psalm/src/Psalm/Checker/ProjectChecker.php

<?php
namespace Psalm\Checker;

use Psalm\Config;
use Psalm\Context;
use Psalm\Exception;
use Psalm\Issue\PossiblyUnusedMethod;
use Psalm\Issue\UnusedClass;
use Psalm\Issue\UnusedMethod;
use Psalm\IssueBuffer;
use Psalm\Provider\CacheProvider;
use Psalm\Provider\FileProvider;
use Psalm\Provider\FileReferenceProvider;
use Psalm\Storage\PropertyStorage;
use Psalm\Type;
use RecursiveDirectoryIterator;
use RecursiveIteratorIterator;

class ProjectChecker
{
    /**
     * Cached config
     *
     * @var Config|null
     */
    private $config;

    /**
     * @var self
     */
    public static $instance;

    /**
     * Whether or not to use colors in error output
     *
     * @var bool
     */
    public $use_color;

    /**
     * Whether or not to show informational messages
     *
     * @var bool
     */
    public $show_info;

    /**
     * @var string
     */
    public $output_format;

    /**
     * @var bool
     */
    public $collect_references = false;

    /**
     * @var string|null
     */
    public $find_references_to;

    /**
     * @var bool
     */
    public $debug_output = false;

    /**
     * @var bool
     */
    public $update_docblocks = false;

    /**
     * @var bool
     */
    public $cache = false;

    /**
     * @var array<string, bool>
     */
    private $existing_classlikes_ci = [];

    /**
     * @var array<string, bool>
     */
    private $existing_classlikes = [];

    /**
     * @var array<string, bool>
     */
    private $existing_classes_ci = [];

    /**
     * @var array<string, bool>
     */
    public $existing_classes = [];

    /**
     * @var array<string, bool>
     */
    private $existing_interfaces_ci = [];

    /**
     * @var array<string, bool>
     */
    public $existing_interfaces = [];

    /**
     * @var array<string, bool>
     */
    private $existing_traits_ci = [];

    /**
     * @var array<string, bool>
     */
    public $existing_traits = [];

    /**
     * @var array<string, string>
     */
    private $classlike_files = [];

    /**
     * @var array<string, string>
     */
    private $files_to_visit = [];

    /**
     * @var array<string, bool>
     */
    private $files_to_analyze = [];

    /**
     * @var array<string, bool>
     */
    private $visited_files = [];

    /**
     * @var array<string, bool>
     */
    private $visited_classes = [];

    /**
     * @var array<string, FileChecker>
     */
    private $file_checkers = [];

    /**
     * @var array<string, MethodChecker>
     */
    public $method_checkers = [];

    /**
     * @var array<string, int>
     */
    public $classlike_references = [];

    /**
     * A map of fully-qualified use declarations to the files
     * that reference them (keyed by filename)
     *
     * @var array<string, array<string, array<int, \Psalm\CodeLocation>>>
     */
    public $use_referencing_locations = [];

    /**
     * A map of file names to the classes that they contain explicit references to
     * used in collaboration with use_referencing_locations
     *
     * @var array<string, array<string, bool>>
     */
    public $use_referencing_files = [];

    /**
     * @var array<string, string>
     */
    public $fake_files = [];

    /**
     * @var bool
     */
    public $server_mode = false;

    /**
     * Whether to log functions just at the file level or globally (for stubs)
     *
     * @var bool
     */
    public $register_global_functions = false;

    const TYPE_CONSOLE = 'console';
    const TYPE_JSON = 'json';
    const TYPE_EMACS = 'emacs';

    /**
     * @param bool $use_color
     * @param bool $show_info
     * @param bool $debug_output
     * @param string  $output_format
     * @param bool    $update_docblocks
     * @param bool    $collect_references
     * @param string  $find_references_to
     */
    public function __construct(
        $use_color = true,
        $show_info = true,
        $output_format = self::TYPE_CONSOLE,
        $debug_output = false,
        $update_docblocks = false,
        $collect_references = false,
        $find_references_to = null
    ) {
        $this->use_color = $use_color;
        $this->show_info = $show_info;
        $this->debug_output = $debug_output;
        $this->update_docblocks = $update_docblocks;
        $this->collect_references = $collect_references;
        $this->find_references_to = $find_references_to;

        if (!in_array($output_format, [self::TYPE_CONSOLE, self::TYPE_JSON, self::TYPE_EMACS], true)) {
            throw new \UnexpectedValueException('Unrecognised output format ' . $output_format);
        }

        $this->output_format = $output_format;
        self::$instance = $this;
    }

    /**
     * @return self
     */
    public static function getInstance()
    {
        return self::$instance;
    }

    /**
     * @param  string  $base_dir
     * @param  bool $is_diff
     *
     * @return void
     */
    public function check($base_dir, $is_diff = false)
    {
        $start_checks = (int)microtime(true);

        if (!$base_dir) {
            throw new \InvalidArgumentException('Cannot work with empty base_dir');
        }

        if (!$this->config) {
            $this->config = $this->getConfigForPath($base_dir, $base_dir);
        }

        $diff_files = null;
        $deleted_files = null;

        if ($is_diff && FileReferenceProvider::loadReferenceCache() && CacheProvider::canDiffFiles()) {
            $deleted_files = FileReferenceProvider::getDeletedReferencedFiles();
            $diff_files = $deleted_files;

            foreach ($this->config->getProjectDirectories() as $dir_name) {
                $diff_files = array_merge($diff_files, self::getDiffFilesInDir($dir_name, $this->config));
            }
        }

        if ($diff_files === null || $deleted_files === null || count($diff_files) > 200) {
            foreach ($this->config->getProjectDirectories() as $dir_name) {
                $this->checkDirWithConfig($dir_name, $this->config);
            }

            $this->visitFiles();

            if (!$this->server_mode) {
                $this->analyzeFiles();
            }
        } else {
            if ($this->debug_output) {
                echo count($diff_files) . ' changed files' . PHP_EOL;
            }

            $file_list = self::getReferencedFilesFromDiff($diff_files);

            // strip out deleted files
            $file_list = array_diff($file_list, $deleted_files);
            $this->checkDiffFilesWithConfig($this->config, $file_list);

            $this->visitFiles();

            if (!$this->server_mode) {
                $this->analyzeFiles();
            }
        }

        $removed_parser_files = CacheProvider::deleteOldParserCaches(
            $is_diff ? CacheProvider::getLastGoodRun() : $start_checks
        );

        if ($this->debug_output && $removed_parser_files) {
            echo 'Removed ' . $removed_parser_files . ' old parser caches' . PHP_EOL;
        }

        if ($is_diff) {
            CacheProvider::touchParserCaches($this->getAllFiles($this->config), $start_checks);
        }

        if ($this->collect_references) {
            if ($this->find_references_to) {
                if (strpos($this->find_references_to, '::') !== false) {
                    $locations_by_files = $this->findReferencesToMethod($this->find_references_to);
                } else {
                    $locations_by_files = $this->findReferencesToClassLike($this->find_references_to);
                }

                foreach ($locations_by_files as $locations) {
                    $bounds_starts = [];

                    foreach ($locations as $location) {
                        $snippet = $location->getSnippet();

                        $snippet_bounds = $location->getSnippetBounds();
                        $selection_bounds = $location->getSelectionBounds();

                        if (isset($bounds_starts[$selection_bounds[0]])) {
                            continue;
                        }

                        $bounds_starts[$selection_bounds[0]] = true;

                        $selection_start = $selection_bounds[0] - $snippet_bounds[0];
                        $selection_length = $selection_bounds[1] - $selection_bounds[0];

                        echo $location->file_name . ':' . $location->getLineNumber() . PHP_EOL .
                            ($this->use_color
                                ? substr($snippet, 0, $selection_start) .
                                "\e[97;42m" . substr($snippet, $selection_start, $selection_length) .
                                "\e[0m" . substr($snippet, $selection_length + $selection_start)
                                : $snippet
                            ) . PHP_EOL . PHP_EOL;
                    }
                }
            } else {
                $this->checkClassReferences();
            }
        }

        IssueBuffer::finish(true, (int)$start_checks, $this->visited_files);
    }

    /**
     * @return void
     */
    private function visitFiles()
    {
        if (!$this->config) {
            throw new \UnexpectedValueException('$this->config cannot be null');
        }

        $filetype_handlers = $this->config->getFiletypeHandlers();

        foreach ($this->files_to_analyze as $file_path => $_) {
            if (!isset($this->visited_files[$file_path])) {
                $this->visitFile($file_path, $filetype_handlers);
            }
        }
    }

    /**
     * @return void
     */
    private function analyzeFiles()
    {
        if (!$this->config) {
            throw new \UnexpectedValueException('$this->config cannot be null');
        }

        $filetype_handlers = $this->config->getFiletypeHandlers();

        foreach ($this->files_to_analyze as $file_path => $_) {
            $file_checker = $this->visitFile($file_path, $filetype_handlers, true);

            if ($this->debug_output) {
                echo 'Analyzing ' . $file_checker->getFilePath() . PHP_EOL;
            }

            $file_checker->analyze($this->update_docblocks);
        }
    }

    /**
     * @param  string $method_id
     *
     * @return array<string, \Psalm\CodeLocation[]>
     */
    public function findReferencesToMethod($method_id)
    {
        list($fq_class_name, $method_name) = explode('::', $method_id);

        if (!isset(ClassLikeChecker::$storage[strtolower($fq_class_name)])) {
            die('Class ' . $fq_class_name . ' cannot be found' . PHP_EOL);
        }

        $class_storage = ClassLikeChecker::$storage[strtolower($fq_class_name)];

        if (!isset($class_storage->methods[strtolower($method_name)])) {
            die('Method ' . $method_id . ' cannot be found' . PHP_EOL);
        }

        $method_storage = $class_storage->methods[strtolower($method_name)];

        if ($method_storage->referencing_locations === null) {
            die('No references found for ' . $method_id . PHP_EOL);
        }

        return $method_storage->referencing_locations;
    }

    /**
     * @param  string $fq_class_name
     *
     * @return array<string, \Psalm\CodeLocation[]>
     */
    public function findReferencesToClassLike($fq_class_name)
    {
        if (!isset(ClassLikeChecker::$storage[strtolower($fq_class_name)])) {
            die('Class ' . $fq_class_name . ' cannot be found' . PHP_EOL);
        }

        $class_storage = ClassLikeChecker::$storage[strtolower($fq_class_name)];

        if ($class_storage->referencing_locations === null) {
            die('No references found for ' . $fq_class_name . PHP_EOL);
        }

        $classlike_references_by_file = $class_storage->referencing_locations;

        if (isset($this->use_referencing_locations[strtolower($fq_class_name)])) {
            foreach ($this->use_referencing_locations[strtolower($fq_class_name)] as $file_path => $locations) {
                if (!isset($classlike_references_by_file[$file_path])) {
                    $classlike_references_by_file[$file_path] = $locations;
                } else {
                    $classlike_references_by_file[$file_path] = array_merge(
                        $locations,
                        $classlike_references_by_file[$file_path]
                    );
                }
            }
        }

        return $classlike_references_by_file;
    }

    /**
     * @return void
     */
    public function checkClassReferences()
    {
        foreach ($this->existing_classlikes_ci as $fq_class_name_ci => $_) {
            if (isset(ClassLikeChecker::$storage[$fq_class_name_ci])) {
                $classlike_storage = ClassLikeChecker::$storage[$fq_class_name_ci];

                if ($classlike_storage->location &&
                    $this->config &&
                    $this->config->isInProjectDirs($classlike_storage->location->file_path)
                ) {
                    if (!isset($this->classlike_references[$fq_class_name_ci])) {
                        if (IssueBuffer::accepts(
                            new UnusedClass(
                                'Class ' . $classlike_storage->name . ' is never used',
                                $classlike_storage->location
                            )
                        )) {
                            // fall through
                        }
                    } else {
                        self::checkMethodReferences($classlike_storage);
                    }
                }
            }
        }
    }

    /**
     * @param  \Psalm\Storage\ClassLikeStorage  $classlike_storage
     *
     * @return void
     */
    protected static function checkMethodReferences($classlike_storage)
    {
        foreach ($classlike_storage->methods as $method_name => $method_storage) {
            if (count($method_storage->referencing_locations) === 0 &&
                !$classlike_storage->overridden_method_ids[$method_name] &&
                (substr($method_name, 0, 2) !== '__' || $method_name === '__construct') &&
                $method_storage->location
            ) {
                $method_id = $classlike_storage->name . '::' . $method_storage->cased_name;

                if ($method_storage->visibility === ClassLikeChecker::VISIBILITY_PUBLIC) {
                    if (IssueBuffer::accepts(
                        new PossiblyUnusedMethod(
                            'Cannot find public calls to method ' . $method_id,
                            $method_storage->location
                        )
                    )) {
                        // fall through
                    }
                } else {
                    if (IssueBuffer::accepts(
                        new UnusedMethod(
                            'Method ' . $method_id . ' is never used',
                            $method_storage->location
                        )
                    )) {
                        // fall through
                    }
                }
            }
        }
    }

    /**
     * @param  string  $dir_name
     * @param  string  $base_dir
     *
     * @return void
     */
    public function checkDir($dir_name, $base_dir)
    {
        if (!$this->config) {
            $this->config = $this->getConfigForPath($dir_name, $base_dir);
            $this->config->hide_external_errors = $this->config->isInProjectDirs($dir_name . DIRECTORY_SEPARATOR);
        }

        FileReferenceProvider::loadReferenceCache();

        $start_checks = (int)microtime(true);

        $this->checkDirWithConfig($dir_name, $this->config, true);

        $this->visitFiles();
        $this->analyzeFiles();

        IssueBuffer::finish(false, $start_checks, $this->visited_files);
    }

    /**
     * @param  string $dir_name
     * @param  Config $config
     * @param  bool   $allow_non_project_files
     *
     * @return void
     */
    private function checkDirWithConfig($dir_name, Config $config, $allow_non_project_files = false)
    {
        $file_extensions = $config->getFileExtensions();

        /** @var RecursiveDirectoryIterator */
        $iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($dir_name));
        $iterator->rewind();

        while ($iterator->valid()) {
            if (!$iterator->isDot()) {
                $extension = $iterator->getExtension();
                if (in_array($extension, $file_extensions, true)) {
                    $file_path = (string)$iterator->getRealPath();

                    if ($allow_non_project_files || $config->isInProjectDirs($file_path)) {
                        $this->files_to_analyze[$file_path] = true;
                    }
                }
            }

            $iterator->next();
        }
    }

    /**
     * @param  Config $config
     *
     * @return array<int, string>
     */
    private function getAllFiles(Config $config)
    {
        $file_extensions = $config->getFileExtensions();
        $file_names = [];

        foreach ($config->getProjectDirectories() as $dir_name) {
            /** @var RecursiveDirectoryIterator */
            $iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($dir_name));
            $iterator->rewind();

            while ($iterator->valid()) {
                if (!$iterator->isDot()) {
                    $extension = $iterator->getExtension();
                    if (in_array($extension, $file_extensions, true)) {
                        $file_names[] = (string)$iterator->getRealPath();
                    }
                }

                $iterator->next();
            }
        }

        return $file_names;
    }

    /**
     * @param  string $dir_name
     * @param  Config $config
     *
     * @return array<string>
     */
    protected static function getDiffFilesInDir($dir_name, Config $config)
    {
        $file_extensions = $config->getFileExtensions();
        $filetype_handlers = $config->getFiletypeHandlers();

        /** @var RecursiveDirectoryIterator */
        $iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($dir_name));
        $iterator->rewind();

        $diff_files = [];

        while ($iterator->valid()) {
            if (!$iterator->isDot()) {
                $extension = $iterator->getExtension();
                if (in_array($extension, $file_extensions, true)) {
                    $file_name = (string)$iterator->getRealPath();

                    if ($config->isInProjectDirs($file_name)) {
                        if (FileProvider::hasFileChanged($file_name)) {
                            $diff_files[] = $file_name;
                        }
                    }
                }
            }

            $iterator->next();
        }

        return $diff_files;
    }

    /**
     * @param  Config           $config
     * @param  array<string>    $file_list
     *
     * @return void
     */
    private function checkDiffFilesWithConfig(Config $config, array $file_list = [])
    {
        foreach ($file_list as $file_path) {
            if (!file_exists($file_path)) {
                continue;
            }

            if (!$config->isInProjectDirs($file_path)) {
                if ($this->debug_output) {
                    echo 'skipping ' . $file_path . PHP_EOL;
                }

                continue;
            }

            $this->files_to_analyze[$file_path] = true;
        }
    }

    /**
     * @param  string  $file_path
     * @param  string  $base_dir
     *
     * @return void
     */
    public function checkFile($file_path, $base_dir)
    {
        if ($this->debug_output) {
            echo 'Checking ' . $file_path . PHP_EOL;
        }

        if (!$this->config) {
            $this->config = $this->getConfigForPath($file_path, $base_dir);
        }

        $start_checks = (int)microtime(true);

        $this->config->hide_external_errors = $this->config->isInProjectDirs($file_path);

        $this->files_to_analyze[$file_path] = true;

        $filetype_handlers = $this->config->getFiletypeHandlers();

        FileReferenceProvider::loadReferenceCache();

        $file_checker = $this->visitFile($file_path, $filetype_handlers, true);

        if ($this->debug_output) {
            echo 'Analyzing ' . $file_checker->getFilePath() . PHP_EOL;
        }

        $file_checker->analyze($this->update_docblocks);

        IssueBuffer::finish(false, $start_checks, $this->visited_files);
    }

    /**
     * @param  string $file_path
     * @param  array  $filetype_handlers
     * @param  bool   $will_analyze
     *
     * @return FileChecker
     */
    private function visitFile($file_path, array $filetype_handlers, $will_analyze = false)
    {
        $extension = (string)pathinfo($file_path)['extension'];

        if (isset($filetype_handlers[$extension])) {
            /** @var FileChecker */
            $file_checker = new $filetype_handlers[$extension]($file_path, $this);
        } else {
            $file_checker = new FileChecker($file_path, $this, null, $will_analyze);
        }

        if ($this->debug_output) {
            $rev_or_V = (isset($this->visited_files[$file_path]) ? 'Rev' : 'V');
            echo $rev_or_V . 'isiting ' . $file_path . PHP_EOL;
        }

        $this->visited_files[$file_path] = true;

        $file_checker->visit();

        return $file_checker;
    }

    /**
     * Checks whether a class exists, and if it does then records what file it's in
     * for later checking
     *
     * @param  string $fq_class_name
     *
     * @return bool
     * @psalm-suppress MixedMethodCall due to Reflection class weirdness
     */
    public function fileExistsForClassLike($fq_class_name)
    {
        $fq_class_name_ci = strtolower($fq_class_name);

        if (isset($this->existing_classlikes_ci[$fq_class_name_ci])) {
            return $this->existing_classlikes_ci[$fq_class_name_ci];
        }

        if (!$this->config) {
            throw new \UnexpectedValueException('Config should not be null here');
        }

        $predefined_classlikes = $this->config->getPredefinedClassLikes();

        if (isset($predefined_classlikes[$fq_class_name_ci])) {
            $this->visited_classes[$fq_class_name_ci] = true;
            $reflected_class = new \ReflectionClass($fq_class_name);
            ClassLikeChecker::registerReflectedClass($reflected_class->name, $reflected_class, $this);

            return true;
        }

        $old_level = error_reporting();
        error_reporting(0);

        try {
            $reflected_class = new \ReflectionClass($fq_class_name);
        } catch (\ReflectionException $e) {
            error_reporting($old_level);

            // do not cache any results here (as case-sensitive filenames can screw things up)

            return false;
        }

        error_reporting($old_level);

        $file_path = (string)$reflected_class->getFileName();

        // if the file was autoloaded but exists in evaled code only, return false
        if (!file_exists($file_path)) {
            return false;
        }

        $fq_class_name = $reflected_class->getName();
        $this->existing_classlikes_ci[$fq_class_name_ci] = true;
        $this->existing_classlikes[$fq_class_name] = true;

        if ($reflected_class->isInterface()) {
            $this->addFullyQualifiedInterfaceName($fq_class_name, $file_path);
        } elseif ($reflected_class->isTrait()) {
            $this->addFullyQualifiedTraitName($fq_class_name, $file_path);
        } else {
            $this->addFullyQualifiedClassName($fq_class_name, $file_path);
        }

        return true;
    }

    /**
     * @param  string       $fq_class_name
     *
     * @return bool
     * @psalm-suppress MixedMethodCall due to Reflection class weirdness
     */
    public function visitFileForClassLike($fq_class_name)
    {
        if (!$fq_class_name || strpos($fq_class_name, '::') !== false) {
            throw new \InvalidArgumentException('Invalid class name ' . $fq_class_name);
        }

        $fq_class_name_ci = strtolower($fq_class_name);

        if (isset($this->visited_classes[$fq_class_name_ci])) {
            return $this->visited_classes[$fq_class_name_ci];
        }

        // this registers the class if it's not user defined
        if (!$this->fileExistsForClassLike($fq_class_name)) {
            return false;
        }

        $this->visited_classes[$fq_class_name_ci] = true;

        if (isset($this->classlike_files[$fq_class_name_ci])) {
            $file_path = $this->classlike_files[$fq_class_name_ci];

            if (isset($this->visited_files[$file_path])) {
                return true;
            }

            $this->visited_files[$file_path] = true;

            $file_checker = new FileChecker(
                $file_path,
                $this,
                null,
                false
            );

            ClassLikeChecker::$file_classes[$file_path][] = $fq_class_name;

            $fq_class_name_lower = strtolower($fq_class_name);

            if ($this->debug_output) {
                echo 'Visiting ' . $file_path . PHP_EOL;
            }

            $file_checker->visit();

            $storage = ClassLikeChecker::$storage[$fq_class_name_lower];

            if (ClassLikeChecker::inPropertyMap($fq_class_name)) {
                $public_mapped_properties = ClassLikeChecker::getPropertyMap()[strtolower($fq_class_name)];

                foreach ($public_mapped_properties as $property_name => $public_mapped_property) {
                    $property_type = Type::parseString($public_mapped_property);
                    $storage->properties[$property_name] = new PropertyStorage();
                    $storage->properties[$property_name]->type = $property_type;
                    $storage->properties[$property_name]->visibility = ClassLikeChecker::VISIBILITY_PUBLIC;

                    $property_id = $fq_class_name . '::$' . $property_name;

                    $storage->declaring_property_ids[$property_name] = $property_id;
                    $storage->appearing_property_ids[$property_name] = $property_id;
                }
            }
        }

        return true;
    }

    /**
     * @return void
     */
    public function enableCache()
    {
        $this->cache = true;
    }

    /**
     * @return void
     */
    public function disableCache()
    {
        $this->cache = false;
    }

    /**
     * @return bool
     */
    public function canCache()
    {
        return $this->cache;
    }

    /**
     * @param  string   $original_method_id
     * @param  Context  $this_context
     *
     * @return void
     */
    public function getMethodMutations($original_method_id, Context $this_context)
    {
        list($fq_class_name) = explode('::', $original_method_id);

        $file_checker = $this->getVisitedFileCheckerForClassLike($fq_class_name);

        $appearing_method_id = (string)MethodChecker::getAppearingMethodId($original_method_id);
        list($appearing_fq_class_name) = explode('::', $appearing_method_id);

        $appearing_class_storage = ClassLikeChecker::$storage[strtolower($appearing_fq_class_name)];

        if (!$appearing_class_storage->user_defined) {
            return;
        }

        if (strtolower($appearing_fq_class_name) !== strtolower($fq_class_name)) {
            $file_checker = $this->getVisitedFileCheckerForClassLike($appearing_fq_class_name);
        }

        $file_checker->analyze(false, true);

        if (!$this_context->self) {
            $this_context->self = $fq_class_name;
            $this_context->vars_in_scope['$this'] = Type::parseString($fq_class_name);
        }

        $file_checker->getMethodMutations($appearing_method_id, $this_context);
    }

    /**
     * @param  string $fq_class_name
     *
     * @return FileChecker
     */
    private function getVisitedFileCheckerForClassLike($fq_class_name)
    {
        $fq_class_name_ci = strtolower($fq_class_name);

        if (!$this->fake_files) {
            // this registers the class if it's not user defined
            if (!$this->fileExistsForClassLike($fq_class_name)) {
                throw new \UnexpectedValueException('File does not exist for ' . $fq_class_name);
            }

            if (!isset($this->classlike_files[$fq_class_name_ci])) {
                throw new \UnexpectedValueException('Class ' . $fq_class_name . ' is not user-defined');
            }

            $file_path = $this->classlike_files[$fq_class_name_ci];
        } else {
            $file_path = array_keys($this->fake_files)[0];
        }

        if ($this->cache && isset($this->file_checkers[$file_path])) {
            return $this->file_checkers[$file_path];
        }

        $file_checker = new FileChecker($file_path, $this, null, true);

        $file_checker->visit();

        if ($this->debug_output) {
            echo 'Visiting ' . $file_path . PHP_EOL;
        }

        if ($this->cache) {
            $this->file_checkers[$file_path] = $file_checker;
        }

        return $file_checker;
    }

    /**
     * Gets a Config object from an XML file.
     *
     * Searches up a folder hierarchy for the most immediate config.
     *
     * @param  string $path
     * @param  string $base_dir
     *
     * @throws Exception\ConfigException if a config path is not found
     *
     * @return Config
     */
    private function getConfigForPath($path, $base_dir)
    {
        $dir_path = realpath($path);

        if (!is_dir($dir_path)) {
            $dir_path = dirname($dir_path);
        }

        $config = null;

        do {
            $maybe_path = $dir_path . DIRECTORY_SEPARATOR . Config::DEFAULT_FILE_NAME;

            if (file_exists($maybe_path)) {
                $config = Config::loadFromXMLFile($maybe_path, $base_dir);

                break;
            }

            $dir_path = dirname($dir_path);
        } while (dirname($dir_path) !== $dir_path);

        if (!$config) {
            if ($this->output_format === self::TYPE_CONSOLE) {
                exit(
                    'Could not locate a config XML file in path ' . $path . '. Have you run \'psalm --init\' ?' .
                    PHP_EOL
                );
            }

            throw new Exception\ConfigException('Config not found for path ' . $path);
        }

        $this->config = $config;

        $config->visitStubFiles($this);
        $config->initializePlugins($this);

        return $config;
    }

    /**
     * @param  Config $config
     *
     * @return void
     */
    public function setConfig(Config $config)
    {
        $this->config = $config;

        $config->visitStubFiles($this);
        $config->initializePlugins($this);
    }

    /**
     * @param string $path_to_config
     * @param string $base_dir
     *
     * @throws Exception\ConfigException if a config file is not found in the given location
     *
     * @return void
     */
    public function setConfigXML($path_to_config, $base_dir)
    {
        if (!file_exists($path_to_config)) {
            throw new Exception\ConfigException('Config not found at location ' . $path_to_config);
        }

        $this->config = Config::loadFromXMLFile($path_to_config, $base_dir);

        $this->config->visitStubFiles($this);
        $this->config->initializePlugins($this);
    }

    /**
     * @param  array<string>  $diff_files
     *
     * @return array<string>
     */
    public static function getReferencedFilesFromDiff(array $diff_files)
    {
        $all_inherited_files_to_check = $diff_files;

        while ($diff_files) {
            $diff_file = array_shift($diff_files);

            $dependent_files = FileReferenceProvider::getFilesInheritingFromFile($diff_file);
            $new_dependent_files = array_diff($dependent_files, $all_inherited_files_to_check);

            $all_inherited_files_to_check += $new_dependent_files;
            $diff_files += $new_dependent_files;
        }

        $all_files_to_check = $all_inherited_files_to_check;

        foreach ($all_inherited_files_to_check as $file_name) {
            $dependent_files = FileReferenceProvider::getFilesReferencingFile($file_name);
            $all_files_to_check = array_merge($dependent_files, $all_files_to_check);
        }

        return array_unique($all_files_to_check);
    }

    /**
     * @param  string $file_path
     * @param  string $file_contents
     *
     * @return void
     */
    public function registerFile($file_path, $file_contents)
    {
        $this->fake_files[$file_path] = $file_contents;
    }

    /**
     * @param  string $file_path
     *
     * @return void
     */
    public function registerAnalyzableFile($file_path)
    {
        $this->visited_files[$file_path] = true;
        $this->files_to_analyze[$file_path] = true;
    }

    /**
     * @param  string $file_path
     *
     * @return string
     */
    public function getFileContents($file_path)
    {
        if (isset($this->fake_files[$file_path])) {
            return $this->fake_files[$file_path];
        }

        return (string)file_get_contents($file_path);
    }

    /**
     * @param string        $fq_class_name
     * @param string|null   $file_path
     *
     * @return void
     */
    public function addFullyQualifiedClassName($fq_class_name, $file_path = null)
    {
        $fq_class_name_ci = strtolower($fq_class_name);
        $this->existing_classlikes_ci[$fq_class_name_ci] = true;
        $this->existing_classes_ci[$fq_class_name_ci] = true;
        $this->existing_traits_ci[$fq_class_name_ci] = false;
        $this->existing_interfaces_ci[$fq_class_name_ci] = false;
        $this->existing_classes[$fq_class_name] = true;

        if ($file_path) {
            $this->classlike_files[$fq_class_name_ci] = $file_path;
        }
    }

    /**
     * @param string        $fq_class_name
     * @param string|null   $file_path
     *
     * @return void
     */
    public function addFullyQualifiedInterfaceName($fq_class_name, $file_path = null)
    {
        $fq_class_name_ci = strtolower($fq_class_name);
        $this->existing_classlikes_ci[$fq_class_name_ci] = true;
        $this->existing_interfaces_ci[$fq_class_name_ci] = true;
        $this->existing_classes_ci[$fq_class_name_ci] = false;
        $this->existing_traits_ci[$fq_class_name_ci] = false;
        $this->existing_interfaces[$fq_class_name] = true;

        if ($file_path) {
            $this->classlike_files[$fq_class_name_ci] = $file_path;
        }
    }

    /**
     * @param string        $fq_class_name
     * @param string|null   $file_path
     *
     * @return void
     */
    public function addFullyQualifiedTraitName($fq_class_name, $file_path = null)
    {
        $fq_class_name_ci = strtolower($fq_class_name);
        $this->existing_classlikes_ci[$fq_class_name_ci] = true;
        $this->existing_traits_ci[$fq_class_name_ci] = true;
        $this->existing_classes_ci[$fq_class_name_ci] = false;
        $this->existing_interfaces_ci[$fq_class_name_ci] = false;
        $this->existing_traits[$fq_class_name] = true;

        if ($file_path) {
            $this->classlike_files[$fq_class_name_ci] = $file_path;
        }
    }

    /**
     * @param string $fq_class_name
     *
     * @return bool
     */
    public function hasFullyQualifiedClassName($fq_class_name)
    {
        $fq_class_name_ci = strtolower($fq_class_name);

        if (!isset($this->existing_classes_ci[$fq_class_name_ci]) ||
            !$this->existing_classes_ci[$fq_class_name_ci]
        ) {
            return false;
        }

        if ($this->collect_references) {
            if (!isset($this->classlike_references[$fq_class_name_ci])) {
                $this->classlike_references[$fq_class_name_ci] = 0;
            }

            ++$this->classlike_references[$fq_class_name_ci];
        }

        return true;
    }

    /**
     * @param string $fq_class_name
     *
     * @return bool
     */
    public function hasFullyQualifiedInterfaceName($fq_class_name)
    {
        $fq_class_name_ci = strtolower($fq_class_name);

        if (!isset($this->existing_interfaces_ci[$fq_class_name_ci]) ||
            !$this->existing_interfaces_ci[$fq_class_name_ci]
        ) {
            return false;
        }

        if ($this->collect_references) {
            if (!isset($this->classlike_references[$fq_class_name_ci])) {
                $this->classlike_references[$fq_class_name_ci] = 0;
            }

            ++$this->classlike_references[$fq_class_name_ci];
        }

        return true;
    }

    /**
     * @param string $fq_class_name
     *
     * @return bool
     */
    public function hasFullyQualifiedTraitName($fq_class_name)
    {
        $fq_class_name_ci = strtolower($fq_class_name);

        if (!isset($this->existing_traits_ci[$fq_class_name_ci]) ||
            !$this->existing_traits_ci[$fq_class_name_ci]
        ) {
            return false;
        }

        if ($this->collect_references) {
            if (!isset($this->classlike_references[$fq_class_name_ci])) {
                $this->classlike_references[$fq_class_name_ci] = 0;
            }

            ++$this->classlike_references[$fq_class_name_ci];
        }

        return true;
    }

    /**
     * @param  string $file_path
     *
     * @return bool
     */
    public function canReportIssues($file_path)
    {
        return isset($this->files_to_analyze[$file_path]);
    }
}