Update comment & expose transformDecl

That will allow direct usage un a plugin to avoid multiple loop to
apply transformation directly in a global plugin

Author: MoOx

index.js

@@ -4,43 +4,46 @@
 var reduceCSSCalc = require("reduce-css-calc")
 
 /**
- * Expose `plugin`.
+ * Expose plugin & helper
  */
-
 module.exports = plugin
+module.exports.transformDecl = transformDecl
 
 /**
- * Plugin to convert all function calls.
- *
- * @param {Object} stylesheet
+ * PostCSS plugin to reduce calc() function calls.
  */
-
 function plugin() {
   return function(style) {
-    style.eachDecl(function declaration(dec) {
-      if (!dec.value) {
-        return
-      }
+    style.eachDecl(transformDecl)
+  }
+}
+
+/**
+ * Reduce CSS calc on a declaration object
+ *
+ * @param {object} dec [description]
+ */
+function transformDecl(dec) {
+  if (!dec.value) {
+    return
+  }
 
-      try {
-        dec.value = convert(dec.value)
-      }
-      catch (err) {
-        err.position = dec.position
-        throw err
-      }
-    })
+  try {
+    dec.value = transform(dec.value)
+  }
+  catch (err) {
+    err.position = dec.position
+    throw err
   }
 }
 
 /**
- * Reduce CSS calc()
+ * Reduce CSS calc() on a declaration value
  *
  * @param {String} string
  * @return {String}
  */
-
-function convert(string) {
+function transform(string) {
   if (string.indexOf("calc(") === -1) {
     return string
   }