Convert string to C# Conditional operator [closed]

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I'd like convert string to ConditionalOperator, few sample :

"and" to &&
"or" to ||
"greatherthan" to >=
"contains" to .Contains

Something like this :

public static class Extension
{
    public static Operator ConditionalOperator(this string logic)
    {
        switch (logic)
        {
            case "and": return   // return && conditionaloperator
            case "or": return    // return || conditionaloperator
            case "greatherthan": return // return >= conditionaloperator
        }
    }
}

The second argument is not all the time a string but can be int, double, bool, ...

I'd like build something like : ConditionalOperator("==", "StringToSearch") return a Func<>

Do you have an idea how to do this ?

Thanks,

Update 1, to clarify: I received a list of object "Filter"

The "FilterOperator" all possible values for a CondtionalOperator.

What is Operator or Opertor? What is the second argument? — shingo
– shingo, Commented Sep 10, 2023 at 8:13
@StephenRoss I read this post but I don't understand where "Operator" comes from Operator.LessThan<T>; — TheBoubou
– TheBoubou, Commented Sep 10, 2023 at 8:19

Charlieface · Accepted Answer · 2023-09-10 09:00:20Z

1

You can use generics

public static bool Operator(string logic, T x, T y) where T : IComparable<T>
{
     var compare = Comparer<T>.Default.Compare(x, y);
     return logic switch
     {
         ">" => compare > 0,
         "<" => compare < 0,
         "==" => compare == 0,
         _ => throw new Exception("invalid logic"),
     };
 }

Optionally you could pass an explicit IComparer

public static bool Operator(string logic, T x, T y, IComparer<T> comparer)
{
     var compare = comparer.Compare(x, y);
     return logic switch
     {
         ">" => compare > 0,
         "<" => compare < 0,
         "==" => compare == 0,
         _ => throw new Exception("invalid logic"),
     };
 }

To return a Func<T, T, bool> you can just do

public static Func<T, T, bool> Operator(string logic, T x, T y, IComparer<T> comparer)
{
     return logic switch
     {
         ">" => (x, y) => comparer.Compare(x, y) > 0,
         "<" => (x, y) => comparer.Compare(x, y) < 0,
         "==" => (x, y) => comparer.Compare(x, y) == 0,
         _ => throw new Exception("invalid logic"),
     };
 }

For string.Contains you should probably make a separate overload just for string, as that cannot be genericized.

edited Sep 10, 2023 at 9:00

answered Sep 10, 2023 at 8:56

Charlieface

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3 Comments

TheBoubou Over a year ago

if there is Contains for a string ?

Charlieface Over a year ago

I don't understand your question. Yes there is a Contains function, but that's not what you asked, and it wouldn't make sense to use that with generics. Perhaps you should make a separate overload just for string.

TheBoubou Over a year ago

I updated the question to clarify. It's more create an expression.

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