// C# Eval Expression

// Doc: https://eval-expression.net/register-unregister

​

// @nuget: Z.Expressions.Eval

​

/*

## RegisterAlias

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The RegisterAlias method registers an alias for a variable, constant, static method or type name. For example, if you register the alias "mymath" for the class "System.Math", you can now create an expression such as "mymath.Min(1, 2)".

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In this example, we will use the alias instead of the real namespace, method, and variable names. In the first example, we will use the `mymath` and `One` alias that will replace the `Math` namespace and `x` variable name. In the second example, we will also use the `MathMin` that will be an alias for the method `Math.Min`.

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Afterward, we will use the method `IsRegisteredAlias` to show that the alias was registered, then use the method `UnregisterAlias` to remove it and check again to show that the alias was successfully unregistered.

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See more: https://eval-expression.net/register-unregister

*/

​

using System;

using Z.Expressions;

​

public class Program

{

    public static void Main()

    {

        // Global Context: EvalManager.DefaultContext.RegisterAlias("mymath", "Math");

        // Global Context: EvalManager.DefaultContext.UnregisterAlias("mymath");

        // Global Context: EvalManager.DefaultContext.IsRegisteredAlias("mymath");

        var context = new EvalContext();

        context.RegisterAlias("mymath", "Math");

        context.RegisterAlias("One", "x");

        context.RegisterAlias("MathMin", "Min");

        // "mymath" is an alias for "Math"

        // "One" is an alias for "x" (the parameter)

        var r1 = context.Execute("mymath.Min(One, y)", new { x = 1, y = 2 });

        Console.WriteLine("1 - Result: " + r1);

        // "MathMin" is an alias for "Min" method from "Math.Min"

        var r2 = context.Execute("MathMin(One, y)", new { x = 1, y = 2 });

        Console.WriteLine("2 - Result: " + r2);

        // Check that the alias "mymath" is registered

        var r3 = context.IsRegisteredAlias("mymath");

        Console.WriteLine("3 - Result: " + r3);

        // Unregister the "mymath" alias

        context.UnregisterAlias("mymath");

        // Check that the alias "mymath" has been succesfully unregistered

        var r4 = context.IsRegisteredAlias("mymath");

        Console.WriteLine("4 - Result: " + r4);

    }

}