Update PrettyPrinter.php

This could be solution to phpowermove#61. This counts lines difference between stms and insert new line character for every empty line.

Author: matak

src/parser/PrettyPrinter.php

@@ -6,6 +6,44 @@
 
 class PrettyPrinter extends Standard {
 
+ /**
+     * Pretty prints an array of nodes (statements) and indents them optionally.
+     *
+     * @param Node[] $nodes  Array of nodes
+     * @param bool   $indent Whether to indent the printed nodes
+     *
+     * @return string Pretty printed statements
+     */
+    protected function pStmts(array $nodes, $indent = true) {
+        $result = '';
+	   $nodeBefore = NULL;
+        foreach ($nodes as $node) {
+            $comments = $node->getAttribute('comments', array());
+            if ($comments) {
+                $result .= "\n" . $this->pComments($comments);
+                if ($node instanceof Stmt\Nop) {
+                    continue;
+                }
+            }
+		  
+		  if ($nodeBefore && $nodeBefore->getLine() && $node->getLine()) {
+			  $diff = $node->getLine()- $nodeBefore->getLine();
+			  if ($diff > 0) {
+				  $result .= str_repeat("\n", $diff - 1);
+			  }
+		  }
+		  
+            $result .= "\n" . $this->p($node) . ($node instanceof Expr ? ';' : '');
+		  $nodeBefore = $node;
+        }
+
+	   if ($indent) {
+            return preg_replace('~\n(?!$|' . $this->noIndentToken . ')~', "\n    ", $result);
+        } else {
+            return $result;
+        }
+    }
+    
 	public function pExpr_Array(Array_ $node) {
 		return '[' . $this->pCommaSeparated($node->items) . ']';
 	}