ExpressionTreeTranslationSampleOne.cs

using System.Linq.Expressions;

namespace ExpressionTreeSamples;

public class ExpressionTreeTranslationSampleOne : Sample
{
    public override string Name { get; } = "Translation Expression Trees, Sample 1: Replacing Constant Nodes";

    public override void Run()
    {
        var one = Expression.Constant(1, typeof(int));
        var two = Expression.Constant(2, typeof(int));
        var addition = Expression.Add(one, two);
        var sum = ReplaceNodes(addition);
        var executableFunc = Expression.Lambda(sum);

        var func = (Func<int>)executableFunc.Compile();
        var answer = func();
        Console.WriteLine(answer);
    }

    private static Expression ReplaceNodes(Expression original)
    {
        if (original.NodeType == ExpressionType.Constant)
        {
            return Expression.Multiply(original, Expression.Constant(10));
        }
        else if (original.NodeType == ExpressionType.Add)
        {
            var binaryExpression = (BinaryExpression)original;
            return Expression.Add(
                ReplaceNodes(binaryExpression.Left),
                ReplaceNodes(binaryExpression.Right));
        }
        return original;
    }
}