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;
    
    /**
     * The libraries dependencies.
     *
     * @var array
     */
    protected $librariesDependencies = [];
    
    /**
     * 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) {
        $return = [];
        foreach ($libraries as $library) {
            if (!isset($this->librariesDependencies[$library])) {
                $this->librariesDependencies[$library] = $this->doGetDependencies([
                    $library,
                ]);
            }
            $return += $this->librariesDependencies[$library];
        }
        return array_values($return);
    }
    
    /**
     * 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 $library) {
            if (!isset($final_libraries[$library])) {
                [
                    $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] = $library;
            }
        }
        return $final_libraries;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getMinimalRepresentativeSubset(array $libraries) {
        assert(count($libraries) === count(array_unique($libraries)), '$libraries can\'t contain duplicate items.');
        // Determine each library's dependencies.
        $all_dependencies = [];
        foreach ($libraries as $library) {
            $with_deps = $this->getLibrariesWithDependencies([
                $library,
            ]);
            // We don't need library itself listed in the dependencies.
            $all_dependencies = array_unique(array_merge($all_dependencies, array_diff($with_deps, [
                $library,
            ])));
        }
        return array_values(array_diff($libraries, array_intersect($all_dependencies, $libraries)));
    }

}