enum._.php

<?php

/**
 * Macro to backport enum from the future 
 */
macro {
    enum T_STRING·name {
        ·ls
        (
            ·rtoken('/^\w+$/')·field
            ,
            ','
        )
        ·fields
    }
} >> {
    final class T_STRING·name {
        private static $store;

        private function __construct(){}

        function __(string $field) : self {
            if(! self::$store) {
                self::$store = new \stdclass;
                ·fields ··· {
                    self::$store->·field = new class extends T_STRING·name {};
                }
            }

            if (! $field = self::$store->$field ?? false)
                throw new \Exception(
                    "Undefined enum field " . __CLASS__ . "->{$field}.");
        }
    }
}

macro { \T_STRING·enum->T_STRING·field } >> { \T_STRING·enum::__(@T_STRING·field) }

// src

enum Fruits {
    Apple,
    Orange
}

var_dump(\Fruits->Orange <=> \Fruits->Apple);

enum.expanded.php

<?php

final class Fruits {
        private static $store;

        private function __construct(){}

        function __(string $field) : self {
            if(! self::$store) {
                self::$store = new \stdclass;
                self::$store->Apple = new class extends Fruits {};
                self::$store->Orange = new class extends Fruits {};
                
            }

            if (! $field = self::$store->$field ?? false)
                throw new \Exception(
                    "Undefined enum field " . __CLASS__ . "->{$field}.");
        }
    }

var_dump(\Fruits::__(@Orange) <=> \Fruits::__(@Apple));