让我们假设我有以下正则表达式:
-(\d+)-
我想用c#将Group 1 (\d+)替换为AA，得到:
-AA-
现在我用:
var text = "example-123-example";
var pattern = @"-(\d+)-";
var replaced = Regex.Replace(text, pattern, "-AA-");
但我真的不喜欢这样，因为如果我改变模式来匹配_(\d+)_，我将不得不改变替换字符串由_AA_，这是违反DRY原则。
我想要的是:
保持匹配的文本完全是如何，但改变组1的文本和组2的另一个文本…
编辑: 这只是一个例子。我只是在寻找一种通用的方法来做上面所说的事情。
它应该适用于:
任何(\d+)更多的文本和任何你能想象的图案。
我所要做的只是替换组，并保留其余的匹配。
当前回答
如果你不想改变你的模式，你可以使用匹配组的Group Index和Length属性。
var text = "example-123-example";
var pattern = @"-(\d+)-";
var regex = new RegEx(pattern);
var match = regex.Match(text);
var firstPart = text.Substring(0,match.Groups[1].Index);
var secondPart = text.Substring(match.Groups[1].Index + match.Groups[1].Length);
var fullReplace = firstPart + "AA" + secondPart;
其他回答
这是另一个很好的干净的选择，不需要改变你的模式。
var text = "example-123-example";
var pattern = @"-(\d+)-";
var replaced = Regex.Replace(text, pattern, (_match) =>
{
Group group = _match.Groups[1];
string replace = "AA";
return String.Format("{0}{1}{2}", _match.Value.Substring(0, group.Index - _match.Index), replace, _match.Value.Substring(group.Index - _match.Index + group.Length));
});
我也有这个需要，我为它创建了以下扩展方法:
public static class RegexExtensions
{
public static string ReplaceGroup(
this Regex regex, string input, string groupName, string replacement)
{
return regex.Replace(
input,
m =>
{
var group = m.Groups[groupName];
var sb = new StringBuilder();
var previousCaptureEnd = 0;
foreach (var capture in group.Captures.Cast<Capture>())
{
var currentCaptureEnd =
capture.Index + capture.Length - m.Index;
var currentCaptureLength =
capture.Index - m.Index - previousCaptureEnd;
sb.Append(
m.Value.Substring(
previousCaptureEnd, currentCaptureLength));
sb.Append(replacement);
previousCaptureEnd = currentCaptureEnd;
}
sb.Append(m.Value.Substring(previousCaptureEnd));
return sb.ToString();
});
}
}
用法:
var input = @"[assembly: AssemblyFileVersion(""2.0.3.0"")][assembly: AssemblyFileVersion(""2.0.3.0"")]";
var regex = new Regex(@"AssemblyFileVersion\(""(?<version>(\d+\.?){4})""\)");
var result = regex.ReplaceGroup(input , "version", "1.2.3");
结果:
[assembly: AssemblyFileVersion("1.2.3")][assembly: AssemblyFileVersion("1.2.3")]
如果你不想改变你的模式，你可以使用匹配组的Group Index和Length属性。
var text = "example-123-example";
var pattern = @"-(\d+)-";
var regex = new RegEx(pattern);
var match = regex.Match(text);
var firstPart = text.Substring(0,match.Groups[1].Index);
var secondPart = text.Substring(match.Groups[1].Index + match.Groups[1].Length);
var fullReplace = firstPart + "AA" + secondPart;
你可以使用前向和后向来做到这一点:
var pattern = @"(?<=-)\d+(?=-)";
var replaced = Regex.Replace(text, pattern, "AA");
替换代码:
var text = "example-123-example";
var pattern = @"-(\d+)-";
var replaced = Regex.ReplaceGroupValue(text, pattern, 1, "AA");
扩展类:
public static class RegexExtensions
{
[Pure]
public static string ReplaceGroupValue(this Regex source, string input, string groupName, string destinationValue)
{
return ReplaceGroupValue(
source,
input,
m => m.Groups[groupName],
p => destinationValue);
}
[Pure]
public static string ReplaceGroupValue(this Regex source, string input, int groupIdx, string destinationValue)
{
return ReplaceGroupValue(
source,
input,
m => m.Groups[groupIdx],
p => destinationValue);
}
[Pure]
public static string ReplaceGroupValue(this Regex source, string input, string groupName, Func<string, string> destinationValueSelector)
{
return ReplaceGroupValue(
source,
input,
m => m.Groups[groupName],
destinationValueSelector);
}
[Pure]
public static string ReplaceGroupValue(this Regex source, string input, int groupIdx, Func<string, string> destinationValueSelector)
{
return ReplaceGroupValue(
source,
input,
m => m.Groups[groupIdx],
destinationValueSelector);
}
[Pure]
private static string ReplaceGroupValue(
Regex source,
string input,
Func<Match, Group> groupSelector,
Func<string, string> destinationValueSelector)
{
var matchResult = source.Matches(input);
if (matchResult.Count <= 0)
{
return input;
}
var text = input;
foreach (var group in matchResult.OfType<Match>().Select(groupSelector).OrderByDescending(p => p.Index))
{
var begin = group.Index > 0 ? text.Substring(0, group.Index) : string.Empty;
var end = group.Index + group.Length < text.Length
? text.Substring(group.Index + group.Length)
: string.Empty;
var destinationValue = destinationValueSelector.Invoke(group.Value);
text = $"{begin}{destinationValue}{end}";
}
return text;
}
}
