feature #26863 [Console] Support iterable in SymfonyStyle::write/writeln (ogizanagi)

This PR was merged into the 4.1-dev branch.

Discussion
----------

[Console] Support iterable in SymfonyStyle::write/writeln

| Q             | A
| ------------- | ---
| Branch?       | master <!-- see below -->
| Bug fix?      | no
| New feature?  | no <!-- don't forget to update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- don't forget to update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | N/A   <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | N/A

Relates to https://github.com/symfony/symfony/pull/26847.

This would enable iterables benefits even when using `SymfonyStyle` output.

Commits
-------

d66827e [Console] Support iterable in SymfonyStyle::write/writeln

src/Symfony/Component/Console/Style/SymfonyStyle.php

@@ -306,11 +306,14 @@ class SymfonyStyle extends OutputStyle
      */
     public function writeln($messages, $type = self::OUTPUT_NORMAL)
     {
-        if ($messages instanceof \Traversable) {
-            $messages = iterator_to_array($messages, false);
+        if (!is_iterable($messages)) {
+            $messages = array($messages);
+        }
+
+        foreach ($messages as $message) {
+            parent::writeln($message, $type);
+            $this->writeBuffer($message, true, $type);
         }
-        parent::writeln($messages, $type);
-        $this->bufferedOutput->writeln($this->reduceBuffer($messages), $type);
     }
 
     /**
@@ -318,11 +321,14 @@ class SymfonyStyle extends OutputStyle
      */
     public function write($messages, $newline = false, $type = self::OUTPUT_NORMAL)
     {
-        if ($messages instanceof \Traversable) {
-            $messages = iterator_to_array($messages, false);
+        if (!is_iterable($messages)) {
+            $messages = array($messages);
+        }
+
+        foreach ($messages as $message) {
+            parent::write($message, $newline, $type);
+            $this->writeBuffer($message, $newline, $type);
         }
-        parent::write($messages, $newline, $type);
-        $this->bufferedOutput->write($this->reduceBuffer($messages), $newline, $type);
     }
 
     /**
@@ -375,13 +381,11 @@ class SymfonyStyle extends OutputStyle
         }
     }
 
-    private function reduceBuffer($messages): array
+    private function writeBuffer(string $message, bool $newLine, int $type): void
     {
         // We need to know if the two last chars are PHP_EOL
         // Preserve the last 4 chars inserted (PHP_EOL on windows is two chars) in the history buffer
-        return array_map(function ($value) {
-            return substr($value, -4);
-        }, array_merge(array($this->bufferedOutput->fetch()), (array) $messages));
+        $this->bufferedOutput->write(substr($message, -4), $newLine, $type);
     }
 
     private function createBlock(iterable $messages, string $type = null, string $style = null, string $prefix = ' ', bool $padding = false, bool $escape = false)

src/Symfony/Component/Console/Tests/Fixtures/Style/SymfonyStyle/command/command_4_with_iterators.php

@@ -0,0 +1,34 @@
+<?php
+
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+
+//Ensure has single blank line after any text and a title
+return function (InputInterface $input, OutputInterface $output) {
+    $output = new SymfonyStyle($input, $output);
+
+    $output->write('Lorem ipsum dolor sit amet');
+    $output->title('First title');
+
+    $output->writeln('Lorem ipsum dolor sit amet');
+    $output->title('Second title');
+
+    $output->write('Lorem ipsum dolor sit amet');
+    $output->write('');
+    $output->title('Third title');
+
+    //Ensure edge case by appending empty strings to history:
+    $output->write('Lorem ipsum dolor sit amet');
+    $output->write(new \ArrayIterator(array('', '', '')));
+    $output->title('Fourth title');
+
+    //Ensure have manual control over number of blank lines:
+    $output->writeln('Lorem ipsum dolor sit amet');
+    $output->writeln(new \ArrayIterator(array('', ''))); //Should append an extra blank line
+    $output->title('Fifth title');
+
+    $output->writeln('Lorem ipsum dolor sit amet');
+    $output->newLine(2); //Should append an extra blank line
+    $output->title('Fifth title');
+};

src/Symfony/Component/Console/Tests/Fixtures/Style/SymfonyStyle/output/output_4_with_iterators.txt

@@ -0,0 +1,32 @@
+Lorem ipsum dolor sit amet
+
+First title
+===========
+
+Lorem ipsum dolor sit amet
+
+Second title
+============
+
+Lorem ipsum dolor sit amet
+
+Third title
+===========
+
+Lorem ipsum dolor sit amet
+
+Fourth title
+============
+
+Lorem ipsum dolor sit amet
+
+
+Fifth title
+===========
+
+Lorem ipsum dolor sit amet
+
+
+Fifth title
+===========
+