feat(connect): add junction

Author: azu

src/connect/junction.js

@@ -0,0 +1,25 @@
+"use strict";
+function applyMiddleware(text, middleware, next) {
+    middleware(text, next);
+}
+
+export default class Junction {
+    constructor() {
+        this.stack = [];
+    }
+
+    use(middleware) {
+        this.stack.push(middleware);
+    }
+
+    process(text, callback) {
+        let next = (error, data) => {
+            let middleware = this.stack.shift();
+            if (!middleware) {
+                return callback(error, data);
+            }
+            applyMiddleware(data, middleware, next);
+        };
+        next(null, text);
+    }
+}