Trying to implement sourcemaps without vinyl-prepare

lib/dest/index.js

@@ -1,22 +1,22 @@
 'use strict';
 
+var koalas = require('koalas');
+var pumpify = require('pumpify');
 var through2 = require('through2');
-var sourcemaps = require('gulp-sourcemaps');
-var duplexify = require('duplexify');
+var vinylSourcemap = require('vinyl-sourcemap');
 var valueOrFunction = require('value-or-function');
 
 var sink = require('../sink');
 var prepareWrite = require('../prepare-write');
 var writeContents = require('./write-contents');
 
+var boolOrString = valueOrFunction.bind(null, ['boolean', 'string']);
+
 function dest(outFolder, opt) {
   if (!opt) {
     opt = {};
   }
 
-  var sourcemapsOpt = valueOrFunction(
-      ['boolean', 'string', 'object'], opt.sourcemaps);
-
   function saveFile(file, enc, callback) {
     prepareWrite(outFolder, file, opt, onPrepare);
 
@@ -28,26 +28,38 @@ function dest(outFolder, opt) {
     }
   }
 
-  var saveStream = through2.obj(opt, saveFile);
-  if (!sourcemapsOpt) {
-    // Sink the save stream to start flowing
-    // Do this on nextTick, it will flow at slowest speed of piped streams
-    process.nextTick(sink(saveStream));
+  function sourcemaps(file, enc, callback) {
+    var stream = this;
+    var sourcemapsOpt = koalas(boolOrString(opt.sourcemaps, file), false);
 
-    return saveStream;
-  }
+    if (!sourcemapsOpt) {
+      return callback(null, file);
+    }
+
+    var sourcemapsPath;
+    if (typeof sourcemapsOpt === 'string') {
+      sourcemapsPath = sourcemapsOpt;
+    }
 
-  if (typeof sourcemapsOpt === 'boolean') {
-    sourcemapsOpt = {};
-  } else if (typeof sourcemapsOpt === 'string') {
-    sourcemapsOpt = {
-      path: sourcemapsOpt,
-    };
+    vinylSourcemap.write(file, sourcemapsPath, onSourcemap);
+
+    function onSourcemap(err, uFile, smFile) {
+      if (err) {
+        return callback(err);
+      }
+
+      stream.push(uFile);
+      if (smFile) {
+        stream.push(smFile);
+      }
+
+      callback();
+    }
   }
 
-  var mapStream = sourcemaps.write(sourcemapsOpt.path, sourcemapsOpt);
-  var outputStream = duplexify.obj(mapStream, saveStream);
-  mapStream.pipe(saveStream);
+  var saveStream = through2.obj(opt, saveFile);
+  var mapStream = through2.obj(sourcemaps);
+  var outputStream = pumpify.obj(mapStream, saveStream);
 
   // Sink the output stream to start flowing
   // Do this on nextTick, it will flow at slowest speed of piped streams

package.json

@@ -36,13 +36,15 @@
     "lazystream": "^1.0.0",
     "merge-stream": "^1.0.0",
     "object-assign": "^4.0.0",
+    "pumpify": "^1.3.5",
     "strip-bom": "^2.0.0",
     "strip-bom-stream": "^1.0.0",
     "through2": "^2.0.0",
     "through2-filter": "^2.0.0",
     "vali-date": "^1.0.0",
     "value-or-function": "^1.2.0",
-    "vinyl": "^2.0.0"
+    "vinyl": "^2.0.0",
+    "vinyl-sourcemap": "gulpjs/vinyl-sourcemap"
   },
   "devDependencies": {
     "del": "^2.2.0",