Parser.java

/**
 *  Parser.java
 *  Copyright 2010 by Michael Peter Christen, mc@yacy.net, Frankfurt am Main, Germany
 *  First released 29.6.2010 at http://yacy.net
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program in the file lgpl21.txt
 *  If not, see <http://www.gnu.org/licenses/>.
 */

// this is a new definition of the parser interface using multiple documents as result set
// and a much simpler method structure with only one single parser method to implement

package net.yacy.document;

import java.io.InputStream;
import java.util.Set;

import net.yacy.cora.document.id.DigestURL;
import net.yacy.cora.document.id.MultiProtocolURL;

public interface Parser {

    /**
     * each parser must define a set of supported mime types
     * @return a set of mime type strings that are supported
     */
    public Set<String> supportedMimeTypes();

    /**
     * each parser must define a set of supported file extensions
     * @return a set of file name extensions that are supported
     */
    public Set<String> supportedExtensions();

    /**
     * parse an input stream
     * @param url the url of the source
     * @param mimeType the mime type of the source, if known
     * @param charset the charset of the source, if known
     * @param scraper an entity scraper to detect facets from text annotation context
     * @param source a input stream
     * @return a list of documents that result from parsing the source
     * @throws Parser.Failure
     * @throws InterruptedException
     */
    public Document[] parse(
            DigestURL url,
            String mimeType,
            String charset,
            VocabularyScraper scraper,
            int timezoneOffset,
            InputStream source
            ) throws Parser.Failure, InterruptedException;


    // methods to that shall make it possible to put Parser objects into a hashtable

    /**
     * get the name of the parser
     * @return the name of the parser
     */
    public String getName();

    /**
     * check equivalence of parsers; this simply tests equality of parser names
     * @return true when this parser is equivalent to o
     */
    @Override
    public boolean equals(Object o);

    /**
     * the hash code of a parser
     * @return the hash code of the parser name string
     */
    @Override
    public int hashCode();

    /**
     * a parser warning
     * thrown as an exception
     */
    public class Failure extends Exception {

        private static final long serialVersionUID = 2278214953869122883L;
        private MultiProtocolURL url = null;
        public Failure() {
            super();
        }

        public Failure(final String message, final MultiProtocolURL url) {
            super(message + "; url = " + url.toNormalform(true));
            this.url = url;
        }

        public Failure(final String message, final MultiProtocolURL url, Throwable e) {
            super(message + "; url = " + url.toNormalform(true), e);
            this.url = url;
        }

        public MultiProtocolURL getURL() {
            return this.url;
        }
    }
}