PHP callable to source code

callable2code.php

<?php

public function callableToCode(mixed $callable): ?string
{
    if (is_string($callable) && str_contains($callable, '@')) {
        $callable = explode('@', $callable);
    }
    if (is_array($callable) && count($callable) === 2) {
        [$class, $method] = $callable;
        $instance = app($class);
        $callable = $instance->$method(...);
    }
    try {
        $reflection = new ReflectionFunction($callable);
    } catch (ReflectionException) {
        return null;
    }
    if ($path = $reflection->getFileName()) {
        $file = file($path);
        $start = $reflection->getStartLine() - 1;
        $end = $reflection->getEndLine();
        $length = $end - $start;
        $lines = collect(array_slice($file, $start, $length))->map(fn($line) => rtrim($line));
        $indent = $lines->filter()->min(fn(string $line) => strlen($line) - strlen(ltrim($line)));

        return $lines->map(function(string $line) use ($indent) {
            if (preg_match('/\S/', $line)) {
                return substr($line, $indent);
            }

            return $line;
        })->join(PHP_EOL);
    }

    return null;
}