preserve order in concat

lib/concat.js

@@ -1,5 +1,5 @@
-import concat from './internal/concat';
-import doParallel from './internal/doParallel';
+import doLimit from './internal/doLimit';
+import concatLimit from './concatLimit';
 
 /**
  * Applies `iteratee` to each item in `coll`, concatenating the results. Returns
@@ -26,4 +26,4 @@ import doParallel from './internal/doParallel';
  * // files is now a list of filenames that exist in the 3 directories
  * });
  */
-export default doParallel(concat);
+export default doLimit(concatLimit, Infinity);

lib/concatLimit.js

@@ -1,5 +1,5 @@
-import doParallelLimit from './internal/doParallelLimit';
-import concat from './internal/concat';
+import noop from 'lodash/noop';
+import mapLimit from './mapLimit';
 
 /**
  * The same as [`concat`]{@link module:Collections.concat} but runs a maximum of `limit` async operations at a time.
@@ -19,4 +19,18 @@ import concat from './internal/concat';
  * containing the concatenated results of the `iteratee` function. Invoked with
  * (err, results).
  */
-export default doParallelLimit(concat);
+// export default doParallelLimit(concat);
+export default function(coll, limit, iteratee, callback) {
+ callback = callback || noop;
+ mapLimit(coll, limit, iteratee, function(err, mapResults) {
+ var result = [];
+
+ for (var i = 0; i < mapResults.length; i++) {
+ if (mapResults[i]) {
+ result = result.concat(mapResults[i]);
+ }
+ }
+
+ return callback(err, result);
+ });
+}

lib/concatSeries.js

@@ -1,5 +1,5 @@
-import concat from './internal/concat';
-import doSeries from './internal/doSeries';
+import doLimit from './internal/doLimit';
+import concatLimit from './concatLimit';
 
 /**
  * The same as [`concat`]{@link module:Collections.concat} but runs only a single async operation at a time.
@@ -19,4 +19,4 @@ import doSeries from './internal/doSeries';
  * containing the concatenated results of the `iteratee` function. Invoked with
  * (err, results).
  */
-export default doSeries(concat);
+export default doLimit(concatLimit, 1);

mocha_test/concat.js

@@ -17,7 +17,7 @@ describe('concat', function() {
  }, x*25);
  };
  async.concat([1,3,2], iteratee, function(err, results){
- expect(results).to.eql([1,2,1,3,2,1]);
+ expect(results).to.eql([1,3,2,1,2,1]);
  expect(call_order).to.eql([1,2,3]);
  assert(err === null, err + " passed instead of 'null'");
  done();
@@ -34,6 +34,19 @@ describe('concat', function() {
  });
  });
 
+ it('concat preserves order', function(done) {
+ var arr = [30, 15];
+ async.concat(arr, function(x, cb) {
+ setTimeout(function() {
+ cb(null, x);
+ }, x);
+ }, function(err, result) {
+ expect(err).to.eql(null);
+ expect(result).to.eql(arr);
+ done();
+ })
+ });
+
  it('concatSeries', function(done) {
  var call_order = [];
  var iteratee = function (x, cb) {

mocha_test/es2017/asyncFunctions.js

@@ -212,6 +212,14 @@ module.exports = function () {
  });
  });
 
+ it('should handle async functions in concatLimit', (done) => {
+ async.concatLimit(input, 2, asyncIdentity, (err, result) => {
+ expect(err).to.eql(null);
+ expect(result).to.eql(input);
+ done(err);
+ });
+ });
+
  it('should handle async functions in concatSeries', (done) => {
  async.concatSeries(input, asyncIdentity, (err, result) => {
  expect(result).to.eql(input);