Add more optimized expression overloads for setting fields

Author: mythz

src/ServiceStack.Text/Common/JsDelegates.cs

@@ -28,6 +28,10 @@ namespace ServiceStack.Text.Common
 
     public delegate void SetPropertyDelegate(object instance, object propertyValue);
 
+    public delegate void SetPropertyDelegateRef(ref object instance, object propertyValue);
+
+    public delegate void SetPropertyDelegateRefGeneric<T>(ref T instance, object value);
+
     public delegate object ParseStringDelegate(string stringValue);
 
     public delegate object ConvertObjectDelegate(object fromObject);

src/ServiceStack.Text/Reflection/StaticAccessors.cs

@@ -15,6 +15,7 @@
 using System.Reflection;
 using System.Threading;
 using ServiceStack.Text;
+using ServiceStack.Text.Common;
 #if !XBOX
 using System.Linq.Expressions;
 #endif
@@ -181,6 +182,25 @@ public static Action<T, object> GetValueSetter<T>(this PropertyInfo propertyInfo
             ).Compile();
         }
 
+        public static Action<object, object> GetValueSetter(this FieldInfo fieldInfo, Type instanceType)
+        {
+            var instance = Expression.Parameter(typeof(object), "i");
+            var argument = Expression.Parameter(typeof(object), "a");
+
+            var field = instanceType != fieldInfo.DeclaringType
+                ? Expression.Field(Expression.TypeAs(instance, fieldInfo.DeclaringType), fieldInfo)
+                : Expression.Field(Expression.Convert(instance, instanceType), fieldInfo);
+
+            var setterCall = Expression.Assign(
+                field,
+                Expression.Convert(argument, fieldInfo.FieldType));
+
+            return Expression.Lambda<Action<object, object>>
+            (
+                setterCall, instance, argument
+            ).Compile();
+        }
+
         public static Action<T, object> GetValueSetter<T>(this FieldInfo fieldInfo)
         {
             var instance = Expression.Parameter(typeof(T), "i");
@@ -199,6 +219,25 @@ public static Action<T, object> GetValueSetter<T>(this FieldInfo fieldInfo)
                 setterCall, instance, argument
             ).Compile();
         }
+
+        public static SetPropertyDelegateRefGeneric<T> GetValueSetterGenericRef<T>(this FieldInfo fieldInfo)
+        {
+            var instance = Expression.Parameter(typeof(T).MakeByRefType(), "i");
+            var argument = Expression.Parameter(typeof(object), "a");
+
+            var field = typeof(T) != fieldInfo.DeclaringType
+                ? Expression.Field(Expression.TypeAs(instance, fieldInfo.DeclaringType), fieldInfo)
+                : Expression.Field(instance, fieldInfo);
+
+            var setterCall = Expression.Assign(
+                field,
+                Expression.Convert(argument, fieldInfo.FieldType));
+
+            return Expression.Lambda<SetPropertyDelegateRefGeneric<T>>
+            (
+                setterCall, instance, argument
+            ).Compile();
+        }
 #endif
 
     }