C＃表達式樹綁定

Question

所以我想做的是使用表達式樹將謂詞應用於集合中的每個值（讀取映射或list.All（predicate））。 看來我沒有使輸入參數綁定到All提供的值的謂詞，而且我有些困惑。 這是我正在使用的代碼（使用linqpad）：

public class SomeType
{
  public IEnumerable<bool> Collection { get; set; }
}

void Main()
{
  var list = new SomeType {
    Collection = new List<bool> { true, true, true }
  };
  var functor = Compiler((SomeType t) => t.Collection, (bool x) => x);
  functor(list).Dump();
}

MethodInfo FindMethod<TInput>(Type location, string name)
{
    var handle = location
        .GetMethods(BindingFlags.Static | BindingFlags.Public)
        .Where(method => method.Name == name).First();

    return handle.MakeGenericMethod(typeof(TInput));
}

Predicate<TObject> Compiler<TObject, TProperty>(
    Expression<Func<TObject, IEnumerable<TProperty>>> selector, 
    Expression<Predicate<TProperty>> predicate)
{
    var query = FindMethod<TProperty>(typeof(Enumerable), "All");
    var expression = Expression.Call(query,
        new Expression[] {
            Expression.Invoke(selector, selector.Parameters),
            Expression.Lambda<Func<TProperty, bool>>(predicate.Body,
                        Expression.Parameter(typeof(TProperty))),
        });         

    return Expression.Lambda<Predicate<TObject>>(expression,
        selector.Parameters).Compile();
}

謝謝，很抱歉，如果在另一個問題中回答了這個問題（我花了一段時間）。

Answer 1

確實可以，但是我不得不將Predicate<TObject>更改為Func<TObject, bool> 。 如果您願意，我可以嘗試將其改回。

static Predicate<TObject> Compiler<TObject, TProperty>(
    Expression<Func<TObject, IEnumerable<TProperty>>> selector,
    Expression<Func<TProperty, bool>> predicate)
{
    var query = FindMethod<TProperty>(typeof(Enumerable), "All");
    var expression = Expression.Call(
        query,
        Expression.Invoke(selector, selector.Parameters), 
        predicate);

    return Expression
        .Lambda<Predicate<TObject>>(expression, selector.Parameters)
        .Compile();
}

5分鍾后...如果您真的想使用Predicate<TObject> ...

static Predicate<TObject> Compiler<TObject, TProperty>(
    Expression<Func<TObject, IEnumerable<TProperty>>> selector,
    Expression<Predicate<TProperty>> predicate)
{
    var query = FindMethod<TProperty>(typeof(Enumerable), "All");

    var predicateAsFunc = Expression.Lambda<Func<TProperty, bool>>(
        predicate.Body, 
        predicate.Parameters);

    var expression = Expression.Call(
        query,
        Expression.Invoke(selector, selector.Parameters), 
        predicateAsFunc);

    return Expression
        .Lambda<Predicate<TObject>>(expression, selector.Parameters)
        .Compile();
}