Convert precompiler template loading to async

lib/precompiler.js

@@ -1,62 +1,85 @@
 /*eslint-disable no-console */
+import Async from 'async';
 import fs from 'fs';
 import * as Handlebars from './handlebars';
 import {basename} from 'path';
 import {SourceMapConsumer, SourceNode} from 'source-map';
 import uglify from 'uglify-js';
 
-module.exports.loadTemplates = function(opts) {
+module.exports.loadTemplates = function(opts, callback) {
   // Build file extension pattern
   let extension = (opts.extension || 'handlebars').replace(/[\\^$*+?.():=!|{}\-\[\]]/g, function(arg) { return '\\' + arg; });
   extension = new RegExp('\\.' + extension + '$');
 
-  let ret = [];
-  function processTemplate(template, root) {
-    let path = template,
-        stat;
-    try {
-      stat = fs.statSync(template);
-    } catch (err) {
-      throw new Handlebars.Exception(`Unable to open template file "${template}"`);
-    }
+  let ret = [],
+      queue = opts.files.map((template) => ({template, root: opts.root}));
+  Async.whilst(() => queue.length, function(callback) {
+    let {template: path, root} = queue.shift();
 
-    if (stat.isDirectory()) {
-      opts.hasDirectory = true;
+    fs.stat(path, function(err, stat) {
+      if (err) {
+        return callback(new Handlebars.Exception(`Unable to open template file "${path}"`));
+      }
 
-      fs.readdirSync(template).map(function(file) {
-        let childPath = template + '/' + file;
+      if (stat.isDirectory()) {
+        opts.hasDirectory = true;
 
-        if (extension.test(childPath) || fs.statSync(childPath).isDirectory()) {
-          processTemplate(childPath, root || template);
-        }
-      });
+        fs.readdir(path, function(err, children) {
+          /* istanbul ignore next : Race condition that being too lazy to test */
+          if (err) {
+            return callback(err);
+          }
+          children.forEach(function(file) {
+            let childPath = path + '/' + file;
+
+            if (extension.test(childPath) || fs.statSync(childPath).isDirectory()) {
+              queue.push({template: childPath, root: root || path});
+            }
+          });
+
+          callback();
+        });
+      } else {
+        fs.readFile(path, 'utf8', function(err, data) {
+          /* istanbul ignore next : Race condition that being too lazy to test */
+          if (err) {
+            return callback(err);
+          }
+
+          if (opts.bom && data.indexOf('\uFEFF') === 0) {
+            data = data.substring(1);
+          }
+
+          // Clean the template name
+          let name = path;
+          if (!root) {
+            name = basename(name);
+          } else if (name.indexOf(root) === 0) {
+            name = name.substring(root.length + 1);
+          }
+          name = name.replace(extension, '');
+
+          ret.push({
+            path: path,
+            name: name,
+            source: data
+          });
+
+          callback();
+        });
+      }
+    });
+  },
+  function(err) {
+    if (err) {
+      callback(err);
     } else {
-      let data = fs.readFileSync(path, 'utf8');
+      opts.templates = ret;
 
-      if (opts.bom && data.indexOf('\uFEFF') === 0) {
-        data = data.substring(1);
-      }
-
-      // Clean the template name
-      if (!root) {
-        template = basename(template);
-      } else if (template.indexOf(root) === 0) {
-        template = template.substring(root.length + 1);
-      }
-      template = template.replace(extension, '');
-
-      ret.push({
-        path: path,
-        name: template,
-        source: data
-      });
+      callback(undefined, opts);
     }
-  }
-  opts.templates.forEach(function(template) {
-    processTemplate(template, opts.root);
   });
-  opts.templates = ret;
-};
+}
 
 module.exports.cli = function(opts) {
   if (opts.version) {