Fix user defined operator resolution when the operator is defined on …

…the right operand's type.

src/DynamicExpresso.Core/Parsing/Parser.cs

@@ -1937,6 +1937,10 @@ private MethodData FindBinaryOperator(string operatorName, Expression left, Expr
  // we found a matching user defined operator on either type, but it might be the same method
  if (userDefinedOperator != null && rightOperator != null && !ReferenceEquals(userDefinedOperator.MethodBase, rightOperator.MethodBase))
  throw error;
+
+ // we didn't find an operator on the left type, but we found one on the right type
+ if (userDefinedOperator == null && rightOperator != null)
+ userDefinedOperator = rightOperator;
  }
 
  return userDefinedOperator;

test/DynamicExpresso.UnitTest/OperatorsTest.cs

@@ -567,6 +567,16 @@ public ClassWithOverloadedBinaryOperators(int value)
  return new ClassWithOverloadedBinaryOperators(-instance._value);
  }
 
+ public static ClassWithOverloadedBinaryOperators operator *(ClassWithOverloadedBinaryOperators left, int right)
+ {
+ return new ClassWithOverloadedBinaryOperators(left._value * right);
+ }
+
+ public static ClassWithOverloadedBinaryOperators operator *(int left, ClassWithOverloadedBinaryOperators right)
+ {
+ return new ClassWithOverloadedBinaryOperators(left * right._value);
+ }
+
  public override bool Equals(object obj)
  {
  if (obj == null)
@@ -613,6 +623,13 @@ public void Can_use_overloaded_operators_on_derived_class()
  var z = new DerivedClassWithOverloadedBinaryOperators(10);
  Assert.IsTrue((x + z) == "13");
  Assert.IsTrue(target.Eval<bool>("(x + z) == \"13\"", new Parameter("z", z)));
+
+ Assert.IsTrue((x * 4) == "12");
+ Assert.IsTrue(target.Eval<bool>("(x * 4) == \"12\""));
+
+ // ensure a user defined operator can be found if it's on the right side operand's type
+ Assert.IsTrue((4 * x) == "12");
+ Assert.IsTrue(target.Eval<bool>("(4 * x) == \"12\""));
  }
 
  [Test]