original_string: protected function maybeFilterCssUrls($css)
      {
          if (!($css = (string) $css)) {
              return $css; // Nothing to do.
          }
          if (!$this->hook_api->hasFilter('css_url()')) {
              return $css; // No reason to do this.
          }
          $import_without_url_regex = '/(?P<import>@(?:\-(?:'.$this->regex_vendor_css_prefixes.')\-)?import\s*)(?P<open_encap>["\'])(?P<url>.+?)(?P<close_encap>\\2)/ui';
          $any_url_regex            = '/(?P<url_>url\s*)(?P<open_bracket>\(\s*)(?P<open_encap>["\']?)(?P<url>.+?)(?P<close_encap>\\3)(?P<close_bracket>\s*\))/ui';
  
          $css = preg_replace_callback($import_without_url_regex, [$this, 'filterCssUrlImportCb'], $css);
          $css = preg_replace_callback($any_url_regex, [$this, 'filterCssUrlCb'], $css);
  
          return $css;
      }
code: protected function maybeFilterCssUrls($css)
      {
          if (!($css = (string) $css)) {
              return $css; // Nothing to do.
          }
          if (!$this->hook_api->hasFilter('css_url()')) {
              return $css; // No reason to do this.
          }
          $import_without_url_regex = '/(?P<import>@(?:\-(?:'.$this->regex_vendor_css_prefixes.')\-)?import\s*)(?P<open_encap>["\'])(?P<url>.+?)(?P<close_encap>\\2)/ui';
          $any_url_regex            = '/(?P<url_>url\s*)(?P<open_bracket>\(\s*)(?P<open_encap>["\']?)(?P<url>.+?)(?P<close_encap>\\3)(?P<close_bracket>\s*\))/ui';
  
          $css = preg_replace_callback($import_without_url_regex, [$this, 'filterCssUrlImportCb'], $css);
          $css = preg_replace_callback($any_url_regex, [$this, 'filterCssUrlCb'], $css);
  
          return $css;
      }
code_tokens: protected function maybeFilterCssUrls ( $ css ) { if ( ! ( $ css = ( string ) $ css ) ) { return $ css ; // Nothing to do. } if ( ! $ this -> hook_api -> hasFilter ( 'css_url()' ) ) { return $ css ; // No reason to do this. } $ import_without_url_regex = '/(?P<import>@(?:\-(?:' . $ this -> regex_vendor_css_prefixes . ')\-)?import\s*)(?P<open_encap>["\'])(?P<url>.+?)(?P<close_encap>\\2)/ui' ; $ any_url_regex = '/(?P<url_>url\s*)(?P<open_bracket>\(\s*)(?P<open_encap>["\']?)(?P<url>.+?)(?P<close_encap>\\3)(?P<close_bracket>\s*\))/ui' ; $ css = preg_replace_callback ( $ import_without_url_regex , [ $ this , 'filterCssUrlImportCb' ] , $ css ) ; $ css = preg_replace_callback ( $ any_url_regex , [ $ this , 'filterCssUrlCb' ] , $ css ) ; return $ css ; }
docstring: Maybe filter URLs in CSS code.
  
  @since 150821 Adding URL filter support.
  
  @param string $css CSS code.
  
  @return string CSS code after having filtered all URLs.
docstring_tokens: Maybe filter URLs in CSS code .