Chore: add cache to exists()

lib/util/exists.js

@@ -11,12 +11,14 @@
 
 const fs = require("fs")
 const path = require("path")
+const Cache = require("./cache")
 
 //------------------------------------------------------------------------------
 // Helpers
 //------------------------------------------------------------------------------
 
 const ROOT = /^(?:[/.]|\.\.|[A-Z]:\\|\\\\)(?:[/\\]\.\.)*$/
+const cache = new Cache()
 
 /**
  * Check whether the file exists or not.
@@ -49,17 +51,23 @@ function existsCaseSensitive(filePath) {
  * @returns {boolean} `true` if the file of a given path exists.
  */
 module.exports = function exists(filePath) {
-    try {
-        const relativePath = path.relative(process.cwd(), filePath)
-        return (
-            fs.statSync(relativePath).isFile() &&
-            existsCaseSensitive(relativePath)
-        )
-    }
-    catch (error) {
-        if (error.code === "ENOENT") {
-            return false
+    let result = cache.get(filePath)
+    if (result == null) {
+        try {
+            const relativePath = path.relative(process.cwd(), filePath)
+            result = (
+                fs.statSync(relativePath).isFile() &&
+                existsCaseSensitive(relativePath)
+            )
         }
-        throw error
+        catch (error) {
+            if (error.code !== "ENOENT") {
+                throw error
+            }
+            result = false
+        }
+        cache.set(filePath, result)
     }
+
+    return result
 }