private object Eval(string expression, Parameter[] pars)
{
Delegate lambda;
if (!_lambdaCache.TryGetValue(expression, out lambda))
{
var parameters = pars.Select(p => p.ParameterExpression).ToArray();
lambda = DynamicExpression.ParseLambda(parameters, typeof(object), expression, _variables).Compile();
_lambdaCache.Add(expression, lambda);
}
return(lambda.DynamicInvoke(pars.Select(p => p.Value).ToArray()));
}
public SubtotalSummaryFunc GetFunc()
{
var func = new SubtotalSummaryFunc(Name, Column);
if (HasParameter("Over"))
{
func.GetExpression = type =>
{
var par = Expression.Parameter(type, "item");
return(DynamicExpression.ParseLambda(new[] { par }, null, GetParameter("Over")));
}
}
;
func.DataSource = DataSource;
return(func);
}
}
public void ExpressionParseTest()
{
var customers = new Customer[]
{
new Customer {
Id = 1, Name = "Customer1"
},
new Customer {
Id = 2, Name = "Customer2"
}
}.AsEnumerable();
string query = "customers.Where(c => (c.Id = 1)).OrderBy(c=>(c.Name)).Select(c=>(c))";
var lambda = DynamicExpression.ParseLambda(new [] { Expression.Parameter(customers.GetType(), "customers") }, null, query);
var dlg = lambda.Compile();
dlg.DynamicInvoke(customers).Should().BeAssignableTo <IEnumerable <Customer> >();
((IEnumerable <Customer>)dlg.DynamicInvoke(customers)).Should().HaveCount(1);
((IEnumerable <Customer>)dlg.DynamicInvoke(customers)).First().Id.Should().Be(1);
}
