@marc-r2/micromark-extension-ofm-highlight/dist/lib/syntax.js

micromark extension to support OFM highlights

// ASCII Codes
const TAB = 9;
const SPACE = 32;
const EQUALS = 61;
/**
 * Create an extension for `micromark` to enable OFM highlight syntax.
 * Highlights use ==text== syntax where the number of equal signs must match.
 */
export function ofmHighlight() {
    return {
        text: {
            [EQUALS]: {
                name: "ofmHighlight",
                tokenize: tokenize,
            },
        },
    };
}
/**
 * A tokenizer for Obsidian highlight syntax.
 * Highlights use ==text== syntax where the number of equal signs matters.
 */
function tokenize(effects, ok, nok) {
    let openingMarkerSize = 0;
    let closingMarkerSize = 0;
    return start;
    function start(code) {
        if (code !== EQUALS) {
            return nok(code);
        }
        effects.enter("ofmHighlight");
        effects.enter("ofmHighlightMarker");
        effects.consume(code);
        openingMarkerSize = 1;
        return openingMarker;
    }
    function openingMarker(code) {
        if (code === EQUALS) {
            effects.consume(code);
            openingMarkerSize++;
            return openingMarker;
        }
        if (openingMarkerSize < 2) {
            return nok(code);
        }
        effects.exit("ofmHighlightMarker");
        effects.enter("ofmHighlightContent");
        if (code === SPACE || code === null) {
            return nok(code);
        }
        effects.consume(code);
        return content;
    }
    function content(code) {
        if (code === null) {
            effects.exit("ofmHighlightContent");
            effects.exit("ofmHighlight");
            return ok(code);
        }
        if (code === TAB) {
            return nok(code);
        }
        if (code === EQUALS) {
            // Start potential closing marker detection
            effects.exit("ofmHighlightContent");
            effects.enter("ofmHighlightMarker");
            effects.consume(code);
            closingMarkerSize = 1;
            return closingMarker;
        }
        effects.consume(code);
        return content;
    }
    function closingMarker(code) {
        if (code === EQUALS) {
            effects.consume(code);
            closingMarkerSize++;
            return closingMarker;
        }
        if (closingMarkerSize >= 2) {
            effects.exit("ofmHighlightMarker");
            effects.exit("ofmHighlight");
            return ok(code);
        }
        // Single equals - not a valid closing marker
        // Exit the marker and continue as content, but consume the single = as content
        effects.exit("ofmHighlightMarker");
        effects.enter("ofmHighlightContent");
        // The single = was already consumed in the marker, it will be processed by mdast utility
        return content(code);
    }
}