[Yaml] recognize when a block scalar is left

The parser did not recognize when the block scalar was completely parsed
and thus treated following comments as they need to be kept leading to
parse errors on the following lines.

src/Symfony/Component/Yaml/Parser.php

@@ -303,7 +303,11 @@ class Parser
     private function getNextEmbedBlock($indentation = null, $inSequence = false)
     {
         $oldLineIndentation = $this->getCurrentLineIndentation();
-        $insideBlockScalar = $this->isBlockScalarHeader();
+        $blockScalarIndentations = array();
+
+        if ($this->isBlockScalarHeader()) {
+            $blockScalarIndentations[] = $this->getCurrentLineIndentation();
+        }
 
         if (!$this->moveToNextLine()) {
             return;
@@ -340,8 +344,8 @@ class Parser
 
         $isItUnindentedCollection = $this->isStringUnIndentedCollectionItem();
 
-        if (!$insideBlockScalar) {
-            $insideBlockScalar = $this->isBlockScalarHeader();
+        if (empty($blockScalarIndentations) && $this->isBlockScalarHeader()) {
+            $blockScalarIndentations[] = $this->getCurrentLineIndentation();
         }
 
         $previousLineIndentation = $this->getCurrentLineIndentation();
@@ -349,8 +353,17 @@ class Parser
         while ($this->moveToNextLine()) {
             $indent = $this->getCurrentLineIndentation();
 
-            if (!$insideBlockScalar && $indent === $previousLineIndentation) {
-                $insideBlockScalar = $this->isBlockScalarHeader();
+            // terminate all block scalars that are more indented than the current line
+            if (!empty($blockScalarIndentations) && $indent < $previousLineIndentation && trim($this->currentLine) !== '') {
+                foreach ($blockScalarIndentations as $key => $blockScalarIndentation) {
+                    if ($blockScalarIndentation >= $this->getCurrentLineIndentation()) {
+                        unset($blockScalarIndentations[$key]);
+                    }
+                }
+            }
+
+            if (empty($blockScalarIndentations) && !$this->isCurrentLineComment() && $this->isBlockScalarHeader()) {
+                $blockScalarIndentations[] = $this->getCurrentLineIndentation();
             }
 
             $previousLineIndentation = $indent;
@@ -366,7 +379,7 @@ class Parser
             }
 
             // we ignore "comment" lines only when we are not inside a scalar block
-            if (!$insideBlockScalar && $this->isCurrentLineComment()) {
+            if (empty($blockScalarIndentations) && $this->isCurrentLineComment()) {
                 continue;
             }
 
@@ -523,7 +536,7 @@ class Parser
             $previousLineIndented = false;
             $previousLineBlank = false;
 
-            for ($i = 0; $i < count($blockLines); $i++) {
+            for ($i = 0; $i < count($blockLines); ++$i) {
                 if ('' === $blockLines[$i]) {
                     $text .= "\n";
                     $previousLineIndented = false;
@@ -618,7 +631,7 @@ class Parser
         //checking explicitly the first char of the trim is faster than loops or strpos
         $ltrimmedLine = ltrim($this->currentLine, ' ');
 
-        return $ltrimmedLine[0] === '#';
+        return '' !== $ltrimmedLine && $ltrimmedLine[0] === '#';
     }
 
     /**

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

@@ -737,7 +737,9 @@ EOF;
 
     public function getCommentLikeStringInScalarBlockData()
     {
-        $yaml1 = <<<'EOT'
+        $tests = array();
+
+        $yaml = <<<'EOT'
 pages:
     -
         title: some title
@@ -752,7 +754,7 @@ pages:
 
             footer # comment3
 EOT;
-        $expected1 = array(
+        $expected = array(
             'pages' => array(
                 array(
                     'title' => 'some title',
@@ -771,8 +773,9 @@ EOT
                 ),
             ),
         );
+        $tests[] = array($yaml, $expected);
 
-        $yaml2 = <<<'EOT'
+        $yaml = <<<'EOT'
 test: |
     foo
     # bar
@@ -787,7 +790,7 @@ collection:
         # bar
         baz
 EOT;
-        $expected2 = array(
+        $expected = array(
             'test' => <<<'EOT'
 foo
 # bar
@@ -814,11 +817,47 @@ EOT
                 ),
             ),
         );
+        $tests[] = array($yaml, $expected);
 
-        return array(
-            array($yaml1, $expected1),
-            array($yaml2, $expected2),
+        $yaml = <<<EOT
+foo:
+  bar:
+    scalar-block: >
+      line1
+      line2>
+  baz:
+# comment
+    foobar: ~
+EOT;
+        $expected = array(
+            'foo' => array(
+                'bar' => array(
+                    'scalar-block' => 'line1 line2>',
+                ),
+                'baz' => array(
+                    'foobar' => null,
+                ),
+            ),
         );
+        $tests[] = array($yaml, $expected);
+
+        $yaml = <<<'EOT'
+a:
+    b: hello
+#    c: |
+#        first row
+#        second row
+    d: hello
+EOT;
+        $expected = array(
+            'a' => array(
+                'b' => 'hello',
+                'd' => 'hello',
+            ),
+        );
+        $tests[] = array($yaml, $expected);
+
+        return $tests;
     }
 
     public function testBlankLinesAreParsedAsNewLinesInFoldedBlocks()