[Data Liberation] Introduce WP_Entity_Reader_Iterator

packages/playground/data-liberation-markdown/src/WP_Markdown_Importer.php

@@ -8,18 +8,20 @@ public static function create_for_markdown_directory( $markdown_directory, $opti
 		return WP_Markdown_Importer::create(
 			function ( $cursor = null ) use ( $markdown_directory ) {
 				// @TODO: Handle $cursor
-				return new WP_Directory_Tree_Entity_Reader(
-					new WP_Filesystem(),
-					array(
-						'root_dir' => $markdown_directory,
-						'first_post_id' => 1,
-						'allowed_extensions' => array( 'md' ),
-						'index_file_patterns' => array( '#^index\.md$#' ),
-						'markup_converter_factory' => function ( $content ) {
-							return new WP_Markdown_To_Blocks( $content );
-						},
-					)
-				);
+				return new WP_Entity_Reader_Iterator(
+                    new WP_Directory_Tree_Entity_Reader(
+                        new WP_Filesystem(),
+                        array(
+                            'root_dir' => $markdown_directory,
+                            'first_post_id' => 1,
+                            'allowed_extensions' => array( 'md' ),
+                            'index_file_patterns' => array( '#^index\.md$#' ),
+                            'markup_converter_factory' => function ( $content ) {
+                                return new WP_Markdown_To_Blocks( $content );
+                            },
+                        )
+                    )
+                );
 			},
 			$options,
 			$cursor

packages/playground/data-liberation/bootstrap.php

@@ -77,6 +77,7 @@
 require_once __DIR__ . '/src/import/WP_Stream_Importer.php';
 require_once __DIR__ . '/src/import/WP_Entity_Iterator_Chain.php';
 require_once __DIR__ . '/src/import/WP_Retry_Frontloading_Iterator.php';
+require_once __DIR__ . '/src/entity-readers/WP_Entity_Reader_Iterator.php';
 require_once __DIR__ . '/src/entity-readers/WP_Entity_Reader.php';
 require_once __DIR__ . '/src/entity-readers/WP_HTML_Entity_Reader.php';
 

packages/playground/data-liberation/src/entity-readers/WP_Directory_Tree_Entity_Reader.php

@@ -8,16 +8,16 @@
  *
  * @TODO: Explore supporting a cursor to allow resuming from where we left off.
  */
-class WP_Directory_Tree_Entity_Reader implements \Iterator {
+class WP_Directory_Tree_Entity_Reader extends WP_Entity_Reader {
 	private $file_visitor;
 	private $filesystem;
 	private $entity;
 
+	private $is_finished = false;
 	private $pending_directory_index;
 	private $pending_files = array();
 	private $parent_ids    = array();
 	private $next_post_id;
-	private $is_finished          = false;
 	private $entities_read_so_far = 0;
 	private $allowed_extensions   = array();
 	private $index_file_patterns  = array();
@@ -154,6 +154,14 @@ public function next_entity() {
 		return false;
 	}
 
+    public function is_finished(): bool {
+        return $this->is_finished;
+    }
+
+	public function get_last_error(): ?string {
+		return null;
+	}
+
 	public function get_entity(): ?\WP_Imported_Entity {
 		return $this->entity;
 	}
@@ -308,35 +316,4 @@ protected function is_valid_file( $path ) {
 		return in_array( $extension, $this->allowed_extensions, true );
 	}
 
-	/**
-	 * @TODO: Either implement this method, or introduce a concept of
-	 *        reentrant and non-reentrant entity readers.
-	 */
-	public function get_reentrancy_cursor() {
-		return '';
-	}
-
-	public function current(): mixed {
-		if ( null === $this->entity && ! $this->is_finished ) {
-			$this->next();
-		}
-		return $this->get_entity();
-	}
-
-	public function next(): void {
-		$this->next_entity();
-	}
-
-	public function key(): int {
-		return $this->entities_read_so_far - 1;
-	}
-
-	public function valid(): bool {
-		return ! $this->is_finished;
-	}
-
-	public function rewind(): void {
-		// @TODO: Either implement this method, or formalize the fact that
-		//        entity readers are not rewindable.
-	}
 }

packages/playground/data-liberation/src/entity-readers/WP_Entity_Reader.php

@@ -7,7 +7,7 @@
  * The reader implements Iterator so you can easily loop through entities:
  * foreach ($reader as $entity) { ... }
  */
-abstract class WP_Entity_Reader implements \Iterator {
+abstract class WP_Entity_Reader {
 
 	/**
 	 * Gets the current entity being processed.
@@ -57,39 +57,4 @@ public function get_reentrancy_cursor() {
 		return '';
 	}
 
-	// The iterator interface:
-
-	public function current(): object {
-		if ( null === $this->get_entity() && ! $this->is_finished() && ! $this->get_last_error() ) {
-			$this->next();
-		}
-		return $this->get_entity();
-	}
-
-	private $last_next_result = null;
-	public function next(): void {
-		// @TODO: Don't keep track of this. Just make sure the next_entity()
-		//        call will make the is_finished() true.
-		$this->last_next_result = $this->next_entity();
-	}
-
-	public function key(): string {
-		return $this->get_reentrancy_cursor();
-	}
-
-	public function valid(): bool {
-		return false !== $this->last_next_result && ! $this->is_finished() && ! $this->get_last_error();
-	}
-
-	public function rewind(): void {
-		// Haven't started yet.
-		if ( null === $this->last_next_result ) {
-			return;
-		}
-		_doing_it_wrong(
-			__METHOD__,
-			'WP_WXR_Entity_Reader does not support rewinding.',
-			null
-		);
-	}
 }

packages/playground/data-liberation/src/entity-readers/WP_Entity_Reader_Iterator.php

@@ -0,0 +1,65 @@
+<?php
+
+/**
+ * An iterator that reads entities from a WP_Entity_Reader.
+ */
+class WP_Entity_Reader_Iterator implements Iterator {
+
+    /**
+     * @var WP_Entity_Reader
+     */
+    private $entity_reader;
+    private $is_initialized = false;
+    private $key = 0;
+
+    public function __construct( WP_Entity_Reader $entity_reader ) {
+        $this->entity_reader = $entity_reader;
+    }
+
+    public function get_entity_reader() {
+        return $this->entity_reader;
+    }
+
+    #[\ReturnTypeWillChange]
+    public function current() {
+        $this->ensure_initialized();
+        return $this->entity_reader->get_entity();
+    }
+
+    #[\ReturnTypeWillChange]
+    public function next() {
+        $this->ensure_initialized();
+        $this->advance_to_next_entity();
+    }
+
+    #[\ReturnTypeWillChange]
+    public function key() {
+        $this->ensure_initialized();
+        return $this->key;
+    }
+
+    #[\ReturnTypeWillChange]
+    public function valid() {
+        $this->ensure_initialized();
+        return ! $this->entity_reader->is_finished();
+    }
+
+    #[\ReturnTypeWillChange]
+    public function rewind() {
+        throw new Data_Liberation_Exception( 'WP_Entity_Reader_Iterator does not support rewinding.' );
+    }
+
+    private function ensure_initialized() {
+        if ( ! $this->is_initialized ) {
+            $this->is_initialized = true;
+            $this->advance_to_next_entity();
+        }
+    }
+
+    private function advance_to_next_entity() {
+        if ( $this->entity_reader->next_entity() ) {
+            $this->key++;
+        }
+    }
+
+}

packages/playground/data-liberation/src/entity-readers/WP_WXR_Entity_Reader.php

@@ -905,39 +905,4 @@ private function after_entity() {
 		$this->last_opener_attributes = array();
 	}
 
-	public function current(): object {
-		// Lazily initialize the iterator when it is first accessed.
-		// The alternative is eager initialization in the constructor.
-		if ( null === $this->entity_data && ! $this->is_finished() && ! $this->get_last_error() ) {
-			$this->next();
-		}
-		return $this->get_entity();
-	}
-
-	private $last_next_result = null;
-	public function next(): void {
-		// @TODO: Don't keep track of this. Just make sure the next_entity()
-		//        call will make the is_finished() true.
-		$this->last_next_result = $this->next_entity();
-	}
-
-	public function key(): string {
-		return $this->get_reentrancy_cursor();
-	}
-
-	public function valid(): bool {
-		return false !== $this->last_next_result && ! $this->is_finished() && ! $this->get_last_error();
-	}
-
-	public function rewind(): void {
-		// Haven't started yet.
-		if ( null === $this->last_next_result ) {
-			return;
-		}
-		_doing_it_wrong(
-			__METHOD__,
-			'WP_WXR_Reader does not support rewinding.',
-			null
-		);
-	}
 }

packages/playground/data-liberation/src/import/WP_Stream_Importer.php

@@ -132,7 +132,9 @@ class WP_Stream_Importer {
 	public static function create_for_wxr_file( $wxr_path, $options = array(), $cursor = null ) {
 		return static::create(
 			function ( $cursor = null ) use ( $wxr_path ) {
-				return WP_WXR_Entity_Reader::create( WP_File_Reader::create( $wxr_path ), $cursor );
+				return new WP_Entity_Reader_Iterator(
+                    WP_WXR_Entity_Reader::create( WP_File_Reader::create( $wxr_path ), $cursor )
+                );
 			},
 			$options,
 			$cursor
@@ -142,7 +144,9 @@ function ( $cursor = null ) use ( $wxr_path ) {
 	public static function create_for_wxr_url( $wxr_url, $options = array(), $cursor = null ) {
 		return static::create(
 			function ( $cursor = null ) use ( $wxr_url ) {
-				return WP_WXR_Entity_Reader::create( new WP_Remote_File_Reader( $wxr_url ), $cursor );
+				return new WP_Entity_Reader_Iterator(
+                    WP_WXR_Entity_Reader::create( new WP_Remote_File_Reader( $wxr_url ), $cursor )
+                );
 			},
 			$options,
 			$cursor
@@ -240,11 +244,11 @@ public function get_reentrancy_cursor() {
 
 	protected static function parse_options( $options ) {
 		if ( ! isset( $options['new_site_url'] ) ) {
-			$options['new_site_url'] = get_site_url();
+			// $options['new_site_url'] = get_site_url();
 		}
 
 		if ( ! isset( $options['uploads_path'] ) ) {
-			$options['uploads_path'] = wp_get_upload_dir()['basedir'];
+			// $options['uploads_path'] = wp_get_upload_dir()['basedir'];
 		}
 		// Remove the trailing slash to make concatenation easier later.
 		$options['uploads_path'] = rtrim( $options['uploads_path'], '/' );
@@ -435,7 +439,7 @@ protected function index_next_entities( $count = 10000 ) {
 
 			$this->entity_iterator->next();
 		}
-		$this->resume_at_entity = $this->entity_iterator->get_reentrancy_cursor();
+		$this->resume_at_entity = $this->entity_iterator->get_entity_reader()->get_reentrancy_cursor();
 		return true;
 	}
 
@@ -570,7 +574,7 @@ protected function frontload_next_entity() {
 		 * and enqueue them for download.
 		 */
 		$entity                            = $this->entity_iterator->current();
-		$cursor                            = $this->entity_iterator->get_reentrancy_cursor();
+		$cursor                            = $this->entity_iterator->get_entity_reader()->get_reentrancy_cursor();
 		$this->active_downloads[ $cursor ] = array();
 
 		$data = $entity->get_data();
@@ -715,7 +719,7 @@ protected function import_next_entity() {
 		/**
 		 * @TODO: Update the progress information.
 		 */
-		$this->resume_at_entity = $this->entity_iterator->get_reentrancy_cursor();
+		$this->resume_at_entity = $this->entity_iterator->get_entity_reader()->get_reentrancy_cursor();
 		$this->entity_iterator->next();
 		return true;
 	}
@@ -744,7 +748,7 @@ protected function enqueue_attachment_download( string $raw_url, $options = arra
 			return false;
 		}
 
-		$entity_cursor                                        = $this->entity_iterator->get_reentrancy_cursor();
+		$entity_cursor                                        = $this->entity_iterator->get_entity_reader()->get_reentrancy_cursor();
 		$this->active_downloads[ $entity_cursor ][ $raw_url ] = true;
 		return true;
 	}