aprogrammer/dotnet-docs: This repository contains .NET Documentation.

samples/csharp/expression-trees/ExpressionTreeBuildingSampleOne.cs

43 строки1 KB

Bill Wagner

Update ci build for ubuntu (#891)

09 авг 2016, 23:02

09 авг 2016, 23:02ce52ada

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;

using ExpressionVisitor;

namespace ExpressionTreeSamples
{
    public class ExpressionTreeBuildingSampleOne : Sample
    {
        public override string Name { get; } = "Building Expression Trees, Sample 1: Creating a statement based tree";
        
        public override void Run()
        {
             var lambda = Expression.Lambda(
                Expression.Add(
                    Expression.Constant(1, typeof(int)),
                    Expression.Constant(2, typeof(int))
                )
            );

            var xParameter = Expression.Parameter(typeof(double), "x");
            var yParameter = Expression.Parameter(typeof(double), "y");

            var xSquared = Expression.Multiply(xParameter, xParameter);
            var ySquared = Expression.Multiply(yParameter, yParameter);
            var sum = Expression.Add(xSquared, ySquared);

            var sqrtMethod = typeof(Math).GetMethod("Sqrt", new[] { typeof(double) });
            var distance = Expression.Call(sqrtMethod, sum);

            var distanceLambda = Expression.Lambda(
                distance,
                xParameter,
                yParameter);

            var visitor = Visitor.CreateFromExpression(distanceLambda);
            visitor.Visit("");
       }
    }
}