1<?php declare(strict_types=1);
2
3namespace PhpParser;
4
5if (!\function_exists('PhpParser\defineCompatibilityTokens')) {
6    function defineCompatibilityTokens(): void {
7        $compatTokens = [
8            // PHP 8.0
9            'T_NAME_QUALIFIED',
10            'T_NAME_FULLY_QUALIFIED',
11            'T_NAME_RELATIVE',
12            'T_MATCH',
13            'T_NULLSAFE_OBJECT_OPERATOR',
14            'T_ATTRIBUTE',
15            // PHP 8.1
16            'T_ENUM',
17            'T_AMPERSAND_NOT_FOLLOWED_BY_VAR_OR_VARARG',
18            'T_AMPERSAND_FOLLOWED_BY_VAR_OR_VARARG',
19            'T_READONLY',
20        ];
21
22        // PHP-Parser might be used together with another library that also emulates some or all
23        // of these tokens. Perform a sanity-check that all already defined tokens have been
24        // assigned a unique ID.
25        $usedTokenIds = [];
26        foreach ($compatTokens as $token) {
27            if (\defined($token)) {
28                $tokenId = \constant($token);
29                if (!\is_int($tokenId)) {
30                    throw new \Error(sprintf(
31                        'Token %s has ID of type %s, should be int. ' .
32                        'You may be using a library with broken token emulation',
33                        $token, \gettype($tokenId)
34                    ));
35                }
36                $clashingToken = $usedTokenIds[$tokenId] ?? null;
37                if ($clashingToken !== null) {
38                    throw new \Error(sprintf(
39                        'Token %s has same ID as token %s, ' .
40                        'you may be using a library with broken token emulation',
41                        $token, $clashingToken
42                    ));
43                }
44                $usedTokenIds[$tokenId] = $token;
45            }
46        }
47
48        // Now define any tokens that have not yet been emulated. Try to assign IDs from -1
49        // downwards, but skip any IDs that may already be in use.
50        $newTokenId = -1;
51        foreach ($compatTokens as $token) {
52            if (!\defined($token)) {
53                while (isset($usedTokenIds[$newTokenId])) {
54                    $newTokenId--;
55                }
56                \define($token, $newTokenId);
57                $newTokenId--;
58            }
59        }
60    }
61
62    defineCompatibilityTokens();
63}
64