UnionType.php

<?php

declare (strict_types=1);

/*
 * This file is part of sebastian/type.
 *
 * (c) Sebastian Bergmann <sebastian@phpunit.de>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
namespace SebastianBergmann\Type;

use function count;
use function implode;
use function sort;
final class UnionType extends Type {
    
    /**
     * @psalm-var non-empty-list<Type>
     */
    private array $types;
    
    /**
     * @throws RuntimeException
     */
    public function __construct(Type ...$types) {
        $this->ensureMinimumOfTwoTypes(...$types);
        $this->ensureOnlyValidTypes(...$types);
        $this->types = $types;
    }
    public function isAssignable(Type $other) : bool {
        foreach ($this->types as $type) {
            if ($type->isAssignable($other)) {
                return true;
            }
        }
        return false;
    }
    public function asString() : string {
        return $this->name();
    }
    public function name() : string {
        $types = [];
        foreach ($this->types as $type) {
            if ($type->isIntersection()) {
                $types[] = '(' . $type->name() . ')';
                continue;
            }
            $types[] = $type->name();
        }
        sort($types);
        return implode('|', $types);
    }
    public function allowsNull() : bool {
        foreach ($this->types as $type) {
            if ($type instanceof NullType) {
                return true;
            }
        }
        return false;
    }
    
    /**
     * @psalm-assert-if-true UnionType $this
     */
    public function isUnion() : bool {
        return true;
    }
    public function containsIntersectionTypes() : bool {
        foreach ($this->types as $type) {
            if ($type->isIntersection()) {
                return true;
            }
        }
        return false;
    }
    
    /**
     * @psalm-return non-empty-list<Type>
     */
    public function types() : array {
        return $this->types;
    }
    
    /**
     * @throws RuntimeException
     */
    private function ensureMinimumOfTwoTypes(Type ...$types) : void {
        if (count($types) < 2) {
            throw new RuntimeException('A union type must be composed of at least two types');
        }
    }
    
    /**
     * @throws RuntimeException
     */
    private function ensureOnlyValidTypes(Type ...$types) : void {
        foreach ($types as $type) {
            if ($type instanceof UnknownType) {
                throw new RuntimeException('A union type must not be composed of an unknown type');
            }
            if ($type instanceof VoidType) {
                throw new RuntimeException('A union type must not be composed of a void type');
            }
        }
    }

}