Add support for Action<> lambdas (#293)

Fix #292

src/DynamicExpresso.Core/Lambda.cs

@@ -4,6 +4,7 @@
 using System.Linq.Expressions;
 using System.Reflection;
 using System.Runtime.ExceptionServices;
+using DynamicExpresso.Reflection;
 
 namespace DynamicExpresso
 {
@@ -151,14 +152,16 @@ public Expression<TDelegate> LambdaExpression<TDelegate>()
 
 		internal LambdaExpression LambdaExpression(Type delegateType)
 		{
+			var parameterExpressions = DeclaredParameters.Select(p => p.Expression).ToArray();
 			var types = delegateType.GetGenericArguments();
 
 			// return type
-			types[types.Length - 1] = _expression.Type;
+			if (delegateType.GetGenericTypeDefinition() == ReflectionExtensions.GetFuncType(parameterExpressions.Length))
+				types[types.Length - 1] = _expression.Type;
 
 			var genericType = delegateType.GetGenericTypeDefinition();
 			var inferredDelegateType = genericType.MakeGenericType(types);
-			return Expression.Lambda(inferredDelegateType, _expression, DeclaredParameters.Select(p => p.Expression).ToArray());
+			return Expression.Lambda(inferredDelegateType, _expression, parameterExpressions);
 		}
 	}
 }

src/DynamicExpresso.Core/Parsing/Parser.cs

@@ -11,6 +11,7 @@
 using System.Security;
 using System.Text;
 using DynamicExpresso.Exceptions;
+using DynamicExpresso.Reflection;
 using DynamicExpresso.Resources;
 using Microsoft.CSharp.RuntimeBinder;
 
@@ -2348,9 +2349,6 @@ private static bool CheckIfMethodIsApplicableAndPrepareIt(MethodData method, Exp
 
 		private static LambdaExpression GenerateLambdaFromInterpreterExpression(InterpreterExpression ie, Type delegateType)
 		{
-			if (delegateType.GetGenericArguments().Length != ie.Parameters.Count + 1)
-				return null;
-
 			return ie.EvalAs(delegateType);
 		}
 
@@ -3453,7 +3451,7 @@ public InterpreterExpression(ParserArguments parserArguments, string expressionT
 				}
 
 				// prior to evaluation, we don't know the generic arguments types
-				_type = typeof(Func<>).Assembly.GetType($"System.Func`{parameters.Length + 1}");
+				_type = ReflectionExtensions.GetFuncType(parameters.Length);
 			}
 
 			public IList<Parameter> Parameters
@@ -3468,16 +3466,22 @@ public override Type Type
 
 			internal LambdaExpression EvalAs(Type delegateType)
 			{
+				if (!IsCompatibleWithDelegate(delegateType))
+					return null;
+
 				var lambdaExpr = _interpreter.ParseAsExpression(delegateType, _expressionText, _parameters.Select(p => p.Name).ToArray());
 				_type = lambdaExpr.Type;
 				return lambdaExpr;
 			}
 
 			internal bool IsCompatibleWithDelegate(Type target)
 			{
-				return target.IsGenericType
-					&& target.BaseType == typeof(MulticastDelegate)
-					&& target.GetGenericArguments().Length == _parameters.Count + 1;
+				if (!target.IsGenericType || target.BaseType != typeof(MulticastDelegate))
+					return false;
+
+				var genericTypeDefinition = target.GetGenericTypeDefinition();
+				return genericTypeDefinition == ReflectionExtensions.GetFuncType(_parameters.Count)
+					|| genericTypeDefinition == ReflectionExtensions.GetActionType(_parameters.Count);
 			}
 		}
 

src/DynamicExpresso.Core/Reflection/ReflectionExtensions.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
@@ -56,5 +56,16 @@ public DelegateInfo(Type returnType, Parameter[] parameters)
 			public Type ReturnType { get; private set; }
 			public Parameter[] Parameters { get; private set; }
 		}
+
+		public static Type GetFuncType(int parameterCount)
+		{
+			// +1 for the return type
+			return typeof(Func<>).Assembly.GetType($"System.Func`{parameterCount + 1}");
+		}
+
+		public static Type GetActionType(int parameterCount)
+		{
+			return typeof(Action<>).Assembly.GetType($"System.Action`{parameterCount}");
+		}
 	}
 }

test/DynamicExpresso.UnitTest/GithubIssues.cs

@@ -663,7 +663,7 @@ public class PageType
 			public string PageName { get; set; }
 			public int VisualCount { get; set; }
 		}
-    
+
 		[Test]
 		public void GitHub_Issue_261()
 		{
@@ -749,10 +749,38 @@ public void GitHub_Issue_287()
 			Assert.AreEqual(str is IEnumerable<int[]>[][], interpreter.Eval("(str is IEnumerable<int[]>[][])"));
 			Assert.AreEqual(str is IEnumerable<int?[][]>[][], interpreter.Eval("(str is IEnumerable<int?[][]>[][])"));
 		}
+
+		private class Npc
+		{
+			public int money { get; set; }
+		}
+
+		[Test]
+		public void GitHub_Issue_292()
+		{
+			var interpreter = new Interpreter(InterpreterOptions.LambdaExpressions);
+
+			var testnpcs = new List<Npc>();
+			for (var i = 0; i < 5; i++)
+				testnpcs.Add(new Npc { money = 0 });
+
+			interpreter.Reference(typeof(GithubIssuesTestExtensionsMethods));
+			interpreter.SetVariable("NearNpcs", testnpcs);
+
+			var func = interpreter.ParseAsDelegate<Action>("NearNpcs.ActionToAll(n => n.money = 10)");
+			func.Invoke();
+
+			Assert.IsTrue(testnpcs.All(n => n.money == 10));
+		}
 	}
 
 	internal static class GithubIssuesTestExtensionsMethods
 	{
 		public static bool IsInFuture(this DateTimeOffset date) => date > DateTimeOffset.UtcNow;
+		public static void ActionToAll<T>(this IEnumerable<T> source, Action<T> action)
+		{
+			foreach (var item in source)
+				action(item);
+		}
 	}
 }

test/DynamicExpresso.UnitTest/LambdaExpressionTest.cs

@@ -421,6 +421,41 @@ public void Lambda_CannotUseDuplicateParameterInSubLambda()
 							)))", new Parameter("root", typeof(NestedLambdaTestClass))));
 		}
 
+		private class Npc
+		{
+			public int Money { get; set; }
+			public void AddMoney(Action<Npc, int, string> action)
+			{
+				action(this, 10, "test");
+			}
+		}
+
+		[Test]
+		public void Lambda_ShouldAllowActionLambda()
+		{
+			var target = new Interpreter(InterpreterOptions.LambdaExpressions);
+
+			var list = new List<Npc>() { new Npc { Money = 10 } };
+			target.SetVariable("list", list);
+
+			var result = target.Eval(@"list.ForEach(n => n.Money = 5)");
+			Assert.IsNull(result);
+			Assert.AreEqual(5, list[0].Money);
+		}
+
+		[Test]
+		public void Lambda_MultipleActionLambdaParameters()
+		{
+			var target = new Interpreter(InterpreterOptions.LambdaExpressions);
+
+			var npc = new Npc { Money = 10 };
+			target.SetVariable("npc", npc);
+
+			var result = target.Eval(@"npc.AddMoney((n, i, str) => n.Money = i + str.Length)");
+			Assert.IsNull(result);
+			Assert.AreEqual(14, npc.Money);
+		}
+
 		private static NestedLambdaTestClass BuildNestedTestClassHierarchy()
 		{
 			return new NestedLambdaTestClass()