Schema: add has_attribute() method

src/Schema.php

@@ -217,4 +217,26 @@ class Schema {
     return $this -> _get_entry('Syntax', $name_or_oid);
   }
 
+  /**
+   * Check if given objectclass have the specified attribute
+   * @param string $attr The attribute name
+   * @param string|array<string> $objectclasses List of objectclass
+   * @return bool
+   */
+  public function has_attribute($attr, ...$objectclasses) {
+    foreach($objectclasses as $objectclass) {
+      if (is_array($objectclass)) {
+        if (call_user_func_array(array($this, 'has_attribute'), array_merge(array($attr), $objectclass)))
+          return true;
+        continue;
+      }
+      $oc = $this -> objectclass($objectclass);
+      if (!$oc)
+        continue;
+      if ($oc->has_attribute($attr))
+        return true;
+    }
+    return false;
+  }
+
 }

src/Schema/ObjectClass.php

@@ -74,4 +74,17 @@ class ObjectClass extends SchemaEntry {
     }
     return parent::__get($key);
   }
+
+  /**
+   * Check if the given attribute is used by the objectclass
+   * @param string $attr The attribute name
+   * @return bool
+   */
+  public function has_attribute($attr) {
+    if (in_array($attr, $this->must))
+      return true;
+    if (in_array($attr, $this->may))
+      return true;
+    return false;
+  }
 }