Question

I can have 0 or many substrings within a text area in the format {key-value}Some text{/key},

For example This is my {link-123}test{/link} text area

I’d like to iterate through any items that match this pattern, perform and action based on the key and value, then replace this substring with a new string (a anchor link that is retreived by the action based on the key).

How would I achieve this in C#?

Answer 1

If these tags are not nested, then you only need to iterate once over the file; if nesting is possible, then you need to do one iteration for each level of nesting.

This answer assumes that braces only occur as tag delimiters (and not, for example, inside comments):

result = Regex.Replace(subject, 
    @"\{                # opening brace
    (?<key>\w+)         # Match the key (alnum), capture into the group 'key'
    -                   # dash
    (?<value>\w+)       # Match the value (alnum), capture it as above
    \}                  # closing brace
    (?<content>         # Match and capture into the group 'content':
     (?:                # Match...
      (?!\{/?\k<key>)   # (unless there's an opening or closing tag
      .                 # of the same name right here) any character
     )*                 # any number of times
    )                   # End of capturing group
    \{/\k<key>\}        # Match the closing tag.", 
    new MatchEvaluator(ComputeReplacement), RegexOptions.Singleline | RegexOptions.IgnorePatternWhitespace);

public String ComputeReplacement(Match m) {
    // You can vary the replacement text for each match on-the-fly
    // m.Groups["key"].Value will contain the key
    // m.Groups["value"].Value will contain the value of the match
    // m.Groups["value"].Value will contain the content between the tags
    return ""; // change this to return the string you generated here
}