content: /*
   * Copyright (C) 2010 A. Horn
   *
   * 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 org.mcsoxford.rss;
  
  import java.io.IOException;
  import java.io.InputStream;
  
  import javax.xml.parsers.ParserConfigurationException;
  import javax.xml.parsers.SAXParser;
  import javax.xml.parsers.SAXParserFactory;
  
  import org.xml.sax.InputSource;
  import org.xml.sax.SAXException;
  import org.xml.sax.XMLReader;
  
  /**
   * Thread-safe RSS parser SPI implementation.
   * 
   * @author Mr Horn
   */
  public class RSSParser implements RSSParserSPI {
  
    private final RSSConfig config;
  
    public RSSParser(RSSConfig config) {
      this.config = config;
    }
  
    /**
     * Parses input stream as RSS feed. It is the responsibility of the caller to
     * close the RSS feed input stream.
     * 
     * @param feed RSS 2.0 feed input stream
     * @return in-memory representation of RSS feed
     * @throws RSSFault if an unrecoverable parse error occurs
     */
    @Override
    public RSSFeed parse(InputStream feed) {
      try {
        // Since SAXParserFactory implementations are not guaranteed to be
        // thread-safe, a new local object is instantiated.
        final SAXParserFactory factory = SAXParserFactory.newInstance();
  
        // Support Android 1.6 (see Issue 1)
        factory.setFeature("http://xml.org/sax/features/namespaces", false);
        factory.setFeature("http://xml.org/sax/features/namespace-prefixes", true);
  
        final SAXParser parser = factory.newSAXParser();
  
        return parse(parser, feed);
      } catch (ParserConfigurationException e) {
        throw new RSSFault(e);
      } catch (SAXException e) {
        throw new RSSFault(e);
      } catch (IOException e) {
        throw new RSSFault(e);
      }
    }
  
    /**
     * Parses input stream as an RSS 2.0 feed.
     * 
     * @return in-memory representation of an RSS feed
     * @throws IllegalArgumentException if either argument is {@code null}
     */
    private RSSFeed parse(SAXParser parser, InputStream feed)
        throws SAXException, IOException {
      if (parser == null) {
        throw new IllegalArgumentException("RSS parser must not be null.");
      } else if (feed == null) {
        throw new IllegalArgumentException("RSS feed must not be null.");
      }
  
      // SAX automatically detects the correct character encoding from the stream
      // See also http://www.w3.org/TR/REC-xml/#sec-guessing
      final InputSource source = new InputSource(feed);
      final XMLReader xmlreader = parser.getXMLReader();
      final RSSHandler handler = new RSSHandler(config);
  
      xmlreader.setContentHandler(handler);
      xmlreader.parse(source);
  
      return handler.feed();
    }
  
  }
  
  