internal static Expression GetCall(this Expression expression)
{
var ei = new ExpressionInterceptor();
MethodCallExpression call = null;
ei.MethodCall += new Func <MethodCallExpression, MethodCallExpression>(x =>
{
call = x;
return(x);
});
ei.Visit(expression);
return(call);
}
static void Main(string[] args)
{
var range = Enumerable.Range(0, 10).AsQueryable().Select(x => new { A = x, B = x % 2 == 0, C = x.ToString() }).Where(x => !x.B).Select(x => x.A).OrderBy(x => x.ToString()).Take(1);
var interceptor = new ExpressionInterceptor();
interceptor.Expression += (source) =>
{
var @ran = range;
var @int = interceptor;
return (source);
};
interceptor.Visit(range.Expression);
var children = range.Expression.GetChildren();
var lettersArray = new String[] { "A", "B", "C" }; //a data source
var lettersQuery = lettersArray.AsQueryable().Where(x => x == "A").OrderByDescending(x => x).Select(x => x.ToUpper()); //a silly query
var lettersInterceptedQuery = interceptor.Visit<String, MethodCallExpression>(lettersQuery, x =>
{
if (x.Method.Name == "ToUpper")
{
//change from uppercase to lowercase
x = Expression.Call(x.Object, typeof(String).GetMethods().First(y => y.Name == "ToLower"));
}
return (x);
});
lettersInterceptedQuery = interceptor.Visit<String, BinaryExpression>(lettersInterceptedQuery, x =>
{
//change from qual to not equal
x = Expression.MakeBinary(ExpressionType.NotEqual, x.Left, x.Right);
return (x);
});
var lettersExpressions = interceptor.Flatten(lettersQuery); //all expressions found
var lettersList = lettersQuery.ToList(); //"A"
var lettersInterceptedList = lettersInterceptedQuery.ToList(); //"c", "b"
}