content: /*
   * ProviderFactory.java January 2010
   *
   * Copyright (C) 2010, Niall Gallagher <niallg@users.sf.net>
   *
   * 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.
   */
  
  package com.aliyun.odps.simpleframework.xml.stream;
  
  /**
   * The <code>ProviderFactory</code> object is used to instantiate a
   * provider of XML parsing to the framework. This scans the classpath
   * for the classes required for StAX, if they are present then this 
   * is what will be used to process XML. If however StAX can not be
   * used then a DOM implementation is provided. A DOM provider as a
   * default suits most Java profiles as it is a very common parser.
   * 
   * @author Niall Gallagher
   * 
   * @see NodeBuilder
   */
  final class ProviderFactory {
  
     /**
      * This is used to acquire the <code>Provider</code> to be used 
      * to process XML documents. The provider returned is determined
      * by scanning the classpath for StAX dependencies, if they are
      * available then the provider used is StAX otherwise it is DOM. 
      * Scanning the classpath in this manner ensures the most suitable
      * parser is used for the host platform.
      * 
      * @return this returns the provider that has been instantiate
      */
     public static Provider getInstance() {
        try {
           try {
              return new StreamProvider();
           } catch(Throwable e) {
              return new PullProvider();
           }
        } catch(Throwable e) {
           return new DocumentProvider();
        }
     }
  }