[Yaml] Allow dumping empty array as YAML sequence

src/Symfony/Component/Yaml/CHANGELOG.md

@@ -1,6 +1,15 @@
 CHANGELOG
 =========
 
+3.2.3
+-----
+
+ * Added support for dumping empty PHP arrays as YAML sequences:
+
+   ```php
+   Yaml::dump([], 0, 0, Yaml::DUMP_EMPTY_ARRAY_AS_SEQUENCE);
+   ```
+
 3.2.0
 -----
 

src/Symfony/Component/Yaml/Inline.php

@@ -252,7 +252,7 @@ class Inline
     private static function dumpArray($value, $flags)
     {
         // array
-        if ($value && !self::isHash($value)) {
+        if (($value || Yaml::DUMP_EMPTY_ARRAY_AS_SEQUENCE & $flags) && !self::isHash($value)) {
             $output = array();
             foreach ($value as $val) {
                 $output[] = self::dump($val, $flags);

src/Symfony/Component/Yaml/Tests/DumperTest.php

@@ -246,6 +246,24 @@ EOF;
         $this->dumper->dump(array('foo' => new A(), 'bar' => 1), 0, 0, true);
     }
 
+    public function testEmptyArray()
+    {
+        $dump = $this->dumper->dump(array());
+        $this->assertEquals('{  }', $dump);
+
+        $dump = $this->dumper->dump(array(), 0, 0, Yaml::DUMP_EMPTY_ARRAY_AS_SEQUENCE);
+        $this->assertEquals('[]', $dump);
+
+        $dump = $this->dumper->dump(array(), 9, 0, Yaml::DUMP_EMPTY_ARRAY_AS_SEQUENCE);
+        $this->assertEquals('[]', $dump);
+
+        $dump = $this->dumper->dump(new \ArrayObject(), 0, 0, Yaml::DUMP_EMPTY_ARRAY_AS_SEQUENCE | Yaml::DUMP_OBJECT_AS_MAP);
+        $this->assertEquals('[]', $dump);
+
+        $dump = $this->dumper->dump(new \stdClass(), 0, 0, Yaml::DUMP_EMPTY_ARRAY_AS_SEQUENCE | Yaml::DUMP_OBJECT_AS_MAP);
+        $this->assertEquals('[]', $dump);
+    }
+
     /**
      * @dataProvider getEscapeSequences
      */

src/Symfony/Component/Yaml/Yaml.php

@@ -29,6 +29,7 @@ class Yaml
     const DUMP_OBJECT_AS_MAP = 64;
     const DUMP_MULTI_LINE_LITERAL_BLOCK = 128;
     const PARSE_CONSTANT = 256;
+    const DUMP_EMPTY_ARRAY_AS_SEQUENCE = 512;
 
     /**
      * Parses YAML into a PHP value.