org.bibsonomy.util.tex.TexDecode.java Source code

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Here is the source code for org.bibsonomy.util.tex.TexDecode.java

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/**
 *
 *  BibSonomy-Common - Common things (e.g., exceptions, enums, utils, etc.)
 *
 *  Copyright (C) 2006 - 2011 Knowledge & Data Engineering Group,
 *                            University of Kassel, Germany
 *                            http://www.kde.cs.uni-kassel.de/
 *
 *  This program 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
 *  of the License, or (at your option) any later version.
 *
 *  This program 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; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

package org.bibsonomy.util.tex;

import java.util.Comparator;
import java.util.Scanner;
import java.util.TreeMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Framework to encode TeX Macros to unicode.
 * 
 * @author Christian Claus, Dominik Benz
 * @version $Id: TexDecode.java,v 1.8 2011-04-29 06:36:52 bibsonomy Exp $
 */
public class TexDecode {

    /** logger */
    private static final Log LOGGER = LogFactory.getLog(TexDecode.class);
    /**
     * file holding the mapping between latex macros and unicode codes
     */
    private static final String LATEXMACRO_UNICODECHAR_MAP_FILENAME = "latex_macro_unicode_char_map.tsv";
    private static final String LATEXMACRO_UNICODECHAR_MAP_DELIM = "\t";
    /**
     * the mapping between latex macros and unicode codes. It needs to be sorted
     * because when we build the regex from it, the "longest" macros need to be
     * present at the beginning of the regex.
     */
    private static TreeMap<String, String> texMap = new TreeMap<String, String>(new StringLengthComp());
    /** regex patterns */
    private static Pattern texRegexpPattern;
    private static final String CURLY_BRACKETS = "[{}]*";
    private static final String BRACKETS = "[()]*[\\[\\]]*";

    /**
     * helper comparator to sort strings by their length
     */
    private static class StringLengthComp implements Comparator<String> {
        @Override
        public int compare(String s1, String s2) {
            if (s1.length() > s2.length())
                return -1;
            if (s1.length() < s2.length())
                return 1;
            return s1.compareTo(s2);
        }
    }

    /**
     * initializes the HashMap 'texMap' with TeX macros as key and a referenced
     * Unicode value as value. Also builds the regex for matching the tex
     * macros.
     */
    static {
        loadMapFile();
        final StringBuffer texRegexp = new StringBuffer();
        texRegexp.append("(");
        for (String macro : texMap.keySet()) {
            // build regex
            texRegexp.append(Pattern.quote(macro));
            texRegexp.append("|");
        }
        // delete last "|", add closing bracket
        texRegexp.deleteCharAt(texRegexp.length() - 1);
        texRegexp.append(")");
        // compile pattern
        texRegexpPattern = Pattern.compile(texRegexp.toString());
    }

    /**
     * Decodes a String which contains TeX macros into it's Unicode
     * representation.
     * 
     * @param s
     * @return Unicode representation of the String
     */
    public static String decode(String s) {
        if (s != null) {
            final Matcher texRegexpMatcher = texRegexpPattern.matcher(s.trim().replaceAll(CURLY_BRACKETS, ""));
            final StringBuffer sb = new StringBuffer();
            int i = 0;
            while (texRegexpMatcher.find()) {
                i++;
                texRegexpMatcher.appendReplacement(sb, texMap.get(texRegexpMatcher.group()));
            }
            texRegexpMatcher.appendTail(sb);
            return sb.toString().trim().replaceAll(BRACKETS, "");
        }
        return "";
    }

    /**
     * Getter for the texMap
     * 
     * @return HashMap of TeX->Unicode representation
     */
    protected static TreeMap<String, String> getTexMap() {
        return texMap;
    }

    /**
     * parse the file containing the mappings of unicode characters to latex
     * macros and store it in texMap.
     */
    private static final void loadMapFile() {
        Scanner scanner = new Scanner(
                TexDecode.class.getClassLoader().getResourceAsStream(LATEXMACRO_UNICODECHAR_MAP_FILENAME), "UTF-8");
        String line;
        String[] parts;
        while (scanner.hasNextLine()) {
            line = scanner.nextLine();
            parts = line.split(LATEXMACRO_UNICODECHAR_MAP_DELIM);
            // convert hex representation into unicode string
            texMap.put(parts[1].trim(), String.valueOf(Character.toChars(Integer.parseInt(parts[0].trim(), 16))));
            LOGGER.debug("added new mapping " + parts[1].trim() + " -> " + texMap.get(parts[1].trim()));
        }

    }

}