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About

The reference printer for TypeLang. It renders TypeLang\Type\* AST nodes back into their string representation.

Two printers are provided:

• NativeTypePrinter — outputs a valid, native PHP type declaration.
• PrettyTypePrinter — outputs the full PHPStan/Psalm-style type, formatted across multiple lines.

Full documentation is available at typelang.dev.

Installation

Install the package via Composer:

composer require type-lang/printer

Requirements:

• PHP 8.1+

Usage

Parse a type into an AST (using type-lang/parser), then print it back with either printer:

$parser = new TypeLang\Parser\TypeParser();

$type = $parser->parse(<<<'PHP'
    array{
        field1: (callable(Example, int): mixed),
        field2: list<Some>,
        ...
    }
    PHP);

echo (new TypeLang\Printer\NativeTypePrinter())->print($type);
// array

echo (new TypeLang\Printer\PrettyTypePrinter())->print($type);
// array{
//     field1: callable(Example, int): mixed,
//     field2: list<Some>,
//     ...
// }

Options

The formatting is set with the PrinterOptions:

use TypeLang\Printer\PrettyTypePrinter;
use TypeLang\Printer\PrinterOptions;
use TypeLang\Printer\PrinterOptions\CommaSpacing;
use TypeLang\Printer\PrinterOptions\ListStyle;
use TypeLang\Printer\PrinterOptions\NullableStyle;
use TypeLang\Printer\PrinterOptions\UnionSpacing;

$printer = new PrettyTypePrinter(new PrinterOptions(
    unionSpacing: UnionSpacing::Spaced,        // int | string
    maxInlineTemplateItems: 2,             // array<K, V> is written one argument per line after 2 of them
    commaSpacing: CommaSpacing::Compact,       // array<K,V>
    nullableStyle: NullableStyle::Union,   // int|null instead of ?int
    listStyle: ListStyle::Generic,         // array<int> instead of int[]
));

Printing a node in your own way

Every kind of node is printed by its own NodePrinterInterface, and a printer looks them up in a registry. To change how a node is printed, replace its printer instead of extending the printer:

use TypeLang\Printer\NodePrinterInterface;
use TypeLang\Printer\PrettyTypePrinter;
use TypeLang\Printer\PrinterContext;
use TypeLang\Printer\TypePrinter;
use TypeLang\Type\NamedTypeNode;
use TypeLang\Type\Node;

/**
 * @template-implements NodePrinterInterface<NamedTypeNode>
 */
final class ShoutingNamePrinter implements NodePrinterInterface
{
    public function printNode(Node $node, PrinterContext $context): string
    {
        return \strtoupper($node->name->toString());
    }
}

$printer = new TypePrinter(
    PrettyTypePrinter::createRegistry()->with(NamedTypeNode::class, new ShoutingNamePrinter()),
);

A node without its own printer is printed by the printer of the closest parent class. The PrinterContext prints the children of a node ($context->print()) and carries the options.