Migrate deprecated curly brace array access syntax to bracket syntax. Requires PHP 7.4.

convert_array_access_braces.php

<?php

error_reporting(E_ALL);
$opts = getopt('f:d:rb:', ['ext:', 'php:', 'diff::']);

if ((int)isset($opts['d']) + (int)isset($opts['f']) !== 1) {
    $self = basename(__FILE__);
    echo <<<EOF
Usage:
      php $self -f<php_script> [-b] [--php <path_to_php>] [ --diff [<file>]]
      php $self -d<dir_name> [-b] [-r] [--php <path_to_php>] [--ext <extension>[,<extension>...] [ --diff [<file>]]

Where:
      -f<php_script>      Convert single file <php_script>.
      -d<dir_name>        Convert all ".php"(see "--ext") files inside <dir_name> directory.
      -r                  Walk through directories recursively. Without this flag only concrete directory will be processed.
      -b<backup_dir>      Backup converted files into <backup_dir>.
      --ext               Comma separated list of file extensions for conversion. If set then ".php" will not be added automatically.
      --php <path_to_php> Path to PHP interpreter to migrate.
      --diff[=<file>]     Redirect diff-info into <file>. Write to stdout if <file> does not specified.

Examples:
      php $self -f./index.php -b --diff
          Convert file ./index.php and make backup to ./index.php_backup and show diff

      php $self -d/srv/http/api -r --ext phpt,php
          Convert all ".php" and ".phpt" files inside whole /srv/http/api directory tree

      php $self -d/srv/http/api --php /root/sapi/bin/php --diff=./diff.out
          Convert all ".php" files inside /srv/http/api directory and write diff to ./diff.out
          using /root/sapi/bin/php for check for deprecation
EOF;
    exit(0);
}

$converter = new Converter($opts);

if (isset($opts['f'])) {
    $converter->convertFile($opts['f']);
} elseif (isset($opts['d'])) {
    $converter->convertDirectory($opts['d'], isset($opts['r']));
}

class Converter
{
    private string $php;
    private string $backupDir;
    private array $ext;

    /**
     * @var bool|string
     */
    private $diff;
    private string $dir = '';
    private string $diffContent = '';

    public function __construct(array $opts)
    {
        $this->php = isset($opts['php']) ? $opts['php'] : PHP_BINARY;
        $this->backupDir = isset($opts['b']) ? rtrim($opts['b'], "/\\") . DIRECTORY_SEPARATOR : '';
        $this->ext = isset($opts['ext']) ? explode(',', $opts['ext']) : ['php'];
        $this->diff = isset($opts['diff']) ? ($opts['diff'] !== false ? $opts['diff'] : true) : false;

        if ($this->backupDir && !is_dir($this->backupDir)) {
            $this->fatalError("Backup directory $this->backupDir not found");
        }
    }

    public function convertDirectory(string $dir, bool $recursively): void
    {
        if (!is_dir($dir)) {
            $this->fatalError("Target directory $dir not found");
        }

        $this->dir = rtrim($dir, "/\\") . DIRECTORY_SEPARATOR;
        $regex = '/^.+\.(' . implode('|', $this->ext) . ')$/';

        if ($recursively) {
            $dirIterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($dir));
            $path = '';
        } else {
            $dirIterator = new DirectoryIterator($dir);
            $path = $this->dir;
        }

        $iterator = new RegexIterator($dirIterator, $regex, RegexIterator::GET_MATCH);

        foreach ($iterator as $file) {
            $this->convertFile($path . $file[0]);
        }
    }

    public function convertFile(string $file): void
    {
        if (!is_file($file)) {
            $this->fatalError("Target file $file not found");
        }

        $deprecated = $this->getDeprecatedLines($file);

        if (empty($deprecated)) {
            return;
        }

        $tokens = token_get_all(file_get_contents($file));
        $actualTokens = $this->actualTokens($tokens);

        while ($braces = $this->findPair($actualTokens)) {
            if (
                $actualTokens[$braces[0]] !== '${'   // Complex string.
                && $this->validNext($tokens, $braces[0], $braces[1])
            ) {
                $tokens[$braces[0]] = '[';
                $tokens[$braces[1]] = ']';
            }

            unset($actualTokens[$braces[0]], $actualTokens[$braces[1]]);
        }

        $convertedFile = $this->writeConverted($tokens, $file);
        $this->diff($file, $convertedFile);
        $this->backup($file, $convertedFile);
        $notConverted = $this->getDeprecatedLines($convertedFile);

        if (!empty($notConverted)) {
            foreach ($notConverted as $line) {
                echo " -  Failed to convert line $line in $file" . PHP_EOL;
            }

            echo " ?  $file is not fully converted." . PHP_EOL;
        } else {
            echo "+   $file successfully converted." . PHP_EOL;
        }

        if (!rename($convertedFile, $file)) {
            $this->fatalError("Failed to replace $file with $convertedFile", $convertedFile);
        }
    }

    private function getDeprecatedLines(string $file): array
    {
        $output = [];
        $escapedFile = escapeshellarg($file);
        exec("$this->php -d error_reporting=E_ALL -l $escapedFile 2>&1", $output, $ret);

        if ($ret !== 0) {
            foreach ($output as $string) {
                echo '>   ' . $string . PHP_EOL;
            }

            $this->fatalError("Processing of file $file is failed");
        }

        $output = array_filter($output, fn($line) => preg_match('/Deprecated: +Array and string/i', $line) !== 0);
        array_walk($output, function (&$line) { $line = (int)trim(strrchr($line, ' ')); });
        return $output;
    }

    private function writeConverted(array $tokens, string $original): string
    {
        do {
            $outputFileName = $original . mt_rand(0, 1000);
        } while (is_file($outputFileName));

        $outputFile = fopen($outputFileName, 'wb');

        if (!$outputFile) {
            $this->fatalError("Cannot create temp file $outputFileName");
        }

        foreach ($tokens as $token) {
            if (is_array($token)) {
                fwrite($outputFile, $token[1]);
            } else {
                fwrite($outputFile, $token);
            }
        }

        fclose($outputFile);

        return $outputFileName;
    }

    private function backup(string $file, string $convertedFile): void
    {
        if ($this->backupDir) {
            $backupFileName = $this->backupDir . str_replace($this->dir, '', $file);
            if (!is_dir(pathinfo($backupFileName, PATHINFO_DIRNAME))) {
                if (!mkdir(pathinfo($backupFileName, PATHINFO_DIRNAME), 0777, true)) {
                    $this->fatalError("Failed to create directory tree for $backupFileName", $convertedFile);
                }
            }
            if (!rename($file, $backupFileName)) {
                $this->fatalError("Failed to backup $file into $backupFileName", $convertedFile);
            }
        }
    }

    private function actualTokens(array $tokens): array
    {
        $result = [];
        $inString = false;
        $depth = 0;

        foreach ($tokens as $key => $token) {
            if ($token === '"') {
                $inString = !$inString;
            }

            $tokenStr = null;

            if ($token === '{' || $token === '}') {
                $tokenStr = $token;
            } else if (is_array($token) && ($token[1] === '${' || $token[1] === '{' || $token[1] === '->')) {
                $tokenStr = $token[1];
            }

            if ($tokenStr !== null) {
                if ($inString) {
                    if ($tokenStr === '}') {
                        $depth--;

                        if ($depth === 0) {
                            continue; // ignore outer closing brace
                        }
                    } else {
                        $depth++;

                        if ($depth === 1) {
                            continue; // ignore outer opening brace
                        }
                    }
                }

                $result[$key] = $tokenStr;
            }
        }

        return $result;
    }

    /**
     * @return int[] | null
     */
    private function findPair(array $tokens): ?array
    {
        if (count($tokens) < 2) {
            return null;
        }

        $last = '';
        $lastKey = 0;

        foreach ($tokens as $key => $token) {
            if ($token === '{' && $last === '->') {
                continue;
            }

            if (($last === '{' || $last === '${') && $token === '}') {
                return [$lastKey, $key];
            } else {
                $last = $token;
                $lastKey = $key;
            }
        }

        return null;
    }

    private function validNext(array $tokens, int $index, int $endIndex): bool
    {
        $index++;

        if ($tokens[$index] === '}') {
            return false; // empty block
        }

        $trivialTokens = [T_COMMENT, T_DOC_COMMENT, T_WHITESPACE];
        $hasNonTrivialTokens = false;

        while ($index < $endIndex) {
            if ($tokens[$index] === ';') {
                return false; // array/string offset accesses can't contain semicolon
            }

            if  (!is_array($tokens[$index]) || !in_array($tokens[$index][0], $trivialTokens, true)) {
                $hasNonTrivialTokens = true;
            }

            $index++;
        }

        return $hasNonTrivialTokens;
    }

    private function fatalError(string $text, string $file = ''): void
    {
        if ($file) {
            unlink($file);
        }

        if ($this->diffContent !== '') {
            $this->writeDiff();
        }

        die($text . PHP_EOL);
    }

    private function diff(string $file, string $convertedFile): void
    {
        if (!$this->diff) {
            return;
        }

        $original = fopen($file, 'rb');
        $converted = fopen($convertedFile, 'rb');
        $i = 1;

        $this->diffContent .= "file: $file" . PHP_EOL;

        while (($line = fgets($original)) !== false) {
            $newLine = fgets($converted);

            if ($line !== $newLine) {
                $this->diffContent .= $i . 'c' . $i . PHP_EOL;
                $this->diffContent .= "< $line";
                $this->diffContent .= '---' . PHP_EOL;
                $this->diffContent .= "> $newLine" . PHP_EOL;
            }

            $i++;
        }

        fclose($converted);
        fclose($original);
    }

    private function writeDiff(): void
    {
        if ($this->diff === true) {
            echo $this->diffContent;
        } else if ($this->diff !== false) {
            file_put_contents($this->diff, $this->diffContent);
        }
    }

    public function __destruct()
    {
        $this->writeDiff();
    }
}

@hassanbouaakab thank you so much. I can't be happier.

Can you please do another favor?

See the error_log below from the Bluehost public_html/error_log file.

Apart from the errors Array and string offset access syntax with curly braces is no longer supported can you shed some light on how to troubleshoot and resolve the other errors? I manually fixed all curly braces references. But with PHP 8.0 and 8.1 I get all the other creepy errors as per the log below. They all seem due to compatibility errors with PHP version 8.x as I am using CherryFramework and Doing Business WordPress Template which seems not compatible with PHP 8.x. I contacted the developer but looks like they are going to charge me for this modification. I am checking if there is a free option. I am a solid developer and I can deal with PHP even though I never worked with it. All I am asking is to give me some pointers.

[14-Dec-2022 00:18:17 UTC] PHP Warning:  The magic method MPCERevisionManager::__wakeup() must have public visibility in /path/to/root/public_html/wp-content/plugins/motopress-content-editor/includes/ce/MPCERevisionManager.php on line 299
[24-Dec-2022 06:08:31 UTC] PHP Warning:  Use of undefined constant CHERRY_PLUGIN_URL - assumed 'CHERRY_PLUGIN_URL' (this will throw an Error in a future version of PHP) in /path/to/root/public_html/wp-content/themes/theme50603/includes/custom-function.php on line 1114
[24-Dec-2022 07:02:50 UTC] PHP Fatal error:  Array and string offset access syntax with curly braces is no longer supported in /path/to/root/public_html/wp-content/themes/CherryFramework/includes/lessc.inc.php on line 657
[24-Dec-2022 07:45:48 UTC] PHP Warning:  array_merge(): Expected parameter 2 to be an array, null given in /path/to/root/public_html/wp-content/plugins/ultimate-product-catalogue/includes/Product.class.php on line 483
[24-Dec-2022 07:45:48 UTC] PHP Warning:  Invalid argument supplied for foreach() in /path/to/root/public_html/wp-content/plugins/ultimate-product-catalogue/ewd-upcp-templates/single-product-additional-images.php on line 3
[24-Dec-2022 08:11:10 UTC] PHP Fatal error:  Array and string offset access syntax with curly braces is no longer supported in /path/to/root/public_html/wp-content/themes/CherryFramework/includes/lessc.inc.php on line 1624
[24-Dec-2022 08:12:23 UTC] PHP Fatal error:  Array and string offset access syntax with curly braces is no longer supported in /path/to/root/public_html/wp-content/themes/CherryFramework/includes/lessc.inc.php on line 2281
[24-Dec-2022 08:13:30 UTC] PHP Fatal error:  Array and string offset access syntax with curly braces is no longer supported in /path/to/root/public_html/wp-content/themes/CherryFramework/includes/lessc.inc.php on line 2335
[24-Dec-2022 08:14:13 UTC] PHP Fatal error:  Array and string offset access syntax with curly braces is no longer supported in /path/to/root/public_html/wp-content/themes/CherryFramework/includes/lessc.inc.php on line 3065
[24-Dec-2022 08:15:23 UTC] PHP Fatal error:  Unparenthesized `a ? b : c ? d : e` is not supported. Use either `(a ? b : c) ? d : e` or `a ? b : (c ? d : e)` in /path/to/root/public_html/wp-content/plugins/cherry-plugin/includes/plugin-assets.php on line 102
[24-Dec-2022 08:21:19 UTC] PHP Fatal error:  Uncaught ArgumentCountError: Too few arguments to function WP_Widget::__construct(), 0 passed in /path/to/root/public_html/wp-includes/class-wp-widget-factory.php on line 61 and at least 2 expected in /path/to/root/public_html/wp-includes/class-wp-widget.php:162
Stack trace:
#0 /path/to/root/public_html/wp-includes/class-wp-widget-factory.php(61): WP_Widget->__construct()
#1 /path/to/root/public_html/wp-includes/widgets.php(115): WP_Widget_Factory->register('My_SocialNetwor...')
#2 /path/to/root/public_html/wp-content/plugins/cherry-plugin/includes/widgets/register-widgets.php(26): register_widget('My_SocialNetwor...')
#3 /path/to/root/public_html/wp-includes/class-wp-hook.php(307): cherry_load_widgets('')
#4 /path/to/root/public_html/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters(NULL, Array)
#5 /path/to/root/public_html/wp-includes/plugin.php(474): WP_Hook->do_action(Array)
#6 /path/to/root/public_html/wp-includes/widgets.php(1854): do_action('widgets_init')
#7 /path/to/root/public_html/wp-includes/class-wp-hook.php(307): wp_widgets_init('')
#8 /path/to/root/public_html/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters(NULL, Array)
#9 /path/to/root/public_html/wp-includes/plugin.php(474): WP_Hook->do_action(Array)
#10 /path/to/root/public_html/wp-settings.php(587): do_action('init')
#11 /path/to/root/public_html/wp-config.php(100): require_once('/path/to/root...')
#12 /path/to/root/public_html/wp-load.php(50): require_once('/path/to/root...')
#13 /path/to/root/public_html/wp-blog-header.php(13): require_once('/path/to/root...')
#14 /path/to/root/public_html/index.php(17): require('/path/to/root...')
#15 {main}
  thrown in /path/to/root/public_html/wp-includes/class-wp-widget.php on line 162

When you update to php 8 you get a lot of error i had this problem i tried to fix them manually but every time a get new ones you can use rector to upgrade your project: https://getrector.org/blog/2020/11/30/smooth-upgrade-to-php-8-in-diffs
You can downgrade your site in bluehost to php 7.4 temporarily but it's best to use the new wordpress version an migrate your projet.

This script saved me a lot of work, thanks for sharing!

One special case needed manual work, though, $ab->cd{123}.