Actually, even better. #475

- also handle x = + ++y, x = - --y;
- don't use parens, a space suffices.

lib/output.js

@@ -455,8 +455,7 @@ function OutputStream(options) {
 
     PARENS(AST_Unary, function(output){
         var p = output.parent();
-        return (p instanceof AST_PropAccess && p.expression === this)
-            || (p instanceof AST_Unary && p.operator == this.operator);
+        return p instanceof AST_PropAccess && p.expression === this;
     });
 
     PARENS(AST_Seq, function(output){
@@ -997,8 +996,12 @@ function OutputStream(options) {
     DEFPRINT(AST_UnaryPrefix, function(self, output){
         var op = self.operator;
         output.print(op);
-        if (/^[a-z]/i.test(op))
+        if (/^[a-z]/i.test(op)
+            || (/[+-]$/.test(op)
+                && self.expression instanceof AST_UnaryPrefix
+                && /^[+-]/.test(self.expression.operator))) {
             output.space();
+        }
         self.expression.print(output);
     });
     DEFPRINT(AST_UnaryPostfix, function(self, output){