private boolean isClass(String result) {
                if (result == null || result.isEmpty()) {
                    return false;
                }
                
                // if it's the class we're compiling, then of course it's a class
                if (result.equals(targetName)) {
                    return true;
                }
                InputStream is = null;
                try {
                    // if this is a class we've already compiled, it's a class
                    is = loader.getResourceAsStream(result);
                    if (is == null) {
                        // use our normal class loader now...
                        String resourceName = result.replace('.', '/') + ".class";
                        is = parentClassLoader.getResourceAsStream(resourceName);
                        if (is == null && !result.contains(".")) {
                            // we couldn't find the class, and it has no package; is it a core class?
                            is = parentClassLoader.getResourceAsStream("java/lang/" + resourceName);
                        }
                    }
                    return is != null;
                } finally {
                    if (is != null) {
                        try {
                            is.close();
                        } catch (IOException ex) { }
                    }
                }
            }
EvaluatorFactory is a factory implementation for creating Evaluator instances

@author tiwe
querydsl-codegen-utils/src/main/java/com/querydsl/codegen/utils/ECJEvaluatorFactory.java