Support for mapping through circular references via link objects / Removing unused usings

Author: SteveWilkes

AgileMapper.PerformanceTester/Program.cs

@@ -5,7 +5,7 @@
 // AgileMapper and AutoMapper perform better with this attribute applied,
 // but ExpressMapper and Mapster throw exceptions - uncomment to test the
 // Agile and Auto at their fastest:
-//[assembly: System.Security.AllowPartiallyTrustedCallers]
+[assembly: System.Security.AllowPartiallyTrustedCallers]
 
 namespace AgileObjects.AgileMapper.PerformanceTester
 {

AgileMapper.UnitTests/WhenMappingCircularReferences.cs

@@ -2,7 +2,6 @@
 {
     using System;
     using System.Collections.Generic;
-    using System.Linq;
     using AgileMapper.Extensions;
     using Shouldly;
     using TestClasses;
@@ -261,6 +260,16 @@ public void ShouldMapMultiplyRecursiveRelationships()
             }
         }
 
+        [Fact]
+        public void ShouldGenerateAMappingPlanForLinkRelationships()
+        {
+            var plan = Mapper.GetPlanFor<Video>().Over<Video>();
+
+            plan.ShouldNotBeNull();
+            plan.ShouldContain("WhenMappingCircularReferences.Video -> WhenMappingCircularReferences.Video");
+            plan.ShouldContain(".MapRecursion(");
+        }
+
         [Fact]
         public void ShouldGenerateAMappingPlanForAOneToOneRelationship()
         {
@@ -304,6 +313,47 @@ internal class MultipleRecursor
             public List<MultipleRecursor> ChildRecursors { get; set; }
         }
 
+        internal class Video
+        {
+            public IEnumerable<VideoPresenter> Presenters { get; set; }
+        }
+
+        internal class VideoPresenter
+        {
+            public Video Video { get; set; }
+
+            public Presenter Presenter { get; set; }
+        }
+
+        internal class Presenter
+        {
+            public IEnumerable<PresenterExpertise> Expertises { get; set; }
+        }
+
+        internal class PresenterExpertise
+        {
+            public Presenter Presenter { get; set; }
+
+            public Expertise Expertise { get; set; }
+        }
+
+        internal class Expertise
+        {
+            public Subject Subject { get; set; }
+        }
+
+        internal class Subject
+        {
+            public IEnumerable<SubjectPresenter> Presenters { get; set; }
+        }
+
+        internal class SubjectPresenter
+        {
+            public Subject Subject { get; set; }
+
+            public Presenter Presenter { get; set; }
+        }
+
         #endregion
     }
 }

AgileMapper/DataSources/DataSourceSet.cs

@@ -2,10 +2,9 @@ namespace AgileObjects.AgileMapper.DataSources
 {
     using System.Collections;
     using System.Collections.Generic;
-#if !NET_STANDARD
-    using System.Diagnostics.CodeAnalysis;
+#if !NET_STANDARD
+    using System.Diagnostics.CodeAnalysis;
 #endif
-    using System.Linq;
     using System.Linq.Expressions;
     using Extensions;
     using Members;

AgileMapper/Members/DictionaryEntrySourceMember.cs

@@ -4,7 +4,6 @@ namespace AgileObjects.AgileMapper.Members
 #if !NET_STANDARD
     using System.Diagnostics.CodeAnalysis;
 #endif
-    using System.Linq;
     using System.Linq.Expressions;
     using Extensions;
     using ReadableExpressions.Extensions;

AgileMapper/Members/MemberMapperDataExtensions.cs

@@ -126,7 +126,8 @@ public static bool TargetMemberEverRecurses(this IMemberMapperData mapperData)
                     // the RecursionMapperFunc which performs the recursive mapping:
                     return TargetMemberIsRecursionWithin(
                         parentMapperData.TargetMember,
-                        mapperData.TargetMember.LeafMember);
+                        mapperData.TargetMember.LeafMember,
+                        new List<Type>());
                 }
 
                 parentMapperData = parentMapperData.Parent;
@@ -135,7 +136,10 @@ public static bool TargetMemberEverRecurses(this IMemberMapperData mapperData)
             return false;
         }
 
-        private static bool TargetMemberIsRecursionWithin(QualifiedMember parentMember, Member member)
+        private static bool TargetMemberIsRecursionWithin(
+            QualifiedMember parentMember,
+            Member member,
+            ICollection<Type> checkedTypes)
         {
             while (true)
             {
@@ -148,7 +152,7 @@ private static bool TargetMemberIsRecursionWithin(QualifiedMember parentMember,
                 var nonSimpleChildMembers = GlobalContext.Instance
                     .MemberFinder
                     .GetTargetMembers(parentMember.Type)
-                    .Where(m => !m.IsSimple)
+                    .Where(m => !m.IsSimple && !checkedTypes.Contains(m.IsEnumerable ? m.ElementType : m.Type))
                     .ToArray();
 
                 if (nonSimpleChildMembers.None())
@@ -165,7 +169,10 @@ private static bool TargetMemberIsRecursionWithin(QualifiedMember parentMember,
                     return childMember.IsRecursion;
                 }
 
-                return nonSimpleChildMembers.Any(m => TargetMemberIsRecursionWithin(parentMember.Append(m), member));
+                checkedTypes.Add(parentMember.Type);
+
+                return nonSimpleChildMembers.Any(m =>
+                    TargetMemberIsRecursionWithin(parentMember.Append(m), member, checkedTypes));
             }
         }
 
@@ -375,6 +382,7 @@ private static Expression GetAccess(
                     .MakeGenericType(contextTypes[0], contextTypes[1])
                     .GetProperty(propertyName);
 
+            // ReSharper disable once AssignNullToNotNullAttribute
             return Expression.Property(contextAccess, property);
         }
 

AgileMapper/Members/QualifiedMember.cs

@@ -2,6 +2,7 @@ namespace AgileObjects.AgileMapper.Members
 {
     using System;
     using System.Collections.Generic;
+    using System.Diagnostics;
 #if !NET_STANDARD
     using System.Diagnostics.CodeAnalysis;
 #endif
@@ -210,6 +211,7 @@ public bool IsRecursionRoot()
 
         IQualifiedMember IQualifiedMember.Append(Member childMember) => Append(childMember);
 
+        [DebuggerStepThrough]
         public QualifiedMember Append(Member childMember)
             => _childMemberCache.GetOrAdd(childMember, CreateChildMember);
 

AgileMapper/ObjectPopulation/ComplexTypes/SourceDictionaryShortCircuitFactory.cs

@@ -2,7 +2,9 @@ namespace AgileObjects.AgileMapper.ObjectPopulation.ComplexTypes
 {
     using System.Collections.Generic;
     using System.Linq.Expressions;
+#if NET_STANDARD
     using System.Reflection;
+#endif
     using DataSources;
     using Extensions;
     using Members;

AgileMapper/ObjectPopulation/DerivedMappingFactory.cs

@@ -2,7 +2,6 @@
 {
     using System;
     using System.Linq.Expressions;
-    using System.Reflection;
     using Extensions;
     using Members;
 

AgileMapper/ObjectPopulation/MappingDataFactory.cs

@@ -1,6 +1,5 @@
 namespace AgileObjects.AgileMapper.ObjectPopulation
 {
-    using System.Linq;
     using System.Reflection;
     using Enumerables;
     using Extensions;