refactor: extract utility methods

Author: dukeluo

lib/rules/folder-naming-convention.js

@@ -17,6 +17,7 @@ const {
   globPatternValidator,
 } = require('../utils/settings');
 const { getDocUrl } = require('../utils/doc');
+const { isNotEmpty } = require('../utils/utility');
 const NAMING_CONVENTION = require('../constants/naming-convention');
 
 /** @typedef {module:eslint} ESLint */
@@ -69,9 +70,10 @@ module.exports = {
             if (!micromatch.isMatch(path, folderPattern)) {
               continue;
             } else {
-              const matchedPaths = micromatch.capture(folderPattern, path);
+              const matchedPaths =
+                micromatch.capture(folderPattern, path) || [];
               const folders = matchedPaths
-                .filter((p) => !!p)
+                .filter(isNotEmpty)
                 .reduce((s, p) => s.concat(getAllFolders(p)), []);
 
               for (const folder of folders) {

lib/utils/filename.js

@@ -5,6 +5,7 @@
 'use strict';
 
 const path = require('path');
+const { pipe, isNotEmpty } = require('./utility');
 
 /**
  * @returns {string} filename without path
@@ -34,8 +35,7 @@ const getBasename = (filename, ignoreMiddleExtensions = false) =>
  * @returns {string[]} all folders
  * @param {string} p path of folder in posix style
  */
-const getAllFolders = (p) =>
-  p.split(path.posix.sep).filter((folder) => folder !== '');
+const getAllFolders = (p) => p.split(path.posix.sep).filter(isNotEmpty);
 
 /**
  * @returns {string[]} all sub paths
@@ -84,21 +84,6 @@ const toPosixPath = (p) => p.split(path.sep).join(path.posix.sep);
  */
 const removeDriveLetter = (p) => p.replace(/^[A-Za-z]:\\/, '');
 
-/**
- * Callback for file path
- *
- * @callback callback
- * @param {string} p file path
- */
-/**
- * @returns {callback} piped function
- * @param {callback[]} fns callback functions
- */
-const pipe =
-  (...fns) =>
-  (x) =>
-    fns.reduce((v, f) => f(v), x);
-
 /** @typedef {module:eslint} ESLint */
 /**
  * @returns {string} file path in posix style

lib/utils/transform.js

@@ -6,6 +6,7 @@
 'use strict';
 
 const micromatch = require('micromatch');
+const { isNil, isEmpty } = require('../utils/utility');
 const { PREFINED_MATCH_SYNTAX_REGEXP } = require('../constants/regex');
 
 /**
@@ -28,22 +29,22 @@ const transformRuleWithPrefinedMatchSyntax = (
     filenameWithPath
   );
 
-  if (!keyCaptureGroups) {
+  if (isNil(keyCaptureGroups)) {
     return [filenamePattern, namingPattern];
   }
 
   const valueCaptureGroups = [
     ...namingPattern.matchAll(new RegExp(PREFINED_MATCH_SYNTAX_REGEXP, 'g')),
   ];
 
-  if (!valueCaptureGroups || !valueCaptureGroups.length) {
+  if (isEmpty(valueCaptureGroups)) {
     return [filenamePattern, namingPattern];
   }
 
   const newNamingPattern = valueCaptureGroups.reduce((value, group) => {
     const groupIndex = +group[1];
 
-    if (!keyCaptureGroups || keyCaptureGroups[groupIndex] === undefined) {
+    if (isNil(keyCaptureGroups[groupIndex])) {
       throw new Error(
         `The capture group "${namingPattern}" is not found in the glob "${filenamePattern}"`
       );

lib/utils/utility.js

@@ -12,6 +12,71 @@
  */
 const isObject = (x) => Object.prototype.toString.call(x) === '[object Object]';
 
+/**
+ * Checks if the given argument is an array
+ *
+ * @param {any} x - The argument to check
+ * @returns {boolean} - True if the argument is an array, false otherwise
+ */
+const isArray = (x) =>
+  x != null &&
+  x.length >= 0 &&
+  Object.prototype.toString.call(x) === '[object Array]';
+
+/**
+ * Checks if a value is undefined or null
+ *
+ * @param {any} x - The value to check
+ * @returns {boolean} - Returns true if the value is undefined or null, false otherwise
+ */
+const isNil = (x) => x === undefined || x === null;
+
+/**
+ * Checks if a value is an empty value
+ *
+ * @param {any} x - The value to check
+ * @returns {boolean} - Returns true if the value is an empty value, false otherwise
+ */
+const isEmpty = (x) =>
+  x === '' ||
+  (isArray(x) && x.length) === 0 ||
+  (isObject(x) && Object.keys(x).length === 0);
+
+/**
+ * Negates a boolean value
+ *
+ * @param {boolean} x - The boolean value to negate
+ * @returns {boolean} The negated boolean value
+ */
+const not = (x) => !x;
+
+/**
+ * Callback for file path
+ *
+ * @callback callback
+ * @param {string} p file path
+ */
+/**
+ * @returns {callback} piped function
+ * @param {callback[]} fns callback functions
+ */
+const pipe =
+  (...fns) =>
+  (x) =>
+    fns.reduce((v, f) => f(v), x);
+
+/**
+ * Checks if a value isnt an empty value
+ *
+ * @param {any} x - The value to check
+ * @returns {boolean} - Returns true if the value isnt an empty value, false otherwise
+ */
+const isNotEmpty = pipe(isEmpty, not);
+
 module.exports = {
   isObject,
+  isNil,
+  isEmpty,
+  isNotEmpty,
+  pipe,
 };