Add twig-debug command

composer.json

@@ -11,6 +11,7 @@
     },
     "require": {
         "php": ">=7.3",
+        "ext-json": "*",
         "drupal/core": "^9.0",
         "twig/twig": "^2.12"
     },

drush.services.yml

@@ -4,3 +4,8 @@ services:
     arguments: ['@twig']
     tags:
       - { name: console.command }
+  twig_tweak.debug:
+    class: Drupal\twig_tweak\Command\DebugCommand
+    arguments: ['@twig']
+    tags:
+      - { name: console.command }

src/Command/DebugCommand.php

@@ -0,0 +1,217 @@
+<?php
+
+namespace Drupal\twig_tweak\Command;
+
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Formatter\OutputFormatter;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+use Twig\Environment;
+use Twig\Loader\ChainLoader;
+use Twig\Loader\FilesystemLoader;
+
+/**
+ * Lists twig functions, filters, and tests present in the current project.
+ *
+ * This is a simplified version of Symfony's Debug command.
+ *
+ * @see https://github.com/symfony/symfony/blob/5.x/src/Symfony/Bridge/Twig/Command/DebugCommand.php
+ */
+final class DebugCommand extends Command {
+
+  /**
+   * Twig environment.
+   *
+   * @var \Twig\Environment
+   */
+  private $twig;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(Environment $twig) {
+    parent::__construct();
+    $this->twig = $twig;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function configure(): void {
+    $this
+      ->setName('twig-tweak:debug')
+      ->setAliases(['twig-debug'])
+      ->addOption('filter', NULL, InputOption::VALUE_REQUIRED, 'Show details for all entries matching this filter.')
+      ->setDescription('Shows a list of twig functions, filters, globals and tests')
+      ->setHelp(<<<'EOF'
+        The <info>%command.name%</info> command outputs a list of twig functions,
+        filters, globals and tests.
+
+          <info>drush %command.name%</info>
+
+        The command lists all functions, filters, etc.
+
+          <info>drush %command.name% --filter=date</info>
+
+        The command lists everything that contains the word date.
+      EOF);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function execute(InputInterface $input, OutputInterface $output): int {
+    $io = new SymfonyStyle($input, $output);
+    $filter = $input->getOption('filter');
+
+    $types = ['functions', 'filters', 'tests'];
+    foreach ($types as $type) {
+      $items = [];
+      foreach ($this->twig->{'get' . ucfirst($type)}() as $name => $entity) {
+        if (!$filter || \strpos($name, $filter) !== FALSE) {
+
+          $signature = '';
+          // Tests are typically implemented as Twig nodes so that it is hard
+          // to get their signatures through reflection.
+          if ($type == 'filters' || $type == 'functions') {
+            try {
+              $meta = $this->getMetadata($type, $entity);
+              $default_signature = $type == 'functions' ? '()' : '';
+              $signature = $meta ? '(' . implode(', ', $meta) . ')' : $default_signature;
+            }
+            catch (\UnexpectedValueException $exception) {
+              $signature = sprintf(' <error>%s</error>', OutputFormatter::escape($exception->getMessage()));
+            }
+          }
+
+          $items[$name] = $name . $signature;
+        }
+      }
+
+      if (!$items) {
+        continue;
+      }
+
+      $io->section(\ucfirst($type));
+
+      ksort($items);
+      $io->listing($items);
+    }
+
+    if (!$filter && $loaderPaths = $this->getLoaderPaths()) {
+      $io->section('Loader Paths');
+      $rows = [];
+      foreach ($loaderPaths as $namespace => $paths) {
+        foreach ($paths as $path) {
+          $rows[] = [$namespace, $path . \DIRECTORY_SEPARATOR];
+        }
+      }
+      $io->table(['Namespace', 'Paths'], $rows);
+
+    }
+
+    return 0;
+  }
+
+  /**
+   * Gets loader paths.
+   */
+  private function getLoaderPaths(): array {
+    $loaderPaths = [];
+    foreach ($this->getFilesystemLoaders() as $loader) {
+      foreach ($loader->getNamespaces() as $namespace) {
+        $paths = $loader->getPaths($namespace);
+        $namespace = FilesystemLoader::MAIN_NAMESPACE === $namespace ?
+          '(None)' : '@' . $namespace;
+        $loaderPaths[$namespace] = array_merge($loaderPaths[$namespace] ?? [], $paths);
+      }
+    }
+    return $loaderPaths;
+  }
+
+  /**
+   * Gets metadata.
+   */
+  private function getMetadata(string $type, $entity): ?array {
+
+    $callable = $entity->getCallable();
+
+    if (!$callable) {
+      return NULL;
+    }
+    if (\is_array($callable)) {
+      if (!method_exists($callable[0], $callable[1])) {
+        return NULL;
+      }
+      $reflection = new \ReflectionMethod($callable[0], $callable[1]);
+    }
+    elseif (\is_object($callable) && method_exists($callable, '__invoke')) {
+      $reflection = new \ReflectionMethod($callable, '__invoke');
+    }
+    elseif (\function_exists($callable)) {
+      $reflection = new \ReflectionFunction($callable);
+    }
+    elseif (\is_string($callable) && preg_match('{^(.+)::(.+)$}', $callable, $m) && method_exists($m[1], $m[2])) {
+      $reflection = new \ReflectionMethod($m[1], $m[2]);
+    }
+    else {
+      throw new \UnexpectedValueException('Unsupported callback type.');
+    }
+
+    $args = $reflection->getParameters();
+
+    // Filter out context/environment args.
+    if ($entity->needsEnvironment()) {
+      array_shift($args);
+    }
+    if ($entity->needsContext()) {
+      array_shift($args);
+    }
+
+    if ($type == 'filters') {
+      // Remove the value the filter is applied on.
+      array_shift($args);
+    }
+
+    // Format args.
+    $args = array_map(
+      static function (\ReflectionParameter $param): string {
+        $arg = $param->getName();
+        if ($param->isDefaultValueAvailable()) {
+          $arg .= ' = ' . \json_encode($param->getDefaultValue());
+        }
+        return $arg;
+      },
+      $args,
+    );
+
+    return $args;
+  }
+
+  /**
+   * Returns files system loaders.
+   *
+   * @return \Twig\Loader\FilesystemLoader[]
+   *   File system loaders.
+   */
+  private function getFilesystemLoaders(): array {
+    $loaders = [];
+
+    $loader = $this->twig->getLoader();
+    if ($loader instanceof FilesystemLoader) {
+      $loaders[] = $loader;
+    }
+    elseif ($loader instanceof ChainLoader) {
+      foreach ($loader->getLoaders() as $chained_loaders) {
+        if ($chained_loaders instanceof FilesystemLoader) {
+          $loaders[] = $chained_loaders;
+        }
+      }
+    }
+
+    return $loaders;
+  }
+
+}