Correctly pretty print negative floats

lib/PhpParser/PrettyPrinter/Standard.php

@@ -98,7 +98,7 @@ class Standard extends PrettyPrinterAbstract
         $stringValue = (string) $node->value;
 
         // ensure that number is really printed as float
-        return ctype_digit($stringValue) ? $stringValue . '.0' : $stringValue;
+        return preg_match('/^-?[0-9]+$/', $stringValue) ? $stringValue . '.0' : $stringValue;
     }
 
     // Assignments

test/code/prettyPrinter/numbers.test

@@ -0,0 +1,35 @@
+Number literals
+-----
+<?php
+
+0;
++0;
+-0;
+0.0;
+-0.0;
+42;
+-42;
+42.0;
+-42.0;
+42.5;
+-42.5;
+1e42;
+-1e42;
+1e1000;
+-1e1000;
+-----
+0;
++0;
+-0;
+0.0;
+-0.0;
+42;
+-42;
+42.0;
+-42.0;
+42.5;
+-42.5;
+1.0E+42;
+-1.0E+42;
+INF;
+-INF;