From 903e1b2fc5ca09f22912d3fda2fdd212f19d633d Mon Sep 17 00:00:00 2001
From: Tom Christie <tom@tomchristie.com>
Date: Mon, 25 Jun 2018 22:23:40 +0100
Subject: [PATCH] Add Router, Path, PathPrefix

---
 starlette/__init__.py |  1 +
 starlette/routing.py  | 64 +++++++++++++++++++++++++++++++++++++++++++
 tests/test_routing.py | 43 +++++++++++++++++++++++++++++
 3 files changed, 108 insertions(+)
 create mode 100644 starlette/routing.py
 create mode 100644 tests/test_routing.py

diff --git a/starlette/__init__.py b/starlette/__init__.py
index 9f44a047..f6104abf 100644
--- a/starlette/__init__.py
+++ b/starlette/__init__.py
@@ -1,6 +1,7 @@
 from starlette.decorators import asgi_application
 from starlette.response import HTMLResponse, JSONResponse, Response, StreamingResponse
 from starlette.request import Request
+from starlette.routing import Path, PathPrefix, Router
 from starlette.testclient import TestClient
 
 
diff --git a/starlette/routing.py b/starlette/routing.py
new file mode 100644
index 00000000..7a563579
--- /dev/null
+++ b/starlette/routing.py
@@ -0,0 +1,64 @@
+from starlette import Response
+import re
+
+
+class Path:
+    def __init__(self, path, app):
+        self.path = path
+        self.app = app
+        regex = '^' + path + '$'
+        regex = re.sub('{([a-zA-Z_][a-zA-Z0-9_]*)}', r'(?P<\1>[^/]*)', regex)
+        self.path_regex = re.compile(regex)
+
+    def matches(self, scope):
+        match = self.path_regex.match(scope['path'])
+        if match:
+            kwargs = dict(scope.get('kwargs', {}))
+            kwargs.update(match.groupdict())
+            child_scope = scope.copy()
+            child_scope['kwargs'] = kwargs
+            return True, child_scope
+        return False, {}
+
+    def __call__(self, scope):
+        return self.app(scope)
+
+
+class PathPrefix:
+    def __init__(self, path, app):
+        self.path = path
+        self.app = app
+        regex = '^' + path
+        regex = re.sub('{([a-zA-Z_][a-zA-Z0-9_]*)}', r'(?P<\1>[^/]*)', regex)
+        self.path_regex = re.compile(regex)
+
+    def matches(self, scope):
+        match = self.path_regex.match(scope['path'])
+        if match:
+            kwargs = dict(scope.get('kwargs', {}))
+            kwargs.update(match.groupdict())
+            child_scope = scope.copy()
+            child_scope['kwargs'] = kwargs
+            child_scope['root_path'] = scope.get('root_path', '') + match.string
+            child_scope['path'] = scope['path'][match.span()[1]:]
+            return True, child_scope
+        return False, {}
+
+    def __call__(self, scope):
+        return self.app(scope)
+
+
+class Router:
+    def __init__(self, routes, default=None):
+        self.routes = routes
+        self.default = self.not_found if default is None else default
+
+    def __call__(self, scope):
+        for route in self.routes:
+            matched, child_scope = route.matches(scope)
+            if matched:
+                return route(child_scope)
+        return self.not_found(scope)
+
+    def not_found(self, scope):
+        return Response('Not found', 404, media_type='text/plain')
diff --git a/tests/test_routing.py b/tests/test_routing.py
new file mode 100644
index 00000000..22029435
--- /dev/null
+++ b/tests/test_routing.py
@@ -0,0 +1,43 @@
+from starlette import Response, Path, PathPrefix, Router, TestClient
+
+
+def homepage(scope):
+    return Response('Hello, world', media_type='text/plain')
+
+
+def users(scope):
+    return Response('All users', media_type='text/plain')
+
+
+def user(scope):
+    content = 'User ' + scope['kwargs']['username']
+    return Response(content, media_type='text/plain')
+
+
+app = Router([
+    Path('/', app=homepage),
+    PathPrefix('/users', app=Router([
+        Path('', app=users),
+        Path('/{username}', app=user),
+    ]))
+])
+
+
+def test_router():
+    client = TestClient(app)
+
+    response = client.get('/')
+    assert response.status_code == 200
+    assert response.text == 'Hello, world'
+
+    response = client.get('/foo')
+    assert response.status_code == 404
+    assert response.text == 'Not found'
+
+    response = client.get('/users')
+    assert response.status_code == 200
+    assert response.text == 'All users'
+
+    response = client.get('/users/tomchristie')
+    assert response.status_code == 200
+    assert response.text == 'User tomchristie'