Cache the result of is_file() calls.

Author: Wes1262

src/Filter.php

@@ -24,6 +24,13 @@ final class Filter
      */
     private $whitelistedFiles = [];
 
+    /**
+     * Remembers the result of the `is_file()` calls.
+     *
+     * @var bool[]
+     */
+    private $isFileCallsCache = [];
+
     /**
      * Adds a directory to the whitelist (recursively).
      */
@@ -85,18 +92,22 @@ public function removeFileFromWhitelist(string $filename): void
      */
     public function isFile(string $filename): bool
     {
-        if ($filename === '-' ||
-            \strpos($filename, 'vfs://') === 0 ||
-            \strpos($filename, 'xdebug://debug-eval') !== false ||
-            \strpos($filename, 'eval()\'d code') !== false ||
-            \strpos($filename, 'runtime-created function') !== false ||
-            \strpos($filename, 'runkit created function') !== false ||
-            \strpos($filename, 'assert code') !== false ||
-            \strpos($filename, 'regexp code') !== false) {
-            return false;
+        if (!isset($this->isFileCallsCache[$filename])) {
+            if ($filename === '-' ||
+                \strpos($filename, 'vfs://') === 0 ||
+                \strpos($filename, 'xdebug://debug-eval') !== false ||
+                \strpos($filename, 'eval()\'d code') !== false ||
+                \strpos($filename, 'runtime-created function') !== false ||
+                \strpos($filename, 'runkit created function') !== false ||
+                \strpos($filename, 'assert code') !== false ||
+                \strpos($filename, 'regexp code') !== false) {
+                $isFile = false;
+            } else {
+                $isFile = \file_exists($filename);
+            }
+            $this->isFileCallsCache[$filename] = $isFile;
         }
-
-        return \file_exists($filename);
+        return $this->isFileCallsCache[$filename];
     }
 
     /**