chrome/browser/resources/chromeos/chromevox/common/math_semantic_attr.js

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /**
   6  * @fileoverview Semantic attributes of Math symbols and expressions.
   7  *
   8  * This file contains the basic functionality to lookup and assign semantic
   9  * attributes for mathematical expressions. Since there is no such thing as a
  10  * well-defined semantics for all of mathematics we compute a default semantics
  11  * that closely models mathematical expressions found in K-12 mathematics as
  12  * well as in general undergraduate curriculum (i.e., calculus, linear algebra,
  13  * etc).
  14  *
  15  * Currently semantic attributes of symbols consist of the following two parts:
  16  *
  17  * type -- An unmutable property of an expression, regardless of its position in
  18  *         the math expression. For example, the letter 'f' will always have the
  19  *         type identifier, regardless of its use in context, e.g. as function
  20  *         symbol or variable.
  21  *
  22  * role -- A mutable description of the role an expression plays in the context
  23  *         of the overall mathematical expression. For instance, the symbol '|'
  24  *         is of type punctuation, but depending on context it has the role of a
  25  *         neutral fence or of a single vertical bar.
  26  *
  27  * In addition for some symbols we record the font as a further attribute.
  28  *
  29  * When a semantically interpreted expression is transformed into a XML
  30  * representation, types become tag names, while role, font, etc. are added as
  31  * attributes.
  32  *
  33  * This file is part of the content script as we do not want to call out to the
  34  * background page every time we need to look up the semantic of a symbol.
  35  *
  36  * TODO (sorge) Move semantic tree translation into the background page
  37  *    alongside MathJax.
  38  *
  39  */
  40
  41 goog.provide('cvox.SemanticAttr');
  42
  43 goog.require('cvox.SemanticUtil');
  44
  45
  46 /**
  47  * Contains the basic mappings of characters/symbols and functions to semantic
  48  * attributes.
  49  *
  50  * Observe that all characters are given as hex code number in order to ease the
  51  * comparison with those in the JSON files that define speech rules per
  52  * character.
  53  * @constructor
  54  */
  55 cvox.SemanticAttr = function() {
  56   // Punctuation Characters.
  57   /**
  58    * @type {Array<string>}
  59    */
  60   this.generalPunctuations =
  61       [
  62         '!', '"', '#', '%', '&', '\'', '*', ',', ':', ';', '?', '@', '\\',
  63         '¡', '§', '¶', '·', '¿', '‗', '†', '‡', '•', '‣', '․', '‥', '‧',
  64         '‰', '‱', '‸', '※', '‼', '‽', '‾', '⁁', '⁂', '⁃', '⁇', '⁈', '⁉',
  65         '⁋', '⁌', '⁍', '⁎', '⁏', '⁐', '⁑', '⁓', '⁕', '⁖', '⁘', '⁙', '⁚',
  66         '⁛', '⁜', '⁝', '⁞', '︐', '︓', '︔', '︕', '︖', '︰', '﹅', '﹆',
  67         '﹉', '﹊', '﹋', '﹌', '﹐', '﹔', '﹕', '﹖', '﹗', '﹟', '﹠', '﹡', '﹨',
  68         '﹪', '﹫', '！', '＂', '＃', '％', '＆', '＇', '＊', '，', '／', '：',
  69         '；', '？', '＠', '＼'
  70       ];
  71   /**
  72    * @type {string}
  73    * @private
  74    */
  75   this.invisibleComma_ = cvox.SemanticUtil.numberToUnicode(0x2063);
  76   this.generalPunctuations.push(this.invisibleComma_);
  77   /**
  78    * @type {Array<string>}
  79    */
  80   this.ellipses =
  81       [
  82         '…', '⋮', '⋯', '⋰', '⋱', '︙'
  83       ];
  84   /**
  85    * @type {Array<string>}
  86    */
  87   this.fullStops =
  88       [
  89         '.', '﹒', '．'
  90       ];
  91   /**
  92    * @type {Array<string>}
  93    */
  94   this.dashes =
  95       [
  96         '‒', '–', '—', '―', '〜', '︱', '︲', '﹘'
  97       ];
  98   /**
  99    * @type {Array<string>}
 100    */
 101   this.primes =
 102       [
 103         '′', '″', '‴', '‵', '‶', '‷', '⁗'
 104       ];
 105
 106   // Fences.
 107   // Fences are treated slightly differently from other symbols as we want to
 108   // record pairs of opening/closing and top/bottom fences.
 109   /**
 110    * Mapping opening to closing fences.
 111    * @type {Object<string>}
 112    */
 113   this.openClosePairs =
 114       {
 115         // Unicode categories Ps and Pe.
 116         // Observe that left quotation 301D could also be matched to 301F,
 117         // but is currently matched to 301E.
 118         '(': ')', '[': ']', '{': '}', '⁅': '⁆', '〈': '〉', '❨': '❩',
 119         '❪': '❫', '❬': '❭', '❮': '❯', '❰': '❱', '❲': '❳', '❴': '❵',
 120         '⟅': '⟆', '⟦': '⟧', '⟨': '⟩', '⟪': '⟫', '⟬': '⟭', '⟮': '⟯',
 121         '⦃': '⦄', '⦅': '⦆', '⦇': '⦈', '⦉': '⦊', '⦋': '⦌', '⦍': '⦎',
 122         '⦏': '⦐', '⦑': '⦒', '⦓': '⦔', '⦕': '⦖', '⦗': '⦘', '⧘': '⧙',
 123         '⧚': '⧛', '⧼': '⧽', '⸢': '⸣', '⸤': '⸥', '⸦': '⸧', '⸨': '⸩',
 124         '〈': '〉', '《': '》', '「': '」', '『': '』', '【': '】',
 125         '〔': '〕', '〖': '〗', '〘': '〙', '〚': '〛', '〝': '〞',
 126         '﴾': '﴿', '︗': '︘', '﹙': '﹚', '﹛': '﹜', '﹝': '﹞', '（': '）',
 127         '［': '］', '｛': '｝', '｟': '｠', '｢': '｣',
 128         // Unicode categories Sm and So.
 129         '⌈': '⌉', '⌊': '⌋', '⌌': '⌍', '⌎': '⌏', '⌜': '⌝', '⌞': '⌟',
 130         // Extender fences.
 131         // Parenthesis.
 132         '⎛': '⎞', '⎜': '⎟', '⎝': '⎠',
 133         // Square bracket.
 134         '⎡': '⎤', '⎢': '⎥', '⎣': '⎦',
 135         // Curly bracket.
 136         '⎧': '⎫', '⎨': '⎬', '⎩': '⎭', '⎰': '⎱', '⎸': '⎹'
 137       };
 138   /**
 139    * Mapping top to bottom fences.
 140    * @type {Object<string>}
 141    */
 142   this.topBottomPairs =
 143       {
 144         '⎴': '⎵', '⏜': '⏝', '⏞': '⏟', '⏠': '⏡', '︵': '︶', '︷': '︸',
 145         '︹': '︺', '︻': '︼', '︽': '︾', '︿': '﹀', '﹁': '﹂',
 146         '﹃': '﹄', '﹇': '﹈'
 147       };
 148   /**
 149    * @type {Array<string>}
 150    */
 151   this.leftFences = cvox.SemanticUtil.objectsToKeys(this.openClosePairs);
 152   /**
 153    * @type {Array<string>}
 154    */
 155   this.rightFences = cvox.SemanticUtil.objectsToValues(this.openClosePairs);
 156   this.rightFences.push('〟');
 157   /**
 158    * @type {Array<string>}
 159    */
 160   this.topFences = cvox.SemanticUtil.objectsToKeys(this.topBottomPairs);
 161   /**
 162    * @type {Array<string>}
 163    */
 164   this.bottomFences = cvox.SemanticUtil.objectsToValues(this.topBottomPairs);
 165   /**
 166    * @type {Array<string>}
 167    */
 168   this.neutralFences =
 169       [
 170         '|', '¦', '‖', '❘', '⦀', '⫴', '￤', '｜'
 171       ];
 172   /** Array of all fences.
 173    * @type {Array<string>}
 174    */
 175   this.fences = this.neutralFences.concat(
 176       this.leftFences, this.rightFences, this.topFences, this.bottomFences);
 177
 178   // Identifiers.
 179   // Latin Alphabets.
 180   /**
 181    * @type {Array<string>}
 182    */
 183   this.capitalLatin =
 184       [
 185         'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
 186         'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'
 187       ];
 188   /**
 189    * @type {Array<string>}
 190    */
 191   this.smallLatin =
 192       [
 193         'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
 194         'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
 195         // dotless i and j.
 196         'ı', 'ȷ'
 197       ];
 198   /**
 199    * @type {Array<string>}
 200    */
 201   this.capitalLatinFullWidth =
 202       [
 203         'Ａ', 'Ｂ', 'Ｃ', 'Ｄ', 'Ｅ', 'Ｆ', 'Ｇ', 'Ｈ', 'Ｉ', 'Ｊ', 'Ｋ', 'Ｌ', 'Ｍ',
 204        'Ｎ', 'Ｏ', 'Ｐ', 'Ｑ', 'Ｒ', 'Ｓ', 'Ｔ', 'Ｕ', 'Ｖ', 'Ｗ', 'Ｘ', 'Ｙ', 'Ｚ'
 205       ];
 206   /**
 207    * @type {Array<string>}
 208    */
 209   this.smallLatinFullWidth =
 210       [
 211         'ａ', 'ｂ', 'ｃ', 'ｄ', 'ｅ', 'ｆ', 'ｇ', 'ｈ', 'ｉ', 'ｊ', 'ｋ', 'ｌ', 'ｍ',
 212         'ｎ', 'ｏ', 'ｐ', 'ｑ', 'ｒ', 'ｓ', 'ｔ', 'ｕ', 'ｖ', 'ｗ', 'ｘ', 'ｙ', 'ｚ'
 213       ];
 214   /**
 215    * @type {Array<string>}
 216    */
 217   this.capitalLatinBold =
 218       [
 219         '𝐀', '𝐁', '𝐂', '𝐃', '𝐄', '𝐅', '𝐆', '𝐇', '𝐈', '𝐉', '𝐊', '𝐋', '𝐌',
 220        '𝐍', '𝐎', '𝐏', '𝐐', '𝐑', '𝐒', '𝐓', '𝐔', '𝐕', '𝐖', '𝐗', '𝐘', '𝐙'
 221         ];
 222   /**
 223    * @type {Array<string>}
 224    */
 225   this.smallLatinBold =
 226       [
 227         '𝐚', '𝐛', '𝐜', '𝐝', '𝐞', '𝐟', '𝐠', '𝐡', '𝐢', '𝐣', '𝐤', '𝐥', '𝐦',
 228        '𝐧', '𝐨', '𝐩', '𝐪', '𝐫', '𝐬', '𝐭', '𝐮', '𝐯', '𝐰', '𝐱', '𝐲', '𝐳'
 229         ];
 230   /**
 231    * @type {Array<string>}
 232    */
 233   this.capitalLatinItalic =
 234       [
 235         '𝐴', '𝐵', '𝐶', '𝐷', '𝐸', '𝐹', '𝐺', '𝐻', '𝐼', '𝐽', '𝐾', '𝐿', '𝑀',
 236        '𝑁', '𝑂', '𝑃', '𝑄', '𝑅', '𝑆', '𝑇', '𝑈', '𝑉', '𝑊', '𝑋', '𝑌', '𝑍'
 237         ];
 238   /**
 239    * @type {Array<string>}
 240    */
 241   this.smallLatinItalic =
 242       [
 243         '𝑎', '𝑏', '𝑐', '𝑑', '𝑒', '𝑓', '𝑔', 'ℎ', '𝑖', '𝑗', '𝑘', '𝑙', '𝑚',
 244        '𝑛', '𝑜', '𝑝', '𝑞', '𝑟', '𝑠', '𝑡', '𝑢', '𝑣', '𝑤', '𝑥', '𝑦', '𝑧',
 245        // dotless i and j.
 246        '𝚤', '𝚥'
 247         ];
 248   /**
 249    * @type {Array<string>}
 250    */
 251   this.capitalLatinScript =
 252       [
 253         '𝒜', 'ℬ', '𝒞', '𝒟', 'ℰ', 'ℱ', '𝒢', 'ℋ', 'ℐ', '𝒥', '𝒦', 'ℒ', 'ℳ',
 254        '𝒩', '𝒪', '𝒫', '𝒬', 'ℛ', '𝒮', '𝒯', '𝒰', '𝒱', '𝒲', '𝒳', '𝒴', '𝒵',
 255        // Powerset Cap P.
 256        '℘'
 257         ];
 258   /**
 259    * @type {Array<string>}
 260    */
 261   this.smallLatinScript =
 262       [
 263         '𝒶', '𝒷', '𝒸', '𝒹', 'ℯ', '𝒻', 'ℊ', '𝒽', '𝒾', '𝒿', '𝓀', '𝓁', '𝓂',
 264        '𝓃', 'ℴ', '𝓅', '𝓆', '𝓇', '𝓈', '𝓉', '𝓊', '𝓋', '𝓌', '𝓍', '𝓎', '𝓏',
 265        // script small l
 266        'ℓ'
 267         ];
 268   /**
 269    * @type {Array<string>}
 270    */
 271   this.capitalLatinBoldScript =
 272       [
 273         '𝓐', '𝓑', '𝓒', '𝓓', '𝓔', '𝓕', '𝓖', '𝓗', '𝓘', '𝓙', '𝓚', '𝓛', '𝓜',
 274        '𝓝', '𝓞', '𝓟', '𝓠', '𝓡', '𝓢', '𝓣', '𝓤', '𝓥', '𝓦', '𝓧', '𝓨', '𝓩'
 275         ];
 276   /**
 277    * @type {Array<string>}
 278    */
 279   this.smallLatinBoldScript =
 280       [
 281         '𝓪', '𝓫', '𝓬', '𝓭', '𝓮', '𝓯', '𝓰', '𝓱', '𝓲', '𝓳', '𝓴', '𝓵', '𝓶',
 282        '𝓷', '𝓸', '𝓹', '𝓺', '𝓻', '𝓼', '𝓽', '𝓾', '𝓿', '𝔀', '𝔁', '𝔂', '𝔃'
 283         ];
 284   /**
 285    * @type {Array<string>}
 286    */
 287   this.capitalLatinFraktur =
 288       [
 289         '𝔄', '𝔅', 'ℭ', '𝔇', '𝔈', '𝔉', '𝔊', 'ℌ', 'ℑ', '𝔍', '𝔎', '𝔏', '𝔐',
 290        '𝔑', '𝔒', '𝔓', '𝔔', 'ℜ', '𝔖', '𝔗', '𝔘', '𝔙', '𝔚', '𝔛', '𝔜', 'ℨ'
 291         ];
 292   /**
 293    * @type {Array<string>}
 294    */
 295   this.smallLatinFraktur =
 296       [
 297         '𝔞', '𝔟', '𝔠', '𝔡', '𝔢', '𝔣', '𝔤', '𝔥', '𝔦', '𝔧', '𝔨', '𝔩', '𝔪',
 298        '𝔫', '𝔬', '𝔭', '𝔮', '𝔯', '𝔰', '𝔱', '𝔲', '𝔳', '𝔴', '𝔵', '𝔶', '𝔷'
 299         ];
 300   /**
 301    * @type {Array<string>}
 302    */
 303   this.capitalLatinDoubleStruck =
 304       [
 305         '𝔸', '𝔹', 'ℂ', '𝔻', '𝔼', '𝔽', '𝔾', 'ℍ', '𝕀', '𝕁', '𝕂', '𝕃', '𝕄',
 306        'ℕ', '𝕆', 'ℙ', 'ℚ', 'ℝ', '𝕊', '𝕋', '𝕌', '𝕍', '𝕎', '𝕏', '𝕐', 'ℤ'
 307         ];
 308   /**
 309    * @type {Array<string>}
 310    */
 311   this.smallLatinDoubleStruck =
 312       [
 313         '𝕒', '𝕓', '𝕔', '𝕕', '𝕖', '𝕗', '𝕘', '𝕙', '𝕚', '𝕛', '𝕜', '𝕝', '𝕞',
 314        '𝕟', '𝕠', '𝕡', '𝕢', '𝕣', '𝕤', '𝕥', '𝕦', '𝕧', '𝕨', '𝕩', '𝕪', '𝕫'
 315         ];
 316   /**
 317    * @type {Array<string>}
 318    */
 319   this.capitalLatinBoldFraktur =
 320       [
 321         '𝕬', '𝕭', '𝕮', '𝕯', '𝕰', '𝕱', '𝕲', '𝕳', '𝕴', '𝕵', '𝕶', '𝕷', '𝕸',
 322        '𝕹', '𝕺', '𝕻', '𝕼', '𝕽', '𝕾', '𝕿', '𝖀', '𝖁', '𝖂', '𝖃', '𝖄', '𝖅'
 323         ];
 324   /**
 325    * @type {Array<string>}
 326    */
 327   this.smallLatinBoldFraktur =
 328       [
 329         '𝖆', '𝖇', '𝖈', '𝖉', '𝖊', '𝖋', '𝖌', '𝖍', '𝖎', '𝖏', '𝖐', '𝖑', '𝖒',
 330        '𝖓', '𝖔', '𝖕', '𝖖', '𝖗', '𝖘', '𝖙', '𝖚', '𝖛', '𝖜', '𝖝', '𝖞', '𝖟'
 331         ];
 332   /**
 333    * @type {Array<string>}
 334    */
 335   this.capitalLatinSansSerif =
 336       [
 337         '𝖠', '𝖡', '𝖢', '𝖣', '𝖤', '𝖥', '𝖦', '𝖧', '𝖨', '𝖩', '𝖪', '𝖫', '𝖬',
 338        '𝖭', '𝖮', '𝖯', '𝖰', '𝖱', '𝖲', '𝖳', '𝖴', '𝖵', '𝖶', '𝖷', '𝖸', '𝖹'
 339         ];
 340   /**
 341    * @type {Array<string>}
 342    */
 343   this.smallLatinSansSerif =
 344       [
 345         '𝖺', '𝖻', '𝖼', '𝖽', '𝖾', '𝖿', '𝗀', '𝗁', '𝗂', '𝗃', '𝗄', '𝗅', '𝗆',
 346        '𝗇', '𝗈', '𝗉', '𝗊', '𝗋', '𝗌', '𝗍', '𝗎', '𝗏', '𝗐', '𝗑', '𝗒', '𝗓'
 347         ];
 348   /**
 349    * @type {Array<string>}
 350    */
 351   this.capitalLatinSansSerifBold =
 352       [
 353         '𝗔', '𝗕', '𝗖', '𝗗', '𝗘', '𝗙', '𝗚', '𝗛', '𝗜', '𝗝', '𝗞', '𝗟', '𝗠',
 354        '𝗡', '𝗢', '𝗣', '𝗤', '𝗥', '𝗦', '𝗧', '𝗨', '𝗩', '𝗪', '𝗫', '𝗬', '𝗭'
 355         ];
 356   /**
 357    * @type {Array<string>}
 358    */
 359   this.smallLatinSansSerifBold =
 360       [
 361         '𝗮', '𝗯', '𝗰', '𝗱', '𝗲', '𝗳', '𝗴', '𝗵', '𝗶', '𝗷', '𝗸', '𝗹', '𝗺',
 362        '𝗻', '𝗼', '𝗽', '𝗾', '𝗿', '𝘀', '𝘁', '𝘂', '𝘃', '𝘄', '𝘅', '𝘆', '𝘇'
 363         ];
 364   /**
 365    * @type {Array<string>}
 366    */
 367   this.capitalLatinSansSerifItalic =
 368       [
 369         '𝘈', '𝘉', '𝘊', '𝘋', '𝘌', '𝘍', '𝘎', '𝘏', '𝘐', '𝘑', '𝘒', '𝘓', '𝘔',
 370        '𝘕', '𝘖', '𝘗', '𝘘', '𝘙', '𝘚', '𝘛', '𝘜', '𝘝', '𝘞', '𝘟', '𝘠', '𝘡'
 371         ];
 372   /**
 373    * @type {Array<string>}
 374    */
 375   this.smallLatinSansSerifItalic =
 376       [
 377         '𝘢', '𝘣', '𝘤', '𝘥', '𝘦', '𝘧', '𝘨', '𝘩', '𝘪', '𝘫', '𝘬', '𝘭', '𝘮',
 378        '𝘯', '𝘰', '𝘱', '𝘲', '𝘳', '𝘴', '𝘵', '𝘶', '𝘷', '𝘸', '𝘹', '𝘺', '𝘻'
 379         ];
 380   /**
 381    * @type {Array<string>}
 382    */
 383   this.capitalLatinMonospace =
 384       [
 385         '𝙰', '𝙱', '𝙲', '𝙳', '𝙴', '𝙵', '𝙶', '𝙷', '𝙸', '𝙹', '𝙺', '𝙻', '𝙼',
 386        '𝙽', '𝙾', '𝙿', '𝚀', '𝚁', '𝚂', '𝚃', '𝚄', '𝚅', '𝚆', '𝚇', '𝚈', '𝚉'
 387         ];
 388   /**
 389    * @type {Array<string>}
 390    */
 391   this.smallLatinMonospace =
 392       [
 393         '𝚊', '𝚋', '𝚌', '𝚍', '𝚎', '𝚏', '𝚐', '𝚑', '𝚒', '𝚓', '𝚔', '𝚕', '𝚖',
 394        '𝚗', '𝚘', '𝚙', '𝚚', '𝚛', '𝚜', '𝚝', '𝚞', '𝚟', '𝚠', '𝚡', '𝚢', '𝚣'
 395         ];
 396   /**
 397    * @type {Array<string>}
 398    */
 399   this.latinDoubleStruckItalic =
 400       [
 401         'ⅅ', 'ⅆ', 'ⅇ', 'ⅈ', 'ⅉ'
 402         ];
 403
 404   // Greek Alphabets
 405   /**
 406    * @type {Array<string>}
 407    */
 408   this.capitalGreek =
 409       [
 410         'Α', 'Β', 'Γ', 'Δ', 'Ε', 'Ζ', 'Η', 'Θ', 'Ι', 'Κ', 'Λ', 'Μ', 'Ν',
 411        'Ξ', 'Ο', 'Π', 'Ρ', 'Σ', 'Τ', 'Υ', 'Φ', 'Χ', 'Ψ', 'Ω'
 412         ];
 413   /**
 414    * @type {Array<string>}
 415    */
 416   this.smallGreek =
 417       [
 418         'α', 'β', 'γ', 'δ', 'ε', 'ζ', 'η', 'θ', 'ι', 'κ', 'λ', 'μ', 'ν',
 419        'ξ', 'ο', 'π', 'ρ', 'ς', 'σ', 'τ', 'υ', 'φ', 'χ', 'ψ', 'ω'
 420         ];
 421   /**
 422    * @type {Array<string>}
 423    */
 424   this.capitalGreekBold =
 425       [
 426         '𝚨', '𝚩', '𝚪', '𝚫', '𝚬', '𝚭', '𝚮', '𝚯', '𝚰', '𝚱', '𝚲', '𝚳', '𝚴',
 427        '𝚵', '𝚶', '𝚷', '𝚸', '𝚺', '𝚻', '𝚼', '𝚽', '𝚾', '𝚿', '𝛀'
 428         ];
 429   /**
 430    * @type {Array<string>}
 431    */
 432   this.smallGreekBold =
 433       [
 434         '𝛂', '𝛃', '𝛄', '𝛅', '𝛆', '𝛇', '𝛈', '𝛉', '𝛊', '𝛋', '𝛌', '𝛍', '𝛎',
 435        '𝛏', '𝛐', '𝛑', '𝛒', '𝛓', '𝛔', '𝛕', '𝛖', '𝛗', '𝛘', '𝛙', '𝛚'
 436         ];
 437   /**
 438    * @type {Array<string>}
 439    */
 440   this.capitalGreekItalic =
 441       [
 442         '𝛢', '𝛣', '𝛤', '𝛥', '𝛦', '𝛧', '𝛨', '𝛩', '𝛪', '𝛫', '𝛬', '𝛭', '𝛮',
 443        '𝛯', '𝛰', '𝛱', '𝛲', '𝛴', '𝛵', '𝛶', '𝛷', '𝛸', '𝛹', '𝛺'
 444         ];
 445   /**
 446    * @type {Array<string>}
 447    */
 448   this.smallGreekItalic =
 449       [
 450         '𝛼', '𝛽', '𝛾', '𝛿', '𝜀', '𝜁', '𝜂', '𝜃', '𝜄', '𝜅', '𝜆', '𝜇', '𝜈',
 451        '𝜉', '𝜊', '𝜋', '𝜌', '𝜍', '𝜎', '𝜏', '𝜐', '𝜑', '𝜒', '𝜓', '𝜔'
 452         ];
 453   /**
 454    * @type {Array<string>}
 455    */
 456   this.capitalGreekSansSerifBold =
 457       [
 458         '𝝖', '𝝗', '𝝘', '𝝙', '𝝚', '𝝛', '𝝜', '𝝝', '𝝞', '𝝟', '𝝠', '𝝡', '𝝢',
 459        '𝝣', '𝝤', '𝝥', '𝝦', '𝝨', '𝝩', '𝝪', '𝝫', '𝝬', '𝝭', '𝝮'
 460         ];
 461   /**
 462    * @type {Array<string>}
 463    */
 464   this.smallGreekSansSerifBold =
 465       [
 466         '𝝰', '𝝱', '𝝲', '𝝳', '𝝴', '𝝵', '𝝶', '𝝷', '𝝸', '𝝹', '𝝺', '𝝻', '𝝼',
 467        '𝝽', '𝝾', '𝝿', '𝞀', '𝞁', '𝞂', '𝞃', '𝞄', '𝞅', '𝞆', '𝞇', '𝞈'
 468         ];
 469   /**
 470    * @type {Array<string>}
 471    */
 472   this.greekDoubleStruck =
 473       [
 474         'ℼ', 'ℽ', 'ℾ', 'ℿ'
 475         ];
 476
 477   // Other alphabets.
 478   /**
 479    * @type {Array<string>}
 480    */
 481   this.hebrewLetters =
 482       [
 483         'ℵ', 'ℶ', 'ℷ', 'ℸ'
 484         ];
 485
 486   //Operator symbols
 487   /**
 488    * @type {Array<string>}
 489    */
 490   this.additions =
 491       [
 492         '+', '±', '∓', '∔', '∧', '∨', '∩', '∪', '⊌', '⊓', '⊔', '⊝', '⊞',
 493         '⊤', '⊥', '⊺', '⊻', '⊼', '⋄', '⋎', '⋏', '⋒', '⋓', '△', '▷', '▽',
 494         '◁', '⩞', '⊕'
 495         ];
 496       /**
 497        * @type {Array<string>}
 498            */
 499   /**
 500    * Invisible operator for plus.
 501    * @type {string}
 502    * @private
 503    */
 504   this.invisiblePlus_ = cvox.SemanticUtil.numberToUnicode(0x2064);
 505   this.additions.push(this.invisiblePlus_);
 506   /**
 507    * @type {Array<string>}
 508    */
 509   this.multiplications =
 510       [
 511         '†', '‡', '∐', '∗', '∘', '∙', '≀', '⊚', '⊛', '⊠', '⊡', '⋅', '⋆', '⋇',
 512         '⋉', '⋊', '⋋', '⋌', '○'
 513         ];
 514   /**
 515    * Invisible operator for multiplication.
 516    * @type {string}
 517    * @private
 518    */
 519   this.invisibleTimes_ = cvox.SemanticUtil.numberToUnicode(0x2062);
 520   this.multiplications.push(this.invisibleTimes_);
 521   /**
 522    * @type {Array<string>}
 523    */
 524   this.subtractions =
 525       [
 526         '-', '⁒', '⁻', '₋', '−', '∖', '∸', '≂', '⊖', '⊟', '➖', '⨩', '⨪',
 527        '⨫', '⨬', '⨺', '⩁', '⩬', '﹣', '－', '‐', '‑'
 528         ];
 529   /**
 530    * @type {Array<string>}
 531    */
 532   this.divisions =
 533       [
 534         '/', '÷', '⁄', '∕', '⊘', '⟌', '⦼', '⨸'
 535         ];
 536   /**
 537    * Invisible operator for function application.
 538    * @type {string}
 539    * @private
 540    */
 541   this.functionApplication_ = cvox.SemanticUtil.numberToUnicode(0x2061);
 542
 543   //Relation symbols
 544   /**
 545    * @type {Array<string>}
 546    */
 547   this.equalities =
 548       [
 549         '=', '~', '⁼', '₌', '∼', '∽', '≃', '≅', '≈', '≊', '≋', '≌', '≍',
 550        '≎', '≑', '≒', '≓', '≔', '≕', '≖', '≗', '≘', '≙', '≚', '≛', '≜',
 551        '≝', '≞', '≟', '≡', '≣', '⧤', '⩦', '⩮', '⩯', '⩰', '⩱', '⩲', '⩳',
 552        '⩴', '⩵', '⩶', '⩷', '⩸', '⋕', '⩭', '⩪', '⩫', '⩬', '﹦', '＝'
 553         ];
 554   /**
 555    * @type {Array<string>}
 556    */
 557   this.inequalities =
 558       [
 559         '<', '>', '≁', '≂', '≄', '≆', '≇', '≉', '≏', '≐', '≠', '≢', '≤',
 560         '≥', '≦', '≧', '≨', '≩', '≪', '≫', '≬', '≭', '≮', '≯', '≰', '≱',
 561         '≲', '≳', '≴', '≵', '≶', '≷', '≸', '≹', '≺', '≻', '≼', '≽', '≾',
 562         '≿', '⊀', '⊁', '⋖', '⋗', '⋘', '⋙', '⋚', '⋛', '⋜', '⋝', '⋞', '⋟',
 563         '⋠', '⋡', '⋢', '⋣', '⋤', '⋥', '⋦', '⋧', '⋨', '⋩', '⩹', '⩺', '⩻',
 564         '⩼', '⩽', '⩾', '⩿', '⪀', '⪁', '⪂', '⪃', '⪄', '⪅', '⪆', '⪇', '⪈',
 565         '⪉', '⪊', '⪋', '⪌', '⪍', '⪎', '⪏', '⪐', '⪑', '⪒', '⪓', '⪔', '⪕',
 566         '⪖', '⪗', '⪘', '⪙', '⪚', '⪛', '⪜', '⪝', '⪞', '⪟', '⪠', '⪡', '⪢',
 567         '⪣', '⪤', '⪥', '⪦', '⪧', '⪨', '⪩', '⪪', '⪫', '⪬', '⪭', '⪮', '⪯',
 568         '⪰', '⪱', '⪲', '⪳', '⪴', '⪵', '⪶', '⪷', '⪸', '⪹', '⪺', '⪻', '⪼',
 569         '⫷', '⫸', '⫹', '⫺', '⧀', '⧁', '﹤', '﹥', '＜', '＞'
 570       ];
 571   /**
 572    * @type {Array<string>}
 573    */
 574   this.relations =
 575       [
 576             // TODO (sorge): Add all the other relations.
 577       ];
 578   /**
 579    * @type {Array<string>}
 580    */
 581   this.arrows =
 582       [
 583         '←', '↑', '→', '↓', '↔', '↕', '↖', '↗', '↘', '↙', '↚', '↛', '↜',
 584         '↝', '↞', '↟', '↠', '↡', '↢', '↣', '↤', '↥', '↦', '↧', '↨', '↩',
 585         '↪', '↫', '↬', '↭', '↮', '↯', '↰', '↱', '↲', '↳', '↴', '↵', '↶',
 586         '↷', '↸', '↹', '↺', '↻', '⇄', '⇅', '⇆', '⇇', '⇈', '⇉', '⇊', '⇍',
 587         '⇎', '⇏', '⇐', '⇑', '⇒', '⇓', '⇔', '⇕', '⇖', '⇗', '⇘', '⇙', '⇚',
 588         '⇛', '⇜', '⇝', '⇞', '⇟', '⇠', '⇡', '⇢', '⇣', '⇤', '⇥', '⇦', '⇧',
 589         '⇨', '⇩', '⇪', '⇫', '⇬', '⇭', '⇮', '⇯', '⇰', '⇱', '⇲', '⇳', '⇴',
 590         '⇵', '⇶', '⇷', '⇸', '⇹', '⇺', '⇻', '⇼', '⇽', '⇾', '⇿', '⌁', '⌃',
 591         '⌄', '⌤', '⎋', '➔', '➘', '➙', '➚', '➛', '➜', '➝', '➞', '➟', '➠',
 592         '➡', '➢', '➣', '➤', '➥', '➦', '➧', '➨', '➩', '➪', '➫', '➬', '➭',
 593         '➮', '➯', '➱', '➲', '➳', '➴', '➵', '➶', '➷', '➸', '➹', '➺', '➻',
 594         '➼', '➽', '➾', '⟰', '⟱', '⟲', '⟳', '⟴', '⟵', '⟶', '⟷', '⟸', '⟹',
 595         '⟺', '⟻', '⟼', '⟽', '⟾', '⟿', '⤀', '⤁', '⤂', '⤃', '⤄', '⤅', '⤆',
 596         '⤇', '⤈', '⤉', '⤊', '⤋', '⤌', '⤍', '⤎', '⤏', '⤐', '⤑', '⤒', '⤓',
 597         '⤔', '⤕', '⤖', '⤗', '⤘', '⤙', '⤚', '⤛', '⤜', '⤝', '⤞', '⤟', '⤠',
 598         '⤡', '⤢', '⤣', '⤤', '⤥', '⤦', '⤧', '⤨', '⤩', '⤪', '⤭', '⤮', '⤯',
 599         '⤰', '⤱', '⤲', '⤳', '⤴', '⤵', '⤶', '⤷', '⤸', '⤹', '⤺', '⤻', '⤼',
 600         '⤽', '⤾', '⤿', '⥀', '⥁', '⥂', '⥃', '⥄', '⥅', '⥆', '⥇', '⥈', '⥉',
 601         '⥰', '⥱', '⥲', '⥳', '⥴', '⥵', '⥶', '⥷', '⥸', '⥹', '⥺', '⥻', '⦳',
 602         '⦴', '⦽', '⧪', '⧬', '⧭', '⨗', '⬀', '⬁', '⬂', '⬃', '⬄', '⬅', '⬆',
 603         '⬇', '⬈', '⬉', '⬊', '⬋', '⬌', '⬍', '⬎', '⬏', '⬐', '⬑', '⬰', '⬱',
 604         '⬲', '⬳', '⬴', '⬵', '⬶', '⬷', '⬸', '⬹', '⬺', '⬻', '⬼', '⬽', '⬾',
 605         '⬿', '⭀', '⭁', '⭂', '⭃', '⭄', '⭅', '⭆', '⭇', '⭈', '⭉', '⭊', '⭋',
 606         '⭌', '￩', '￪', '￫', '￬',
 607         // Harpoons
 608         '↼', '↽', '↾', '↿', '⇀', '⇁', '⇂', '⇃', '⇋', '⇌', '⥊', '⥋', '⥌',
 609         '⥍', '⥎', '⥏', '⥐', '⥑', '⥒', '⥓', '⥔', '⥕', '⥖', '⥗', '⥘', '⥙',
 610         '⥚', '⥛', '⥜', '⥝', '⥞', '⥟', '⥠', '⥡', '⥢', '⥣', '⥤', '⥥', '⥦',
 611         '⥧', '⥨', '⥩', '⥪', '⥫', '⥬', '⥭', '⥮', '⥯', '⥼', '⥽', '⥾', '⥿'
 612       ];
 613
 614   //Big operation symbols
 615   /**
 616    * @type {Array<string>}
 617    */
 618   this.sumOps =
 619       [
 620         '⅀', // double struck
 621         '∏', '∐', '∑', '⋀', '⋁', '⋂', '⋃', '⨀', '⨁', '⨂', '⨃', '⨄', '⨅',
 622         '⨆', '⨇', '⨈', '⨉', '⨊', '⨋', '⫼', '⫿'
 623         ];
 624   /**
 625    * @type {Array<string>}
 626    */
 627   this.intOps =
 628       [
 629         '∫', '∬', '∭', '∮', '∯', '∰', '∱', '∲', '∳', '⨌', '⨍', '⨎', '⨏',
 630         '⨐', '⨑', '⨒', '⨓', '⨔', '⨕', '⨖', '⨗', '⨘', '⨙', '⨚', '⨛', '⨜'
 631       ];
 632   /**
 633    * @type {Array<string>}
 634    */
 635   this.prefixOps =
 636       // TODO (sorge) Insert nabla, differential operators etc.
 637       [
 638         '∀', '∃'
 639       ];
 640   /**
 641    * @type {Array<string>}
 642    */
 643   this.operatorBits =
 644       // TODO (sorge) What to do if single glyphs of big ops occur on their own.
 645       [
 646         '⌠', '⌡', '⎶', '⎪', '⎮', '⎯', '⎲', '⎳', '⎷'
 647       ];
 648
 649   // Accents.
 650   // TODO (sorge) Add accented characters.
 651
 652   // Numbers.
 653   // Digits.
 654   /**
 655    * @type {Array<string>}
 656    */
 657   this.digitsNormal =
 658       [
 659         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'
 660         ];
 661   /**
 662    * @type {Array<string>}
 663    */
 664   this.digitsFullWidth =
 665       [
 666         '０', '１', '２', '３', '４', '５', '６', '７', '８', '９'
 667       ];
 668   /**
 669    * @type {Array<string>}
 670    */
 671   this.digitsBold =
 672       [
 673         '𝟎', '𝟏', '𝟐', '𝟑', '𝟒', '𝟓', '𝟔', '𝟕', '𝟖', '𝟗'
 674         ];
 675   /**
 676    * @type {Array<string>}
 677    */
 678   this.digitsDoubleStruck =
 679       [
 680         '𝟘', '𝟙', '𝟚', '𝟛', '𝟜', '𝟝', '𝟞', '𝟟', '𝟠', '𝟡'
 681         ];
 682   /**
 683    * @type {Array<string>}
 684    */
 685   this.digitsSansSerif =
 686       [
 687         '𝟢', '𝟣', '𝟤', '𝟥', '𝟦', '𝟧', '𝟨', '𝟩', '𝟪', '𝟫'
 688         ];
 689   /**
 690    * @type {Array<string>}
 691    */
 692   this.digitsSansSerifBold =
 693       [
 694         '𝟬', '𝟭', '𝟮', '𝟯', '𝟰', '𝟱', '𝟲', '𝟳', '𝟴', '𝟵'
 695         ];
 696   /**
 697    * @type {Array<string>}
 698    */
 699   this.digitsMonospace =
 700       [
 701         '𝟶', '𝟷', '𝟸', '𝟹', '𝟺', '𝟻', '𝟼', '𝟽', '𝟾', '𝟿'
 702         ];
 703   /**
 704    * @type {Array<string>}
 705    */
 706   this.digitsSuperscript =
 707       [
 708         '²', '³', '¹', '⁰', '⁴', '⁵', '⁶', '⁷', '⁸', '⁹'
 709         ];
 710   /**
 711    * @type {Array<string>}
 712    */
 713   this.digitsSubscript =
 714       [
 715         '₀', '₁', '₂', '₃', '₄', '₅', '₆', '₇', '₈', '₉'
 716         ];
 717   /**
 718    * @type {Array<string>}
 719    */
 720   this.fractions =
 721       [
 722         '¼', '½', '¾', '⅐', '⅑', '⅒', '⅓', '⅔', '⅕', '⅖', '⅗', '⅘', '⅙',
 723         '⅚', '⅛', '⅜', '⅝', '⅞', '⅟', '↉'
 724       ];
 725   /**
 726    * @type {Array<string>}
 727    */
 728   this.enclosedNumbers =
 729       // Encircled numbers.
 730       [
 731         '①', '②', '③', '④', '⑤', '⑥', '⑦', '⑧', '⑨', '⑩', '⑪', '⑫', '⑬',
 732         '⑭', '⑮', '⑯', '⑰', '⑱', '⑲', '⑳', '⓪', '⓫', '⓬', '⓭', '⓮', '⓯',
 733         '⓰', '⓱', '⓲', '⓳', '⓴', '⓵', '⓶', '⓷', '⓸', '⓹', '⓺', '⓻', '⓼',
 734         '⓽', '⓾', '⓿', '❶', '❷', '❸', '❹', '❺', '❻', '❼', '❽', '❾', '❿',
 735         '➀', '➁', '➂', '➃', '➄', '➅', '➆', '➇', '➈', '➉', '➊', '➋', '➌',
 736         '➍', '➎', '➏', '➐', '➑', '➒', '➓', '㉈', '㉉', '㉊', '㉋', '㉌',
 737         '㉍', '㉎', '㉏', '㉑', '㉒', '㉓', '㉔', '㉕', '㉖', '㉗', '㉘',
 738         '㉙', '㉚', '㉛', '㉜', '㉝', '㉞', '㉟', '㊱', '㊲', '㊳', '㊴',
 739         '㊵', '㊶', '㊷', '㊸', '㊹', '㊺', '㊻', '㊼', '㊽', '㊾', '㊿'];
 740   /**
 741    * @type {Array<string>}
 742    */
 743   this.fencedNumbers =
 744       // Numbers in Parenthesis.
 745       [
 746         '⑴', '⑵', '⑶', '⑷', '⑸', '⑹', '⑺', '⑻', '⑼', '⑽', '⑾', '⑿', '⒀',
 747         '⒁', '⒂', '⒃', '⒄', '⒅', '⒆', '⒇'
 748       ];
 749   /**
 750    * @type {Array<string>}
 751    */
 752   this.punctuatedNumbers =
 753       // Numbers with other punctuation.
 754       ['⒈', '⒉', '⒊', '⒋', '⒌', '⒍', '⒎', '⒏', '⒐', '⒑', '⒒', '⒓', '⒔',
 755        '⒕', '⒖', '⒗', '⒘', '⒙', '⒚', '⒛', // full stop.
 756        '🄀', '🄁', '🄂', '🄃', '🄄', '🄅', '🄆', '🄇', '🄈', '🄉', '🄊' // comma.
 757       ];
 758   /** Array of all single digits.
 759    * @type {Array<string>}
 760    */
 761   this.digits = this.digitsNormal.concat(
 762       this.digitsFullWidth, this.digitsBold, this.digitsDoubleStruck,
 763       this.digitsSansSerif, this.digitsSansSerifBold, this.digitsMonospace);
 764   /** Array of all non-digit number symbols.
 765    * @type {Array<string>}
 766    */
 767   this.numbers = this.fractions.concat(
 768       this.digitsSuperscript, this.digitsSubscript,
 769       this.enclosedNumbers, this.fencedNumbers, this.punctuatedNumbers);
 770   /** Array of all number symbols.
 771    * @type {Array<string>}
 772    */
 773   this.allNumbers = this.digits.concat(this.numbers);
 774
 775   // Functions.
 776   /**
 777    * @type {Array<string>}
 778    */
 779   this.trigonometricFunctions =
 780       [
 781         'cos', 'cot', 'csc', 'sec', 'sin', 'tan', 'arccos', 'arccot',
 782         'arccsc', 'arcsec', 'arcsin', 'arctan'
 783       ];
 784   /**
 785    * @type {Array<string>}
 786    */
 787   this.hyperbolicFunctions =
 788       [
 789         'cosh', 'coth', 'csch', 'sech', 'sinh', 'tanh',
 790         'arcosh', 'arcoth', 'arcsch', 'arsech', 'arsinh', 'artanh',
 791         'arccosh', 'arccoth', 'arccsch', 'arcsech', 'arcsinh', 'arctanh'
 792       ];
 793   /**
 794    * @type {Array<string>}
 795    */
 796   this.algebraicFunctions =
 797       [
 798         'deg', 'det', 'dim', 'hom', 'ker', 'Tr', 'tr'
 799       ];
 800   /**
 801    * @type {Array<string>}
 802    */
 803   this.elementaryFunctions =
 804       [
 805         'log', 'ln', 'lg', 'exp', 'expt', 'gcd', 'gcd', 'arg', 'im', 're', 'Pr'
 806       ];
 807   /** All predefined prefix functions.
 808    * @type {Array<string>}
 809    */
 810   this.prefixFunctions = this.trigonometricFunctions.concat(
 811       this.hyperbolicFunctions,
 812       this.algebraicFunctions,
 813       this.elementaryFunctions
 814       );
 815   /** Limit functions are handled separately as they can have lower (and upper)
 816    * limiting expressions.
 817    * @type {Array<string>}
 818    */
 819   this.limitFunctions =
 820       [
 821         'inf', 'lim', 'liminf', 'limsup', 'max', 'min', 'sup', 'injlim',
 822         'projlim'
 823       ];
 824   /**
 825    * @type {Array<string>}
 826    */
 827   this.infixFunctions =
 828       [
 829         'mod', 'rem'
 830       ];
 831   /**
 832    * Default assignments of semantic attributes.
 833    * @type  {Array<{set: Array<string>,
 834    *         role: cvox.SemanticAttr.Role,
 835    *         type: cvox.SemanticAttr.Type,
 836    *         font: cvox.SemanticAttr.Font}>} The semantic meaning of the symbol.
 837    * @private
 838    */
 839   this.symbolSetToSemantic_ = [
 840     // Punctuation
 841     {set: this.generalPunctuations,
 842      type: cvox.SemanticAttr.Type.PUNCTUATION,
 843      role: cvox.SemanticAttr.Role.UNKNOWN
 844     },
 845     {set: this.ellipses,
 846      type: cvox.SemanticAttr.Type.PUNCTUATION,
 847      role: cvox.SemanticAttr.Role.ELLIPSIS
 848     },
 849     {set: this.fullStops,
 850      type: cvox.SemanticAttr.Type.PUNCTUATION,
 851      role: cvox.SemanticAttr.Role.FULLSTOP
 852     },
 853     {set: this.dashes,
 854      type: cvox.SemanticAttr.Type.PUNCTUATION,
 855      role: cvox.SemanticAttr.Role.DASH
 856     },
 857     {set: this.primes,
 858      type: cvox.SemanticAttr.Type.PUNCTUATION,
 859      role: cvox.SemanticAttr.Role.PRIME
 860     },
 861     // Fences
 862     {set: this.leftFences,
 863      type: cvox.SemanticAttr.Type.FENCE,
 864      role: cvox.SemanticAttr.Role.OPEN
 865     },
 866     {set: this.rightFences,
 867      type: cvox.SemanticAttr.Type.FENCE,
 868      role: cvox.SemanticAttr.Role.CLOSE
 869     },
 870     {set: this.topFences,
 871      type: cvox.SemanticAttr.Type.FENCE,
 872      role: cvox.SemanticAttr.Role.TOP
 873     },
 874     {set: this.bottomFences,
 875      type: cvox.SemanticAttr.Type.FENCE,
 876      role: cvox.SemanticAttr.Role.BOTTOM
 877     },
 878     {set: this.neutralFences,
 879      type: cvox.SemanticAttr.Type.FENCE,
 880      role: cvox.SemanticAttr.Role.NEUTRAL
 881     },
 882     // Single characters.
 883     // Latin alphabets.
 884     {set: this.smallLatin,
 885      type: cvox.SemanticAttr.Type.IDENTIFIER,
 886      role: cvox.SemanticAttr.Role.LATINLETTER,
 887      font: cvox.SemanticAttr.Font.NORMAL
 888     },
 889     {set: this.capitalLatin,
 890      type: cvox.SemanticAttr.Type.IDENTIFIER,
 891      role: cvox.SemanticAttr.Role.LATINLETTER,
 892      font: cvox.SemanticAttr.Font.NORMAL
 893     },
 894     {set: this.smallLatinFullWidth,
 895      type: cvox.SemanticAttr.Type.IDENTIFIER,
 896      role: cvox.SemanticAttr.Role.LATINLETTER,
 897      font: cvox.SemanticAttr.Font.NORMAL
 898     },
 899     {set: this.capitalLatinFullWidth,
 900      type: cvox.SemanticAttr.Type.IDENTIFIER,
 901      role: cvox.SemanticAttr.Role.LATINLETTER,
 902      font: cvox.SemanticAttr.Font.NORMAL
 903     },
 904     {set: this.smallLatinBold,
 905      type: cvox.SemanticAttr.Type.IDENTIFIER,
 906      role: cvox.SemanticAttr.Role.LATINLETTER,
 907      font: cvox.SemanticAttr.Font.BOLD
 908     },
 909     {set: this.capitalLatinBold,
 910      type: cvox.SemanticAttr.Type.IDENTIFIER,
 911      role: cvox.SemanticAttr.Role.LATINLETTER,
 912      font: cvox.SemanticAttr.Font.BOLD
 913     },
 914     {set: this.smallLatinItalic,
 915      type: cvox.SemanticAttr.Type.IDENTIFIER,
 916      role: cvox.SemanticAttr.Role.LATINLETTER,
 917      font: cvox.SemanticAttr.Font.ITALIC
 918     },
 919     {set: this.capitalLatinItalic,
 920      type: cvox.SemanticAttr.Type.IDENTIFIER,
 921      role: cvox.SemanticAttr.Role.LATINLETTER,
 922      font: cvox.SemanticAttr.Font.ITALIC
 923     },
 924     {set: this.smallLatinScript,
 925      type: cvox.SemanticAttr.Type.IDENTIFIER,
 926      role: cvox.SemanticAttr.Role.LATINLETTER,
 927      font: cvox.SemanticAttr.Font.SCRIPT
 928     },
 929     {set: this.capitalLatinScript,
 930      type: cvox.SemanticAttr.Type.IDENTIFIER,
 931      role: cvox.SemanticAttr.Role.LATINLETTER,
 932      font: cvox.SemanticAttr.Font.SCRIPT
 933     },
 934     {set: this.smallLatinBoldScript,
 935      type: cvox.SemanticAttr.Type.IDENTIFIER,
 936      role: cvox.SemanticAttr.Role.LATINLETTER,
 937      font: cvox.SemanticAttr.Font.BOLDSCRIPT
 938     },
 939     {set: this.capitalLatinBoldScript,
 940      type: cvox.SemanticAttr.Type.IDENTIFIER,
 941      role: cvox.SemanticAttr.Role.LATINLETTER,
 942      font: cvox.SemanticAttr.Font.BOLDSCRIPT
 943     },
 944     {set: this.smallLatinFraktur,
 945      type: cvox.SemanticAttr.Type.IDENTIFIER,
 946      role: cvox.SemanticAttr.Role.LATINLETTER,
 947      font: cvox.SemanticAttr.Font.FRAKTUR
 948     },
 949     {set: this.capitalLatinFraktur,
 950      type: cvox.SemanticAttr.Type.IDENTIFIER,
 951      role: cvox.SemanticAttr.Role.LATINLETTER,
 952      font: cvox.SemanticAttr.Font.FRAKTUR
 953     },
 954     {set: this.smallLatinDoubleStruck,
 955      type: cvox.SemanticAttr.Type.IDENTIFIER,
 956      role: cvox.SemanticAttr.Role.LATINLETTER,
 957      font: cvox.SemanticAttr.Font.DOUBLESTRUCK
 958     },
 959     {set: this.capitalLatinDoubleStruck,
 960      type: cvox.SemanticAttr.Type.IDENTIFIER,
 961      role: cvox.SemanticAttr.Role.LATINLETTER,
 962      font: cvox.SemanticAttr.Font.DOUBLESTRUCK
 963     },
 964     {set: this.smallLatinBoldFraktur,
 965      type: cvox.SemanticAttr.Type.IDENTIFIER,
 966      role: cvox.SemanticAttr.Role.LATINLETTER,
 967      font: cvox.SemanticAttr.Font.BOLDFRAKTUR
 968     },
 969     {set: this.capitalLatinBoldFraktur,
 970      type: cvox.SemanticAttr.Type.IDENTIFIER,
 971      role: cvox.SemanticAttr.Role.LATINLETTER,
 972      font: cvox.SemanticAttr.Font.BOLDFRAKTUR
 973     },
 974     {set: this.smallLatinSansSerif,
 975      type: cvox.SemanticAttr.Type.IDENTIFIER,
 976      role: cvox.SemanticAttr.Role.LATINLETTER,
 977      font: cvox.SemanticAttr.Font.SANSSERIF
 978     },
 979     {set: this.capitalLatinSansSerif,
 980      type: cvox.SemanticAttr.Type.IDENTIFIER,
 981      role: cvox.SemanticAttr.Role.LATINLETTER,
 982      font: cvox.SemanticAttr.Font.SANSSERIF
 983     },
 984     {set: this.smallLatinSansSerifBold,
 985      type: cvox.SemanticAttr.Type.IDENTIFIER,
 986      role: cvox.SemanticAttr.Role.LATINLETTER,
 987      font: cvox.SemanticAttr.Font.SANSSERIFBOLD
 988     },
 989     {set: this.capitalLatinSansSerifBold,
 990      type: cvox.SemanticAttr.Type.IDENTIFIER,
 991      role: cvox.SemanticAttr.Role.LATINLETTER,
 992      font: cvox.SemanticAttr.Font.SANSSERIFBOLD
 993     },
 994     {set: this.smallLatinSansSerifItalic,
 995      type: cvox.SemanticAttr.Type.IDENTIFIER,
 996      role: cvox.SemanticAttr.Role.LATINLETTER,
 997      font: cvox.SemanticAttr.Font.SANSSERIFITALIC
 998     },
 999     {set: this.capitalLatinSansSerifItalic,
1000      type: cvox.SemanticAttr.Type.IDENTIFIER,
1001      role: cvox.SemanticAttr.Role.LATINLETTER,
1002      font: cvox.SemanticAttr.Font.SANSSERIFITALIC
1003     },
1004     {set: this.smallLatinMonospace,
1005      type: cvox.SemanticAttr.Type.IDENTIFIER,
1006      role: cvox.SemanticAttr.Role.LATINLETTER,
1007      font: cvox.SemanticAttr.Font.MONOSPACE
1008     },
1009     {set: this.capitalLatinMonospace,
1010      type: cvox.SemanticAttr.Type.IDENTIFIER,
1011      role: cvox.SemanticAttr.Role.LATINLETTER,
1012      font: cvox.SemanticAttr.Font.MONOSPACE
1013     },
1014     {set: this.latinDoubleStruckItalic,
1015      type: cvox.SemanticAttr.Type.IDENTIFIER,
1016      role: cvox.SemanticAttr.Role.LATINLETTER,
1017      font: cvox.SemanticAttr.Font.DOUBLESTRUCKITALIC
1018     },
1019     // Greek alphabets.
1020     {set: this.smallGreek,
1021      type: cvox.SemanticAttr.Type.IDENTIFIER,
1022      role: cvox.SemanticAttr.Role.GREEKLETTER,
1023      font: cvox.SemanticAttr.Font.NORMAL
1024     },
1025     {set: this.capitalGreek,
1026      type: cvox.SemanticAttr.Type.IDENTIFIER,
1027      role: cvox.SemanticAttr.Role.GREEKLETTER,
1028      font: cvox.SemanticAttr.Font.NORMAL
1029     },
1030     {set: this.smallGreekBold,
1031      type: cvox.SemanticAttr.Type.IDENTIFIER,
1032      role: cvox.SemanticAttr.Role.GREEKLETTER,
1033      font: cvox.SemanticAttr.Font.BOLD
1034     },
1035     {set: this.capitalGreekBold,
1036      type: cvox.SemanticAttr.Type.IDENTIFIER,
1037      role: cvox.SemanticAttr.Role.GREEKLETTER,
1038      font: cvox.SemanticAttr.Font.BOLD
1039     },
1040     {set: this.smallGreekItalic,
1041      type: cvox.SemanticAttr.Type.IDENTIFIER,
1042      role: cvox.SemanticAttr.Role.GREEKLETTER,
1043      font: cvox.SemanticAttr.Font.ITALIC
1044     },
1045     {set: this.capitalGreekItalic,
1046      type: cvox.SemanticAttr.Type.IDENTIFIER,
1047      role: cvox.SemanticAttr.Role.GREEKLETTER,
1048      font: cvox.SemanticAttr.Font.ITALIC
1049     },
1050     {set: this.smallGreekSansSerifBold,
1051      type: cvox.SemanticAttr.Type.IDENTIFIER,
1052      role: cvox.SemanticAttr.Role.GREEKLETTER,
1053      font: cvox.SemanticAttr.Font.SANSSERIFBOLD
1054     },
1055     {set: this.capitalGreekSansSerifBold,
1056      type: cvox.SemanticAttr.Type.IDENTIFIER,
1057      role: cvox.SemanticAttr.Role.GREEKLETTER,
1058      font: cvox.SemanticAttr.Font.SANSSERIFBOLD
1059     },
1060     {set: this.greekDoubleStruck,
1061      type: cvox.SemanticAttr.Type.IDENTIFIER,
1062      role: cvox.SemanticAttr.Role.GREEKLETTER,
1063      font: cvox.SemanticAttr.Font.DOUBLESTRUCK
1064     },
1065     // Other alphabets.
1066     {set: this.hebrewLetters,
1067      type: cvox.SemanticAttr.Type.IDENTIFIER,
1068      role: cvox.SemanticAttr.Role.OTHERLETTER,
1069      font: cvox.SemanticAttr.Font.NORMAL
1070     },
1071     // Numbers.
1072     {set: this.digitsNormal,
1073      type: cvox.SemanticAttr.Type.NUMBER,
1074      role: cvox.SemanticAttr.Role.INTEGER,
1075      font: cvox.SemanticAttr.Font.NORMAL
1076     },
1077     {set: this.digitsFullWidth,
1078      type: cvox.SemanticAttr.Type.NUMBER,
1079      role: cvox.SemanticAttr.Role.INTEGER,
1080      font: cvox.SemanticAttr.Font.NORMAL
1081     },
1082     {set: this.digitsBold,
1083      type: cvox.SemanticAttr.Type.NUMBER,
1084      role: cvox.SemanticAttr.Role.INTEGER,
1085      font: cvox.SemanticAttr.Font.BOLD
1086     },
1087     {set: this.digitsDoubleStruck,
1088      type: cvox.SemanticAttr.Type.NUMBER,
1089      role: cvox.SemanticAttr.Role.INTEGER,
1090      font: cvox.SemanticAttr.Font.DOUBLESTRUCK
1091     },
1092     {set: this.digitsSansSerif,
1093      type: cvox.SemanticAttr.Type.NUMBER,
1094      role: cvox.SemanticAttr.Role.INTEGER,
1095      font: cvox.SemanticAttr.Font.SANSSERIF
1096     },
1097     {set: this.digitsSansSerifBold,
1098      type: cvox.SemanticAttr.Type.NUMBER,
1099      role: cvox.SemanticAttr.Role.INTEGER,
1100      font: cvox.SemanticAttr.Font.SANSSERIFBOLD
1101     },
1102     {set: this.digitsMonospace,
1103      type: cvox.SemanticAttr.Type.NUMBER,
1104      role: cvox.SemanticAttr.Role.INTEGER,
1105      font: cvox.SemanticAttr.Font.MONOSPACE
1106     },
1107    {set: this.numbers,
1108      type: cvox.SemanticAttr.Type.NUMBER,
1109      role: cvox.SemanticAttr.Role.INTEGER
1110     },
1111     // Operators.
1112     {set: this.additions,
1113      type: cvox.SemanticAttr.Type.OPERATOR,
1114      role: cvox.SemanticAttr.Role.ADDITION
1115     },
1116     {set: this.multiplications,
1117      type: cvox.SemanticAttr.Type.OPERATOR,
1118      role: cvox.SemanticAttr.Role.MULTIPLICATION
1119     },
1120     {set: this.subtractions,
1121      type: cvox.SemanticAttr.Type.OPERATOR,
1122      role: cvox.SemanticAttr.Role.SUBTRACTION
1123     },
1124     {set: this.divisions,
1125      type: cvox.SemanticAttr.Type.OPERATOR,
1126      role: cvox.SemanticAttr.Role.DIVISION
1127     },
1128     {set: this.prefixOps,
1129      type: cvox.SemanticAttr.Type.PREFIXOP,
1130      role: cvox.SemanticAttr.Role.PREFIXFUNC
1131     },
1132     // Relations
1133     {set: this.equalities,
1134      type: cvox.SemanticAttr.Type.RELATION,
1135      role: cvox.SemanticAttr.Role.EQUALITY
1136     },
1137     {set: this.inequalities,
1138      type: cvox.SemanticAttr.Type.RELATION,
1139      role: cvox.SemanticAttr.Role.INEQUALITY
1140     },
1141     {set: this.relations,
1142      type: cvox.SemanticAttr.Type.RELATION,
1143      role: cvox.SemanticAttr.Role.UNKNOWN
1144     },
1145     {set: this.arrows,
1146      type: cvox.SemanticAttr.Type.RELATION,
1147      role: cvox.SemanticAttr.Role.ARROW
1148     },
1149     // Large operators
1150     {set: this.sumOps,
1151      type: cvox.SemanticAttr.Type.LARGEOP,
1152      role: cvox.SemanticAttr.Role.SUM},
1153     {set: this.intOps,
1154      type: cvox.SemanticAttr.Type.LARGEOP,
1155      role: cvox.SemanticAttr.Role.INTEGRAL},
1156     // Functions
1157     {set: this.limitFunctions,
1158      type: cvox.SemanticAttr.Type.FUNCTION,
1159      role: cvox.SemanticAttr.Role.LIMFUNC},
1160     {set: this.prefixFunctions,
1161      type: cvox.SemanticAttr.Type.FUNCTION,
1162      role: cvox.SemanticAttr.Role.PREFIXFUNC},
1163     {set: this.infixFunctions,
1164      type: cvox.SemanticAttr.Type.OPERATOR,
1165      role: cvox.SemanticAttr.Role.MULTIPLICATION
1166     }
1167     // TODO (sorge) Add some of the remaining elements.
1168   ];
1169 };
1170 goog.addSingletonGetter(cvox.SemanticAttr);
1171
1172
1173 /**
1174  * Union type of semantic attributes.
1175  * @typedef {cvox.SemanticAttr.Type|cvox.SemanticAttr.Role}
1176  */
1177 cvox.SemanticAttr.Attr;
1178
1179
1180 /**
1181  * Mapping for types of elements.
1182  * @enum {string}
1183  */
1184 cvox.SemanticAttr.Type = {
1185   // Leafs.
1186   // Punctuation like comma, dot, ellipses.
1187   PUNCTUATION: 'punctuation',
1188   // Fence symbol.
1189   FENCE: 'fence',
1190   // One or several digits, plus some punctuation.
1191   NUMBER: 'number',
1192   // Single or multiple letters.
1193   IDENTIFIER: 'identifier',
1194   // Regular text in a math expression.
1195   TEXT: 'text',
1196   // e.g. +, *.
1197   OPERATOR: 'operator',
1198   // Relation symbol, e.g. equals.
1199   RELATION: 'relation',
1200   // e.g. Sum, product, integral.
1201   LARGEOP: 'largeop',
1202   // Some named function.
1203   FUNCTION: 'function',
1204
1205   // Branches.
1206   // Compound Symbols.
1207   ACCENT: 'accent',
1208   FENCED: 'fenced',
1209   FRACTION: 'fraction',
1210   PUNCTUATED: 'punctuated',
1211
1212   // Relations.
1213   // Relation sequence of a single relation.
1214   RELSEQ: 'relseq',
1215   // Relation sequence containing at least two different relations.
1216   MULTIREL: 'multirel',
1217   // Operations.
1218   INFIXOP: 'infixop',
1219   PREFIXOP: 'prefixop',
1220   POSTFIXOP: 'postfixop',
1221
1222   // Function and Bigop Application.
1223   APPL: 'appl',
1224   INTEGRAL: 'integral',
1225   BIGOP: 'bigop',
1226
1227   SQRT: 'sqrt',
1228   ROOT: 'root',
1229   // These are bigops or functions with limits.
1230   LIMUPPER: 'limupper',
1231   LIMLOWER: 'limlower',
1232   LIMBOTH: 'limboth',
1233   SUBSCRIPT: 'subscript',
1234   SUPERSCRIPT: 'superscript',
1235   UNDERSCORE: 'underscore',
1236   OVERSCORE: 'overscore',
1237
1238   // Tables and their elements.
1239   TABLE: 'table',
1240   MULTILINE: 'multiline',
1241   MATRIX: 'matrix',
1242   VECTOR: 'vector',
1243   CASES: 'cases',
1244   ROW: 'row',
1245   // Lines are effectively single cell rows.
1246   LINE: 'line',
1247   CELL: 'cell',
1248
1249   // General.
1250   UNKNOWN: 'unknown',
1251   EMPTY: 'empty'
1252 };
1253
1254
1255 /**
1256  * Mapping for roles of nodes.
1257  * Roles are more specific than types.
1258  * @enum {string}
1259  */
1260 cvox.SemanticAttr.Role = {
1261   // Punctuation.
1262   ELLIPSIS: 'ellipsis',
1263   FULLSTOP: 'fullstop',
1264   DASH: 'dash',
1265   PRIME: 'prime',   // Superscript.
1266   VBAR: 'vbar',  // A vertical bar.
1267   OPENFENCE: 'openfence',
1268   CLOSEFENCE: 'closefence',
1269   APPLICATION: 'application', // Function Application.
1270
1271   // Fences.
1272   OPEN: 'open',
1273   CLOSE: 'close',
1274   TOP: 'top',
1275   BOTTOM: 'bottom',
1276   NEUTRAL: 'neutral',
1277
1278   // Letters.
1279   LATINLETTER: 'latinletter',
1280   GREEKLETTER: 'greekletter',
1281   OTHERLETTER: 'otherletter',
1282
1283   // Numbers.
1284   INTEGER: 'integer',
1285   FLOAT: 'float',
1286   OTHERNUMBER: 'othernumber',
1287
1288   // Accents.
1289   MULTIACCENT: 'multiaccent',
1290   OVERACCENT: 'overaccent',
1291   UNDERACCENT: 'underaccent',
1292
1293   // Fenced.
1294   LEFTRIGHT: 'leftright',
1295   ABOVEBELOW: 'abovebelow',
1296
1297   // Punctuated elements.
1298   SEQUENCE: 'sequence',
1299   ENDPUNCT: 'endpunct',
1300   STARTPUNCT: 'startpunct',
1301
1302   // Operators.
1303   NEGATIVE: 'negative',
1304   NEGATION: 'negation',
1305   MULTIOP: 'multiop',
1306
1307   // Functions.
1308   LIMFUNC: 'limit function',
1309   INFIXFUNC: 'infix function',
1310   PREFIXFUNC: 'prefix function',
1311   POSTFIXFUNC: 'postfix function',
1312
1313   // Large operators.
1314   SUM: 'sum',
1315   INTEGRAL: 'integral',
1316
1317   // Binary operations.
1318   ADDITION: 'addition',
1319   MULTIPLICATION: 'multiplication',
1320   DIVISION: 'division',
1321   SUBTRACTION: 'subtraction',
1322   IMPLICIT: 'implicit',
1323
1324   // Relations.
1325   EQUALITY: 'equality',
1326   INEQUALITY: 'inequality',
1327   ELEMENT: 'element',
1328   BINREL: 'binrel',
1329   ARROW: 'arrow',
1330
1331   // Roles of rows, lines, cells.
1332   // They mirror the different types for tables.
1333   MULTILINE: 'multiline',
1334   MATRIX: 'matrix',
1335   VECTOR: 'vector',
1336   CASES: 'cases',
1337   TABLE: 'table',
1338
1339   // General
1340   UNKNOWN: 'unknown'
1341 };
1342
1343
1344 /**
1345  * Mapping for font annotations. (Taken from MathML2 section 3.2.2, with the
1346  * exception of double-struck-italic.)
1347  * @enum {string}
1348  */
1349 cvox.SemanticAttr.Font = {
1350   BOLD: 'bold',
1351   BOLDFRAKTUR: 'bold-fraktur',
1352   BOLDITALIC: 'bold-italic',
1353   BOLDSCRIPT: 'bold-script',
1354   DOUBLESTRUCK: 'double-struck',
1355   DOUBLESTRUCKITALIC: 'double-struck-italic',
1356   FRAKTUR: 'fraktur',
1357   ITALIC: 'italic',
1358   MONOSPACE: 'monospace',
1359   NORMAL: 'normal',
1360   SCRIPT: 'script',
1361   SANSSERIF: 'sans-serif',
1362   SANSSERIFITALIC: 'sans-serif-italic',
1363   SANSSERIFBOLD: 'sans-serif-bold',
1364   SANSSERIFBOLDITALIC: 'sans-serif-bold-italic',
1365   UNKNOWN: 'unknown'
1366 };
1367
1368
1369 /**
1370  * Lookup the semantic type of a symbol.
1371  * @param {string} symbol The symbol to which we want to determine the type.
1372  * @return {cvox.SemanticAttr.Type} The semantic type of the symbol.
1373  */
1374 cvox.SemanticAttr.prototype.lookupType = function(symbol) {
1375   return cvox.SemanticAttr.Type.UNKNOWN;
1376 };
1377
1378
1379 /**
1380  * Lookup the semantic role of a symbol.
1381  * @param {string} symbol The symbol to which we want to determine the role.
1382  * @return {cvox.SemanticAttr.Role} The semantic role of the symbol.
1383  */
1384 cvox.SemanticAttr.prototype.lookupRole = function(symbol) {
1385   return cvox.SemanticAttr.Role.UNKNOWN;
1386 };
1387
1388
1389 /**
1390  * Lookup the semantic meaning of a symbol in terms of type and role.
1391  * @param {string} symbol The symbol to which we want to determine the meaning.
1392  * @return {{role: cvox.SemanticAttr.Role,
1393  *           type: cvox.SemanticAttr.Type}} The semantic meaning of the symbol.
1394  */
1395 cvox.SemanticAttr.lookupMeaning = function(symbol) {
1396   return cvox.SemanticAttr.getInstance().lookupMeaning_(symbol);
1397 };
1398
1399
1400 /**
1401  * String representation of the invisible times unicode character.
1402  * @return {string} The invisible times character.
1403  */
1404 cvox.SemanticAttr.invisibleTimes = function() {
1405   return cvox.SemanticAttr.getInstance().invisibleTimes_;
1406 };
1407
1408
1409 /**
1410  * String representation of the invisible comma unicode character.
1411  * @return {string} The invisible comma character.
1412  */
1413 cvox.SemanticAttr.invisibleComma = function() {
1414   return cvox.SemanticAttr.getInstance().invisibleComma_;
1415 };
1416
1417
1418 /**
1419  * String representation of the function application character.
1420  * @return {string} The invisible function application character.
1421  */
1422 cvox.SemanticAttr.functionApplication = function() {
1423   return cvox.SemanticAttr.getInstance().functionApplication_;
1424 };
1425
1426
1427 /**
1428  * Decide when two fences match. Currently we match any right to left
1429  * or bottom to top fence and neutral to neutral.
1430  * @param {cvox.SemanticAttr.Role} open Opening fence.
1431  * @param {cvox.SemanticAttr.Role} close Closing fence.
1432  * @return {boolean} True if the fences are matching.
1433  */
1434 cvox.SemanticAttr.isMatchingFenceRole = function(open, close) {
1435   return (open == cvox.SemanticAttr.Role.OPEN &&
1436       close == cvox.SemanticAttr.Role.CLOSE) ||
1437           (open == cvox.SemanticAttr.Role.NEUTRAL &&
1438               close == cvox.SemanticAttr.Role.NEUTRAL) ||
1439                   (open == cvox.SemanticAttr.Role.TOP &&
1440                       close == cvox.SemanticAttr.Role.BOTTOM);
1441 };
1442
1443
1444 /**
1445  * Decide when opening and closing fences match. For neutral fences they have to
1446  * be the same.
1447  * @param {string} open Opening fence.
1448  * @param {string} close Closing fence.
1449  * @return {boolean} True if the fences are matching.
1450  */
1451 cvox.SemanticAttr.isMatchingFence = function(open, close) {
1452   return cvox.SemanticAttr.getInstance().isMatchingFence_(open, close);
1453 };
1454
1455
1456 /**
1457  * Determines if a fence is an opening fence.
1458  * @param {cvox.SemanticAttr.Role} fence Opening fence.
1459  * @return {boolean} True if the fence is open or neutral.
1460  */
1461 cvox.SemanticAttr.isOpeningFence = function(fence) {
1462   return (fence == cvox.SemanticAttr.Role.OPEN ||
1463           fence == cvox.SemanticAttr.Role.NEUTRAL);
1464 };
1465
1466
1467 /**
1468  * Determines if a fence is a closing fence.
1469  * @param {cvox.SemanticAttr.Role} fence Closing fence.
1470  * @return {boolean} True if the fence is close or neutral.
1471  */
1472 cvox.SemanticAttr.isClosingFence = function(fence) {
1473   return (fence == cvox.SemanticAttr.Role.CLOSE ||
1474           fence == cvox.SemanticAttr.Role.NEUTRAL);
1475 };
1476
1477
1478 // TODO (sorge) Make this depended on position in the alphabets.
1479 /**
1480  * Check if a character is a small 'd' in some font.
1481  * @param {!string} chr The character string.
1482  * @return {boolean} True if the character is indeed a single small d.
1483  */
1484 cvox.SemanticAttr.isCharacterD = function(chr) {
1485   var Ds = ['d', 'ⅆ', 'ｄ', '𝐝', '𝑑', '𝒹', '𝓭', '𝔡',
1486             '𝕕', '𝖉', '𝖽', '𝗱', '𝘥', '𝚍'];
1487   return Ds.indexOf(chr) != -1;
1488 };
1489
1490
1491 /**
1492  * Decide when opening and closing fences match. For neutral fences they have to
1493  * be the same.
1494  * @param {!string} open Opening fence.
1495  * @param {!string} close Closing fence.
1496  * @return {boolean} True if the fences are matching.
1497  * @private
1498  */
1499 cvox.SemanticAttr.prototype.isMatchingFence_ = function(open, close) {
1500   if (this.neutralFences.indexOf(open) != -1) {
1501     return open == close;
1502   }
1503   return this.openClosePairs[open] == close ||
1504       this.topBottomPairs[open] == close;
1505 };
1506
1507
1508 /**
1509  * Lookup the semantic meaning of a symbol in terms of type and role.
1510  * @param {!string} symbol The symbol to which we want to determine the meaning.
1511  * @return {{role: cvox.SemanticAttr.Role,
1512  *           type: cvox.SemanticAttr.Type,
1513  *           font: cvox.SemanticAttr.Font}} The semantic meaning of the symbol.
1514  * @private
1515  */
1516 cvox.SemanticAttr.prototype.lookupMeaning_ = function(symbol) {
1517   for (var i = 0, set; set = this.symbolSetToSemantic_[i]; i++) {
1518     if (set.set.indexOf(symbol) != -1) {
1519       return {role: set.role || cvox.SemanticAttr.Role.UNKNOWN,
1520               type: set.type || cvox.SemanticAttr.Type.UNKNOWN,
1521               font: set.font || cvox.SemanticAttr.Font.UNKNOWN
1522              };
1523     }
1524   }
1525   return {role: cvox.SemanticAttr.Role.UNKNOWN,
1526           type: cvox.SemanticAttr.Type.UNKNOWN,
1527           font: cvox.SemanticAttr.Font.UNKNOWN
1528          };
1529 };