How to write List All method using expression trees?

I have below code snippet.

var list= new List<CustomClass>(){ new CustomClass(){Id=10}};
var result= list.All(a=>a.Id==10);

How can we write it in an Expression Tree?

Purpose: It's part of a bigger expression tree logic which we are implementing, I am just stuck at generating the expression tree for "All" method of the list.

Thanks

Solution

It isn't exactly clear what you are trying to do, but let's start from here...

This is the Enumerable.All method:

static readonly MethodInfo allTSource = (from x in typeof(Enumerable).GetMethods(BindingFlags.Static | BindingFlags.Public)
                                         where x.Name == nameof(Enumerable.All)
                                         let args = x.GetGenericArguments()
                                         where args.Length == 1
                                         let pars = x.GetParameters()
                                         where pars.Length == 2 &&
                                             pars[0].ParameterType == typeof(IEnumerable<>).MakeGenericType(args[0]) &&
                                             pars[1].ParameterType == typeof(Func<,>).MakeGenericType(args[0], typeof(bool))
                                         select x).Single();

Then the lambda expression used in .All(...):

// a => 
var par = Expression.Parameter(typeof(CustomClass), "a");

// a.Id
var id = Expression.Property(par, nameof(CustomClass.Id));

// 10
var val = Expression.Constant(10);

// a.Id == 10
var eq = Expression.Equal(id, val);

// a => a.Id == 10
var lambda = Expression.Lambda<Func<CustomClass, bool>>(eq, par);

Then the problem: it isn't clear if the list is a constant or an external expression... I don't know how to connect my code to yours... Let's say for simplicity that it is a constant:

// Unclear what lst should be, a parameter of an external lambda or a constant
var lst = Expression.Constant(list);

// list.All(...)
var all = Expression.Call(allTSource.MakeGenericMethod(typeof(CustomClass)), lst, lambda);

// () => list.All(...)
Expression<Func<bool>> exp = Expression.Lambda<Func<bool>>(all);
Func<bool> fn = exp.Compile();
bool res = fn();