feat: start map Override

Author: DocSvartz

src/Mapster/TypeAdapterSetter.cs

@@ -22,6 +22,16 @@ public TypeAdapterSetter(TypeAdapterSettings settings, TypeAdapterConfig config)
             Settings = settings;
             Config = config;
         }
+
+        internal static TypeAdapterSetter CreateMapTypeOverride()
+        {
+            return new TypeAdapterSetter(new TypeAdapterSettings(), null);
+        }
+
+        internal static TypeAdapterSetter<TSource, TDestination> CreateMapTypeOverride<TSource, TDestination>()
+        {
+            return new TypeAdapterSetter<TSource, TDestination>(new TypeAdapterSettings(), null);
+        }
     }
     public static class TypeAdapterSetterExtensions
     {
@@ -629,6 +639,40 @@ public TypeAdapterSetter<TDestination> IgnoredRemove(params Expression<Func<TDes
 
         #endregion
 
+        public TypeAdapterSetter<TSource, TDestination> MapOverride<TDestinationMember, TSourceMember>(
+            Expression<Func<TDestination, TDestinationMember>> member,
+            Expression<Func<TSource, TSourceMember>> source,
+            Action<TypeAdapterSetter<TSourceMember, TDestinationMember>>? configAction = null)
+        {
+            this.CheckCompiled();
+
+            var invoker = Expression.Lambda(source.Body, Expression.Parameter(typeof(object)));
+            if (member.IsIdentity())
+            {
+                Settings.ExtraSources.Add(invoker);
+                return this;
+            }
+
+            if (configAction != null)
+            {
+                var settings = TypeAdapterSetter.CreateMapTypeOverride<TSourceMember, TDestinationMember>();
+
+                configAction(settings);
+
+            }
+
+
+            Settings.Resolvers.Add(new InvokerModel
+            {
+                DestinationMemberName = member.GetMemberPath()!,
+                Invoker = invoker,
+                Condition = null
+            });
+            return this;
+        }
+
+
+
         public TypeAdapterSetter<TSource, TDestination> IgnoreIf(
             Expression<Func<TSource, TDestination, bool>> condition,
             params Expression<Func<TDestination, object>>[] members)