content: package org.openstack4j.openstack.identity.functions;
  
  import com.google.common.base.Function;
  
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * Functions to help resolve specific Services and Versions
   *
   * @author Jeremy Unruh
   */
  public final class ServiceFunctions {
  
      private static final Pattern VERSION_PATTERN = Pattern.compile("(.*)v(\\d+)");
  
      /**
       * Takes a Service Type or Service Name and strips off any version (if applicable) and returns the
       * common name.  For example: {@code nova21} would be returned as {@code nova}.
       */
      public static final Function<String, String> TYPE_WITHOUT_VERSION = new Function<String, String>() {
          @Override
          public String apply(String serviceType) {
              return matchForVersion(serviceType, false);
          }
      };
  
      /**
       * Determines the version from a Service Type or Name.  If the current service does not match the pattern
       * then a version 1 is always returned.  For example: {@code nova21} would return {@code 21}, {@code compute} would
       * return {@code 1}
       */
      public static final Function<String, Integer> VERSION_FROM_TYPE = new Function<String, Integer>() {
  
          @Override
          public Integer apply(String serviceType) {
              return matchForVersion(serviceType, true);
          }
      };
  
      @SuppressWarnings("unchecked")
      private static <T> T matchForVersion(String service, boolean returnVersion) {
          Matcher m = VERSION_PATTERN.matcher(service);
          if (m.matches()) {
              if (returnVersion) {
                  return (T) Integer.valueOf(m.group(2));
              }
              return (T) m.group(1);
          }
          if (returnVersion) {
              return (T) Integer.valueOf(1);
          }
          return (T) service;
      }
  
  }
  