将多个正则表达式匹配项替换为不同的替换项 [英] Replace multiple Regex Matches each with a different replacement

问题描述

我有一个字符串，该字符串可能与指定模式的多个匹配项匹配，也可能不与之匹配.

I have a string that may or may not have multiple matches for a designated pattern.

每个都需要更换.

我有此代码:

var pattern = @"\$\$\@[a-zA-Z0-9_]*\b";
var stringVariableMatches = Regex.Matches(strValue, pattern);
var sb = new StringBuilder(strValue);

foreach (Match stringVarMatch in stringVariableMatches)
{
    var stringReplacment = variablesDictionary[stringVarMatch.Value];
    sb.Remove(stringVarMatch.Index, stringVarMatch.Length)
            .Insert(stringVarMatch.Index, stringReplacment);
}

return sb.ToString();

问题是，当我有多个匹配项时，第一个匹配项被替换，另一个匹配项的起始索引被更改，以便在替换后的某些情况下，当字符串缩短时，我得到的索引超出范围.

The problem is that when I have several matches the first is replaced and the starting index of the other is changed so that in some cases after the replacement when the string is shorten I get an index out of bounds..

我知道我只能为每个匹配项使用 Regex.Replace ，但是这种声音表现很沉重，我想看看是否有人可以指出不同的解决方案，以多个匹配项替换为不同的字符串.

I know I could just use Regex.Replace for each match but this sound performance heavy and wanted to see if someone could point a different solution to substitute multiple matches each with a different string.

推荐答案

在 Regex.Replace 内使用Match评估程序:

Use a Match evaluator inside the Regex.Replace:

var pattern = @"\$\$\@[a-zA-Z0-9_]*\b";
var stringVariableMatches = Regex.Replace(strValue, pattern, 
        m => variablesDictionary[m.Value]);

Regex.Replace 方法将执行 global 替换，即搜索与指定模式匹配的所有不重叠子字符串，并将每个找到的匹配值替换为 variablesDictionary [m.Value] .

The Regex.Replace method will perform global replacements, i.e. will search for all non-overlapping substrings that match the indicated pattern, and will replace each found match value with the variablesDictionary[m.Value].

请注意，参见 C#演示:

using System;
using System.IO;
using System.Text.RegularExpressions;
using System.Collections.Generic;
using System.Linq;
public class Test
{
    public static void Main()
    {
        var variablesDictionary = new Dictionary<string, string>();
        variablesDictionary.Add("$$@Key", "Value");
        var pattern = @"\$\$@[a-zA-Z0-9_]+\b";
        var stringVariableMatches = Regex.Replace("$$@Unknown and $$@Key", pattern, 
                m => variablesDictionary.ContainsKey(m.Value) ? variablesDictionary[m.Value] : m.Value);
        Console.WriteLine(stringVariableMatches);
    }
}

输出: $$ @ Unknown and Value .

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