From ca50853aba0cbd9337dc39613f0847701babfd57 Mon Sep 17 00:00:00 2001
From: Sam Glider <smahaseeb97@gmail.com>
Date: Wed, 4 Dec 2019 22:03:01 +0530
Subject: [PATCH] Use returned object in 'function' mode (#88)

* Use returned parsedPath in 'function' mode

* Test for return values in 'function' mode

* Fix quote marks

* Discard return value if null

* Test null return values

* Update docs for changes in function mode

* Update README.md
---
 README.md           | 20 +++++++++++++++++---
 index.js            |  6 +++++-
 test/rename.spec.js | 20 +++++++++++++++-----
 3 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/README.md b/README.md
index 4fdd30b..3dafdea 100644
--- a/README.md
+++ b/README.md
@@ -14,21 +14,34 @@ gulp-rename provides simple file renaming methods.
 ```javascript
 var rename = require("gulp-rename");
 
-// rename via string
+// rename to a fixed value
 gulp.src("./src/main/text/hello.txt")
   .pipe(rename("main/text/ciao/goodbye.md"))
   .pipe(gulp.dest("./dist")); // ./dist/main/text/ciao/goodbye.md
 
-// rename via function
+// rename via mutating function
 gulp.src("./src/**/hello.txt")
   .pipe(rename(function (path) {
+    // Updates the object in-place
     path.dirname += "/ciao";
     path.basename += "-goodbye";
     path.extname = ".md";
   }))
   .pipe(gulp.dest("./dist")); // ./dist/main/text/ciao/hello-goodbye.md
 
-// rename via hash
+// rename via a map function
+gulp.src("./src/**/hello.txt")
+  .pipe(rename(function (path) {
+    // Returns a completely new object, make sure you return all keys needed!
+    return {
+      dirname: path.dirname + "/ciao",
+      basename: path.basename + "-goodbye",
+      extname: ".md"
+    };
+  }))
+  .pipe(gulp.dest("./dist")); // ./dist/main/text/ciao/hello-goodbye.md
+
+// rename via a fixed object
 gulp.src("./src/main/text/hello.txt", { base: process.cwd() })
   .pipe(rename({
     dirname: "main/text/ciao",
@@ -50,6 +63,7 @@ gulp.src("./src/main/text/hello.txt", { base: process.cwd() })
 * `basename` is the filename without the extension like path.basename(filename, path.extname(filename)).
 * `extname` is the file extension including the '.' like path.extname(filename).
 * when using a function, a second `file` argument is provided with the whole context and original file value
+* when using a function, if no `Object` is returned then the passed parameter object (along with any modifications) is re-used
 
 ## License
 
diff --git a/index.js b/index.js
index c249a71..8e75e56 100644
--- a/index.js
+++ b/index.js
@@ -33,7 +33,11 @@ function gulpRename(obj, options) {
 
     } else if (type === 'function') {
 
-      obj(parsedPath, file);
+      let newParsedPath = obj(parsedPath, file);
+      if (typeof newParsedPath === 'object' && newParsedPath !== null) {
+        parsedPath = newParsedPath;
+      }
+      
       path = Path.join(parsedPath.dirname, parsedPath.basename + parsedPath.extname);
 
     } else if (type === 'object' && obj !== undefined && obj !== null) {
diff --git a/test/rename.spec.js b/test/rename.spec.js
index 03d4470..a60ace0 100644
--- a/test/rename.spec.js
+++ b/test/rename.spec.js
@@ -153,15 +153,25 @@ describe('gulp-rename', function () {
       helper(srcPattern, obj, expectedPath, done);
     });
 
-    it('ignores the return value', function (done) {
-      var obj = function (/*path*/) {
+    it('receives object from return value', function (done) {
+      var obj = function (path) {
         return {
-          dirname: 'elsewhere',
-          basename: 'aloha',
+          dirname: path.dirname,
+          basename: path.basename,
           extname: '.md'
         };
       };
-      var expectedPath = 'test/fixtures/hello.txt';
+      var expectedPath = 'test/fixtures/hello.md';
+      helper(srcPattern, obj, expectedPath, done);
+    });
+
+    it('ignores null return value but uses passed object', function (done) {
+      var obj = function (path) {
+        path.extname.should.equal('.txt');
+        path.extname = '.md';
+        return null;
+      };
+      var expectedPath = 'test/fixtures/hello.md';
       helper(srcPattern, obj, expectedPath, done);
     });