title: Get access to value that failed validation, in a replacer?
body: <p>When using a custom validation rule and replacer within Laravel, I am really struggling to find any documentation that would simply allow you to get the value that failed validation.</p>
  
  <p>For example, I have created a file exists validator:</p>
  
  <pre><code>Validator::extend('view_exists', function($field,$value,$parameters) 
  {
      return View::exists($value);
  });
  Validator::replacer('view_exists', function($message, $attribute, $rule, $parameters)
  {
      return str_replace(':filename', 'THE ENTERED VALUE', $message);
  });
  </code></pre>
  
  <p>Now, when I create a rule that is:</p>
  
  <pre><code>$rules = array('filename' =&gt; 'required|view_exists');
  $messages = array('filename.view_exists' =&gt; 'Filename \':filename\' does not exist');
  </code></pre>
  
  <p>When I enter an invalid path, such as <code>safsakjhdsafkljh</code>, I was hoping it could return </p>
  
  <pre><code>Filename 'safsakjhdsafkljh' does not exist
  </code></pre>
  
  <p>However the <code>replacer</code> is not able to access the value that failed the validation. I've tried outputting all parameters that are passed to the closure, including <code>$this</code> and it's no where to be seen :( </p>
  
  <p>Before I resort to using <code>Input::get</code> (urgh), am I missing something completely obvious?</p>
  
  <p>Thanks</p>
  
  <p>Gavin</p>