Add plugins option

Close #118

Author: MoOx

CHANGELOG.md

@@ -1,3 +1,6 @@
+
+- Added: `plugins` option that allows you to pipe your own transformation ([#118](https://github.com/cssnext/cssnext/issues/118))
+
 # 1.6.0 - 2015-06-02
 
 - Added: prevent mutability issues with frozen options objects ([#147](https://github.com/cssnext/cssnext/pull/147))

docs/content/usage.md

@@ -96,6 +96,26 @@ By default, `url()` are rebased according to `from` (and `to`) option(s). This i
 
 _Note: you can pass [postcss-url options](https://github.com/postcss/postcss-url#options) directly in order to inline or have more control over urls._
 
+## `plugins`
+
+(default: undefined)
+
+Allows you to pass your own array of transformations. You can just pass your own
+[PostCSS](https://github.com/postcss/postcss) plugins.
+
+```js
+{
+  plugins: [
+    require("postcss-sass-stuff"),
+    require("postcss-more-crazy-stuff"),
+    // custom transformation code
+    function(styles) {
+
+    },
+  ],
+}
+```
+
 ## `compress`
 
 (default: `false`)

src/__tests__/option.plugins.js

@@ -0,0 +1,25 @@
+import test from "tape"
+
+import cssnext from ".."
+
+test("cssnext option: plugins", (t) => {
+
+  t.equal(
+    cssnext(
+      ":root{} @notOk",
+      {
+        plugins: [
+          styles => {
+            styles.eachAtRule(atRule => {
+              atRule.name = "ok"
+            })
+          },
+        ],
+      }
+    ),
+    "@ok",
+    "should allow to add custom plugins"
+  )
+
+  t.end()
+})

src/index.js

@@ -198,6 +198,17 @@ function cssnext(string, options) {
     }
   })
 
+  if (options.plugins) {
+    if (!Array.isArray(options.plugins)) {
+      throw new Error(
+        "cssnext 'plugins' option expect an array of PostCSS plugins. " +
+        "You provided " + (typeof options.plugins)
+      )
+    }
+
+    options.plugins.forEach(plugin => postcssInstance.use(plugin))
+  }
+
   // minification
   if (options.compress) {
     var nano = require("cssnano")