Java API for composing regular expressions

Question

I am writing an application that needs to define and compile patterns at runtime. Using the Java Pattern API, I need to pass a string and get a pattern. Something like this:

Pattern.compile("ab*|c*");

The problem is that my patterns are modular and I would like to compose them using alternative, kleene star, etc, for example:

Char a = new Char('a');
Char b = new Char('b');
Char c = new Char('c');
Regex r = new Regex(new Alt(new Seq(a, new KleeneStar(b)), new KleeneStar(c)));
Pattern.compile(r);

I haven't found an API in JDK to allow me such a thing. I assume that the underlying implementation of pattern should have such an API. Does any one know how I can get such an API from the standard Java, or are there third party libraries for that?

In the end, I think I can create such an API myself with some recursive visitors to printout the string, but would be nice if it already exits.

Answer 1

Try http://itsallbinary.com/project-simply-regex/

https://github.com/itsallbinary/simply-regex

Code examples:

String builtRegex = SimpleRegex.regex().startingWith().exactString("abc")
                                       .then().oneOfTheCharacters('d', 'e', 'f')
                                       .build();

SimpleRegex.regex().anywhereInText().oneOrMoreOf('a').build();

String builtRegex = SimpleRegex.regex().anywhereInText().oneOrMoreOf(groupHaving().exactString("abc").then().anyDigitChar().build())
                       .build()