JsOptimizer.php

<?php

namespace Drupal\Core\Asset;

use Drupal\Component\Utility\Unicode;
use Drupal\Core\Utility\Error;
use Peast\Formatter\Compact as CompactFormatter;
use Peast\Peast;
use Peast\Renderer;
use Peast\Syntax\Exception as PeastSyntaxException;
use Psr\Log\LoggerInterface;

/**
 * Optimizes a JavaScript asset.
 */
class JsOptimizer implements AssetOptimizerInterface {
    
    /**
     * Constructs a new JsOptimizer object.
     *
     * @param \Psr\Log\LoggerInterface $logger
     *   The logger.
     */
    public function __construct(LoggerInterface $logger) {
    }
    
    /**
     * {@inheritdoc}
     */
    public function optimize(array $js_asset) {
        if ($js_asset['type'] !== 'file') {
            throw new \Exception('Only file JavaScript assets can be optimized.');
        }
        if (!$js_asset['preprocess']) {
            throw new \Exception('Only file JavaScript assets with preprocessing enabled can be optimized.');
        }
        // If a BOM is found, convert the file to UTF-8, then use substr() to
        // remove the BOM from the result.
        $data = file_get_contents($js_asset['data']);
        if ($encoding = Unicode::encodingFromBOM($data)) {
            $data = mb_substr(Unicode::convertToUtf8($data, $encoding), 1);
        }
        elseif (isset($js_asset['attributes']['charset'])) {
            $data = Unicode::convertToUtf8($data, $js_asset['attributes']['charset']);
        }
        // Remove comments, whitespace, and optional braces.
        try {
            $ast = Peast::latest($data)->parse();
            $renderer = new Renderer();
            $renderer->setFormatter(new CompactFormatter());
            return $renderer->render($ast);
        } catch (\Exception $exception) {
            if ($exception instanceof PeastSyntaxException) {
                $position = $exception->getPosition();
                Error::logException($this->logger, $exception, 'Syntax error:  @message, File: @asset_file, Line: @asset_line, Column: @asset_column, Index: @asset_index', [
                    '@asset_file' => $js_asset['data'],
                    '@asset_line' => $position->getLine(),
                    '@asset_column' => $position->getColumn(),
                    '@asset_index' => $position->getIndex(),
                ]);
            }
            else {
                Error::logException($this->logger, $exception);
            }
            return $data;
        }
    }
    
    /**
     * Processes the contents of a javascript asset for cleanup.
     *
     * @param string $contents
     *   The contents of the javascript asset.
     *
     * @return string
     *   Contents of the javascript asset.
     */
    public function clean($contents) {
        // Remove JS source and source mapping URLs or these may cause 404 errors.
        $contents = preg_replace('/\\/\\/(#|@)\\s(sourceURL|sourceMappingURL)=\\s*(\\S*?)\\s*$/m', '', $contents);
        return $contents;
    }

}