Regex or String operation to derive automatic module name from String

Mordechai :

I need to find the Automatic Module name given a String filename, as:

"common-io-1.2.3.jar" -> "common.io"
"---apple...orange..jar" -> "apple.orange"
"google-api-v1-beta.jar" -> "google.api.v1.beta"

I know I can use ModuleFinder.of(Path) but my requirement is to derive it without any file-system IO.

What I found so far:

Looking up the source code how ModuleFinder.of() works I found this method, but that is too much for what I need.

How can I do it with simple Regex or string operation?

Mordechai :

Following this JavaDoc:

public static String deriveModule(String filename) {

    // strip ".jar" at the end
    filename = filename.replaceAll("\\.jar$", "");

    // drop everything after the version
    filename = filename.replaceAll("-\\d.*", "");

    // all non alphanumeric get's converted to "."
    filename = filename.replaceAll("[^A-Za-z0-9]", ".");

    // strip "." at beginning and end
    filename = filename.replaceAll("^\\.*|\\.*$", "");

    // all double "." stripped to single
    filename = filename.replaceAll("\\.{2,}", ".");


    return filename;
}

You can also check if it is a valid module name:

public static boolean isValidModuleName(String name) {
    String VALID_REGEX = "([\\p{L}_$][\\p{L}\\p{N}_$]*\\.)*[\\p{L}_$][\\p{L}\\p{N}_$]*";


    if (!name.matches(VALID_REGEX))
        return false;


    Set<String> keywords = Set.of("abstract", "continue", "for", "new", 
                    "switch", "assert", "default", "goto", "package",
                    "synchronized", "boolean", "do", "if", "private", "this",
                    "break", "double", "implements","protected", "throw", 
                    "byte", "else", "import", "public", "throws", "case", 
                    "enum", "instanceof", "return", "transient", "catch", 
                    "extends",  "int", "short", "try", "char", "final",
                    "interface", "static", "void", "class", "finally", 
                    "long", "strictfp", "volatile", "const",
                    "float", "native", "super", "while", "module", "open", 
                    "opens", "exports", "requires",
                    "transitive", "to", "with", "provides", "uses");


    String[] tokens = name.split("\\.");
    for (String t : tokens) {
        if (keywords.contains(t))
            return false;
    }

    return true;
}