PHP-Parser/UPGRADE-5.0.md

Upgrading from PHP-Parser 4.x to 5.0
====================================

### PHP version requirements

PHP-Parser now requires PHP 7.1 or newer to run. It is however still possible to *parse* code for older versions, while running on a newer version.

### Changes to the default pretty printer

A number of changes to the standard pretty printer have been made, to make it match contemporary coding style conventions (and in particular PSR-12). Options to restore the previous behavior are not provided, but it is possible to override the formatting methods (such as `pStmt_ClassMethod`) with your preferred formatting.

Return types are now formatted without a space before the `:`:

```php
# Before
function test() : Type
{
}

# After
function test(): Type
{
}
```

`abstract` and `final` are now printed before visibility modifiers:

```php
# Before
public abstract function test();

# After
abstract public function test();
```

A space is now printed between `use` and the following `(` for closures:

```php
# Before
function () use($var) {
};

# After
function () use ($var) {
};
```

### Changes to token representation

Tokens are now internally represented using the `PhpParser\Token` class, which exposes the same base interface as
the `PhpToken` class introduced in PHP 8.0. On PHP 8.0 or newer, `PhpParser\Token` extends from `PhpToken`, otherwise
it extends from a polyfill implementation. The most important parts of the interface may be summarized as follows:

```php
class Token {
    public int $id;
    public string $text;
    public int $line;
    public int $pos;

    public function is(int|string|array $kind): bool;
}
```

The `Lexer::getTokens()` method will now return an array of `Token`s, rather than an array of arrays and strings.
Additionally, the token array is now terminated by a sentinel token with ID 0.