Add \lim and customLetters, fix \lbrack and companions, parse \left\lfloor and ceil, and parse lone ampersands properly

src/commands/math.ts

@@ -617,8 +617,23 @@ class MathBlock extends MathElement {
   }
   chToCmd(ch: string, options: CursorOptions) {
     var cons;
-    // exclude f because it gets a dedicated command with more spacing
-    if (ch.match(/^[a-eg-zA-Z]$/)) return new Letter(ch);
+    // extract customCharacters early so we can easily default it to 'f'
+    var customCharacters = options?.customCharacters ?? 'f';
+    if (
+      customCharacters.indexOf(ch) >= 0 &&
+      (cons = (CharCmds as CharCmdsAny)[ch] || (LatexCmds as LatexCmdsAny)[ch])
+    ) {
+      if (cons.constructor) {
+        return new cons(ch);
+      } else {
+        return cons(ch);
+      }
+    } else if (
+      // the patch to exclude 'f' from this regex is no longer needed since we
+      // usecustomCharacters
+      ch.match(/^[a-zA-Z]$/)
+    )
+      return new Letter(ch);
     else if (/^\d$/.test(ch)) return new Digit(ch);
     else if (options && options.typingSlashWritesDivisionSymbol && ch === '/')
       return (LatexCmds as LatexCmdsSingleCharBuilder)['÷'](ch);

src/commands/math/advancedSymbols.ts

@@ -644,12 +644,12 @@ LatexCmds.closecurlybrace = LatexCmds.rbrace = bindVanillaSymbol(
   '}',
   'right brace'
 );
-LatexCmds.lbrack = bindVanillaSymbol('[', 'left bracket');
-LatexCmds.rbrack = bindVanillaSymbol(']', 'right bracket');
+LatexCmds.lbrack = bindVanillaSymbol('[', '[', 'left bracket');
+LatexCmds.rbrack = bindVanillaSymbol(']', ']', 'right bracket');
 
 //various symbols
-LatexCmds.slash = bindVanillaSymbol('/', 'slash');
-LatexCmds.vert = bindVanillaSymbol('|', 'vertical bar');
+LatexCmds.slash = bindVanillaSymbol('/', '/', 'slash');
+LatexCmds.vert = bindVanillaSymbol('|', '|', 'vertical bar');
 LatexCmds.perp = LatexCmds.perpendicular = bindVanillaSymbol(
   '\\perp ',
   '⊥',

src/commands/math/basicSymbols.ts

@@ -647,7 +647,7 @@ function defaultAutoOpNames() {
     _maxLength: 9,
   };
   var mostOps = (
-    'arg deg det dim exp gcd hom inf ker lg lim ln log max min sup' +
+    'arg deg det dim exp gcd hom inf ker lg ln log max min sup' +
     ' limsup liminf injlim projlim Pr'
   ).split(' ');
   for (var i = 0; i < mostOps.length; i += 1) {

src/commands/math/commands.ts

@@ -953,7 +953,9 @@ var LiveFraction =
                   leftward._groupingClass === 'mq-ellipsis-end') ||
                 leftward instanceof (LatexCmds.text || noop) ||
                 leftward instanceof SummationNotation ||
+                leftward instanceof Limit ||
                 leftward.ctrlSeq === '\\ ' ||
+                leftward.ctrlSeq === '&' ||
                 /^[,;:]$/.test(leftward.ctrlSeq as string)
               ) //lookbehind for operator
             )
@@ -1616,7 +1618,9 @@ LatexCmds.left = class extends MathCommand {
     var optWhitespace = Parser.optWhitespace;
 
     return optWhitespace
-      .then(regex(/^(?:[([|]|\\\{|\\langle(?![a-zA-Z])|\\lVert(?![a-zA-Z]))/))
+      .then(
+        regex(/^(?:[([|]|\\\{|\\(?:lfloor|lceil|langle|lVert)(?![a-zA-z]))/)
+      )
       .then(function (ctrlSeq) {
         var open = ctrlSeq.replace(/^\\/, '');
         if (ctrlSeq == '\\langle') {
@@ -1630,9 +1634,7 @@ LatexCmds.left = class extends MathCommand {
         return latexMathParser.then(function (block) {
           return string('\\right')
             .skip(optWhitespace)
-            .then(
-              regex(/^(?:[\])|]|\\\}|\\rangle(?![a-zA-Z])|\\rVert(?![a-zA-Z]))/)
-            )
+            .then(regex(/^(?:[\])|]|\\\}|\\[a-zA-z]+)/))
             .map(function (end) {
               var close = end.replace(/^\\/, '');
               if (end == '\\rangle') {
@@ -1869,3 +1871,40 @@ class EmbedNode extends MQSymbol {
   }
 }
 LatexCmds.embed = EmbedNode;
+class Limit extends MathCommand {
+  constructor(ctrlSeq?: string, domView?: DOMView, textTemplate?: string[]) {
+    super(ctrlSeq, domView, textTemplate);
+    this.ctrlSeq = '\\lim';
+    this.domView = new DOMView(1, function (blocks) {
+      return h('span', { class: 'mq-limit mq-non-leaf' }, [
+        h('span', { class: 'mq-limit-label' }, [h.text('lim')]),
+        h.block('span', { class: 'mq-limit-sub mq-non-leaf' }, blocks[0]),
+      ]);
+    });
+    this.textTemplate = ['lim(', ')'];
+    this.mathspeakTemplate = ['Limit', 'EndLimit'];
+  }
+
+  override latexRecursive(ctx: LatexContext) {
+    this.checkCursorContextOpen(ctx);
+    ctx.latex += '\\lim_{';
+    this.getEnd(L).latexRecursive(ctx);
+    ctx.latex += '}';
+    this.checkCursorContextClose(ctx);
+  }
+
+  override parser() {
+    return Parser.string('_')
+      .then(function () {
+        return latexMathParser;
+      })
+      .map(function (block) {
+        const limit = new Limit('\\lim', undefined!, undefined!);
+        limit.blocks = [block];
+        block.adopt(limit, 0, 0);
+        return limit;
+      })
+      .or(super.parser());
+  }
+}
+LatexCmds.limit = LatexCmds.lim = Limit;