问Regex:命名组和替换

EN

string text = @"The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog.";
string[] searchKeywords = { "quick", "fox", "lazy" };

// build pattern based on keywords - you probably had a routine in place for this
var patternQuery = searchKeywords
                        .Select((s, i) => 
                            String.Format("(?<c{0}>{1})", i, s) +
                            (i < searchKeywords.Length - 1 ? "|" : ""))
                        .Distinct();
string pattern = String.Join("", patternQuery.ToArray());
Console.WriteLine("Dynamic pattern: {0}\n", pattern);

// use RegexOptions.IgnoreCase for case-insensitve search
Regex rx = new Regex(pattern);

// Notes:
// - Skip(1): used to ignore first groupname of 0 (entire match)
// - The idea is to use the groupname and its corresponding match. The Where
//   clause matches the pair up correctly based on the current match value
//   and returns the appropriate groupname
string result = rx.Replace(text, m => String.Format(@"<span class=""{0}"">{1}</span>", 
                    rx.GetGroupNames()
                    .Skip(1)
                    .Where(g => m.Value == m.Groups[rx.GroupNumberFromName(g)].Value)
                    .Single(),
                    m.Value));

Console.WriteLine("Original Text: {0}\n", text);
Console.WriteLine("Result: {0}", result);

Dynamic pattern: (?<c0>quick)|(?<c1>fox)|(?<c2>lazy)

Original Text: The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog.

Result: The <span class="c0">quick</span> brown <span class="c1">fox</span> jumps over the <span class="c2">lazy</span> dog. The <span class="c0">quick</span> brown <span class="c1">fox</span> jumps over the <span class="c2">lazy</span> dog.