CamelCase to Snake_case

CamelToSnake.php

<?php
function camelToSnake($input)
{
 if (preg_match('/[A-Z]/', $input) === 0) {
   return $input;
 }
 $pattern = '/([a-z])([A-Z])/';
 $r = strtolower(preg_replace_callback($pattern, function ($a) {
  return $a[1] ."_". strtolower($a[2]); 
 }, $input));
 return $r;
}