I need help doing a Regex.Replace with multiple results
Question
I'm building a custom page caching utility that uses a syntax like {Substitution:GetNonCachedData} to get data that's not supposed to be cached. The solution is very similar to the built-in <@ OutputCache %> stuff but not as flexible (I don't need it to be) and, most importantly, allows the session state to be available when retrieving non-cached data.
Anyway, I have a method that replaces the tokens in the html with the result of the static method named in the {Substitution} tag.
For example my page:
<html>
<body>
<p>This is cached</p>
<p>This is not: {Substitution:GetCurrentTime}</p>
</body>
</html>
will fill in the {Substitution:GetCurrentTime} with results of a static method. Here's where the processing happens:
private static Regex SubstitutionRegex = new Regex(@"{substitution:(?<method>\w+)}", RegexOptions.IgnoreCase);
public static string WriteTemplates(string template)
{
foreach (Match match in SubstitutionRegex.Matches(template))
{
var group = match.Groups["method"];
var method = group.Value;
var substitution = (string) typeof (Substitution).GetMethod(method).Invoke(null, null);
template = SubstitutionRegex.Replace()
}
return template;
}
the variable template is the html with custom tokens in it that need to be replaced. The problem with this method is that everytime I update the template variable with the updated html the match.Index variable no longer points to the right character start because of the template now has more characters added to it.
I can come up with a solution that works by either counting characters etc or some other screwball way of doing it, but I first want to make sure there's not some easier way to achieve this with the Regex object. Anyone know how to this?
thanks!
2 answers
solution1
1 ACCPTED 2010-08-05 18:13:20
You should call the overload of Regex.Replace that takes a MatchEvaluator delegate.
For example:
return SubstitutionRegex.Replace(template, delegate(Match match) {
var group = match.Groups["method"];
var method = group.Value;
return (string) typeof (Substitution).GetMethod(method).Invoke(null, null);
});
solution2
0 2010-08-05 18:14:07
将正则表达式设置为已编译，然后在while循环中使用单个Match，直到它停止匹配，而不是使用Matches并在结果上循环。
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