Class MathNode

src/mathMLTree.ts:47–146

 * `"mspace"`, corresponding to `<mo>` and `<mspace>` tags).
 */
export class MathNode implements MathDomNode {
    type: MathNodeType;
    attributes: Record<string, string>;
    children: MathDomNode[];
    classes: string[];

    constructor(
        type: MathNodeType,
        children?: MathDomNode[],
        classes?: string[]
    ) {
        this.type = type;
        this.attributes = {};
        this.children = children || [];
        this.classes = classes || [];
    }

    /**
     * Sets an attribute on a MathML node. MathML depends on attributes to convey a
     * semantic content, so this is used heavily.
     */
    setAttribute(name: string, value: string) {
        this.attributes[name] = value;
    }

    /**
     * Gets an attribute on a MathML node.
     */
    getAttribute(name: string): string {
        return this.attributes[name];
    }

    /**
     * Converts the math node into a MathML-namespaced DOM element.
     */
    toNode(): Node {
        const node = document.createElementNS(
            "http://www.w3.org/1998/Math/MathML", this.type);

        for (const [attr, value] of Object.entries(this.attributes)) {
            node.setAttribute(attr, value);
        }

        if (this.classes.length > 0) {
            node.className = createClass(this.classes);
        }

        for (let i = 0; i < this.children.length; i++) {
            // Combine multiple TextNodes into one TextNode, to prevent
            // screen readers from reading each as a separate word [#3995]
            if (this.children[i] instanceof TextNode &&
                this.children[i + 1] instanceof TextNode) {
                let text = this.children[i].toText() + this.children[++i].toText();
                while (this.children[i + 1] instanceof TextNode) {
                    text += this.children[++i].toText();
                }
                node.appendChild(new TextNode(text).toNode());
            } else {