CallableType.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 assert;
use function class_exists;
use function count;
use function explode;
use function function_exists;
use function is_array;
use function is_object;
use function is_string;
use function str_contains;
use Closure;
use ReflectionClass;
use ReflectionObject;
final class CallableType extends Type {
    private bool $allowsNull;
    public function __construct(bool $nullable) {
        $this->allowsNull = $nullable;
    }
    public function isAssignable(Type $other) : bool {
        if ($this->allowsNull && $other instanceof NullType) {
            return true;
        }
        if ($other instanceof self) {
            return true;
        }
        if ($other instanceof ObjectType) {
            if ($this->isClosure($other)) {
                return true;
            }
            if ($this->hasInvokeMethod($other)) {
                return true;
            }
        }
        if ($other instanceof SimpleType) {
            if ($this->isFunction($other)) {
                return true;
            }
            if ($this->isClassCallback($other)) {
                return true;
            }
            if ($this->isObjectCallback($other)) {
                return true;
            }
        }
        return false;
    }
    public function name() : string {
        return 'callable';
    }
    public function allowsNull() : bool {
        return $this->allowsNull;
    }
    
    /**
     * @psalm-assert-if-true CallableType $this
     */
    public function isCallable() : bool {
        return true;
    }
    private function isClosure(ObjectType $type) : bool {
        return $type->className()
            ->qualifiedName() === Closure::class;
    }
    private function hasInvokeMethod(ObjectType $type) : bool {
        $className = $type->className()
            ->qualifiedName();
        assert(class_exists($className));
        return (new ReflectionClass($className))->hasMethod('__invoke');
    }
    private function isFunction(SimpleType $type) : bool {
        if (!is_string($type->value())) {
            return false;
        }
        return function_exists($type->value());
    }
    private function isObjectCallback(SimpleType $type) : bool {
        if (!is_array($type->value())) {
            return false;
        }
        if (count($type->value()) !== 2) {
            return false;
        }
        if (!isset($type->value()[0], $type->value()[1])) {
            return false;
        }
        if (!is_object($type->value()[0]) || !is_string($type->value()[1])) {
            return false;
        }
        [
            $object,
            $methodName,
        ] = $type->value();
        return (new ReflectionObject($object))->hasMethod($methodName);
    }
    private function isClassCallback(SimpleType $type) : bool {
        if (!is_string($type->value()) && !is_array($type->value())) {
            return false;
        }
        if (is_string($type->value())) {
            if (!str_contains($type->value(), '::')) {
                return false;
            }
            [
                $className,
                $methodName,
            ] = explode('::', $type->value());
        }
        if (is_array($type->value())) {
            if (count($type->value()) !== 2) {
                return false;
            }
            if (!isset($type->value()[0], $type->value()[1])) {
                return false;
            }
            if (!is_string($type->value()[0]) || !is_string($type->value()[1])) {
                return false;
            }
            [
                $className,
                $methodName,
            ] = $type->value();
        }
        assert(isset($className) && is_string($className));
        assert(isset($methodName) && is_string($methodName));
        if (!class_exists($className)) {
            return false;
        }
        $class = new ReflectionClass($className);
        if (!$class->hasMethod($methodName)) {
            return false;
        }
        $method = $class->getMethod($methodName);
        return $method->isPublic() && $method->isStatic();
    }

}