Merge pull request #333 from mde/mde/promise_support

Added Promise support with capabilities test to renderFile

lib/ejs.js

@@ -93,6 +93,16 @@ exports.fileLoader = fs.readFileSync;
 
 exports.localsName = _DEFAULT_LOCALS_NAME;
 
+/**
+ * Promise implementation -- defaults to the native implementation if available
+ * This is mostly just for testability
+ *
+ * @type {Function}
+ * @public
+ */
+
+exports.promiseImpl = (new Function('return this;'))().Promise;
+
 /**
  * Get the path to the included file from the parent file path and the
  * specified path.
@@ -220,13 +230,32 @@ function handleCache(options, template) {
 
 function tryHandleCache(options, data, cb) {
   var result;
-  try {
-    result = handleCache(options)(data);
+  if (!cb) {
+    if (typeof exports.promiseImpl == 'function') {
+      return new exports.promiseImpl(function (resolve, reject) {
+        try {
+          result = handleCache(options)(data);
+          resolve(result);
+        }
+        catch (err) {
+          reject(err);
+        }
+      });
+    }
+    else {
+      throw new Error('Please provide a callback function');
+    }
   }
-  catch (err) {
-    return cb(err);
+  else {
+    try {
+      result = handleCache(options)(data);
+    }
+    catch (err) {
+      return cb(err);
+    }
+
+    cb(null, result);
   }
-  return cb(null, result);
 }
 
 /**
@@ -399,17 +428,27 @@ exports.render = function (template, d, o) {
  */
 
 exports.renderFile = function () {
-  var filename = arguments[0];
-  var cb = arguments[arguments.length - 1];
+  var args = Array.prototype.slice.call(arguments);
+  var filename = args.shift();
+  var cb;
   var opts = {filename: filename};
   var data;
 
-  if (arguments.length > 2) {
-    data = arguments[1];
-
-    // No options object -- if there are optiony names
-    // in the data, copy them to options
-    if (arguments.length === 3) {
+  // Do we have a callback?
+  if (typeof arguments[arguments.length - 1] == 'function') {
+    cb = args.pop();
+  }
+  // Do we have data/opts?
+  if (args.length) {
+    // Should always have data obj
+    data = args.shift();
+    // Normal passed opts (data obj + opts obj)
+    if (args.length) {
+      // Use shallowCopy so we don't pollute passed in opts obj with new vals
+      utils.shallowCopy(opts, args.pop());
+    }
+    // Special casing for Express (opts-in-data)
+    else {
       // Express 4
       if (data.settings) {
         if (data.settings.views) {
@@ -424,11 +463,6 @@ exports.renderFile = function () {
         utils.shallowCopyFromList(opts, data, _OPTS_EXPRESS);
       }
     }
-    else {
-      // Use shallowCopy so we don't pollute passed in opts obj with new vals
-      utils.shallowCopy(opts, arguments[2]);
-    }
-
     opts.filename = filename;
   }
   else {

test/ejs.js

@@ -292,7 +292,7 @@ suite('ejs.render(str, data, opts)', function () {
 
 });
 
-suite('ejs.renderFile(path, [data], [options], fn)', function () {
+suite('ejs.renderFile(path, [data], [options], [fn])', function () {
   test('render a file', function(done) {
     ejs.renderFile('test/fixtures/para.ejs', function(err, html) {
       if (err) {
@@ -303,6 +303,51 @@ suite('ejs.renderFile(path, [data], [options], fn)', function () {
     });
   });
 
+  test('Promise support', function(done) {
+    var AsyncCtor;
+    var func;
+    function checkResult(html) {
+      assert.equal(html, '<p>hey</p>\n');
+    }
+    // Environments without Promise support -- should throw
+    // when no callback provided
+    function checkNoPromise() {
+      delete ejs.promiseImpl;
+      assert.throws(function () {
+        ejs.renderFile('test/fixtures/para.ejs');
+      });
+      ejs.promiseImpl = global.Promise;
+      done();
+    }
+
+    // Check for async/await support -- have to use eval for check because
+    // envs without async will break at parsing step
+    try {
+      eval('AsyncCtor = (async function () {}).constructor;');
+    }
+    catch (e) {
+      // No-op
+    }
+
+    // Both async and Promise -- in both cases, also check the call
+    // correctly throws in non-Promise envs if no callback provided
+    // -------------------
+    // Async support -- have to use eval for constructing async func for
+    // same reasons as above
+    if (AsyncCtor) {
+      func = new AsyncCtor('ejs', 'checkResult', 'checkNoPromise',
+        "let res = await ejs.renderFile('test/fixtures/para.ejs'); checkResult(res); checkNoPromise();");
+      func(ejs, checkResult, checkNoPromise);
+    }
+    // Ordinary Promise support
+    else {
+      ejs.renderFile('test/fixtures/para.ejs').then(function (res) {
+        checkResult(res);
+        checkNoPromise();
+      });
+    }
+  });
+
   test('accept locals', function(done) {
     var data =  {name: 'fonebone'};
     var options = {delimiter: '$'};