refactor(preprocessor): update lib/preprocessor.js to ES6

lib/preprocessor.js

@@ -1,16 +1,12 @@
-var fs = require('graceful-fs')
-var crypto = require('crypto')
-var mm = require('minimatch')
-var isBinaryFile = require('isbinaryfile')
-var combineLists = require('combine-lists')
-
-var log = require('./logger').create('preprocess')
-
-function sha1 (data) {
-  var hash = crypto.createHash('sha1')
-  hash.update(data)
-  return hash.digest('hex')
-}
+'use strict'
+
+const fs = require('graceful-fs')
+const mm = require('minimatch')
+const isBinaryFile = require('isbinaryfile')
+const combineLists = require('combine-lists')
+const CryptoUtils = require('./utils/crypto-utils')
+
+const log = require('./logger').create('preprocess')
 
 function createNextProcessor (preprocessors, file, done) {
   return function nextPreprocessor (error, content) {
@@ -29,7 +25,7 @@ function createNextProcessor (preprocessors, file, done) {
     if (!preprocessors.length) {
       file.contentPath = null
       file.content = content
-      file.sha = sha1(content)
+      file.sha = CryptoUtils.sha1(content)
       return done()
     }
 
@@ -38,27 +34,25 @@ function createNextProcessor (preprocessors, file, done) {
 }
 
 function createPreprocessor (config, basePath, injector) {
-  var alreadyDisplayedErrors = {}
-  var instances = {}
-  var patterns = Object.keys(config)
-
-  var emitter = injector.get('emitter')
+  const emitter = injector.get('emitter')
+  const alreadyDisplayedErrors = {}
+  const instances = {}
+  let patterns = Object.keys(config)
 
   function instantiatePreprocessor (name) {
     if (alreadyDisplayedErrors[name]) {
       return
     }
 
-    var p
+    let p
 
     try {
       p = injector.get('preprocessor:' + name)
     } catch (e) {
-      if (e.message.indexOf('No provider for "preprocessor:' + name + '"') !== -1) {
-        log.error('Can not load "%s", it is not registered!\n  ' +
-          'Perhaps you are missing some plugin?', name)
+      if (e.message.indexOf(`No provider for "preprocessor:${name}"`) !== -1) {
+        log.error(`Can not load "${name}", it is not registered!\n  Perhaps you are missing some plugin?`)
       } else {
-        log.error('Can not load "%s"!\n  ' + e.stack, name)
+        log.error(`Can not load "${name}"!\n  ` + e.stack)
       }
       alreadyDisplayedErrors[name] = true
       emitter.emit('load_error', 'preprocessor', name)
@@ -67,16 +61,16 @@ function createPreprocessor (config, basePath, injector) {
     return p
   }
 
-  var allPreprocessors = []
-  patterns.forEach(function (pattern) {
+  let allPreprocessors = []
+  patterns.forEach((pattern) => {
     allPreprocessors = combineLists(allPreprocessors, config[pattern])
   })
   allPreprocessors.forEach(instantiatePreprocessor)
 
   return function preprocess (file, done) {
     patterns = Object.keys(config)
-    var retryCount = 0
-    var maxRetries = 3
+    let retryCount = 0
+    let maxRetries = 3
     function readFileCallback (err, buffer) {
       if (err) {
         log.warn(err)
@@ -90,25 +84,22 @@ function createPreprocessor (config, basePath, injector) {
         }
       }
 
-      isBinaryFile(buffer, buffer.length, function (err, thisFileIsBinary) {
+      isBinaryFile(buffer, buffer.length, function (err, isBinary) {
         if (err) {
           throw err
         }
 
         var preprocessorNames = []
-        for (var i = 0; i < patterns.length; i++) {
-          if (mm(file.originalPath, patterns[i], {dot: true})) {
-            preprocessorNames = combineLists(preprocessorNames, config[patterns[i]])
+        patterns.forEach((pattern) => {
+          if (mm(file.originalPath, pattern, {dot: true})) {
+            preprocessorNames = combineLists(preprocessorNames, config[pattern])
           }
-        }
+        })
 
-        var preprocessors = []
-        var nextPreprocessor = createNextProcessor(preprocessors, file, done)
-        preprocessorNames.forEach(function (name) {
-          var p = instances[name]
-          if (p == null) {
-            p = instantiatePreprocessor(name)
-          }
+        let preprocessors = []
+        const nextPreprocessor = createNextProcessor(preprocessors, file, done)
+        preprocessorNames.forEach((name) => {
+          const p = instances[name] || instantiatePreprocessor(name)
 
           if (p == null) {
             if (!alreadyDisplayedErrors[name]) {
@@ -120,20 +111,21 @@ function createPreprocessor (config, basePath, injector) {
           }
 
           instances[name] = p
-          if (!thisFileIsBinary || p.handleBinaryFiles) {
+          if (!isBinary || p.handleBinaryFiles) {
             preprocessors.push(p)
           } else {
             log.warn('Ignored preprocessing %s because %s has handleBinaryFiles=false.',
               file.originalPath, name)
           }
         })
 
-        nextPreprocessor(null, thisFileIsBinary ? buffer : buffer.toString())
+        nextPreprocessor(null, isBinary ? buffer : buffer.toString())
       })
     }
     return fs.readFile(file.originalPath, readFileCallback)
   }
 }
+
 createPreprocessor.$inject = ['config.preprocessors', 'config.basePath', 'injector']
 
 exports.createPreprocessor = createPreprocessor

lib/utils/crypto-utils.js

@@ -0,0 +1,14 @@
+'use strict'
+
+const crypto = require('crypto')
+
+const CryptoUtils = {
+  sha1 (data) {
+    return crypto
+      .createHash('sha1')
+      .update(data)
+      .digest('hex')
+  }
+}
+
+module.exports = CryptoUtils