param>
-    /// <returns>Either new or existing tuple descriptor
-    /// describing the specified set of fields.</returns>
-    public TupleDescriptor Head(int fieldCount)
-    {
-      ArgumentValidator.EnsureArgumentIsInRange(fieldCount, 1, Count, nameof(fieldCount));
-      var fieldTypes = new Type[fieldCount];
-      Array.Copy(FieldTypes, 0, fieldTypes, 0, fieldCount);
-      return new TupleDescriptor(fieldTypes);
-    }
-
-    /// <summary>
-    /// Creates tuple descriptor containing tail of the current one.
-    /// </summary>
-    /// <param name="tailFieldCount">Tail field count.</param>
-    /// <returns>Either new or existing tuple descriptor
-    /// describing the specified set of fields.</returns>
-    public TupleDescriptor Tail(int tailFieldCount)
-    {
-      ArgumentValidator.EnsureArgumentIsInRange(tailFieldCount, 1, Count, nameof(tailFieldCount));
-      var fieldTypes = new Type[tailFieldCount];
-      Array.Copy(FieldTypes, Count - tailFieldCount, fieldTypes, 0, tailFieldCount);
-      return new TupleDescriptor(fieldTypes);
-    }
-
     #endregion
 
     #region Create<...> methods (generic shortcuts)