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<?php |
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/** |
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* Metasync_CSS_Minifier |
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* Regex-based CSS minification engine. |
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* Hooks into style_loader_tag to rewrite enqueued stylesheets to cached minified versions. |
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* |
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* @package Search Atlas SEO |
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* @copyright Copyright (C) 2021-2025, Search Atlas Group - support@searchatlas.com |
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* @since 2.5.23 |
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*/ |
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|
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if (!defined('ABSPATH')) { |
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exit; |
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} |
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|
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class Metasync_CSS_Minifier { |
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|
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/** @var array */ |
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private $settings; |
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|
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/** @var array Handles to exclude from minification. */ |
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private $excluded_handles = []; |
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|
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public function __construct(array $settings) { |
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$this->settings = $settings; |
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$this->excluded_handles = array_filter( |
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array_map('trim', explode(',', $settings['css_exclude_handles'] ?? '')) |
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); |
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|
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add_filter('style_loader_tag', [$this, 'maybe_minify_style'], 999, 4); |
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} |
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|
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/** |
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* Filter: attempt to minify the stylesheet and rewrite the tag to use the cached version. |
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* |
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* @param string $tag The full <link> tag HTML. |
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* @param string $handle The style's registered handle. |
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* @param string $href The stylesheet's source URL. |
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* @param string $media The stylesheet's media attribute. |
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* @return string Modified or original tag. |
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*/ |
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public function maybe_minify_style(string $tag, string $handle, string $href, string $media): string { |
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// Skip admin, login, excluded handles |
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if (is_admin() || $this->is_excluded($handle) || $this->is_login_page()) { |
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return $tag; |
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} |
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|
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// Only process local files |
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$local_path = $this->url_to_local_path($href); |
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if (!$local_path || !file_exists($local_path)) { |
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return $tag; |
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} |
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|
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// Skip already-minified files |
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if (preg_match('/\.min\.css$/i', $local_path)) { |
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return $tag; |
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} |
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|
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// Check cache |
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$cached = Metasync_Minification_Cache::get_cached_file($handle, 'css', $local_path); |
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if ($cached) { |
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return str_replace($href, $cached['url'], $tag); |
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} |
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|
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// Read and minify |
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// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents |
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$content = file_get_contents($local_path); |
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if ($content === false || strlen($content) === 0) { |
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return $tag; |
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} |
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|
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$minified = self::minify($content); |
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|
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// Store in cache |
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$cached = Metasync_Minification_Cache::store_cached_file($handle, 'css', $local_path, $minified); |
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if ($cached) { |
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return str_replace($href, $cached['url'], $tag); |
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} |
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|
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return $tag; |
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} |
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|
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/** |
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* Minify a CSS string using regex-based transformations. |
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* |
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* @param string $css Raw CSS content. |
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* @return string Minified CSS. |
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*/ |
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public static function minify(string $css): string { |
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// 1. Remove CSS comments |
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$css = preg_replace('/\/\*[\s\S]*?\*\//', '', $css); |
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|
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// 2. Collapse whitespace |
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$css = preg_replace('/\s+/', ' ', $css); |
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|
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// 3. Remove spaces around { } : ; , |
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$css = preg_replace('/\s*\{\s*/', '{', $css); |
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$css = preg_replace('/\s*\}\s*/', '}', $css); |
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$css = preg_replace('/\s*:\s*/', ':', $css); |
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$css = preg_replace('/\s*;\s*/', ';', $css); |
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$css = preg_replace('/\s*,\s*/', ',', $css); |
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|
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// 4. Remove trailing semicolons before } |
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$css = str_replace(';}', '}', $css); |
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|
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// 5. Remove units after zero (0px -> 0), but not 0% (used in keyframes/gradients) |
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$css = preg_replace('/(?<=[\s:,])0(?:px|em|rem|ex|ch|vw|vh|vmin|vmax|cm|mm|in|pt|pc)\b/', '0', $css); |
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|
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return trim($css); |
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} |
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|
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/** |
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* Check if a handle is excluded. |
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*/ |
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private function is_excluded(string $handle): bool { |
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return in_array($handle, $this->excluded_handles, true); |
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} |
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|
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/** |
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* Convert a URL to a local filesystem path. |
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* |
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* @param string $url The stylesheet URL. |
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* @return string|false Local path or false if not local. |
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*/ |
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private function url_to_local_path(string $url) { |
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// Remove query string |
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$url = strtok($url, '?'); |
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|
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// Handle protocol-relative URLs |
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if (strpos($url, '//') === 0) { |
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$url = 'https:' . $url; |
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} |
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|
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$site_url = site_url(); |
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$content_url = content_url(); |
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$abspath = ABSPATH; |
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|
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// Check if the URL is local |
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if (strpos($url, $site_url) === 0) { |
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$relative = str_replace($site_url, '', $url); |
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return $abspath . ltrim($relative, '/'); |
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} |
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|
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if (strpos($url, $content_url) === 0) { |
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$relative = str_replace($content_url, '', $url); |
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return WP_CONTENT_DIR . '/' . ltrim($relative, '/'); |
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} |
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|
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// Check for relative URLs |
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if (strpos($url, '/wp-content/') === 0 || strpos($url, '/wp-includes/') === 0) { |
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return $abspath . ltrim($url, '/'); |
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} |
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|
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return false; |
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} |
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|
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/** |
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* Check if current request is the login page. |
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*/ |
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private function is_login_page(): bool { |
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return in_array($GLOBALS['pagenow'] ?? '', ['wp-login.php', 'wp-register.php'], true); |
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} |
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} |
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|
