Fix pretty printing of -(-$x) and +(+$x)

Fixes #459.

CHANGELOG.md

@@ -1,7 +1,9 @@
 Version 3.1.4-dev
 -----------------
 
-Nothing yet.
+### Fixed
+
+* Fixed pretty printing of `-(-$x)` and `+(+$x)`. (#459)
 
 Version 3.1.3 (2017-12-26)
 --------------------------

lib/PhpParser/PrettyPrinter/Standard.php

@@ -374,10 +374,18 @@ class Standard extends PrettyPrinterAbstract
     }
 
     protected function pExpr_UnaryMinus(Expr\UnaryMinus $node) {
+        if ($node->expr instanceof Expr\UnaryMinus) {
+            // Enforce -(-$expr) instead of --$expr
+            return '-(' . $this->p($node->expr) . ')';
+        }
         return $this->pPrefixOp('Expr_UnaryMinus', '-', $node->expr);
     }
 
     protected function pExpr_UnaryPlus(Expr\UnaryPlus $node) {
+        if ($node->expr instanceof Expr\UnaryPlus) {
+            // Enforce +(+$expr) instead of ++$expr
+            return '+(' . $this->p($node->expr) . ')';
+        }
         return $this->pPrefixOp('Expr_UnaryPlus', '+', $node->expr);
     }
 

test/code/prettyPrinter/expr/parentheses.test

@@ -38,6 +38,9 @@ yield from ($a and yield from $b);
 
 print ($a and print $b);
 
+-(-$a);
++(+$a);
+
 // The following will currently add unnecessary parentheses, because the pretty printer is not aware that assignment
 // and incdec only work on variables.
 !$a = $b;
@@ -70,6 +73,8 @@ $a ** $b ** $c;
 yield from $a and yield from $b;
 yield from ($a and yield from $b);
 print ($a and print $b);
+-(-$a);
++(+$a);
 // The following will currently add unnecessary parentheses, because the pretty printer is not aware that assignment
 // and incdec only work on variables.
 !($a = $b);