psalm/src/Psalm/Checker/InterfaceChecker.php

<?php
namespace Psalm\Checker;

use PhpParser;
use Psalm\StatementsSource;

class InterfaceChecker extends ClassLikeChecker
{
    /**
     * @param PhpParser\Node\Stmt\Interface_ $interface
     * @param StatementsSource               $source
     * @param string                         $fq_interface_name
     */
    public function __construct(PhpParser\Node\Stmt\Interface_ $interface, StatementsSource $source, $fq_interface_name)
    {
        parent::__construct($interface, $source, $fq_interface_name);
    }

    /**
     * @param  string       $fq_interface_name
     * @param  FileChecker  $file_checker
     *
     * @return bool
     */
    public static function interfaceExists(ProjectChecker $project_checker, $fq_interface_name)
    {
        if (isset(self::$SPECIAL_TYPES[strtolower($fq_interface_name)])) {
            return false;
        }

        return $project_checker->hasFullyQualifiedInterfaceName($fq_interface_name);
    }

    /**
     * @param  string       $fq_interface_name
     * @param  FileChecker  $file_checker
     *
     * @return bool
     */
    public static function hasCorrectCasing(ProjectChecker $project_checker, $fq_interface_name)
    {
        return isset($project_checker->existing_interfaces[$fq_interface_name]);
    }

    /**
     * @param  string       $interface_name
     * @param  string       $possible_parent
     * @param  FileChecker  $file_checker
     *
     * @return bool
     */
    public static function interfaceExtends(ProjectChecker $project_checker, $interface_name, $possible_parent)
    {
        return in_array($possible_parent, self::getParentInterfaces($project_checker, $interface_name), true);
    }

    /**
     * @param  string       $fq_interface_name
     * @param  FileChecker  $file_checker
     *
     * @return array<string>   all interfaces extended by $interface_name
     */
    public static function getParentInterfaces(ProjectChecker $project_checker, $fq_interface_name)
    {
        $fq_interface_name = strtolower($fq_interface_name);

        $extended_interfaces = [];

        $storage = $project_checker->classlike_storage_provider->get($fq_interface_name);

        return $storage->parent_interfaces;
    }
}