Merge pull request #1095 from mathjax/fix-mathaccents

Update handling of math accents to round-trip through SRE

Author: dpvc

ts/core/MmlTree/MmlNodes/mo.ts

@@ -124,6 +124,7 @@ export class MmlMo extends AbstractMmlTokenNode {
 
   /**
    * Regular expression matching characters that are marked as math accents
+   *  (property mathaccent = true)
    */
   protected static mathaccents = new RegExp([
     '^[',
@@ -135,14 +136,27 @@ export class MmlMo extends AbstractMmlTokenNode {
     '\u02D8\u0306',        // breve
     '\u02C7\u030C',        // check
     '\u005E\u0302\u02C6',  // hat
-    '\u2192\u20D7',        // vec
+    '\u20D0\u20D1',        // harpoons
+    '\u20D6\u20D7\u20E1',  // vec (backward, forward, double)
     '\u02D9\u0307',        // dot
     '\u02DA\u030A',        // mathring
     '\u20DB',              // dddot
     '\u20DC',              // ddddot
     ']$'
   ].join(''));
 
+  /**
+   * Regular expression matching characters that are marked as math accents
+   *   whose widths are to be respected (property mathaccent = false)
+   */
+  protected static mathaccentsWithWidth = new RegExp([
+    '^[',
+    '\u2015',              // overline and underline
+    '\u2190\u2192\u2194',  // arrows
+    '\u23DC\u23DD',        // over and under parens
+    ']$'
+  ].join(''));
+
   /**
    * The internal TeX class of the node (for use with getter/setter below)
    */
@@ -470,10 +484,33 @@ export class MmlMo extends AbstractMmlTokenNode {
     const isUnder = !!(under && under.isEmbellished && under.coreMO() === this);
     const isOver = !!(over && over.isEmbellished && under.coreMO() === this);
     if (!isUnder && !isOver) return;
-    const MATHACCENT = (this.constructor as typeof MmlMo).mathaccents;
-    if (mo.match(MATHACCENT)) {
-      this.setProperty('mathaccent', true);
+    if (this.isMathAccent(mo)) {
+      this.setProperty('mathaccent', true);   // math accent whose width is replaced by 0
+    } else if (this.isMathAccentWithWidth(mo)) {
+      this.setProperty('mathaccent', false);  // math accent whose width is normal
     }
   }
 
+  /**
+   * Check a string for being a mathaccent
+   *
+   * @param {string} mo   The string to check
+   * @return {boolean}    True if the string should be a mathaccent
+   */
+  public isMathAccent(mo: string = this.getText()): boolean {
+    const MATHACCENT = (this.constructor as typeof MmlMo).mathaccents;
+    return !!mo.match(MATHACCENT);
+  }
+
+  /**
+   * Check a string for being a mathaccent with non-zero width
+   *
+   * @param {string} mo   The string to check
+   * @return {boolean}    True if the string should be a mathaccent
+   */
+  public isMathAccentWithWidth(mo: string = this.getText()): boolean {
+    const MATHACCENT = (this.constructor as typeof MmlMo).mathaccentsWithWidth;
+    return !!mo.match(MATHACCENT);
+  }
+
 }

ts/core/MmlTree/MmlVisitor.ts

@@ -22,6 +22,7 @@
  */
 
 import {MmlNode, TextNode, XMLNode, TEXCLASS, TEXCLASSNAMES} from './MmlNode.js';
+import {MmlMo} from './MmlNodes/mo.js';
 import {MmlMi} from './MmlNodes/mi.js';
 import {HtmlNode} from './MmlNodes/HtmlNode.js';
 import {MmlFactory} from './MmlFactory.js';
@@ -167,6 +168,13 @@ export class MmlVisitor extends AbstractVisitor<MmlNode> {
     vbox && this.setDataAttribute(data, 'vbox', vbox);
     const scriptalign = node.getProperty('scriptalign') as string;
     scriptalign && this.setDataAttribute(data, 'script-align', scriptalign);
+    const accent = node.getProperty('mathaccent') as boolean;
+    if (accent !== undefined) {
+      if ((accent && !(node as MmlMo).isMathAccent()) ||
+          (!accent && !(node as MmlMo).isMathAccentWithWidth())) {
+        this.setDataAttribute(data, 'mathaccent', accent.toString());
+      }
+    }
     const texclass = node.getProperty('texClass') as number;
     if (texclass !== undefined) {
       let setclass = true;

ts/input/mathml/MathMLCompile.ts

@@ -201,7 +201,7 @@ export class MathMLCompile<N, T, D> {
           mml.setProperty('scriptlevel', 1);
           mml.setProperty('useHeight', false);
           break;
-        case 'accent':
+        case 'mathaccent':
           mml.setProperty('mathaccent', value === 'true');
           break;
         case 'auto-op':

ts/output/common/Wrappers/scriptbase.ts

@@ -793,7 +793,7 @@ export function CommonScriptbaseMixin<
       //  Determine if we are setting a mathaccent
       //
       this.isMathAccent = this.baseIsChar &&
-        (this.scriptChild && !!this.scriptChild.coreMO().node.getProperty('mathaccent')) as boolean;
+        (this.scriptChild && this.scriptChild.coreMO().node.getProperty('mathaccent') !== undefined);
       //
       // Check for overline/underline accents
       //