LibraryDependencyResolver.php

<?php

namespace Drupal\Core\Asset;


/**
 * Resolves the dependencies of asset (CSS/JavaScript) libraries.
 */
class LibraryDependencyResolver implements LibraryDependencyResolverInterface {
    
    /**
     * The library discovery service.
     *
     * @var \Drupal\Core\Asset\LibraryDiscoveryInterface
     */
    protected $libraryDiscovery;
    
    /**
     * Constructs a new LibraryDependencyResolver instance.
     *
     * @param \Drupal\Core\Asset\LibraryDiscoveryInterface $library_discovery
     *   The library discovery service.
     */
    public function __construct(LibraryDiscoveryInterface $library_discovery) {
        $this->libraryDiscovery = $library_discovery;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getLibrariesWithDependencies(array $libraries) {
        return $this->doGetDependencies($libraries);
    }
    
    /**
     * Gets the given libraries with its dependencies.
     *
     * Helper method for ::getLibrariesWithDependencies().
     *
     * @param string[] $libraries_with_unresolved_dependencies
     *   A list of libraries, with unresolved dependencies, in the order they
     *   should be loaded.
     * @param string[] $final_libraries
     *   The final list of libraries (the return value) that is being built
     *   recursively.
     *
     * @return string[]
     *   A list of libraries, in the order they should be loaded, including their
     *   dependencies.
     */
    protected function doGetDependencies(array $libraries_with_unresolved_dependencies, array $final_libraries = []) {
        foreach ($libraries_with_unresolved_dependencies as $library) {
            if (!in_array($library, $final_libraries)) {
                list($extension, $name) = explode('/', $library, 2);
                $definition = $this->libraryDiscovery
                    ->getLibraryByName($extension, $name);
                if (!empty($definition['dependencies'])) {
                    $final_libraries = $this->doGetDependencies($definition['dependencies'], $final_libraries);
                }
                $final_libraries[] = $library;
            }
        }
        return $final_libraries;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getMinimalRepresentativeSubset(array $libraries) {
        assert(count($libraries) === count(array_unique($libraries)), '$libraries can\'t contain duplicate items.');
        $minimal = [];
        // Determine each library's dependencies.
        $with_deps = [];
        foreach ($libraries as $library) {
            $with_deps[$library] = $this->getLibrariesWithDependencies([
                $library,
            ]);
        }
        foreach ($libraries as $library) {
            $exists = FALSE;
            foreach ($with_deps as $other_library => $dependencies) {
                if ($library == $other_library) {
                    continue;
                }
                if (in_array($library, $dependencies)) {
                    $exists = TRUE;
                    break;
                }
            }
            if (!$exists) {
                $minimal[] = $library;
            }
        }
        return $minimal;
    }

}