Middleman没有在本地运行Regex功能

Question

I have this simple php function

<?php
$ELASTIC_SEARCH_SPECIAL_KEYWORDS = "/[\\+\\-\\=\\&\\|\\!\\(\\)\\{\\}\\[\\]\\^\\\"\\~\\*\\<\\>\\?\\:\\\\\\/]/";

function escapeESReservedChars($text) {
  global $ELASTIC_SEARCH_SPECIAL_KEYWORDS;
  $result = preg_replace_callback ($ELASTIC_SEARCH_SPECIAL_KEYWORDS,
    function ($matches) {
      return "\\" . $matches[0];
    }, $text);
  return $result;
}

Here $text is any text message where if there is any special chars,it will replace that with \\

It run only when i make build & upload to server. If i run this file on localhost it neither run not throw any error. There is no problem with this function. I think middleman is doing something behind the screen.