Implement isDefaultValueConstant and fix getDefaultValueConstantName

hphp/runtime/ext/reflection/ext_reflection-classes.php

@@ -358,6 +358,36 @@ public function isDefaultValueAvailable() {
     return (!$defaultValue instanceof stdClass);
   }
 
+  /**
+   * ( excerpt from
+   * http://php.net/manual/en/reflectionparameter.isdefaultvalueconstant.php
+   * )
+   *
+   * Returns whether the default value of this parameter is constant.
+   *
+   * @return mixed true if a default value is constant, false if it is not
+   * or NULL on failure.
+   */
+  public function isDefaultValueConstant() {
+    if (array_key_exists('default', $this->info)) {
+      $defaultText = $this->info['defaultText'];
+
+      $quoted_pattern = '/^(["\']).*\1$/';
+      $braketed_pattern  = '/^\[.*\]$/';
+
+      if(is_numeric($defaultText) ||
+         in_array($defaultText, array('NULL', 'true', 'false')) ||
+         preg_match($quoted_pattern, $defaultText) ||
+         preg_match($braketed_pattern, $defaultText) ||
+         substr($defaultText, 0, 5) === 'array')
+         return false;
+
+      return true;
+
+    }
+    return NULL;
+  }
+
   // This doc comment block generated by idl/sysdoc.php
   /**
    * ( excerpt from
@@ -399,11 +429,11 @@ public function getDefaultValueText() {
    * @return     mixed   Returns string on success or NULL on failure.
    */
   public function getDefaultValueConstantName() {
-    if (array_key_exists('defaultText', $this->info)) {
+    if ($this->isDefaultValueConstant()) {
       return $this->info['defaultText'];
     }
 
-    return '';
+    return NULL;
   }
 
   // This doc comment block generated by idl/sysdoc.php

hphp/test/slow/reflection/is_default_value_constant.php

@@ -0,0 +1,26 @@
+<?php
+
+const ONE = 1;
+const TWO = 3.1415;
+const THREE = "this is a constant string";
+const FOUR = true;
+
+function params($a = "string param",
+                $b = ONE,
+                $c=TWO,
+                $d=THREE,
+                $e=FOUR,
+                $f=[1,2,3]) {
+}
+
+function test($param) {
+  $r = new ReflectionParameter('params', $param);
+  var_dump($r->isDefaultValueConstant());
+}
+
+test('a');
+test('b');
+test('c');
+test('d');
+test('e');
+test('f');

hphp/test/slow/reflection/is_default_value_constant.php.expect

@@ -0,0 +1,6 @@
+bool(false)
+bool(true)
+bool(true)
+bool(true)
+bool(true)
+bool(false)