Support hashbang before namespace declaration

Fixes issue #243.

lib/PhpParser/ParserAbstract.php

@@ -444,7 +444,7 @@ abstract class ParserAbstract
     private function getNamespacingStyle(array $stmts) {
         $style = null;
         $hasNotAllowedStmts = false;
-        foreach ($stmts as $stmt) {
+        foreach ($stmts as $i => $stmt) {
             if ($stmt instanceof Node\Stmt\Namespace_) {
                 $currentStyle = null === $stmt->stmts ? 'semicolon' : 'brace';
                 if (null === $style) {
@@ -455,9 +455,21 @@ abstract class ParserAbstract
                 } elseif ($style !== $currentStyle) {
                     throw new Error('Cannot mix bracketed namespace declarations with unbracketed namespace declarations', $stmt->getLine());
                 }
-            } elseif (!$stmt instanceof Node\Stmt\Declare_ && !$stmt instanceof Node\Stmt\HaltCompiler) {
-                $hasNotAllowedStmts = true;
+                continue;
             }
+
+            /* declare() and __halt_compiler() can be used before a namespace declaration */
+            if ($stmt instanceof Node\Stmt\Declare_ || $stmt instanceof Node\Stmt\HaltCompiler) {
+                continue;
+            }
+
+            /* There may be a hashbang line at the very start of the file */
+            if ($i == 0 && $stmt instanceof Node\Stmt\InlineHTML && preg_match('/\A#!.*\r?\n\z/', $stmt->value)) {
+                continue;
+            }
+
+            /* Everything else if forbidden before namespace declarations */
+            $hasNotAllowedStmts = true;
         }
         return $style;
     }

test/code/parser/stmt/namespace/nsAfterHashbang.test

@@ -0,0 +1,22 @@
+Hashbang followed by namespace declaration
+-----
+#!/usr/bin/env php
+<?php
+
+namespace A;
+-----
+array(
+    0: Stmt_InlineHTML(
+        value: #!/usr/bin/env php
+
+    )
+    1: Stmt_Namespace(
+        name: Name(
+            parts: array(
+                0: A
+            )
+        )
+        stmts: array(
+        )
+    )
+)