Const map trait

ConstMapTrait.php

<?php
trait ConstMapTrait{
	private static $const_map = [];
	public static function const_map($prefix = 0){
		if(! isset(self::$const_map[$prefix])){
			if(0 === $prefix){
				self::$const_map[$prefix] = (new \ReflectionClass(get_called_class()))->getConstants();
			} else {
				self::const_map();
				$list = self::$const_map[0];
				// $filterd = array_filter($list, function($key){ return 0 === stripos($key, $prefix); }, ARRAY_FILTER_USE_KEY); // PHP 5.6
				$filterd = [];
				foreach($list as $key => $value){
					if( 0 === stripos($key, $prefix) ) $filterd[$key] = $value;
				}
				self::$const_map[$prefix] = $filterd;
			}
		}
		return array_flip(self::$const_map[$prefix]);
	}
}