Add a "main loop" that processes each stage of the pipeline explicitly

pipes-controller.php

@@ -599,6 +599,11 @@ function (ZipStreamReader $zip_reader, ByteStreamState $state) {
     }
 }
 
+// ----------------------------------------------------------------------------
+// Here's a stream-based pipeline that fetches a ZIP file from a remote server,
+// unzips it, skips the first file, processes the XML files, and uppercases the
+// output.
+// ----------------------------------------------------------------------------
 $chain = new StreamChain(
     [
         'http' => HTTP_Client::stream([
@@ -624,18 +629,92 @@ function (ZipStreamReader $zip_reader, ByteStreamState $state) {
 // var_dump([$chain->next_chunk(), strlen($chain->get_bytes()), $chain->get_last_error()]);
 
 // Or like this:
-$chain->stop_on_errors(true);
-foreach($chain as $chunk) {
-    switch($chunk->get_chunk_type()) {
-        case '#error':
-            echo "Error: " . $chunk->get_last_error() . "\n";
-            break;
-        case '#bytes':
-            var_dump([
-                $chunk->get_bytes(),
-                'zip file_id' => isset($chain['zip']) ? $chain['zip']->get_file_id() : null
-            ]);
+// $chain->stop_on_errors(true);
+// foreach($chain as $chunk) {
+//     switch($chunk->get_chunk_type()) {
+//         case '#error':
+//             echo "Error: " . $chunk->get_last_error() . "\n";
+//             break;
+//         case '#bytes':
+//             var_dump([
+//                 $chunk->get_bytes(),
+//                 'zip file_id' => isset($chain['zip']) ? $chain['zip']->get_file_id() : null
+//             ]);
+//             break;
+//     }
+// }
+
+
+// ----------------------------------------------------------
+// And here's a loop-based pipeline that does the same thing:
+// ----------------------------------------------------------
+
+$client = new Client();
+$client->enqueue([
+    new Request('http://127.0.0.1:9864/export.wxr.zip'),
+    new Request('http://127.0.0.1:9865')
+]);
+
+$zip_readers = [];
+$xml_processors = [];
+$xml_tokens_found = [];
+while ($client->await_next_event()) {
+    // Fetch HTTP data
+    $request = $client->get_request();
+    switch ($client->get_event()) {
+        case Client::EVENT_BODY_CHUNK_AVAILABLE:
+            // Continue to the next stage
             break;
+        case Client::EVENT_FAILED:
+            error_log('Request failed: ' . $request->error);
+        default:
+            continue 2;
+    }
+
+    // Unzip the file
+    $zip_reader = $zip_readers[$request->id] ?? new ZipStreamReader();
+    $zip_reader->append_bytes($client->get_response_body_chunk());
+    while ($zip_reader->next()) {
+        switch ($zip_reader->get_state()) {
+            case ZipStreamReader::STATE_FILE_ENTRY:
+                // Continue to the next stage
+                break;
+            default:
+                continue 2;
+        }
+
+        if($zip_reader->get_file_path() === 'export.wxr') {
+            continue;
+        }
+
+        // Process the XML
+        $xml_processor = $xml_processors[$request->id] ?? new WP_XML_Processor('', [], WP_XML_Processor::IN_PROLOG_CONTEXT);
+        $xml_processor->append_bytes($zip_reader->get_file_body_chunk());
+
+        $xml_tokens_found[$request->id] ??= 0;
+        while ($xml_processor->next_token()) {
+            ++$xml_tokens_found[$request->id];
+            // Process the XML
+        }
+
+        $buffer = '';
+        if ($xml_tokens_found[$request->id] > 0) {
+            $buffer .= $xml_processor->get_updated_xml();
+        } else if (
+            $xml_tokens_found[$request->id] === 0 &&
+            !$xml_processor->is_paused_at_incomplete_input() &&
+            $xml_processor->get_current_depth() === 0
+        ) {
+            // We've reached the end of the document, let's finish up.
+            // @TODO: Fix this so it doesn't return the entire XML
+            $buffer .= $xml_processor->get_unprocessed_xml();
+        }
+
+        if (!strlen($buffer)) {
+            continue;
+        }
+
+        // Uppercase the output
+        echo strtoupper($buffer);
     }
 }
-