[Yaml] parse multi-line strings

src/Symfony/Component/Yaml/Parser.php

@@ -295,6 +295,42 @@ class Parser
                     return $value;
                 }
 
+                // try to parse the value as a multi-line string as a last resort
+                if (0 === $this->currentLineNb) {
+                    $parseError = false;
+                    $previousLineWasNewline = false;
+                    $value = '';
+
+                    foreach ($this->lines as $line) {
+                        try {
+                            $parsedLine = Inline::parse($line, $flags, $this->refs);
+
+                            if (!is_string($value)) {
+                                $parseError = true;
+                                break;
+                            }
+
+                            if ('' === trim($parsedLine)) {
+                                $value .= "\n";
+                                $previousLineWasNewline = true;
+                            } elseif ($previousLineWasNewline) {
+                                $value .= trim($parsedLine);
+                                $previousLineWasNewline = false;
+                            } else {
+                                $value .= ' '.trim($parsedLine);
+                                $previousLineWasNewline = false;
+                            }
+                        } catch (ParseException $e) {
+                            $parseError = true;
+                            break;
+                        }
+                    }
+
+                    if (!$parseError) {
+                        return trim($value);
+                    }
+                }
+
                 switch (preg_last_error()) {
                     case PREG_INTERNAL_ERROR:
                         $error = 'Internal PCRE error.';
@@ -462,7 +498,7 @@ class Parser
 
             $previousLineIndentation = $indent;
 
-            if ($isItUnindentedCollection && !$this->isStringUnIndentedCollectionItem() && $newIndent === $indent) {
+            if ($isItUnindentedCollection && !$this->isCurrentLineEmpty() && !$this->isStringUnIndentedCollectionItem() && $newIndent === $indent) {
                 $this->moveToPreviousLine();
                 break;
             }

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

@@ -1449,6 +1449,32 @@ EOT;
 
         $this->assertSame(array('foo' => 'bar baz foobar foo', 'bar' => 'baz'), $this->parser->parse($yaml));
     }
+
+    public function testParseMultiLineString()
+    {
+        $this->assertEquals("foo bar\nbaz", $this->parser->parse("foo\nbar\n\nbaz"));
+    }
+
+    public function testParseMultiLineMappingValue()
+    {
+        $yaml = <<<'EOF'
+foo:
+- bar:
+    one
+
+    two
+    three
+EOF;
+        $expected = array(
+            'foo' => array(
+                array(
+                    'bar' => "one\ntwo three",
+                ),
+            ),
+        );
+
+        $this->assertEquals($expected, $this->parser->parse($yaml));
+    }
 }
 
 class B