Is there an equivalent of java.util.regex for "glob" type patterns?

Paul_Tomblin_3333 0
Viewed 42433

Is there a standard (preferably Apache Commons or similarly non-viral) library for doing "glob" type matches in Java? When I had to do similar in Perl once, I just changed all the "." to "\.", the "*" to ".*" and the "?" to "." and that sort of thing, but I'm wondering if somebody has done the work for me.

Similar question: Create regex from glob expression

glob java
13 Answers
finnw_120480

There's nothing built-in, but it's pretty simple to convert something glob-like to a regex:

public static String createRegexFromGlob(String glob)
{
    String out = "^";
    for(int i = 0; i < glob.length(); ++i)
    {
        final char c = glob.charAt(i);
        switch(c)
        {
        case '*': out += ".*"; break;
        case '?': out += '.'; break;
        case '.': out += "\\."; break;
        case '\\': out += "\\\\"; break;
        default: out += c;
        }
    }
    out += '$';
    return out;
}

this works for me, but I'm not sure if it covers the glob "standard", if there is one :)

Update by Paul Tomblin: I found a perl program that does glob conversion, and adapting it to Java I end up with:

    private String convertGlobToRegEx(String line)
    {
    LOG.info("got line [" + line + "]");
    line = line.trim();
    int strLen = line.length();
    StringBuilder sb = new StringBuilder(strLen);
    // Remove beginning and ending * globs because they're useless
    if (line.startsWith("*"))
    {
        line = line.substring(1);
        strLen--;
    }
    if (line.endsWith("*"))
    {
        line = line.substring(0, strLen-1);
        strLen--;
    }
    boolean escaping = false;
    int inCurlies = 0;
    for (char currentChar : line.toCharArray())
    {
        switch (currentChar)
        {
        case '*':
            if (escaping)
                sb.append("\\*");
            else
                sb.append(".*");
            escaping = false;
            break;
        case '?':
            if (escaping)
                sb.append("\\?");
            else
                sb.append('.');
            escaping = false;
            break;
        case '.':
        case '(':
        case ')':
        case '+':
        case '|':
        case '^':
        case '$':
        case '@':
        case '%':
            sb.append('\\');
            sb.append(currentChar);
            escaping = false;
            break;
        case '\\':
            if (escaping)
            {
                sb.append("\\\\");
                escaping = false;
            }
            else
                escaping = true;
            break;
        case '{':
            if (escaping)
            {
                sb.append("\\{");
            }
            else
            {
                sb.append('(');
                inCurlies++;
            }
            escaping = false;
            break;
        case '}':
            if (inCurlies > 0 && !escaping)
            {
                sb.append(')');
                inCurlies--;
            }
            else if (escaping)
                sb.append("\\}");
            else
                sb.append("}");
            escaping = false;
            break;
        case ',':
            if (inCurlies > 0 && !escaping)
            {
                sb.append('|');
            }
            else if (escaping)
                sb.append("\\,");
            else
                sb.append(",");
            break;
        default:
            escaping = false;
            sb.append(currentChar);
        }
    }
    return sb.toString();
}

I'm editing into this answer rather than making my own because this answer put me on the right track.

Dave_Ray_403100

It may be a slightly hacky approach. I've figured it out from NIO2's Files.newDirectoryStream(Path dir, String glob) code. Pay attention that every match new Path object is created. So far I was able to test this only on Windows FS, however, I believe it should work on Unix as well.

// a file system hack to get a glob matching
PathMatcher matcher = ("*".equals(glob)) ? null
    : FileSystems.getDefault().getPathMatcher("glob:" + glob);

if ("*".equals(glob) || matcher.matches(Paths.get(someName))) {
    // do you stuff here
}

UPDATE Works on both - Mac and Linux.

user_19008590

I don't know about a "standard" implementation, but I know of a sourceforge project released under the BSD license that implemented glob matching for files. It's implemented in one file, maybe you can adapt it for your requirements.

Greg_139400

The previous solution by Vincent Robert/dimo414 relies on Pattern.quote() being implemented in terms of \Q...\E, which is not documented in the API and therefore may not be the case for other/future Java implementations. The following solution removes that implementation dependency by escaping all occurrences of \E instead of using quote(). It also activates DOTALL mode ((?s)) in case the string to be matched contains newlines.

    public static Pattern globToRegex(String glob)
    {
        return Pattern.compile(
            "(?s)^\\Q" +
            glob.replace("\\E", "\\E\\\\E\\Q")
                .replace("*", "\\E.*\\Q")
                .replace("?", "\\E.\\Q") +
            "\\E$"
        );
    }
user_6237630

There is sun.nio.fs.Globs but it is not part of the public API. You can use it indirectly via:

FileSystems.getDefault().getPathMatcher("glob:<myPattern>")

But it returns PathMatcher, which is inconvenient to work with. Since it can accept only Path as parameter (not File).

One possible option is to convert the PathMatcher to regex pattern (just call its 'toString()' method).

Another option is to use dedicated Glob library like glob-library-java.

user_43995760
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