added ref-counted api

fixes #4

README.md

@@ -2,12 +2,14 @@
 
 ## Usage
 
+### Simple API
+
 ``` javascript
 require("style!raw!./file.css");
 // => add rules in file.css to document
 ```
 
-It's recommended to combine it with the [`css`](https://github.com/webpack/css-loader) loader: `require("style!css!./file.css")`.
+It's recommended to combine it with the [`css-loader`](https://github.com/webpack/css-loader): `require("style!css!./file.css")`.
 
 It also possible to add a URL instead of a css string:
 
@@ -16,6 +18,18 @@ require("style/url!file!./file.css");
 // => add a <link rel="stlyesheet"> to file.css to document
 ```
 
+### Reference-counted API
+
+``` javascript
+var style = require("style/useable!css!./file.css");
+style.use(); // = style.ref();
+style.unuse(); // = style.unref();
+```
+
+Styles are not added on require, but instead on call to `use`/`ref`. Styles are removed from page if `unuse`/`unref` is called exactly as often as `use`/`ref`.
+
+Note: Behavior is undefined when `unuse`/`unref` is called more often than `use`/`ref`. Don't do that.
+
 ## License
 
 MIT (http://www.opensource.org/licenses/mit-license.php)

useable.js

@@ -0,0 +1,39 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+var path = require("path");
+module.exports = function() {};
+module.exports.pitch = function(remainingRequest) {
+	this.cacheable && this.cacheable();
+	return [
+		"var refs = 0;",
+		"var dispose;",
+		"exports.use = exports.ref = function() {",
+		"	if(!(refs++)) {",
+		"		dispose = require(" + JSON.stringify("!" + path.join(__dirname, "addStyle.js")) + ")(require(" + JSON.stringify("!!" + remainingRequest) + "));",
+		"	}",
+		"	return exports",
+		"};",
+		"exports.unuse = exports.unref = function() {",
+		"	if(!(--refs)) {",
+		"		dispose();",
+		"		dispose = null;",
+		"	}",
+		"};",
+		"if(module.hot) {",
+		"	refs = module.hot.data && module.hot.data.refs || 0;",
+		"	if(refs) {",
+		"		refs--;",
+		"		exports.ref();",
+		"	}",
+		"	module.hot.accept();",
+		"	module.hot.dispose(function(data) {",
+		"		data.refs = refs;",
+		"		if(dispose) {",
+		"			dispose();",
+		"		}",
+		"	});",
+		"}",
+	].join("\n");
+};