"use strict";
// @flow
/* These are helpers that deal with the insertRule (aka speedy) API
 * They are used in the StyleTags and specifically the speedy tag
 */
Object.defineProperty(exports, "__esModule", { value: true });
/* retrieve a sheet for a given style tag */
exports.sheetForTag = (tag) => {
    // $FlowFixMe
    if (tag.sheet)
        return tag.sheet;
    /* Firefox quirk requires us to step through all stylesheets to find one owned by the given tag */
    const size = document.styleSheets.length;
    for (let i = 0; i < size; i += 1) {
        const sheet = document.styleSheets[i];
        // $FlowFixMe
        if (sheet.ownerNode === tag)
            return sheet;
    }
    /* we should always be able to find a tag */
    throw new Error();
};
/* insert a rule safely and return whether it was actually injected */
exports.safeInsertRule = (sheet, cssRule, index) => {
    /* abort early if cssRule string is falsy */
    if (!cssRule)
        return false;
    const maxIndex = sheet.cssRules.length;
    try {
        /* use insertRule and cap passed index with maxIndex (no of cssRules) */
        sheet.insertRule(cssRule, index <= maxIndex ? index : maxIndex);
    }
    catch (err) {
        /* any error indicates an invalid rule */
        return false;
    }
    return true;
};
/* deletes `size` rules starting from `removalIndex` */
exports.deleteRules = (sheet, removalIndex, size) => {
    const lowerBound = removalIndex - size;
    for (let i = removalIndex; i > lowerBound; i -= 1) {
        sheet.deleteRule(i);
    }
};
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