<?php
function enum($x) {
    $tmp = array_flip(preg_split('/\W+/', $x, -1, PREG_SPLIT_NO_EMPTY));
    array_walk($tmp, function($value, $key){$GLOBALS[$key] = $value;});
}

enum(<<<'S'
    NULL
    ONE
    TWO
    THREE
    FORTH
S
);

printf("%d %d %d %d %d\n",  $NULL, $ONE, $TWO, $THREE, $FORTH);