add examples

.npmignore

@@ -7,3 +7,4 @@ circle.yml
 .babelrc
 .gitignore
 /coverage.lcov
+/examples/

README.md

@@ -4,3 +4,42 @@
 [![Codecov](https://img.shields.io/codecov/c/github/KOBA789/dfa-router.svg?style=flat-square)](https://codecov.io/gh/KOBA789/dfa-router)
 
 A simple server-side url router using Deterministic Finite Automaton.
+
+## How to Use
+
+It behaves like a simple key-value map.
+
+```
+const router = new Router();
+router.add('GET', '/foo', 'foo');
+router.add('GET', '/bar', 'bar');
+
+const foo = router.route('GET', '/foo');
+assert.deepEqual(foo, {
+  type: 'found',
+  value: 'foo',
+  params: {},
+});
+const bar = router.route('GET', '/bar');
+assert.deepEqual(bar, {
+  type: 'found',
+  value: 'bar',
+  params: {},
+});
+```
+
+And also, it can capture parameters.
+
+```
+const router = new Router();
+router.add('GET', '/:param', 'foo');
+
+const foo = router.route('GET', '/value');
+assert.deepEqual(foo, {
+  type: 'found',
+  value: 'foo',
+  params: { param: 'value' },
+});
+```
+
+See `examples/server.js` and `test/` to learn more.

examples/server.js

@@ -0,0 +1,39 @@
+const http = require('http');
+const url = require('url');
+
+const Router = require('../');
+
+const router = new Router();
+router.add('GET', '/', (req, res, params) => {
+  res.writeHead(200, { 'Content-Type': 'text/plain' });
+  res.end('root');
+});
+
+router.add('POST', '/post', (req, res, params) => {
+  res.writeHead(200, { 'Content-Type': 'text/plain' });
+  res.end('/post');
+});
+
+const app = http.createServer((req, res) => {
+  const urlObj = url.parse(req.url);
+  const result = router.route(req.method, urlObj.pathname, true);
+  switch (result.type) {
+  case 'found':
+    result.value(req, res, Object.assign({}, urlObj.query, result.params));
+    break;
+  case 'not_found':
+    res.writeHead(404);
+    res.end();
+    break;
+  case 'method_not_allowed':
+    res.writeHead(405);
+    res.end(`Allowed methods are: ${result.allowed.join(', ')}`);
+    break;
+  }
+});
+
+const PORT = process.env.PORT || 8124;
+const HOSTNAME = process.env.HOSTNAME || '127.0.0.1';
+app.listen(PORT, HOSTNAME, () => {
+  console.log(`Server running at http://${HOSTNAME}:${PORT}/`);
+});