content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one or more
   *  contributor license agreements.  See the NOTICE file distributed with
   *  this work for additional information regarding copyright ownership.
   *  The ASF licenses this file to You 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
   *
   *      https://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.
   *
   */
  package org.apache.tools.ant.util.regexp;
  
  import org.apache.tools.ant.BuildException;
  import org.apache.tools.ant.MagicNames;
  import org.apache.tools.ant.Project;
  import org.apache.tools.ant.util.ClasspathUtils;
  
  /***
   * Regular expression factory, which will create Regexp objects.  The
   * actual implementation class depends on the System or Ant Property:
   * <code>ant.regexp.regexpimpl</code>.
   *
   */
  public class RegexpFactory extends RegexpMatcherFactory {
  
      /***
       * Create a new regular expression matcher instance.
       * @return the matcher instance
       * @throws BuildException on error
       */
      public Regexp newRegexp() throws BuildException {
          return newRegexp(null);
      }
  
      /***
       * Create a new regular expression matcher instance.
       *
       * @param p Project whose ant.regexp.regexpimpl property will be used.
       * @return the matcher instance
       * @throws BuildException on error
       */
      public Regexp newRegexp(Project p) throws BuildException {
          String systemDefault;
          if (p == null) {
              systemDefault = System.getProperty(MagicNames.REGEXP_IMPL);
          } else {
              systemDefault = p.getProperty(MagicNames.REGEXP_IMPL);
          }
  
          if (systemDefault != null) {
              return createRegexpInstance(systemDefault);
              // TODO     should we silently catch possible exceptions and try to
              //         load a different implementation?
          }
  
          return new Jdk14RegexpRegexp();
      }
  
      /**
       * Wrapper over RegexpMatcherFactory.createInstance that ensures that
       * we are dealing with a Regexp implementation.
       * @param classname the name of the class to use.
       * @return the instance.
       * @throws BuildException if there is a problem.
       * @since 1.3
       *
       * @see RegexpMatcherFactory#createInstance(String)
       */
      protected Regexp createRegexpInstance(String classname) throws BuildException {
          return ClasspathUtils.newInstance(classname,
              RegexpFactory.class.getClassLoader(), Regexp.class);
      }
  
  }
  