Function buildMathML

src/buildMathML.ts:283–332

(
    tree: AnyParseNode[],
    texExpression: string,
    options: Options,
    isDisplayMode: boolean,
    forMathmlOnly: boolean,
)

 * we can do appropriate styling.
 */
export default function buildMathML(
    tree: AnyParseNode[],
    texExpression: string,
    options: Options,
    isDisplayMode: boolean,
    forMathmlOnly: boolean,
): DomSpan {
    const expression = buildExpression(tree, options);

    // TODO: Make a pass thru the MathML similar to buildHTML.traverseNonSpaceNodes
    // and add spacing nodes. This is necessary only adjacent to math operators
    // like \sin or \lim or to subsup elements that contain math operators.
    // MathML takes care of the other spacing issues.

    // Wrap up the expression in an mrow so it is presented in the semantics
    // tag correctly, unless it's a single <mrow> or <mtable>.
    let wrapper;
    if (expression.length === 1 && expression[0] instanceof MathNode &&
        rowLikeTypes.has(expression[0].type)) {
        wrapper = expression[0];
    } else {
        wrapper = new MathNode("mrow", expression);
    }

    // Build a TeX annotation of the source
    const annotation = new MathNode(
        "annotation", [new TextNode(texExpression)]);

    annotation.setAttribute("encoding", "application/x-tex");

    const semantics = new MathNode(
        "semantics", [wrapper, annotation]);

    const math = new MathNode("math", [semantics]);
    math.setAttribute("xmlns", "http://www.w3.org/1998/Math/MathML");
    if (isDisplayMode) {
        math.setAttribute("display", "block");
    }

    // You can't style <math> nodes, so we wrap the node in a span.
    // NOTE: The span class is not typed to have <math> nodes as children, and
    // we don't want to make the children type more generic since the children
    // of span are expected to have more fields in `buildHtml` contexts.
    // The MathNode implements VirtualNode (toNode/toMarkup) which is all that
    // Span needs from its children for rendering.
    // TODO(ts): Span's child type is HtmlDomNode, but MathNode only implements
    // VirtualNode. The double-cast acknowledges this architectural limitation.
    const wrapperClass = forMathmlOnly ? "katex" : "katex-mathml";
    return makeSpan([wrapperClass], [math as unknown as HtmlDomNode]);
}