@adguard/aglint/dist/linter/rules/single-selector.js

Universal adblock filter list linter.

/*
 * AGLint v3.0.0 (build date: Wed, 21 May 2025 13:24:14 GMT)
 * (c) 2025 AdGuard Software Ltd.
 * Released under the MIT license
 * https://github.com/AdguardTeam/AGLint#readme
 */
import cloneDeep from 'clone-deep';
import { RuleCategory, CosmeticRuleType } from '@adguard/agtree';
import { SEVERITY } from '../severity.js';
import { isNull } from '../../utils/type-guards.js';
import { CssTreeParsingContext } from '../helpers/css-tree-types.js';
import { generateSelector } from '../helpers/css-generate.js';

/**
 * Rule that checks if a cosmetic rule contains multiple selectors
 */
const SingleSelector = {
    meta: {
        severity: SEVERITY.warn,
    },
    events: {
        onRule: (context) => {
            // Get actually iterated adblock rule
            const ast = context.getActualAdblockRuleAst();
            // Check if the rule is an element hiding rule
            if (ast.category === RuleCategory.Cosmetic && ast.type === CosmeticRuleType.ElementHidingRule) {
                const rawSelectorList = ast.body.selectorList;
                const selectorListNode = context.getCssNode(rawSelectorList, CssTreeParsingContext.SelectorList);
                if (isNull(selectorListNode)) {
                    return;
                }
                // Only makes sense to check this, if there are at least two selectors within the rule
                if (selectorListNode.children.size < 2) {
                    return;
                }
                // Prepare the problem report
                const report = {
                    message: 'An element hiding rule should contain only one selector',
                    node: ast.body.selectorList,
                };
                // Suggest a fix for the problem if the user wants to fix the problem automatically
                if (context.fixingEnabled()) {
                    // Collect selectors into different rules (one selector per rule)
                    report.fix = [];
                    // Iterate over all selectors in the current rule
                    for (const selector of selectorListNode.children) {
                        // Create a new rule with the same properties as the current rule.
                        const clone = cloneDeep(ast);
                        // Replace the selector list with a new selector list containing only
                        // the currently iterated selector
                        clone.body.selectorList.value = generateSelector(selector);
                        // The only difference is that the new rule only contains one selector,
                        // which has the currently iterated selector in its body.
                        report.fix.push(clone);
                    }
                }
                // Report the problem to the linting context
                context.report(report);
            }
        },
    },
};

export { SingleSelector };