feature: root option allows array of strings

src/util/fs.js

@@ -0,0 +1,34 @@
+const fs = require('fs');
+
+function readFileAsync(filepath) {
+    return new Promise(function(resolve, reject) {
+        fs.readFile(filepath, 'utf8', function(err, content) {
+            err ? reject(err) : resolve(content);
+        });
+    });
+};
+
+function statFileAsync(path) {
+    return new Promise(function(resolve, reject) {
+        fs.stat(path, (err, stat) => err ? reject(err) : resolve(stat))
+    });
+};
+
+function pathResolve(root, path) {
+    if (path[0] == '/') return path;
+
+    var arr = root.split('/').concat(path.split('/'));
+    var result = [];
+    arr.forEach(function(slug) {
+        if (slug == '..') result.pop();
+        else if (!slug || slug == '.');
+        else result.push(slug);
+    });
+    return '/' + result.join('/');
+}
+
+module.exports = {
+    readFileAsync,
+    pathResolve,
+    statFileAsync
+};

src/util/promise.js

@@ -0,0 +1,19 @@
+const Promise = require('any-promise');
+
+/*
+ * Call functions in serial until someone resolved.
+ * @param {Array} iterable the array to iterate with.
+ * @param {Array} iteratee returns a new promise.
+ * The iteratee is invoked with three arguments: (value, index, iterable). 
+ */
+function someSeries(iterable, iteratee) {
+    var ret = Promise.reject(new Error('init'));
+    iterable.forEach(function(item, idx) {
+        ret = ret
+            .then(x => x)
+            .catch(e => iteratee(item, idx, iterable));
+    });
+    return ret;
+}
+
+exports.someSeries = someSeries;

src/util/underscore.js

@@ -13,7 +13,7 @@ function isString(value) {
  * Iteratee functions may exit iteration early by explicitly returning false.
  * @param {Object} object The object to iterate over.
  * @param {Function} iteratee The function invoked per iteration.
- * @return {Object} Returs object.
+ * @return {Object} Returns object.
  */
 function forOwn(object, iteratee) {
     object = object || {};
@@ -25,5 +25,10 @@ function forOwn(object, iteratee) {
     return object;
 }
 
+function isArray(value) {
+    return value instanceof Array;
+}
+
 exports.isString = isString;
+exports.isArray = isArray;
 exports.forOwn = forOwn;