Add composite expression fragment translator

src/EFCore.PG/Extensions/NpgsqlServiceCollectionExtensions.cs

@@ -112,6 +112,7 @@ public static IServiceCollection AddEntityFrameworkNpgsql([NotNull] this IServic
                     .TryAdd<IQueryCompilationContextFactory, NpgsqlQueryCompilationContextFactory>()
                     .TryAdd<IMemberTranslator, NpgsqlCompositeMemberTranslator>()
                     .TryAdd<ICompositeMethodCallTranslator, NpgsqlCompositeMethodCallTranslator>()
+                    .TryAdd<IExpressionFragmentTranslator, NpgsqlCompositeExpressionFragmentTranslator>()
                     .TryAdd<IQuerySqlGeneratorFactory, NpgsqlQuerySqlGeneratorFactory>()
                     .TryAdd<ISqlTranslatingExpressionVisitorFactory, NpgsqlSqlTranslatingExpressionVisitorFactory>()
                     .TryAdd<ISingletonOptions, INpgsqlOptions>(p => p.GetService<INpgsqlOptions>())

src/EFCore.PG/Query/ExpressionTranslators/Internal/NpgsqlCompositeExpressionFragmentTranslator.cs

@@ -0,0 +1,59 @@
+#region License
+
+// The PostgreSQL License
+//
+// Copyright (C) 2016 The Npgsql Development Team
+//
+// Permission to use, copy, modify, and distribute this software and its
+// documentation for any purpose, without fee, and without a written
+// agreement is hereby granted, provided that the above copyright notice
+// and this paragraph and the following two paragraphs appear in all copies.
+//
+// IN NO EVENT SHALL THE NPGSQL DEVELOPMENT TEAM BE LIABLE TO ANY PARTY
+// FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
+// INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
+// DOCUMENTATION, EVEN IF THE NPGSQL DEVELOPMENT TEAM HAS BEEN ADVISED OF
+// THE POSSIBILITY OF SUCH DAMAGE.
+//
+// THE NPGSQL DEVELOPMENT TEAM SPECIFICALLY DISCLAIMS ANY WARRANTIES,
+// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
+// ON AN "AS IS" BASIS, AND THE NPGSQL DEVELOPMENT TEAM HAS NO OBLIGATIONS
+// TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+
+#endregion
+
+using System.Collections.Generic;
+using JetBrains.Annotations;
+using Microsoft.EntityFrameworkCore.Query.ExpressionTranslators;
+
+namespace Npgsql.EntityFrameworkCore.PostgreSQL.Query.ExpressionTranslators.Internal
+{
+    /// <summary>
+    /// A composite expression fragment translator that dispatches to multiple specialized translators specific to Npgsql.
+    /// </summary>
+    public class NpgsqlCompositeExpressionFragmentTranslator : RelationalCompositeExpressionFragmentTranslator
+    {
+        /// <summary>
+        /// The default expression fragment translators registered by the Npgsql provider.
+        /// </summary>
+        [NotNull] [ItemNotNull] static readonly IExpressionFragmentTranslator[] ExpressionFragmentTranslators =
+            {};
+
+        /// <inheritdoc />
+        public NpgsqlCompositeExpressionFragmentTranslator(
+            [NotNull] RelationalCompositeExpressionFragmentTranslatorDependencies dependencies)
+            : base(dependencies)
+        {
+            // ReSharper disable once DoNotCallOverridableMethodsInConstructor
+            AddTranslators(ExpressionFragmentTranslators);
+        }
+
+        /// <summary>
+        /// Adds additional dispatches to the translators list.
+        /// </summary>
+        /// <param name="translators">The translators.</param>
+        public new virtual void AddTranslators([NotNull] IEnumerable<IExpressionFragmentTranslator> translators)
+            => base.AddTranslators(translators);
+    }
+}