SearchMatcher.java

/*
    Licensed to the Apache Software Foundation (ASF) under one
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    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

       http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing,
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    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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 */
package org.apache.wiki.search;

import java.io.IOException;
import java.io.BufferedReader;
import java.io.StringReader;

import org.apache.wiki.WikiEngine;
import org.apache.wiki.WikiPage;


/**
 * SearchMatcher performs the task of matching a search query to a page's
 * contents. This utility class is isolated to simplify WikiPageProvider
 * implementations and to offer an easy target for upgrades. The upcoming(?)
 * TranslatorReader rewrite will presumably invalidate this, among other things.
 *
 * @since 2.1.5
 */
public class SearchMatcher {
	
    private QueryItem[] m_queries;
    private WikiEngine m_engine;

    /**
     *  Creates a new SearchMatcher.
     *  
     *  @param engine The WikiEngine
     *  @param queries A list of queries
     */
    public SearchMatcher( WikiEngine engine, QueryItem[] queries ) {
        m_engine = engine;
        m_queries = queries != null ? queries.clone() : null;
    }

    /**
     * Compares the page content, available through the given stream, to the
     * query items of this matcher. Returns a search result object describing
     * the quality of the match.
     *
     * <p>This method would benefit of regexps (1.4) and streaming. FIXME!
     * 
     * @param wikiname The name of the page
     * @param pageText The content of the page
     * @return A SearchResult item, or null, there are no queries
     * @throws IOException If reading page content fails
     */
    public SearchResult matchPageContent( String wikiname, String pageText ) throws IOException {
        if( m_queries == null ) {
            return null;
        }

        int[] scores = new int[ m_queries.length ];
        BufferedReader in = new BufferedReader( new StringReader( pageText ) );
        String line = null;

        while( (line = in.readLine() ) != null ) {
            line = line.toLowerCase();

            for( int j = 0; j < m_queries.length; j++ ) {
                int index = -1;

                while( (index = line.indexOf( m_queries[j].word, index + 1 ) ) != -1 ) {
                    if( m_queries[j].type != QueryItem.FORBIDDEN ) {
                        scores[j]++; // Mark, found this word n times
                    } else {
                        // Found something that was forbidden.
                        return null;
                    }
                }
            }
        }

        //
        //  Check that we have all required words.
        //
        int totalscore = 0;

        for( int j = 0; j < scores.length; j++ ) {
            // Give five points for each occurrence
            // of the word in the wiki name.

            if( wikiname.toLowerCase().indexOf( m_queries[j].word ) != -1 && m_queries[j].type != QueryItem.FORBIDDEN ) {
                scores[j] += 5;
            }

            //  Filter out pages if the search word is marked 'required'
            //  but they have no score.

            if( m_queries[j].type == QueryItem.REQUIRED && scores[j] == 0 ) {
                return null;
            }

            //
            //  Count the total score for this page.
            //
            totalscore += scores[j];
        }

        if( totalscore > 0 ) {
            return new SearchResultImpl( wikiname, totalscore );
        }

        return null;
    }

    /**
     *  A local search result.
     */
    public class SearchResultImpl implements SearchResult {
    	
        int      m_score;
        WikiPage m_page;

        /**
         *  Create a new SearchResult with a given name and a score.
         *  
         *  @param name Page Name
         *  @param score A score from 0+
         */
        public SearchResultImpl( String name, int score ) {
            m_page  = new WikiPage( m_engine, name );
            m_score = score;
        }

        /**
         *  Returns Wikipage for this result.
         *  @return WikiPage
         */
        public WikiPage getPage() {
            return m_page;
        }

        /**
         *  Returns a score for this match.
         *  
         *  @return Score from 0+
         */
        public int getScore() {
            return m_score;
        }

        /**
         *  Returns an empty array, since BasicSearchProvider does not support
         *  context matching.
         *  
         *  @return an empty array
         */
        public String[] getContexts() {
            // Unimplemented
            return new String[0];
        }
    }

}