Would this replaceAll function be a good addition to the Regex class?

[Colin Bartolome]

I've found this function I wrote to be pretty useful:

"Finds all matches of the given [[expression]] in the given [[input]] and replaces them using the
 given [[replacement]] function."
shared String replaceAll(Regex|String expression, String input,
        String(String)|String(MatchResult) replacement) {
    value output = StringBuilder();
    variable value lastEnd = 0;
    value matches = (if (is String expression) then regex(expression) else expression)
            .findAll(input);
   
    for (match in matches) {
        output.append(input.substring(lastEnd, match.start));
       
        if (is String(String) replacement) {
            output.append(replacement(match.matched));
        } else {
            output.append(replacement(match));
        }
       
        lastEnd = match.end;
    }
   
    output.append(input.substring(lastEnd));
   
    return output.string;
}

In one spot, I use it like this:

String escape(String string) {
    function replaceUnsafeCharacter(String string)
        => switch (string)
            case ("&") "&"
            case ("<") "&lt;"
            case (">") "&gt;"
            case ("\"") "&quot;"
            else string;
   
    return replaceAll("""[&<>"]""", string, replaceUnsafeCharacter);
}

Basically, it's Regex.replace(), but you can determine the replacement string depending on exactly what matched. Here's another way I used it, to preprocess some of the ceylon-lang.org Markdown:

    function preprocess(Map<String,String> properties, String markdown) {
        value regex = """#\{page\.(\w+)\}""";
        function replacement(MatchResult match) {
            value key = match.groups.first;
           
            if (exists key) {
                return properties[key] else match.matched;
            } else {
                return match.matched;
            }
        }
       
        return replaceAll(regex, markdown, replacement);
    }

(Interestingly, this use of replaceAll doesn't show up when I hit Ctrl-G in Eclipse. I may try to boil that down to a reproducible case and file it.)

Does something like this already exist in the SDK? If not, would this be a good addition to the Regex class?

[Colin Bartolome]

Working on this here:

https://github.com/ceylon/ceylon-sdk/issues/625