feat: change expected module API

BREAKING CHANGE: This commit introduces a major refactoring of the loader.

- Remove node 0.10 and node 0.12 support
- The loaded module must now export a function
- This function will be called with the loader options
- This function must return an object with this structure

Property | Type | Description
:--------|:-----|:-----------
`code`   | `string|Buffer` | **Required**. The code that is passed to the next loader or to webpack.
`sourceMap` | [`SourceMap`](https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit) | **Optional**. Will be pased to the next loader or to webpack.
`ast` | `any` | **Optional**. An [Abstract Syntax Tree](https://en.wikipedia.org/wiki/Abstract_syntax_tree) that will be passed to the next loader. Useful to speed up the build time if the next loader uses the same AST.
`dependencies` | `Array<string>` | **Default: `[]`**. An array of absolute, native paths to file dependencies that need to be watched for changes. 
`cacheable` | `boolean` | **Default: `false`**. Flag whether the code can be re-used in watch mode if none of the `dependencies` have changed.

- The function may also return a promise for async results
- Switch tooling to webpack-defaults

#11

.babelrc

@@ -0,0 +1,25 @@
+{
+  "presets": [
+    [
+      "env",
+      {
+        "modules": false,
+        "useBuiltIns": true,
+        "targets": {
+          "node": 4.3
+        },
+        "exclude": [
+          "transform-async-to-generator",
+          "transform-regenerator"
+        ]
+      }
+    ]
+  ],
+  "env": {
+    "test": {
+      "presets": [
+        "env"
+      ]
+    }
+  }
+}

.editorconfig

@@ -0,0 +1,17 @@
+# editorconfig.org
+root = true
+
+[*]
+charset = utf-8
+indent_style = space
+indent_size = 2
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[package.json]
+indent_size = 2
+
+[.md]
+insert_final_newline = false
+trim_trailing_whitespace = false

.eslintignore

@@ -0,0 +1,3 @@
+/node_modules
+/dist
+/test/output

.eslintrc

@@ -0,0 +1,3 @@
+{
+  "extends": "webpack"
+}

.gitattributes

@@ -0,0 +1,3 @@
+yarn.lock -diff
+* text=auto
+bin/* eol=lf

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,5 @@
+1. Check the version of package you are using. If it's not the newest version, update and try again (see changelog while updating!).
+2. If the issue is still there, write a minimal project showing the problem and expected output.
+3. Link to the project and mention Node version and OS in your report.
+
+**IMPORTANT! You should use [Stack Overflow](https://stackoverflow.com/) for support related questions.**

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,5 @@
+<!--
+1. [Read and sign the CLA](https://cla.js.foundation/webpack/webpack.js.org). This needs to be done only once. PRs that haven't signed it won't be accepted.
+2. Check out the [development guide](https://webpack.js.org/development/) for the API and development guidelines.
+3. Read through the PR diff carefully as sometimes this can reveal issues. The work will be reviewed, but this can save some effort.
+-->

.gitignore

@@ -1 +1,14 @@
-node_modules
+yarn-debug.log*
+.eslintcache
+/coverage
+/dist
+/local
+/reports
+/node_modules
+.DS_Store
+Thumbs.db
+.idea
+.vscode
+*.sublime-project
+*.sublime-workspace
+/test/output

.travis.yml

@@ -0,0 +1,32 @@
+sudo: false
+language: node_js
+branches:
+  only:
+    - master
+matrix:
+  fast_finish: true
+  include:
+    - os: linux
+      node_js: '7'
+      env: WEBPACK_VERSION="2.2.0" JOB_PART=lint
+    - os: linux
+      node_js: '4.3'
+      env: WEBPACK_VERSION="2.2.0" JOB_PART=test
+    - os: linux
+      node_js: '6'
+      env: WEBPACK_VERSION="2.2.0" JOB_PART=test
+    - os: linux
+      node_js: '7'
+      env: WEBPACK_VERSION="2.2.0" JOB_PART=coverage
+before_install:
+  - nvm --version
+  - node --version
+before_script:
+  - |-
+    if [ "$WEBPACK_VERSION" ]; then
+      yarn add webpack@^$WEBPACK_VERSION
+    fi
+script:
+  - 'yarn run travis:$JOB_PART'
+after_success:
+  - 'bash <(curl -s https://codecov.io/bash)'

CHANGELOG.md

@@ -0,0 +1,11 @@
+# Change Log
+
+All notable changes to this project will be documented in this file. See [standard-version](https://github.com/conventional-changelog/standard-version) for commit guidelines.
+
+x.x.x / <year>-<month>-<day>
+==================
+
+  * Bug fix -
+  * Feature -
+  * Chore -
+  * Docs -

LICENSE

@@ -1,4 +1,3 @@
-
 Copyright JS Foundation and other contributors
 
 Permission is hereby granted, free of charge, to any person obtaining

README.md

@@ -1,5 +1,10 @@
-[![npm][npm]][npm-url]
-[![deps][deps]][deps-url]
+[![npm][npm]][npm-url]
+[![node][node]][node-url]
+[![npm-stats][npm-stats]][npm-url]
+[![deps][deps]][deps-url]
+[![travis][travis]][travis-url]
+[![appveyor][appveyor]][appveyor-url]
+[![coverage][cover]][cover-url]
 [![chat][chat]][chat-url]
 
 <div align="center">
@@ -9,33 +14,139 @@
       src="https://cdn.rawgit.com/webpack/media/e7485eb2/logo/icon.svg">
   </a>
   <h1>Val Loader</h1>
-  <p>Provides data to another loader<p>
+  <p>Executes the given module to generate source code on build time.<p>
 </div>
 
 <h2 align="center">Install</h2>
 
 ```bash
-npm i val-loader --save
+npm install val-loader --save-dev
 ```
+
+<h2 align="center">Examples</h2>
+
+If you have a module `findAnswer.js` like this:
+
+```js
+function findAnswer() {
+    return {
+        code: 'module.exports = 42;'
+    };
+}
+
+module.exports = findAnswer;
+```
+
+you can use the **val-loader** to generate source code on build time:
+
+```js
+// webpack.config.js
+module.exports = {
+    ...
+    module: {
+        rules: [{
+            test: require.resolve('path/to/findAnswer.js'),
+            use: [{
+                loader: 'val-loader'
+            }]
+        }]
+    }
+};
+```
+
+---
+
+A complete example of all available features looks like this:
+
+```js
+const ask = require('./ask.js');
+const generateResult = require('./generateResult.js');
+
+function findAnswer(options) {
+    return ask(options.question)
+        .then(generateResult)
+        .then(result => ({
+
+            code: result.code,
+            sourceMap: result.sourceMap,
+            ast: result.abstractSyntaxTree,
+
+            // Mark dependencies of findAnswer().
+            // The function will be re-executed if one of these
+            // dependencies has changed in watch mode.
+            dependencies: [
+                // Array of absolute native paths!
+                require.resolve('./ask.js'),
+                require.resolve('./generateResult.js')
+            ],
+
+            // Flag the generated code as cacheable.
+            // If none of the dependencies have changed,
+            // the function won't be executed again.
+            cacheable: true
+
+        }));
+}
+
+module.exports = findAnswer;
+```
+
+```js
+// webpack.config.js
+module.exports = {
+    ...
+    module: {
+        rules: [{
+            test: require.resolve('path/to/findAnswer.js'),
+            use: [{
+                loader: 'val-loader',
+                options: {
+                    question: 'What is the meaning of life?'
+                }
+            }]
+        }]
+    }
+};
+```
 
-<h2 align="center">Usage</h2>
+<h2 align="center">Usage</h2>
+
+The module that is loaded with this loader must stick to the following interfaces:
+
+### Expected module interface
+
+The loaded module must export a function as `default` export with the following *function interface*.
+
+```js
+module.exports = function (...) { ... };
+```
+
+Modules transpiled by [Babel](https://babeljs.io/) are also supported.
+
+```js
+export default function (...) { ... }
+```
+
+### Expected function interface
+
+The function will be called with the loader [`options`](https://webpack.js.org/configuration/module/#useentry) and must either return:
+
+- an object with the following *object interface* or
+- a promise that resolves to the following *object interface*
+
+### Expected object interface
+
+Property | Type | Description
+:--------|:-----|:-----------
+`code`   | `string|Buffer` | **Required**. The code that is passed to the next loader or to webpack.
+`sourceMap` | [`SourceMap`](https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit) | **Optional**. Will be pased to the next loader or to webpack.
+`ast` | `any` | **Optional**. An [Abstract Syntax Tree](https://en.wikipedia.org/wiki/Abstract_syntax_tree) that will be passed to the next loader. Useful to speed up the build time if the next loader uses the same AST.
+`dependencies` | `Array<string>` | **Default: `[]`**. An array of absolute, native paths to file dependencies that need to be watched for changes. 
+`cacheable` | `boolean` | **Default: `false`**. Flag whether the code can be re-used in watch mode if none of the `dependencies` have changed.
 
-``` javascript
-var a = require("val-loader!./file.js");
-// => excute file.js while compiling and 
-//    take the result as javascript code for including
-```
-
-Don't forget to polyfill `require` if you want to use it in node.
-See `webpack` documentation.
-
-The excution of file.js has polyfill already applied.
-
-Provide data for another loader:
-
-``` javascript
-require("css-loader!val-loader!./generateCss.js");
-```
+### Loader Options
+
+The **val-loader** itself has no options. The options are passed as they are (without cloning them) to the exported function.
 
 <h2 align="center">Maintainers</h2>
 
@@ -62,20 +173,33 @@ require("css-loader!val-loader!./generateCss.js");
       </td>
       <td align="center">
         <img width="150" height="150"
-        src="https://avatars3.githubusercontent.com/u/3408176?v=3&s=150">
+        src="https://avatars3.githubusercontent.com/u/781746?v=3&s=150">
         </br>
-        <a href="https://github.com/TheLarkInn">Sean Larkin</a>
+        <a href="https://github.com/jhnns">Johannes Ewald</a>
       </td>
     </tr>
   <tbody>
 </table>
 
 
-[npm]: https://img.shields.io/npm/v/val-loader.svg
-[npm-url]: https://npmjs.com/package/val-loader
-
-[deps]: https://david-dm.org/webpack-contrib/val-loader.svg
-[deps-url]: https://david-dm.org/webpack-contrib/val-loader
-
-[chat]: https://img.shields.io/badge/gitter-webpack%2Fwebpack-brightgreen.svg
-[chat-url]: https://gitter.im/webpack/webpack
+[npm]: https://img.shields.io/npm/v/val-loader.svg
+[npm-stats]: https://img.shields.io/npm/dm/val-loader.svg
+[npm-url]: https://npmjs.com/package/val-loader
+
+[node]: https://img.shields.io/node/v/val-loader.svg
+[node-url]: https://nodejs.org
+
+[deps]: https://david-dm.org/webpack-contrib/val-loader.svg
+[deps-url]: https://david-dm.org/webpack-contrib/val-loader
+
+[travis]: http://img.shields.io/travis/webpack-contrib/val-loader.svg
+[travis-url]: https://travis-ci.org/webpack-contrib/val-loader
+
+[appveyor-url]: https://ci.appveyor.com/project/jhnns/val-loader/branch/master
+[appveyor]: https://ci.appveyor.com/api/projects/status/github/webpack-contrib/val-loader?svg=true
+
+[cover]: https://coveralls.io/repos/github/webpack-contrib/val-loader/badge.svg
+[cover-url]: https://coveralls.io/github/webpack-contrib/val-loader
+
+[chat]: https://badges.gitter.im/webpack-contrib/webpack.svg
+[chat-url]: https://gitter.im/webpack-contrib/webpack

appveyor.yml

@@ -0,0 +1,19 @@
+# appveyor file
+# http://www.appveyor.com/docs/appveyor-yml
+
+init:
+  - git config --global core.autocrlf input
+
+install:
+  - ps: Install-Product node $env:nodejs_version x64
+  - npm install
+
+build: off
+
+matrix:
+  fast_finish: true
+
+test_script:
+  - node --version
+  - npm --version
+  - cmd: npm run test