/*
 * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.com
 * The software in this package is published under the terms of the CPAL v1.0
 * license, a copy of which has been included with this distribution in the
 * LICENSE.txt file.
 */
package org.mule.runtime.core.internal.util;

import org.mule.runtime.core.api.util.StringUtils;

import java.io.IOException;
import java.io.Writer;
import java.util.HashMap;
import java.util.Map;

/**
 * This encoder contains methods that convert characters to Character entities as defined by
 * http://www.w3.org/TR/REC-html40/sgml/entities.html. More precisely it combines the functionality of
 * {@link org.apache.commons.lang3.StringEscapeUtils#escapeXml(String)} and
 * {@link org.apache.commons.lang3.StringEscapeUtils#escapeHtml(String)} into a single pass.
 */
// @ThreadSafe
public final class XMLEntityCodec {

  private static final Entities MuleEntities = new Entities();

  static {
    MuleEntities.addEntities(Entities.APOS_ARRAY);
    MuleEntities.addEntities(Entities.BASIC_ARRAY);
    MuleEntities.addEntities(Entities.ISO8859_1_ARRAY);
    MuleEntities.addEntities(Entities.HTML40_ARRAY);
  }

  protected XMLEntityCodec() {
    // no-op
  }

  public static String encodeString(String str) {
    if (StringUtils.isEmpty(str)) {
      return str;
    }

    return MuleEntities.escape(str);
  }

  public static String decodeString(String str) {
    if (StringUtils.isEmpty(str)) {
      return str;
    }

    return MuleEntities.unescape(str);
  }

  /**
   * <p>
   * Returns the name of the entity identified by the specified value.
   * </p>
   * 
   * @param value the value to locate
   * @return entity name associated with the specified value
   */
  public static String entityName(int value) {
    return MuleEntities.map.name(value);
  }

  /**
   * <p>
   * Returns the value of the entity identified by the specified name.
   * </p>
   * 
   * @param name the name to locate
   * @return entity value associated with the specified name
   */
  public static int entityValue(String name) {
    return MuleEntities.map.value(name);
  }


  //
  // everything from here on is copied from commons-lang 2.2 + svn since it is not
  // extensible and referencing the package-private class can lead to classloader
  // problems :-(
  //

  /*
   * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file
   * distributed with this work for additional information 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, 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.
   */

  /**
   * <p>
   * Provides HTML and XML entity utilities.
   * </p>
   *
   * @see <a href="http://hotwired.lycos.com/webmonkey/reference/special_characters/">ISO Entities</a>
   * @see <a href="http://www.w3.org/TR/REC-html32#latin1">HTML 3.2 Character Entities for ISO Latin-1</a>
   * @see <a href="http://www.w3.org/TR/REC-html40/sgml/entities.html">HTML 4.0 Character entity references</a>
   * @see <a href="http://www.w3.org/TR/html401/charset.html#h-5.3">HTML 4.01 Character References</a>
   * @see <a href="http://www.w3.org/TR/html401/charset.html#code-position">HTML 4.01 Code positions</a>
   *
   * @author <a href="mailto:alex@purpletech.com">Alexander Day Chaffee</a>
   * @author <a href="mailto:ggregory@seagullsw.com">Gary Gregory</a>
   * @since 2.0
   * @version $Id$
   */
  private static class Entities {

    private static final String[][] BASIC_ARRAY = {{"quot", "34"}, // " - double-quote
        {"amp", "38"}, // & - ampersand
        {"lt", "60"}, // < - less-than
        {"gt", "62"}, // > - greater-than
    };

    private static final String[][] APOS_ARRAY = {{"apos", "39"}, // XML apostrophe
    };

    // package scoped for testing
    static final String[][] ISO8859_1_ARRAY = {{"nbsp", "160"}, // non-breaking space
        {"iexcl", "161"}, // inverted exclamation mark
        {"cent", "162"}, // cent sign
        {"pound", "163"}, // pound sign
        {"curren", "164"}, // currency sign
        {"yen", "165"}, // yen sign = yuan sign
        {"brvbar", "166"}, // broken bar = broken vertical bar
        {"sect", "167"}, // section sign
        {"uml", "168"}, // diaeresis = spacing diaeresis
        {"copy", "169"}, // © - copyright sign
        {"ordf", "170"}, // feminine ordinal indicator
        {"laquo", "171"}, // left-pointing double angle quotation mark = left pointing guillemet
        {"not", "172"}, // not sign
        {"shy", "173"}, // soft hyphen = discretionary hyphen
        {"reg", "174"}, // ® - registered trademark sign
        {"macr", "175"}, // macron = spacing macron = overline = APL overbar
        {"deg", "176"}, // degree sign
        {"plusmn", "177"}, // plus-minus sign = plus-or-minus sign
        {"sup2", "178"}, // superscript two = superscript digit two = squared
        {"sup3", "179"}, // superscript three = superscript digit three = cubed
        {"acute", "180"}, // acute accent = spacing acute
        {"micro", "181"}, // micro sign
        {"para", "182"}, // pilcrow sign = paragraph sign
        {"middot", "183"}, // middle dot = Georgian comma = Greek middle dot
        {"cedil", "184"}, // cedilla = spacing cedilla
        {"sup1", "185"}, // superscript one = superscript digit one
        {"ordm", "186"}, // masculine ordinal indicator
        {"raquo", "187"}, // right-pointing double angle quotation mark = right pointing guillemet
        {"frac14", "188"}, // vulgar fraction one quarter = fraction one quarter
        {"frac12", "189"}, // vulgar fraction one half = fraction one half
        {"frac34", "190"}, // vulgar fraction three quarters = fraction three quarters
        {"iquest", "191"}, // inverted question mark = turned question mark
        {"Agrave", "192"}, // À - uppercase A, grave accent
        {"Aacute", "193"}, // Á - uppercase A, acute accent
        {"Acirc", "194"}, // Â - uppercase A, circumflex accent
        {"Atilde", "195"}, // Ã - uppercase A, tilde
        {"Auml", "196"}, // Ä - uppercase A, umlaut
        {"Aring", "197"}, // Å - uppercase A, ring
        {"AElig", "198"}, // Æ - uppercase AE
        {"Ccedil", "199"}, // Ç - uppercase C, cedilla
        {"Egrave", "200"}, // È - uppercase E, grave accent
        {"Eacute", "201"}, // É - uppercase E, acute accent
        {"Ecirc", "202"}, // Ê - uppercase E, circumflex accent
        {"Euml", "203"}, // Ë - uppercase E, umlaut
        {"Igrave", "204"}, // Ì - uppercase I, grave accent
        {"Iacute", "205"}, // Í - uppercase I, acute accent
        {"Icirc", "206"}, // Î - uppercase I, circumflex accent
        {"Iuml", "207"}, // Ï - uppercase I, umlaut
        {"ETH", "208"}, // Ð - uppercase Eth, Icelandic
        {"Ntilde", "209"}, // Ñ - uppercase N, tilde
        {"Ograve", "210"}, // Ò - uppercase O, grave accent
        {"Oacute", "211"}, // Ó - uppercase O, acute accent
        {"Ocirc", "212"}, // Ô - uppercase O, circumflex accent
        {"Otilde", "213"}, // Õ - uppercase O, tilde
        {"Ouml", "214"}, // Ö - uppercase O, umlaut
        {"times", "215"}, // multiplication sign
        {"Oslash", "216"}, // Ø - uppercase O, slash
        {"Ugrave", "217"}, // Ù - uppercase U, grave accent
        {"Uacute", "218"}, // Ú - uppercase U, acute accent
        {"Ucirc", "219"}, // Û - uppercase U, circumflex accent
        {"Uuml", "220"}, // Ü - uppercase U, umlaut
        {"Yacute", "221"}, // Ý - uppercase Y, acute accent
        {"THORN", "222"}, // Þ - uppercase THORN, Icelandic
        {"szlig", "223"}, // ß - lowercase sharps, German
        {"agrave", "224"}, // à - lowercase a, grave accent
        {"aacute", "225"}, // á - lowercase a, acute accent
        {"acirc", "226"}, // â - lowercase a, circumflex accent
        {"atilde", "227"}, // ã - lowercase a, tilde
        {"auml", "228"}, // ä - lowercase a, umlaut
        {"aring", "229"}, // å - lowercase a, ring
        {"aelig", "230"}, // æ - lowercase ae
        {"ccedil", "231"}, // ç - lowercase c, cedilla
        {"egrave", "232"}, // è - lowercase e, grave accent
        {"eacute", "233"}, // é - lowercase e, acute accent
        {"ecirc", "234"}, // ê - lowercase e, circumflex accent
        {"euml", "235"}, // ë - lowercase e, umlaut
        {"igrave", "236"}, // ì - lowercase i, grave accent
        {"iacute", "237"}, // í - lowercase i, acute accent
        {"icirc", "238"}, // î - lowercase i, circumflex accent
        {"iuml", "239"}, // ï - lowercase i, umlaut
        {"eth", "240"}, // ð - lowercase eth, Icelandic
        {"ntilde", "241"}, // ñ - lowercase n, tilde
        {"ograve", "242"}, // ò - lowercase o, grave accent
        {"oacute", "243"}, // ó - lowercase o, acute accent
        {"ocirc", "244"}, // ô - lowercase o, circumflex accent
        {"otilde", "245"}, // õ - lowercase o, tilde
        {"ouml", "246"}, // ö - lowercase o, umlaut
        {"divide", "247"}, // division sign
        {"oslash", "248"}, // ø - lowercase o, slash
        {"ugrave", "249"}, // ù - lowercase u, grave accent
        {"uacute", "250"}, // ú - lowercase u, acute accent
        {"ucirc", "251"}, // û - lowercase u, circumflex accent
        {"uuml", "252"}, // ü - lowercase u, umlaut
        {"yacute", "253"}, // ý - lowercase y, acute accent
        {"thorn", "254"}, // þ - lowercase thorn, Icelandic
        {"yuml", "255"}, // ÿ - lowercase y, umlaut
    };

    // http://www.w3.org/TR/REC-html40/sgml/entities.html
    // package scoped for testing
    static final String[][] HTML40_ARRAY = {
        // <!-- Latin Extended-B -->
        {"fnof", "402"}, // latin small f with hook = function= florin, U+0192 ISOtech -->
        // <!-- Greek -->
        {"Alpha", "913"}, // greek capital letter alpha, U+0391 -->
        {"Beta", "914"}, // greek capital letter beta, U+0392 -->
        {"Gamma", "915"}, // greek capital letter gamma,U+0393 ISOgrk3 -->
        {"Delta", "916"}, // greek capital letter delta,U+0394 ISOgrk3 -->
        {"Epsilon", "917"}, // greek capital letter epsilon, U+0395 -->
        {"Zeta", "918"}, // greek capital letter zeta, U+0396 -->
        {"Eta", "919"}, // greek capital letter eta, U+0397 -->
        {"Theta", "920"}, // greek capital letter theta,U+0398 ISOgrk3 -->
        {"Iota", "921"}, // greek capital letter iota, U+0399 -->
        {"Kappa", "922"}, // greek capital letter kappa, U+039A -->
        {"Lambda", "923"}, // greek capital letter lambda,U+039B ISOgrk3 -->
        {"Mu", "924"}, // greek capital letter mu, U+039C -->
        {"Nu", "925"}, // greek capital letter nu, U+039D -->
        {"Xi", "926"}, // greek capital letter xi, U+039E ISOgrk3 -->
        {"Omicron", "927"}, // greek capital letter omicron, U+039F -->
        {"Pi", "928"}, // greek capital letter pi, U+03A0 ISOgrk3 -->
        {"Rho", "929"}, // greek capital letter rho, U+03A1 -->
        // <!-- there is no Sigmaf, and no U+03A2 character either -->
        {"Sigma", "931"}, // greek capital letter sigma,U+03A3 ISOgrk3 -->
        {"Tau", "932"}, // greek capital letter tau, U+03A4 -->
        {"Upsilon", "933"}, // greek capital letter upsilon,U+03A5 ISOgrk3 -->
        {"Phi", "934"}, // greek capital letter phi,U+03A6 ISOgrk3 -->
        {"Chi", "935"}, // greek capital letter chi, U+03A7 -->
        {"Psi", "936"}, // greek capital letter psi,U+03A8 ISOgrk3 -->
        {"Omega", "937"}, // greek capital letter omega,U+03A9 ISOgrk3 -->
        {"alpha", "945"}, // greek small letter alpha,U+03B1 ISOgrk3 -->
        {"beta", "946"}, // greek small letter beta, U+03B2 ISOgrk3 -->
        {"gamma", "947"}, // greek small letter gamma,U+03B3 ISOgrk3 -->
        {"delta", "948"}, // greek small letter delta,U+03B4 ISOgrk3 -->
        {"epsilon", "949"}, // greek small letter epsilon,U+03B5 ISOgrk3 -->
        {"zeta", "950"}, // greek small letter zeta, U+03B6 ISOgrk3 -->
        {"eta", "951"}, // greek small letter eta, U+03B7 ISOgrk3 -->
        {"theta", "952"}, // greek small letter theta,U+03B8 ISOgrk3 -->
        {"iota", "953"}, // greek small letter iota, U+03B9 ISOgrk3 -->
        {"kappa", "954"}, // greek small letter kappa,U+03BA ISOgrk3 -->
        {"lambda", "955"}, // greek small letter lambda,U+03BB ISOgrk3 -->
        {"mu", "956"}, // greek small letter mu, U+03BC ISOgrk3 -->
        {"nu", "957"}, // greek small letter nu, U+03BD ISOgrk3 -->
        {"xi", "958"}, // greek small letter xi, U+03BE ISOgrk3 -->
        {"omicron", "959"}, // greek small letter omicron, U+03BF NEW -->
        {"pi", "960"}, // greek small letter pi, U+03C0 ISOgrk3 -->
        {"rho", "961"}, // greek small letter rho, U+03C1 ISOgrk3 -->
        {"sigmaf", "962"}, // greek small letter final sigma,U+03C2 ISOgrk3 -->
        {"sigma", "963"}, // greek small letter sigma,U+03C3 ISOgrk3 -->
        {"tau", "964"}, // greek small letter tau, U+03C4 ISOgrk3 -->
        {"upsilon", "965"}, // greek small letter upsilon,U+03C5 ISOgrk3 -->
        {"phi", "966"}, // greek small letter phi, U+03C6 ISOgrk3 -->
        {"chi", "967"}, // greek small letter chi, U+03C7 ISOgrk3 -->
        {"psi", "968"}, // greek small letter psi, U+03C8 ISOgrk3 -->
        {"omega", "969"}, // greek small letter omega,U+03C9 ISOgrk3 -->
        {"thetasym", "977"}, // greek small letter theta symbol,U+03D1 NEW -->
        {"upsih", "978"}, // greek upsilon with hook symbol,U+03D2 NEW -->
        {"piv", "982"}, // greek pi symbol, U+03D6 ISOgrk3 -->
        // <!-- General Punctuation -->
        {"bull", "8226"}, // bullet = black small circle,U+2022 ISOpub -->
        // <!-- bullet is NOT the same as bullet operator, U+2219 -->
        {"hellip", "8230"}, // horizontal ellipsis = three dot leader,U+2026 ISOpub -->
        {"prime", "8242"}, // prime = minutes = feet, U+2032 ISOtech -->
        {"Prime", "8243"}, // double prime = seconds = inches,U+2033 ISOtech -->
        {"oline", "8254"}, // overline = spacing overscore,U+203E NEW -->
        {"frasl", "8260"}, // fraction slash, U+2044 NEW -->
        // <!-- Letterlike Symbols -->
        {"weierp", "8472"}, // script capital P = power set= Weierstrass p, U+2118 ISOamso -->
        {"image", "8465"}, // blackletter capital I = imaginary part,U+2111 ISOamso -->
        {"real", "8476"}, // blackletter capital R = real part symbol,U+211C ISOamso -->
        {"trade", "8482"}, // trade mark sign, U+2122 ISOnum -->
        {"alefsym", "8501"}, // alef symbol = first transfinite cardinal,U+2135 NEW -->
        // <!-- alef symbol is NOT the same as hebrew letter alef,U+05D0 although the
        // same glyph could be used to depict both characters -->
        // <!-- Arrows -->
        {"larr", "8592"}, // leftwards arrow, U+2190 ISOnum -->
        {"uarr", "8593"}, // upwards arrow, U+2191 ISOnum-->
        {"rarr", "8594"}, // rightwards arrow, U+2192 ISOnum -->
        {"darr", "8595"}, // downwards arrow, U+2193 ISOnum -->
        {"harr", "8596"}, // left right arrow, U+2194 ISOamsa -->
        {"crarr", "8629"}, // downwards arrow with corner leftwards= carriage return, U+21B5 NEW -->
        {"lArr", "8656"}, // leftwards double arrow, U+21D0 ISOtech -->
        // <!-- ISO 10646 does not say that lArr is the same as the 'is implied by'
        // arrow but also does not have any other character for that function.
        // So ? lArr canbe used for 'is implied by' as ISOtech suggests -->
        {"uArr", "8657"}, // upwards double arrow, U+21D1 ISOamsa -->
        {"rArr", "8658"}, // rightwards double arrow,U+21D2 ISOtech -->
        // <!-- ISO 10646 does not say this is the 'implies' character but does not
        // have another character with this function so ?rArr can be used for
        // 'implies' as ISOtech suggests -->
        {"dArr", "8659"}, // downwards double arrow, U+21D3 ISOamsa -->
        {"hArr", "8660"}, // left right double arrow,U+21D4 ISOamsa -->
        // <!-- Mathematical Operators -->
        {"forall", "8704"}, // for all, U+2200 ISOtech -->
        {"part", "8706"}, // partial differential, U+2202 ISOtech -->
        {"exist", "8707"}, // there exists, U+2203 ISOtech -->
        {"empty", "8709"}, // empty set = null set = diameter,U+2205 ISOamso -->
        {"nabla", "8711"}, // nabla = backward difference,U+2207 ISOtech -->
        {"isin", "8712"}, // element of, U+2208 ISOtech -->
        {"notin", "8713"}, // not an element of, U+2209 ISOtech -->
        {"ni", "8715"}, // contains as member, U+220B ISOtech -->
        // <!-- should there be a more memorable name than 'ni'? -->
        {"prod", "8719"}, // n-ary product = product sign,U+220F ISOamsb -->
        // <!-- prod is NOT the same character as U+03A0 'greek capital letter pi'
        // though the same glyph might be used for both -->
        {"sum", "8721"}, // n-ary summation, U+2211 ISOamsb -->
        // <!-- sum is NOT the same character as U+03A3 'greek capital letter sigma'
        // though the same glyph might be used for both -->
        {"minus", "8722"}, // minus sign, U+2212 ISOtech -->
        {"lowast", "8727"}, // asterisk operator, U+2217 ISOtech -->
        {"radic", "8730"}, // square root = radical sign,U+221A ISOtech -->
        {"prop", "8733"}, // proportional to, U+221D ISOtech -->
        {"infin", "8734"}, // infinity, U+221E ISOtech -->
        {"ang", "8736"}, // angle, U+2220 ISOamso -->
        {"and", "8743"}, // logical and = wedge, U+2227 ISOtech -->
        {"or", "8744"}, // logical or = vee, U+2228 ISOtech -->
        {"cap", "8745"}, // intersection = cap, U+2229 ISOtech -->
        {"cup", "8746"}, // union = cup, U+222A ISOtech -->
        {"int", "8747"}, // integral, U+222B ISOtech -->
        {"there4", "8756"}, // therefore, U+2234 ISOtech -->
        {"sim", "8764"}, // tilde operator = varies with = similar to,U+223C ISOtech -->
        // <!-- tilde operator is NOT the same character as the tilde, U+007E,although
        // the same glyph might be used to represent both -->
        {"cong", "8773"}, // approximately equal to, U+2245 ISOtech -->
        {"asymp", "8776"}, // almost equal to = asymptotic to,U+2248 ISOamsr -->
        {"ne", "8800"}, // not equal to, U+2260 ISOtech -->
        {"equiv", "8801"}, // identical to, U+2261 ISOtech -->
        {"le", "8804"}, // less-than or equal to, U+2264 ISOtech -->
        {"ge", "8805"}, // greater-than or equal to,U+2265 ISOtech -->
        {"sub", "8834"}, // subset of, U+2282 ISOtech -->
        {"sup", "8835"}, // superset of, U+2283 ISOtech -->
        // <!-- note that nsup, 'not a superset of, U+2283' is not covered by the
        // Symbol font encoding and is not included. Should it be, for symmetry?
        // It is in ISOamsn --> <!ENTITY nsub", "8836"},
        // not a subset of, U+2284 ISOamsn -->
        {"sube", "8838"}, // subset of or equal to, U+2286 ISOtech -->
        {"supe", "8839"}, // superset of or equal to,U+2287 ISOtech -->
        {"oplus", "8853"}, // circled plus = direct sum,U+2295 ISOamsb -->
        {"otimes", "8855"}, // circled times = vector product,U+2297 ISOamsb -->
        {"perp", "8869"}, // up tack = orthogonal to = perpendicular,U+22A5 ISOtech -->
        {"sdot", "8901"}, // dot operator, U+22C5 ISOamsb -->
        // <!-- dot operator is NOT the same character as U+00B7 middle dot -->
        // <!-- Miscellaneous Technical -->
        {"lceil", "8968"}, // left ceiling = apl upstile,U+2308 ISOamsc -->
        {"rceil", "8969"}, // right ceiling, U+2309 ISOamsc -->
        {"lfloor", "8970"}, // left floor = apl downstile,U+230A ISOamsc -->
        {"rfloor", "8971"}, // right floor, U+230B ISOamsc -->
        {"lang", "9001"}, // left-pointing angle bracket = bra,U+2329 ISOtech -->
        // <!-- lang is NOT the same character as U+003C 'less than' or U+2039 'single left-pointing angle quotation mark' -->
        {"rang", "9002"}, // right-pointing angle bracket = ket,U+232A ISOtech -->
        // <!-- rang is NOT the same character as U+003E 'greater than' or U+203A
        // 'single right-pointing angle quotation mark' -->
        // <!-- Geometric Shapes -->
        {"loz", "9674"}, // lozenge, U+25CA ISOpub -->
        // <!-- Miscellaneous Symbols -->
        {"spades", "9824"}, // black spade suit, U+2660 ISOpub -->
        // <!-- black here seems to mean filled as opposed to hollow -->
        {"clubs", "9827"}, // black club suit = shamrock,U+2663 ISOpub -->
        {"hearts", "9829"}, // black heart suit = valentine,U+2665 ISOpub -->
        {"diams", "9830"}, // black diamond suit, U+2666 ISOpub -->

        // <!-- Latin Extended-A -->
        {"OElig", "338"}, // -- latin capital ligature OE,U+0152 ISOlat2 -->
        {"oelig", "339"}, // -- latin small ligature oe, U+0153 ISOlat2 -->
        // <!-- ligature is a misnomer, this is a separate character in some languages -->
        {"Scaron", "352"}, // -- latin capital letter S with caron,U+0160 ISOlat2 -->
        {"scaron", "353"}, // -- latin small letter s with caron,U+0161 ISOlat2 -->
        {"Yuml", "376"}, // -- latin capital letter Y with diaeresis,U+0178 ISOlat2 -->
        // <!-- Spacing Modifier Letters -->
        {"circ", "710"}, // -- modifier letter circumflex accent,U+02C6 ISOpub -->
        {"tilde", "732"}, // small tilde, U+02DC ISOdia -->
        // <!-- General Punctuation -->
        {"ensp", "8194"}, // en space, U+2002 ISOpub -->
        {"emsp", "8195"}, // em space, U+2003 ISOpub -->
        {"thinsp", "8201"}, // thin space, U+2009 ISOpub -->
        {"zwnj", "8204"}, // zero width non-joiner,U+200C NEW RFC 2070 -->
        {"zwj", "8205"}, // zero width joiner, U+200D NEW RFC 2070 -->
        {"lrm", "8206"}, // left-to-right mark, U+200E NEW RFC 2070 -->
        {"rlm", "8207"}, // right-to-left mark, U+200F NEW RFC 2070 -->
        {"ndash", "8211"}, // en dash, U+2013 ISOpub -->
        {"mdash", "8212"}, // em dash, U+2014 ISOpub -->
        {"lsquo", "8216"}, // left single quotation mark,U+2018 ISOnum -->
        {"rsquo", "8217"}, // right single quotation mark,U+2019 ISOnum -->
        {"sbquo", "8218"}, // single low-9 quotation mark, U+201A NEW -->
        {"ldquo", "8220"}, // left double quotation mark,U+201C ISOnum -->
        {"rdquo", "8221"}, // right double quotation mark,U+201D ISOnum -->
        {"bdquo", "8222"}, // double low-9 quotation mark, U+201E NEW -->
        {"dagger", "8224"}, // dagger, U+2020 ISOpub -->
        {"Dagger", "8225"}, // double dagger, U+2021 ISOpub -->
        {"permil", "8240"}, // per mille sign, U+2030 ISOtech -->
        {"lsaquo", "8249"}, // single left-pointing angle quotation mark,U+2039 ISO proposed -->
        // <!-- lsaquo is proposed but not yet ISO standardized -->
        {"rsaquo", "8250"}, // single right-pointing angle quotation mark,U+203A ISO proposed -->
        // <!-- rsaquo is proposed but not yet ISO standardized -->
        {"euro", "8364"}, // -- euro sign, U+20AC NEW -->
    };

    // package scoped for testing
    private EntityMap map = new Entities.LookupEntityMap();

    /**
     * <p>
     * Adds entities to this entity.
     * </p>
     * 
     * @param entityArray array of entities to be added
     */
    public void addEntities(String[][] entityArray) {
      for (int i = 0; i < entityArray.length; ++i) {
        addEntity(entityArray[i][0], Integer.parseInt(entityArray[i][1]));
      }
    }

    /**
     * <p>
     * Add an entity to this entity.
     * </p>
     * 
     * @param name name of the entity
     * @param value vale of the entity
     */
    public void addEntity(String name, int value) {
      map.add(name, value);
    }

    /**
     * <p>
     * Returns the name of the entity identified by the specified value.
     * </p>
     * 
     * @param value the value to locate
     * @return entity name associated with the specified value
     */
    public String entityName(int value) {
      return map.name(value);
    }

    /**
     * <p>
     * Returns the value of the entity identified by the specified name.
     * </p>
     * 
     * @param name the name to locate
     * @return entity value associated with the specified name
     */
    public int entityValue(String name) {
      return map.value(name);
    }

    /**
     * <p>
     * Escapes the characters in a <code>String</code>.
     * </p>
     * <p>
     * For example, if you have called addEntity(&quot;foo&quot;, 0xA1), escape(&quot;\u00A1&quot;) will return
     * &quot;&amp;foo;&quot;
     * </p>
     * 
     * @param str The <code>String</code> to escape.
     * @return A new escaped <code>String</code>.
     */
    public String escape(String str) {
      // TODO: rewrite to use a Writer
      StringBuilder buf = new StringBuilder(str.length() * 2);
      for (int i = 0; i < str.length(); ++i) {
        char ch = str.charAt(i);
        String entityName = this.entityName(ch);
        if (entityName == null) {
          if (ch > 0x7F) {
            buf.append('&');
            buf.append('#');
            buf.append((int) ch);
            buf.append(';');
          } else {
            buf.append(ch);
          }
        } else {
          buf.append('&');
          buf.append(entityName);
          buf.append(';');
        }
      }
      return buf.toString();
    }

    /**
     * <p>
     * Escapes the characters in the <code>String</code> passed and writes the result to the <code>Writer</code> passed.
     * </p>
     * 
     * @param writer The <code>Writer</code> to write the results of the escaping to. Assumed to be a non-null value.
     * @param str The <code>String</code> to escape. Assumed to be a non-null value.
     * @throws IOException when <code>Writer</code> passed throws the exception from calls to the {@link Writer#write(int)}
     *         methods.
     * @see #escape(String)
     * @see Writer
     */
    public void escape(Writer writer, String str) throws IOException {
      int len = str.length();
      for (int i = 0; i < len; i++) {
        char c = str.charAt(i);
        String entityName = this.entityName(c);
        if (entityName == null) {
          if (c > 0x7F) {
            writer.write("&#");
            writer.write(Integer.toString(c, 10));
            writer.write(';');
          } else {
            writer.write(c);
          }
        } else {
          writer.write('&');
          writer.write(entityName);
          writer.write(';');
        }
      }
    }

    /**
     * <p>
     * Unescapes the entities in a <code>String</code>.
     * </p>
     * <p>
     * For example, if you have called addEntity(&quot;foo&quot;, 0xA1), unescape(&quot;&amp;foo;&quot;) will return
     * &quot;\u00A1&quot;
     * </p>
     * 
     * @param str The <code>String</code> to escape.
     * @return A new escaped <code>String</code> or str itself if no unescaping was necessary.
     */
    public String unescape(String str) {
      int firstAmp = str.indexOf('&');
      if (firstAmp < 0) {
        return str;
      }

      StringBuilder buf = new StringBuilder(str.length());
      buf.append(str.substring(0, firstAmp));
      for (int i = firstAmp; i < str.length(); ++i) {
        char ch = str.charAt(i);
        if (ch == '&') {
          int semi = str.indexOf(';', i + 1);
          if (semi == -1) {
            buf.append(ch);
            continue;
          }
          int amph = str.indexOf('&', i + 1);
          if (amph != -1 && amph < semi) {
            // Then the text looks like &...&...;
            buf.append(ch);
            continue;
          }
          String entityName = str.substring(i + 1, semi);
          int entityValue;
          if (entityName.length() == 0) {
            entityValue = -1;
          } else if (entityName.charAt(0) == '#') {
            if (entityName.length() == 1) {
              entityValue = -1;
            } else {
              char charAt1 = entityName.charAt(1);
              try {
                if (charAt1 == 'x' || charAt1 == 'X') {
                  entityValue = Integer.valueOf(entityName.substring(2), 16).intValue();
                } else {
                  entityValue = Integer.parseInt(entityName.substring(1));
                }
                if (entityValue > 0xFFFF) {
                  entityValue = -1;
                }
              } catch (NumberFormatException ex) {
                entityValue = -1;
              }
            }
          } else {
            entityValue = this.entityValue(entityName);
          }
          if (entityValue == -1) {
            buf.append('&');
            buf.append(entityName);
            buf.append(';');
          } else {
            buf.append((char) (entityValue));
          }
          i = semi;
        } else {
          buf.append(ch);
        }
      }
      return buf.toString();
    }

    /**
     * <p>
     * Unescapes the escaped entities in the <code>String</code> passed and writes the result to the <code>Writer</code> passed.
     * </p>
     * 
     * @param writer The <code>Writer</code> to write the results to; assumed to be non-null.
     * @param string The <code>String</code> to write the results to; assumed to be non-null.
     * @throws IOException when <code>Writer</code> passed throws the exception from calls to the {@link Writer#write(int)}
     *         methods.
     * @see #escape(String)
     * @see Writer
     */
    public void unescape(Writer writer, String string) throws IOException {
      int firstAmp = string.indexOf('&');
      if (firstAmp < 0) {
        writer.write(string);
        return;
      }

      writer.write(string, 0, firstAmp);
      int len = string.length();
      for (int i = firstAmp; i < len; i++) {
        char c = string.charAt(i);
        if (c == '&') {
          int nextIdx = i + 1;
          int semiColonIdx = string.indexOf(';', nextIdx);
          if (semiColonIdx == -1) {
            writer.write(c);
            continue;
          }
          int amphersandIdx = string.indexOf('&', i + 1);
          if (amphersandIdx != -1 && amphersandIdx < semiColonIdx) {
            // Then the text looks like &...&...;
            writer.write(c);
            continue;
          }
          String entityContent = string.substring(nextIdx, semiColonIdx);
          int entityValue = -1;
          int entityContentLen = entityContent.length();
          if (entityContentLen > 0) {
            if (entityContent.charAt(0) == '#') { // escaped value content is an integer (decimal or
                                                  // hexidecimal)
              if (entityContentLen > 1) {
                char isHexChar = entityContent.charAt(1);
                try {
                  switch (isHexChar) {
                    case 'X':
                    case 'x':
                      entityValue = Integer.parseInt(entityContent.substring(2), 16);
                      break;
                    default:
                      entityValue = Integer.parseInt(entityContent.substring(1), 10);
                  }
                  if (entityValue > 0xFFFF) {
                    entityValue = -1;
                  }
                } catch (NumberFormatException e) {
                  entityValue = -1;
                }
              }
            } else { // escaped value content is an entity name
              entityValue = this.entityValue(entityContent);
            }
          }

          if (entityValue == -1) {
            writer.write('&');
            writer.write(entityContent);
            writer.write(';');
          } else {
            writer.write(entityValue);
          }
          i = semiColonIdx; // move index up to the semi-colon
        } else {
          writer.write(c);
        }
      }
    }

    private static interface EntityMap {

      /**
       * <p>
       * Add an entry to this entity map.
       * </p>
       * 
       * @param name the entity name
       * @param value the entity value
       */
      void add(String name, int value);

      /**
       * <p>
       * Returns the name of the entity identified by the specified value.
       * </p>
       * 
       * @param value the value to locate
       * @return entity name associated with the specified value
       */
      String name(int value);

      /**
       * <p>
       * Returns the value of the entity identified by the specified name.
       * </p>
       * 
       * @param name the name to locate
       * @return entity value associated with the specified name
       */
      int value(String name);
    }

    private static class PrimitiveEntityMap implements EntityMap {

      private Map mapNameToValue = new HashMap();
      private IntHashMap mapValueToName = new IntHashMap();

      /**
       * {@inheritDoc}
       */
      public void add(String name, int value) {
        mapNameToValue.put(name, new Integer(value));
        mapValueToName.put(value, name);
      }

      /**
       * {@inheritDoc}
       */
      public String name(int value) {
        return (String) mapValueToName.get(value);
      }

      /**
       * {@inheritDoc}
       */
      public int value(String name) {
        Object value = mapNameToValue.get(name);
        if (value == null) {
          return -1;
        }
        return ((Integer) value).intValue();
      }
    }

    private static class LookupEntityMap extends PrimitiveEntityMap {

      private static final int LOOKUP_TABLE_SIZE = 256;
      private String[] lookupTable;

      /**
       * {@inheritDoc}
       */
      public String name(int value) {
        if (value < LOOKUP_TABLE_SIZE) {
          return lookupTable()[value];
        }
        return super.name(value);
      }

      /**
       * <p>
       * Returns the lookup table for this entity map. The lookup table is created if it has not been previously.
       * </p>
       * 
       * @return the lookup table
       */
      private String[] lookupTable() {
        if (lookupTable == null) {
          createLookupTable();
        }
        return lookupTable;
      }

      /**
       * <p>
       * Creates an entity lookup table of LOOKUP_TABLE_SIZE elements, initialized with entity names.
       * </p>
       */
      private void createLookupTable() {
        lookupTable = new String[LOOKUP_TABLE_SIZE];
        for (int i = 0; i < LOOKUP_TABLE_SIZE; ++i) {
          lookupTable[i] = super.name(i);
        }
      }
    }

    /**
     * <p>
     * A hash map that uses primitive ints for the key rather than objects.
     * </p>
     * <p>
     * Note that this class is for internal optimization purposes only, and may not be supported in future releases of Jakarta
     * Commons Lang. Utilities of this sort may be included in future releases of Jakarta Commons Collections.
     * </p>
     * 
     * @author Justin Couch
     * @author Alex Chaffee (alex@apache.org)
     * @author Stephen Colebourne
     * @since 2.0
     * @version $Revision$
     * @see java.util.HashMap
     */
    private static class IntHashMap {

      /**
       * The hash table data.
       */
      private transient Entry table[];

      /**
       * The total number of entries in the hash table.
       */
      private transient int count;

      /**
       * The table is rehashed when its size exceeds this threshold. (The value of this field is (int)(capacity * loadFactor).)
       * 
       * @serial
       */
      private int threshold;

      /**
       * The load factor for the hashtable.
       * 
       * @serial
       */
      private float loadFactor;

      /**
       * <p>
       * Innerclass that acts as a datastructure to create a new entry in the table.
       * </p>
       */
      private static class Entry {

        int hash;
        int key;
        Object value;
        Entry next;

        /**
         * <p>
         * Create a new entry with the given values.
         * </p>
         * 
         * @param hash The code used to hash the object with
         * @param key The key used to enter this in the table
         * @param value The value for this key
         * @param next A reference to the next entry in the table
         */
        protected Entry(int hash, int key, Object value, Entry next) {
          this.hash = hash;
          this.key = key;
          this.value = value;
          this.next = next;
        }
      }

      /**
       * <p>
       * Constructs a new, empty hashtable with a default capacity and load factor, which is <code>20</code> and <code>0.75</code>
       * respectively.
       * </p>
       */
      public IntHashMap() {
        this(20, 0.75f);
      }

      /**
       * <p>
       * Constructs a new, empty hashtable with the specified initial capacity and default load factor, which is
       * <code>0.75</code>.
       * </p>
       * 
       * @param initialCapacity the initial capacity of the hashtable.
       * @throws IllegalArgumentException if the initial capacity is less than zero.
       */
      public IntHashMap(int initialCapacity) {
        this(initialCapacity, 0.75f);
      }

      /**
       * <p>
       * Constructs a new, empty hashtable with the specified initial capacity and the specified load factor.
       * </p>
       * 
       * @param initialCapacity the initial capacity of the hashtable.
       * @param loadFactor the load factor of the hashtable.
       * @throws IllegalArgumentException if the initial capacity is less than zero, or if the load factor is nonpositive.
       */
      public IntHashMap(int initialCapacity, float loadFactor) {
        super();
        if (initialCapacity < 0) {
          throw new IllegalArgumentException("Illegal Capacity: " + initialCapacity);
        }
        if (loadFactor <= 0) {
          throw new IllegalArgumentException("Illegal Load: " + loadFactor);
        }
        if (initialCapacity == 0) {
          initialCapacity = 1;
        }

        this.loadFactor = loadFactor;
        table = new Entry[initialCapacity];
        threshold = (int) (initialCapacity * loadFactor);
      }

      /**
       * <p>
       * Returns the number of keys in this hashtable.
       * </p>
       * 
       * @return the number of keys in this hashtable.
       */
      public int size() {
        return count;
      }

      /**
       * <p>
       * Tests if this hashtable maps no keys to values.
       * </p>
       * 
       * @return <code>true</code> if this hashtable maps no keys to values; <code>false</code> otherwise.
       */
      public boolean isEmpty() {
        return count == 0;
      }

      /**
       * <p>
       * Tests if some key maps into the specified value in this hashtable. This operation is more expensive than the
       * <code>containsKey</code> method.
       * </p>
       * <p>
       * Note that this method is identical in functionality to containsValue, (which is part of the Map interface in the
       * collections framework).
       * </p>
       * 
       * @param value a value to search for.
       * @return <code>true</code> if and only if some key maps to the <code>value</code> argument in this hashtable as determined
       *         by the <tt>equals</tt> method; <code>false</code> otherwise.
       * @throws NullPointerException if the value is <code>null</code>.
       * @see #containsKey(int)
       * @see #containsValue(Object)
       * @see java.util.Map
       */
      public boolean contains(Object value) {
        if (value == null) {
          throw new IllegalArgumentException("parameter value may not be null");
        }

        Entry tab[] = table;
        for (int i = tab.length; i-- > 0;) {
          for (Entry e = tab[i]; e != null; e = e.next) {
            if (e.value.equals(value)) {
              return true;
            }
          }
        }
        return false;
      }

      /**
       * <p>
       * Returns <code>true</code> if this HashMap maps one or more keys to this value.
       * </p>
       * <p>
       * Note that this method is identical in functionality to contains (which predates the Map interface).
       * </p>
       * 
       * @param value value whose presence in this HashMap is to be tested.
       * @return boolean <code>true</code> if the value is contained
       * @see java.util.Map
       * @since JDK1.2
       */
      public boolean containsValue(Object value) {
        return contains(value);
      }

      /**
       * <p>
       * Tests if the specified object is a key in this hashtable.
       * </p>
       * 
       * @param key possible key.
       * @return <code>true</code> if and only if the specified object is a key in this hashtable, as determined by the
       *         <tt>equals</tt> method; <code>false</code> otherwise.
       * @see #contains(Object)
       */
      public boolean containsKey(int key) {
        Entry tab[] = table;
        int hash = key;
        int index = (hash & 0x7FFFFFFF) % tab.length;
        for (Entry e = tab[index]; e != null; e = e.next) {
          if (e.hash == hash) {
            return true;
          }
        }
        return false;
      }

      /**
       * <p>
       * Returns the value to which the specified key is mapped in this map.
       * </p>
       * 
       * @param key a key in the hashtable.
       * @return the value to which the key is mapped in this hashtable; <code>null</code> if the key is not mapped to any value
       *         in this hashtable.
       * @see #put(int, Object)
       */
      public Object get(int key) {
        Entry tab[] = table;
        int hash = key;
        int index = (hash & 0x7FFFFFFF) % tab.length;
        for (Entry e = tab[index]; e != null; e = e.next) {
          if (e.hash == hash) {
            return e.value;
          }
        }
        return null;
      }

      /**
       * <p>
       * Increases the capacity of and internally reorganizes this hashtable, in order to accommodate and access its entries more
       * efficiently.
       * </p>
       * <p>
       * This method is called automatically when the number of keys in the hashtable exceeds this hashtable's capacity and load
       * factor.
       * </p>
       */
      protected void rehash() {
        int oldCapacity = table.length;
        Entry oldMap[] = table;

        int newCapacity = oldCapacity * 2 + 1;
        Entry newMap[] = new Entry[newCapacity];

        threshold = (int) (newCapacity * loadFactor);
        table = newMap;

        for (int i = oldCapacity; i-- > 0;) {
          for (Entry old = oldMap[i]; old != null;) {
            Entry e = old;
            old = old.next;

            int index = (e.hash & 0x7FFFFFFF) % newCapacity;
            e.next = newMap[index];
            newMap[index] = e;
          }
        }
      }

      /**
       * <p>
       * Maps the specified <code>key</code> to the specified <code>value</code> in this hashtable. The key cannot be
       * <code>null</code>.
       * </p>
       * <p>
       * The value can be retrieved by calling the <code>get</code> method with a key that is equal to the original key.
       * </p>
       * 
       * @param key the hashtable key.
       * @param value the value.
       * @return the previous value of the specified key in this hashtable, or <code>null</code> if it did not have one.
       * @throws NullPointerException if the key is <code>null</code>.
       * @see #get(int)
       */
      public Object put(int key, Object value) {
        // Makes sure the key is not already in the hashtable.
        Entry tab[] = table;
        int hash = key;
        int index = (hash & 0x7FFFFFFF) % tab.length;
        for (Entry e = tab[index]; e != null; e = e.next) {
          if (e.hash == hash) {
            Object old = e.value;
            e.value = value;
            return old;
          }
        }

        if (count >= threshold) {
          // Rehash the table if the threshold is exceeded
          rehash();

          tab = table;
          index = (hash & 0x7FFFFFFF) % tab.length;
        }

        // Creates the new entry.
        Entry e = new Entry(hash, key, value, tab[index]);
        tab[index] = e;
        count++;
        return null;
      }

      /**
       * <p>
       * Removes the key (and its corresponding value) from this hashtable.
       * </p>
       * <p>
       * This method does nothing if the key is not present in the hashtable.
       * </p>
       * 
       * @param key the key that needs to be removed.
       * @return the value to which the key had been mapped in this hashtable, or <code>null</code> if the key did not have a
       *         mapping.
       */
      public Object remove(int key) {
        Entry tab[] = table;
        int hash = key;
        int index = (hash & 0x7FFFFFFF) % tab.length;
        for (Entry e = tab[index], prev = null; e != null; prev = e, e = e.next) {
          if (e.hash == hash) {
            if (prev != null) {
              prev.next = e.next;
            } else {
              tab[index] = e.next;
            }
            count--;
            Object oldValue = e.value;
            e.value = null;
            return oldValue;
          }
        }
        return null;
      }

      /**
       * <p>
       * Clears this hashtable so that it contains no keys.
       * </p>
       */
      public synchronized void clear() {
        Entry tab[] = table;
        for (int index = tab.length; --index >= 0;) {
          tab[index] = null;
        }
        count = 0;
      }

    }

  }
}
