expression-trees

I'm currently trying to parse math expression into expression tree. But I'm stuck on the stage where I need to implement functions and negates. I don't understand logic to do it using Shunting-Yard algorithm. What I currently want to do is to support Negates, like -(x+5) Function calls, like min(x,y) Power just after function name, like cos^2(x) Implicit multiplication, like 2x is same as 2*x Scientific notation Constants e and pi Can somebody tell me hints how to implement this? An working , PSR-0 compatible implementation of the shunting yard algorithm can be found here: https://github.com

I know the compiler can't convert an async lambda expression to an expression tree, but is it possible to generate the expression tree manually ? var expr = Expression.Lambda<Func<Task>>( // how do I use 'await' in the body here? ); var func = expr.Compile(); I can't find any method related to async or await in the Expression class, but perhaps there's another way? await involves significant compiler re-writing; the generated IL is quite dissimilar to the original C#, with variable hoisting (onto a class) and branching, tasks, continuations, etc. It certainly isn't something that can be

Are LINQ expression trees proper trees, as in, graphs (directed or not, wikipedia does not seem too agree) without cycles? What is the root of an expression tree from the following C# expression? (string s) => s.Length The expression tree looks like this, with "->" denoting the name of the property of the node the other node is accessible through. ->Parameters[0] Lambda---------Parameter(string s) \ / \->Body /->Expression \ / Member(Length) When using ExpressionVisitor to visit the LambdaExpression, the ParameterExpression is visited twice. Is there a way to use the ExpressionVisitor to visit

public class Job { public string Name { get; set; } public int Salary { get; set; } } public class Employee { public string Name { get; set; } public Job Job { get; set; } } If I want to create an expression tree of a member access to Employee.Name this is what I do: var param = Expression.Parameter(type, "x"); var memberAccess = Expression.PropertyOrField(param, memberName); return Expression.Lambda<Func<TModel, TMember>>(memberAccess, param); What is the equivalent to this for a member access to Employee.Job.Salary ? You need: var jobProperty = Expression.PropertyOrField(param, "Job"); var

Here's the scenario: Silverlight 4.0, DataGrid, PagedCollectionView itemssource. The objective is to apply a Filter to the PCV. The filter needs to be a Predicate<object>(Method) - where Method implements some logic against the object and returns true/false for inclusion. What I have is a need to optionally include 3 different criteria in the filter logic and explicit code quickly gets ugly. We don't want that, do we? So I see that there is a way to build an expression tree using PredicateBuilder and pass that into Linq.Where, a la: IQueryable<Product> SearchProducts (params string[] keywords)

I tried to answer this question but failed: So let's take the original query: var result = db.Employees.GroupBy(x => x.Region) .Select(g => new { Region = g.Key, Avg = g.Average(x => x.BaseSalary)}); Works fine. Now we want to dynamically decide what to average. I try to create the lambda for Average dynamically: string property = "BaseSalary"; var parameter = Expression.Parameter(typeof(Employee)); var propAccess = Expression.PropertyOrField(parameter, property); var expression = (Expression<Func<Employee,int?>>)Expression.Lambda(propAccess, parameter); var lambda = expression.Compile(); and