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<?php
namespace Drupal\Core\Asset;
use Drupal\Component\Utility\Unicode;
/**
* Optimizes a CSS asset.
*/
class CssOptimizer implements AssetOptimizerInterface {
/**
* The base path used by rewriteFileURI().
*
* @var string
*/
public $rewriteFileURIBasePath;
/**
* {@inheritdoc}
*/
public function optimize(array $css_asset) {
if ($css_asset['type'] != 'file') {
throw new \Exception('Only file CSS assets can be optimized.');
if (!$css_asset['preprocess']) {
throw new \Exception('Only file CSS assets with preprocessing enabled can be optimized.');
}
return $this->processFile($css_asset);
}
/**
* Processes the contents of a CSS asset for cleanup.
*
* @param string $contents
* The contents of the CSS asset.
*
* @return string
* Contents of the CSS asset.
*/
public function clean($contents) {
// Remove multiple charset declarations for standards compliance (and fixing
// Safari problems).
$contents = preg_replace('/^@charset\s+[\'"](\S*?)\b[\'"];/i', '', $contents);
return $contents;
}
/**
* Build aggregate CSS file.
*/
protected function processFile($css_asset) {
$contents = $this->loadFile($css_asset['data'], TRUE);
$contents = $this->clean($contents);
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// Get the parent directory of this file, relative to the Drupal root.
$css_base_path = substr($css_asset['data'], 0, strrpos($css_asset['data'], '/'));
// Store base path.
$this->rewriteFileURIBasePath = $css_base_path . '/';
// Anchor all paths in the CSS with its base URL, ignoring external and absolute paths.
return preg_replace_callback('/url\(\s*[\'"]?(?![a-z]+:|\/+)([^\'")]+)[\'"]?\s*\)/i', array($this, 'rewriteFileURI'), $contents);
}
/**
* Loads the stylesheet and resolves all @import commands.
*
* Loads a stylesheet and replaces @import commands with the contents of the
* imported file. Use this instead of file_get_contents when processing
* stylesheets.
*
* The returned contents are compressed removing white space and comments only
* when CSS aggregation is enabled. This optimization will not apply for
* color.module enabled themes with CSS aggregation turned off.
*
* Note: the only reason this method is public is so color.module can call it;
* it is not on the AssetOptimizerInterface, so future refactorings can make
* it protected.
*
* @param $file
* Name of the stylesheet to be processed.
* @param $optimize
* Defines if CSS contents should be compressed or not.
* @param $reset_basepath
* Used internally to facilitate recursive resolution of @import commands.
*
* @return
* Contents of the stylesheet, including any resolved @import commands.
*/
public function loadFile($file, $optimize = NULL, $reset_basepath = TRUE) {
// These statics are not cache variables, so we don't use drupal_static().
static $_optimize, $basepath;
if ($reset_basepath) {
$basepath = '';
}
// Store the value of $optimize for preg_replace_callback with nested
// @import loops.
if (isset($optimize)) {
$_optimize = $optimize;
}
// Stylesheets are relative one to each other. Start by adding a base path
// prefix provided by the parent stylesheet (if necessary).
if ($basepath && !file_uri_scheme($file)) {
$file = $basepath . '/' . $file;
}
// Store the parent base path to restore it later.
$parent_base_path = $basepath;
// Set the current base path to process possible child imports.
$basepath = dirname($file);
// Load the CSS stylesheet. We suppress errors because themes may specify
// stylesheets in their .info.yml file that don't exist in the theme's path,
// but are merely there to disable certain module CSS files.
$content = '';
if ($contents = @file_get_contents($file)) {
// If a BOM is found, convert the file to UTF-8, then use substr() to
// remove the BOM from the result.
if ($encoding = (Unicode::encodingFromBOM($contents))) {
$contents = Unicode::substr(Unicode::convertToUtf8($contents, $encoding), 1);
}
// If no BOM, check for fallback encoding. Per CSS spec the regex is very strict.
elseif (preg_match('/^@charset "([^"]+)";/', $contents, $matches)) {
if ($matches[1] !== 'utf-8' && $matches[1] !== 'UTF-8') {
$contents = substr($contents, strlen($matches[0]));
$contents = Unicode::convertToUtf8($contents, $matches[1]);
}
}
// Return the processed stylesheet.
$content = $this->processCss($contents, $_optimize);
}
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// Restore the parent base path as the file and its children are processed.
$basepath = $parent_base_path;
return $content;
}
/**
* Loads stylesheets recursively and returns contents with corrected paths.
*
* This function is used for recursive loading of stylesheets and
* returns the stylesheet content with all url() paths corrected.
*
* @param array $matches
* An array of matches by a preg_replace_callback() call that scans for
* @import-ed CSS files, except for external CSS files.
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*
* @return
* The contents of the CSS file at $matches[1], with corrected paths.
*
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* @see \Drupal\Core\Asset\AssetOptimizerInterface::loadFile()
*/
protected function loadNestedFile($matches) {
$filename = $matches[1];
// Load the imported stylesheet and replace @import commands in there as
// well.
$file = $this->loadFile($filename, NULL, FALSE);
// Determine the file's directory.
$directory = dirname($filename);
// If the file is in the current directory, make sure '.' doesn't appear in
// the url() path.
$directory = $directory == '.' ? '' : $directory . '/';
// Alter all internal url() paths. Leave external paths alone. We don't need
// to normalize absolute paths here because that will be done later.
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return preg_replace('/url\(\s*([\'"]?)(?![a-z]+:|\/+)([^\'")]+)([\'"]?)\s*\)/i', 'url(\1' . $directory . '\2\3)', $file);
}
/**
* Processes the contents of a stylesheet for aggregation.
*
* @param $contents
* The contents of the stylesheet.
* @param $optimize
* (optional) Boolean whether CSS contents should be minified. Defaults to
* FALSE.
*
* @return
* Contents of the stylesheet including the imported stylesheets.
*/
protected function processCss($contents, $optimize = FALSE) {
// Remove unwanted CSS code that cause issues.
$contents = $this->clean($contents);
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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('<
# 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+
>xS',
// Only one of the three capturing groups will match, so its reference
// will contain the wanted value and the references for the
// two non-matching groups will be replaced with empty strings.
'$1$2$3',
$contents
);
// End the file with a new line.
$contents = trim($contents);
$contents .= "\n";
}
// Replaces @import commands with the actual stylesheet content.
// This happens recursively but omits external files.
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$contents = preg_replace_callback('/@import\s*(?:url\(\s*)?[\'"]?(?![a-z]+:)(?!\/\/)([^\'"\()]+)[\'"]?\s*\)?\s*;/', array($this, 'loadNestedFile'), $contents);
return $contents;
}
/**
* Prefixes all paths within a CSS file for processFile().
*
* Note: the only reason this method is public is so color.module can call it;
* it is not on the AssetOptimizerInterface, so future refactorings can make
* it protected.
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*
* @param array $matches
* An array of matches by a preg_replace_callback() call that scans for
* url() references in CSS files, except for external or absolute ones.
*
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* @return string
* The file path.
*/
public function rewriteFileURI($matches) {
// Prefix with base and remove '../' segments where possible.
$path = $this->rewriteFileURIBasePath . $matches[1];
$last = '';
while ($path != $last) {
$last = $path;
$path = preg_replace('`(^|/)(?!\.\./)([^/]+)/\.\./`', '$1', $path);
}
return 'url(' . file_url_transform_relative(file_create_url($path)) . ')';