consistently parse omitted keys as the colon

Author: xabbuh

Inline.php

@@ -459,11 +459,11 @@ private static function parseMapping($mapping, $flags, &$i = 0, $references = ar
             // key
             $key = self::parseScalar($mapping, $flags, array(':', ' '), array('"', "'"), $i, false);
 
-            if (false === $i = strpos($mapping, ':', $i)) {
+            if (':' !== $key && false === $i = strpos($mapping, ':', $i)) {
                 break;
             }
 
-            if (!isset($mapping[$i + 1]) || !in_array($mapping[$i + 1], array(' ', ',', '[', ']', '{', '}'), true)) {
+            if (':' !== $key && (!isset($mapping[$i + 1]) || !in_array($mapping[$i + 1], array(' ', ',', '[', ']', '{', '}'), true))) {
                 @trigger_error('Using a colon that is not followed by an indication character (i.e. " ", ",", "[", "]", "{", "}" is deprecated since version 3.2 and will throw a ParseException in 4.0.', E_USER_DEPRECATED);
             }
 

Tests/InlineTest.php

@@ -686,4 +686,9 @@ public function testVeryLongQuotedStrings()
 
         $this->assertEquals($longStringWithQuotes, $arrayFromYaml['longStringWithQuotes']);
     }
+
+    public function testOmittedMappingKeyIsParsedAsColon()
+    {
+        $this->assertSame(array(':' => 'foo'), Inline::parse('{: foo}'));
+    }
 }