// C# Eval Expression

// Doc: https://eval-expression.net/options

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// @nuget: Z.Expressions.Eval

​

/*

## DisableAutoReplaceDictionaryKey

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The DisableAutoReplaceDictionaryKey option lets you get or sets if the feature that allows using the dictionary keys directly in the expression should be disabled. Only keys that are not valid variable names, such as `!@#` or `123`, are replaced automatically in the text which might cause some impact without disabling that option. This option does not impact valid variable names as we never replaced them in the text since they are valid. By default, the DisableAutoReplaceDictionaryKey value is `false`.

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In this example, we will first evaluate an expression with an invalid variable name as a key and get the expected result. Then we will evaluate a simple `1+2` expression and get a weird result return as the `2` has been automatically replaced by `12` since this is an invalid variable name. Finally, we will disable the option and now see that `1+2` is giving the expected result again.

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See more: https://eval-expression.net/options

*/

​

using System;

using System.Collections.Generic;

using System.Reflection;

using Z.Expressions;

​

public class Program

{

    public static void Main()

    {

        // Global Context: EvalManager.DefaultContext.DisableAutoReplaceDictionaryKey = true;

        var context = new EvalContext();

        context.UseCache = false;

        var dict = new Dictionary<string, object>();

        dict.Add("!@#", 12);

        dict.Add("2", 12);

        // Automatically replacing the dictionary keys that are not a valid variable names can be something useful

        var r1 = context.Execute<int>("1 + !@#", dict); // return 13 (1 + 12)

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

        // But it can also sometimes have some weird side impact

        var r2 = context.Execute<int>("1 + 2", dict); // return 13 (1 + 12)

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

        // This option allows avoiding those side impact

        context.DisableAutoReplaceDictionaryKey = true;

        var r3 = context.Execute<int>("1 + 2", dict); // return 3

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

    }

}