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https://github.com/Smaug123/KaTeX
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Migrate genfrac, lap, smash, op, mod, and katex into their own files in src/functions (#871)
Fixes #869
This commit is contained in:
Kevin Barabash
GitHub
253
src/functions/genfrac.js
Normal file
253
src/functions/genfrac.js
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@@ -0,0 +1,253 @@
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// @flow
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import defineFunction from "../defineFunction";
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import buildCommon from "../buildCommon";
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import delimiter from "../delimiter";
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import mathMLTree from "../mathMLTree";
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import Style from "../Style";
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import * as html from "../buildHTML";
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import * as mml from "../buildMathML";
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defineFunction({
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type: "genfrac",
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names: [
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"\\dfrac", "\\frac", "\\tfrac",
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"\\dbinom", "\\binom", "\\tbinom",
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"\\\\atopfrac", // can’t be entered directly
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],
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props: {
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numArgs: 2,
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greediness: 2,
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},
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handler: (context, args) => {
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const numer = args[0];
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const denom = args[1];
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let hasBarLine;
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let leftDelim = null;
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let rightDelim = null;
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let size = "auto";
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switch (context.funcName) {
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case "\\dfrac":
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case "\\frac":
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case "\\tfrac":
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hasBarLine = true;
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break;
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case "\\\\atopfrac":
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hasBarLine = false;
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break;
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case "\\dbinom":
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case "\\binom":
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case "\\tbinom":
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hasBarLine = false;
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leftDelim = "(";
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rightDelim = ")";
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break;
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default:
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throw new Error("Unrecognized genfrac command");
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}
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switch (context.funcName) {
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case "\\dfrac":
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case "\\dbinom":
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size = "display";
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break;
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case "\\tfrac":
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case "\\tbinom":
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size = "text";
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break;
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}
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return {
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type: "genfrac",
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numer: numer,
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denom: denom,
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hasBarLine: hasBarLine,
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leftDelim: leftDelim,
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rightDelim: rightDelim,
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size: size,
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};
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},
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htmlBuilder: (group, options) => {
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// Fractions are handled in the TeXbook on pages 444-445, rules 15(a-e).
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// Figure out what style this fraction should be in based on the
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// function used
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let style = options.style;
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if (group.value.size === "display") {
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style = Style.DISPLAY;
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} else if (group.value.size === "text") {
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style = Style.TEXT;
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}
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const nstyle = style.fracNum();
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const dstyle = style.fracDen();
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let newOptions;
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newOptions = options.havingStyle(nstyle);
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const numerm = html.buildGroup(group.value.numer, newOptions, options);
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newOptions = options.havingStyle(dstyle);
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const denomm = html.buildGroup(group.value.denom, newOptions, options);
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let rule;
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let ruleWidth;
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let ruleSpacing;
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if (group.value.hasBarLine) {
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rule = html.makeLineSpan("frac-line", options);
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ruleWidth = rule.height;
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ruleSpacing = rule.height;
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} else {
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rule = null;
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ruleWidth = 0;
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ruleSpacing = options.fontMetrics().defaultRuleThickness;
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}
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// Rule 15b
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let numShift;
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let clearance;
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let denomShift;
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if (style.size === Style.DISPLAY.size) {
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numShift = options.fontMetrics().num1;
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if (ruleWidth > 0) {
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clearance = 3 * ruleSpacing;
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} else {
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clearance = 7 * ruleSpacing;
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}
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denomShift = options.fontMetrics().denom1;
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} else {
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if (ruleWidth > 0) {
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numShift = options.fontMetrics().num2;
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clearance = ruleSpacing;
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} else {
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numShift = options.fontMetrics().num3;
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clearance = 3 * ruleSpacing;
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}
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denomShift = options.fontMetrics().denom2;
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}
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let frac;
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if (ruleWidth === 0) {
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// Rule 15c
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const candidateClearance =
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(numShift - numerm.depth) - (denomm.height - denomShift);
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if (candidateClearance < clearance) {
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numShift += 0.5 * (clearance - candidateClearance);
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denomShift += 0.5 * (clearance - candidateClearance);
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}
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frac = buildCommon.makeVList({
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positionType: "individualShift",
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children: [
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{type: "elem", elem: denomm, shift: denomShift},
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{type: "elem", elem: numerm, shift: -numShift},
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],
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}, options);
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} else {
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// Rule 15d
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const axisHeight = options.fontMetrics().axisHeight;
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if ((numShift - numerm.depth) - (axisHeight + 0.5 * ruleWidth) <
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clearance) {
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numShift +=
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clearance - ((numShift - numerm.depth) -
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(axisHeight + 0.5 * ruleWidth));
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}
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if ((axisHeight - 0.5 * ruleWidth) - (denomm.height - denomShift) <
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clearance) {
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denomShift +=
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clearance - ((axisHeight - 0.5 * ruleWidth) -
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(denomm.height - denomShift));
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}
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const midShift = -(axisHeight - 0.5 * ruleWidth);
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frac = buildCommon.makeVList({
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positionType: "individualShift",
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children: [
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{type: "elem", elem: denomm, shift: denomShift},
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{type: "elem", elem: rule, shift: midShift},
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{type: "elem", elem: numerm, shift: -numShift},
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],
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}, options);
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}
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// Since we manually change the style sometimes (with \dfrac or \tfrac),
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// account for the possible size change here.
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newOptions = options.havingStyle(style);
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frac.height *= newOptions.sizeMultiplier / options.sizeMultiplier;
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frac.depth *= newOptions.sizeMultiplier / options.sizeMultiplier;
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// Rule 15e
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let delimSize;
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if (style.size === Style.DISPLAY.size) {
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delimSize = options.fontMetrics().delim1;
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} else {
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delimSize = options.fontMetrics().delim2;
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}
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let leftDelim;
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let rightDelim;
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if (group.value.leftDelim == null) {
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leftDelim = html.makeNullDelimiter(options, ["mopen"]);
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} else {
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leftDelim = delimiter.customSizedDelim(
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group.value.leftDelim, delimSize, true,
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options.havingStyle(style), group.mode, ["mopen"]);
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}
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if (group.value.rightDelim == null) {
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rightDelim = html.makeNullDelimiter(options, ["mclose"]);
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} else {
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rightDelim = delimiter.customSizedDelim(
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group.value.rightDelim, delimSize, true,
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options.havingStyle(style), group.mode, ["mclose"]);
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}
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return buildCommon.makeSpan(
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["mord"].concat(newOptions.sizingClasses(options)),
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[leftDelim, buildCommon.makeSpan(["mfrac"], [frac]), rightDelim],
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options);
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},
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mathmlBuilder: (group, options) => {
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const node = new mathMLTree.MathNode(
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"mfrac",
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[
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mml.buildGroup(group.value.numer, options),
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mml.buildGroup(group.value.denom, options),
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]);
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if (!group.value.hasBarLine) {
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node.setAttribute("linethickness", "0px");
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}
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if (group.value.leftDelim != null || group.value.rightDelim != null) {
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const withDelims = [];
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if (group.value.leftDelim != null) {
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const leftOp = new mathMLTree.MathNode(
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"mo", [new mathMLTree.TextNode(group.value.leftDelim)]);
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leftOp.setAttribute("fence", "true");
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withDelims.push(leftOp);
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}
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withDelims.push(node);
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if (group.value.rightDelim != null) {
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const rightOp = new mathMLTree.MathNode(
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"mo", [new mathMLTree.TextNode(group.value.rightDelim)]);
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rightOp.setAttribute("fence", "true");
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withDelims.push(rightOp);
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}
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const outerNode = new mathMLTree.MathNode("mrow", withDelims);
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return outerNode;
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}
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return node;
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},
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});
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