bug #25309 [Yaml] parse newlines in quoted multiline strings (xabbuh)

This PR was merged into the 3.3 branch.

Discussion
----------

[Yaml] parse newlines in quoted multiline strings

| Q             | A
| ------------- | ---
| Branch?       | 3.3
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Commits
-------

b23b957ae9 parse newlines in quoted multiline strings

src/Symfony/Component/Yaml/Parser.php

@@ -700,6 +700,8 @@ class Parser
                 return Inline::parse($value, $flags, $this->refs);
             }
 
+            $lines = array();
+
             while ($this->moveToNextLine()) {
                 // unquoted strings end before the first unindented line
                 if (null === $quotation && 0 === $this->getCurrentLineIndentation()) {
@@ -708,7 +710,7 @@ class Parser
                     break;
                 }
 
-                $value .= ' '.trim($this->currentLine);
+                $lines[] = trim($this->currentLine);
 
                 // quoted string values end with a line that is terminated with the quotation character
                 if ('' !== $this->currentLine && substr($this->currentLine, -1) === $quotation) {
@@ -716,6 +718,19 @@ class Parser
                 }
             }
 
+            for ($i = 0, $linesCount = count($lines), $previousLineBlank = false; $i < $linesCount; ++$i) {
+                if ('' === $lines[$i]) {
+                    $value .= "\n";
+                    $previousLineBlank = true;
+                } elseif ($previousLineBlank) {
+                    $value .= $lines[$i];
+                    $previousLineBlank = false;
+                } else {
+                    $value .= ' '.$lines[$i];
+                    $previousLineBlank = false;
+                }
+            }
+
             Inline::$parsedLineNumber = $this->getRealCurrentLineNb();
             $parsedValue = Inline::parse($value, $flags, $this->refs);
 

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

@@ -1572,6 +1572,20 @@ YAML;
         $this->assertSame($expected, $this->parser->parse($yaml));
     }
 
+    public function testBlankLinesInQuotedMultiLineString()
+    {
+        $yaml = <<<YAML
+foobar: 'foo
+
+    bar'
+YAML;
+        $expected = array(
+            'foobar' => "foo\nbar",
+        );
+
+        $this->assertSame($expected, $this->parser->parse($yaml));
+    }
+
     public function testParseMultiLineUnquotedString()
     {
         $yaml = <<<EOT