protected function CssOptimizer::processCss

Processes the contents of a stylesheet for aggregation.

Parameters

$contents: The contents of the stylesheet.

$optimize: (optional) Boolean whether CSS contents should be minified. Defaults to FALSE.

Return value

string Contents of the stylesheet including the imported stylesheets.

File

core/lib/Drupal/Core/Asset/CssOptimizer.php, line 215

Class

CssOptimizer

Optimizes a CSS asset.

Namespace

Code

protected function processCss($contents, $optimize = FALSE) {

  // Remove unwanted CSS code that cause issues.
  $contents = $this
    ->clean($contents);
  if ($optimize) {

    // Perform some safe CSS optimizations.
    // Regexp to match comment blocks.
    $comment = '/\\*[^*]*\\*+(?:[^/*][^*]*\\*+)*/';

    // Regexp to match double quoted strings.
    $double_quot = '"[^"\\\\]*(?:\\\\.[^"\\\\]*)*"';

    // Regexp to match single quoted strings.
    $single_quot = "'[^'\\\\]*(?:\\\\.[^'\\\\]*)*'";

    // Strip all comment blocks, but keep double/single quoted strings.
    $contents = preg_replace("<({$double_quot}|{$single_quot})|{$comment}>Ss", "\$1", $contents);

    // Remove certain whitespace.
    // There are different conditions for removing leading and trailing
    // whitespace.
    // @see http://php.net/manual/regexp.reference.subpatterns.php
    $contents = preg_replace('<
        # Do not strip any space from within single or double quotes
          (' . $double_quot . '|' . $single_quot . ')
        # Strip leading and trailing whitespace.
        | \\s*([@{};,])\\s*
        # Strip only leading whitespace from:
        # - Closing parenthesis: Retain "@media (bar) and foo".
        | \\s+([\\)])
        # Strip only trailing whitespace from:
        # - Opening parenthesis: Retain "@media (bar) and foo".
        # - Colon: Retain :pseudo-selectors.
        | ([\\(:])\\s+
      >xSs', '$1$2$3$4', $contents);

    // End the file with a new line.
    $contents = trim($contents);
    $contents .= "\n";
  }

  // Replaces @import commands with the actual stylesheet content.
  // This happens recursively but omits external files and local files
  // with supports- or media-query qualifiers, as those are conditionally
  // loaded depending on the user agent.
  $contents = preg_replace_callback('/@import\\s*(?:url\\(\\s*)?[\'"]?(?![a-z]+:)(?!\\/\\/)([^\'"\\()]+)[\'"]?\\s*\\)?\\s*;/', [
    $this,
    'loadNestedFile',
  ], $contents);
  return $contents;
}