如何在.NET中为正则表达式编码字符串？

Question

我需要动态构建一个Regex来捕获给定的关键字,比如

string regex = "(some|predefined|words";
foreach (Product product in products)
    regex += "|" + product.Name; // Need to encode product.Name because it can include special characters.
regex += ")";

是否有某种Regex.Encode可以做到这一点？

Answer 1

你可以用Regex.Escape.例如:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

public class Test
{
    static void Main()
    {
        string[] predefined = { "some", "predefined", "words" };
        string[] products = { ".NET", "C#", "C# (2)" };

        IEnumerable<string> escapedKeywords = 
            predefined.Concat(products)
                      .Select(Regex.Escape);
        Regex regex = new Regex("(" + string.Join("|", escapedKeywords) + ")");
        Console.WriteLine(regex);
    }
}

输出:

(some|predefined|words|\.NET|C\#|C\#\ \(2\))

或者没有LINQ,但是根据原始代码在循环中使用字符串连接(我试图避免):

string regex = "(some|predefined|words";
foreach (Product product)
    regex += "|" + Regex.Escape(product.Name);
regex += ")";