content: package act.internal.util;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2017 ActFramework
   * %%
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   * 
   *      http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   * #L%
   */
  
  import org.osgl.util.E;
  import org.osgl.util.S;
  
  /**
   * Provides utility methods relevant to Java names, e.g. package name validator etc
   */
  public final class JavaNames {
  
      /**
       * Check if a given string is a valid java package or class name.
       *
       * This method use the technique documented in
       * [this SO question](https://stackoverflow.com/questions/13557195/how-to-check-if-string-is-a-valid-class-identifier)
       * with the following extensions:
       *
       * * if the string does not contain `.` then assume it is not a valid package or class name
       *
       * @param s
       *      the string to be checked
       * @return
       *      `true` if `s` is a valid java package or class name
       */
      public static boolean isPackageOrClassName(String s) {
          if (S.blank(s)) {
              return false;
          }
          S.List parts = S.fastSplit(s, ".");
          if (parts.size() < 2) {
              return false;
          }
          for (String part: parts) {
              if (!Character.isJavaIdentifierStart(part.charAt(0))) {
                  return false;
              }
              for (int i = 1, len = part.length(); i < len; ++i) {
                  if (!Character.isJavaIdentifierPart(part.charAt(i))) {
                      return false;
                  }
              }
          }
          return true;
      }
  
      /**
       * Returns package name of a class
       *
       * @param clazz
       *      the class
       * @return
       *      the package name of the class
       */
      public static String packageNameOf(Class<?> clazz) {
          String name = clazz.getName();
          int pos = name.lastIndexOf('.');
          E.unexpectedIf(pos < 0, "Class does not have package: " + name);
          return name.substring(0, pos);
      }
  
  }
  