@marc-r2/mdast-util-ofm-highlight/dist/lib/fromMarkdown.js

mdast extension to support OFM highlights

/**
 * Create an extension for `mdast-util-from-markdown` to enable OFM highlights in markdown.
 */
export function ofmHighlightFromMarkdown() {
    return {
        enter: {
            ofmHighlight: function (token) {
                this.enter({ type: "ofmHighlight", value: "", pre: 0, post: 0 }, token);
            },
            ofmHighlightMarker: function (token) {
                const node = this.stack.at(-1);
                if (node?.type === "ofmHighlight") {
                    const markerText = this.sliceSerialize(token);
                    const markerSize = markerText.length;
                    // If pre is 0, this is the opening marker
                    if (node.pre === 0) {
                        node.pre = markerSize;
                    }
                    else if (markerSize >= 2) {
                        // This is a valid closing marker
                        node.post = markerSize;
                    }
                    else {
                        // This is a failed closing marker (single =)
                        // Treat it as content instead
                        node.value += markerText;
                    }
                }
            },
            ofmHighlightContent: function (token) {
                const node = this.stack.at(-1);
                if (node?.type === "ofmHighlight") {
                    const contentText = this.sliceSerialize(token);
                    // Always append content, handling multiple content tokens
                    node.value += contentText;
                }
            },
        },
        exit: {
            ofmHighlight: function (token) {
                this.exit(token);
            },
        },
    };
}