svelte/src/compiler/phases/2-analyze/css/css-warn.js

Cybernetically enhanced web apps

/** @import { Visitors } from 'zimmerframe' */
/** @import { AST } from '#compiler' */
import { walk } from 'zimmerframe';
import * as w from '../../../warnings.js';
import { is_keyframes_node } from '../../css.js';

/**
 * @param {AST.CSS.StyleSheet} stylesheet
 */
export function warn_unused(stylesheet) {
	walk(stylesheet, { stylesheet }, visitors);
}

/** @type {Visitors<AST.CSS.Node, { stylesheet: AST.CSS.StyleSheet }>} */
const visitors = {
	Atrule(node, context) {
		if (!is_keyframes_node(node)) {
			context.next();
		}
	},
	PseudoClassSelector(node, context) {
		if (node.name === 'is' || node.name === 'where') {
			context.next();
		}
	},
	ComplexSelector(node, context) {
		if (
			!node.metadata.used &&
			// prevent double-marking of `.unused:is(.unused)`
			(context.path.at(-2)?.type !== 'PseudoClassSelector' ||
				/** @type {AST.CSS.ComplexSelector} */ (context.path.at(-4))?.metadata.used)
		) {
			const content = context.state.stylesheet.content;
			const text = content.styles.substring(node.start - content.start, node.end - content.start);
			w.css_unused_selector(node, text);
		}

		context.next();
	},
	Rule(node, context) {
		if (node.metadata.is_global_block) {
			context.visit(node.prelude);
		} else {
			context.next();
		}
	}
};