class_alias.php

<?php

declare(strict_types=1);

namespace Psl\ObjectOriented;

use function class_alias as php_class_alias;
use function function_exists as php_function_exists;

/**
 * Creates an alias for a class.
 *
 * Example:
 *
 *      $class_name = Collection\Vector::class;
 *      $alias = 'AwesomeVector';
 *
 *      ObjectOriented\class_alias($class_name, $alias);
 *      => Bool(true)
 *
 *      $vector = new $alias(['a', 'b']);
 *
 *      Type\object($class_name)->matches($vector);
 *      => Bool(true)
 *
 * @template T
 *
 * @param class-string<T> $class_name
 *
 * @psalm-assert-if-true class-string<T> $alias
 *
 * @return bool Returns false if unable to create an alias.
 */
function class_alias(string $class_name, string $alias): bool
{
    // This is a weird scenario.
    // assuming $alias is `Psl\Str\contains`
    // attempting to call `class_exists` will result in the autoloader being triggered.
    // trying to find the class `Psl\Str\contains`.
    // this results composer autoloader including `src/Psl/Str/contains.php` again,
    // which contains the function definition, leading to a fatal error due to
    // redeclaration of the function.
    //
    // so we have to ensure we don't call `*_exists` function in this case.
    if (!php_function_exists($alias)) {
        if (class_exists($alias)) {
            return false;
        }

        if (interface_exists($alias)) {
            return false;
        }

        if (trait_exists($alias)) {
            return false;
        }
    }

    return php_class_alias($class_name, $alias);
}