bug #25043 [Yaml] added ability for substitute aliases when mapping is on single line (Michał Strzelecki, xabbuh)

This PR was merged into the 2.7 branch.

Discussion
----------

[Yaml] added ability for substitute aliases when mapping is on single line

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11569
| License       | MIT
| Doc PR        |

Commits
-------

dd26c80aa9 substitute aliases in inline mappings
675a3fe7f6 added ability for substitute aliases when mapping in YAML is on single line

src/Symfony/Component/Yaml/Inline.php

@@ -365,6 +365,7 @@ class Inline
         $output = array();
         $len = strlen($mapping);
         ++$i;
+        $allowOverwrite = false;
 
         // {foo: bar, bar:foo, ...}
         while ($i < $len) {
@@ -384,6 +385,10 @@ class Inline
             // key
             $key = self::parseScalar($mapping, array(':', ' '), array('"', "'"), $i, false);
 
+            if ('<<' === $key) {
+                $allowOverwrite = true;
+            }
+
             // value
             $done = false;
 
@@ -395,7 +400,12 @@ class Inline
                         // Spec: Keys MUST be unique; first one wins.
                         // Parser cannot abort this mapping earlier, since lines
                         // are processed sequentially.
-                        if (!isset($output[$key])) {
+                        // But overwriting is allowed when a merge node is used in current block.
+                        if ('<<' === $key) {
+                            foreach ($value as $parsedValue) {
+                                $output += $parsedValue;
+                            }
+                        } elseif ($allowOverwrite || !isset($output[$key])) {
                             $output[$key] = $value;
                         }
                         $done = true;
@@ -406,7 +416,10 @@ class Inline
                         // Spec: Keys MUST be unique; first one wins.
                         // Parser cannot abort this mapping earlier, since lines
                         // are processed sequentially.
-                        if (!isset($output[$key])) {
+                        // But overwriting is allowed when a merge node is used in current block.
+                        if ('<<' === $key) {
+                            $output += $value;
+                        } elseif ($allowOverwrite || !isset($output[$key])) {
                             $output[$key] = $value;
                         }
                         $done = true;
@@ -419,7 +432,10 @@ class Inline
                         // Spec: Keys MUST be unique; first one wins.
                         // Parser cannot abort this mapping earlier, since lines
                         // are processed sequentially.
-                        if (!isset($output[$key])) {
+                        // But overwriting is allowed when a merge node is used in current block.
+                        if ('<<' === $key) {
+                            $output += $value;
+                        } elseif ($allowOverwrite || !isset($output[$key])) {
                             $output[$key] = $value;
                         }
                         $done = true;

src/Symfony/Component/Yaml/Tests/Fixtures/sfMergeKey.yml

@@ -22,6 +22,7 @@ yaml: |
             foo: bar
             foo: ignore
             bar: foo
+    bar_inline: {a: before, d: other, <<: *foo, b: new, x: Oren, c: { foo: bar, foo: ignore, bar: foo}}
     duplicate:
         foo: bar
         foo: ignore
@@ -46,15 +47,20 @@ yaml: |
             p: 12345
         z:
             <<: *nestedref
+    head_inline: &head_inline { <<: [ *foo , *dong , *foo2 ] }
+    recursive_inline: { <<: *head_inline, c: { <<: *foo2 } }
 php: |
     array(
         'foo' => array('a' => 'Steve', 'b' => 'Clark', 'c' => 'Brian', 'e' => 'notnull'),
         'bar' => array('a' => 'before', 'd' => 'other', 'e' => null, 'b' => 'new', 'c' => array('foo' => 'bar', 'bar' => 'foo'), 'x' => 'Oren'),
+        'bar_inline' => array('a' => 'before', 'd' => 'other', 'b' => 'new', 'c' => array('foo' => 'bar', 'bar' => 'foo'), 'e' => 'notnull', 'x' => 'Oren'),
         'duplicate' => array('foo' => 'bar'),
         'foo2' => array('a' => 'Ballmer'),
         'ding' => array('fi', 'fei', 'fo', 'fam'),
         'check' => array('a' => 'Steve', 'b' => 'Clark', 'c' => 'Brian', 'e' => 'notnull', 'fi', 'fei', 'fo', 'fam', 'isit' => 'tested'),
         'head' => array('a' => 'Steve', 'b' => 'Clark', 'c' => 'Brian', 'e' => 'notnull', 'fi', 'fei', 'fo', 'fam'),
         'taz' => array('a' => 'Steve', 'w' => array('p' => 1234)),
-        'nested' => array('a' => 'Steve', 'w' => array('p' => 12345), 'd' => 'Doug', 'z' => array('p' => 12345))
+        'nested' => array('a' => 'Steve', 'w' => array('p' => 12345), 'd' => 'Doug', 'z' => array('p' => 12345)),
+        'head_inline' => array('a' => 'Steve', 'b' => 'Clark', 'c' => 'Brian', 'e' => 'notnull', 'fi', 'fei', 'fo', 'fam'),
+        'recursive_inline' => array('a' => 'Steve', 'b' => 'Clark', 'c' => array('a' => 'Ballmer'), 'e' => 'notnull', 'fi', 'fei', 'fo', 'fam'),
     )

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

@@ -1207,6 +1207,18 @@ YAML;
 
         $this->assertSame($expected, $this->parser->parse($yaml));
     }
+
+    /**
+     * @expectedException \Symfony\Component\Yaml\Exception\ParseException
+     * @expectedExceptionMessage Reference "foo" does not exist
+     */
+    public function testEvalRefException()
+    {
+        $yaml = <<<EOE
+foo: { &foo { a: Steve, <<: *foo} }
+EOE;
+        $this->parser->parse($yaml);
+    }
 }
 
 class B