resource/Site: Add regular expression support for path names

aiocoap/resource.py

@@ -26,6 +26,7 @@
 dispatch requests based on the Uri-Path header.
 """
 
+import re
 import hashlib
 import asyncio
 
@@ -161,6 +162,9 @@ def render_get(self, request):
         response.opt.content_format = self.ct
         return response
 
+class PathRegex(str):
+    """Regular expression match in resource path components"""
+
 class Site(interfaces.ObservableResource):
     """Typical root element that gets passed to a :class:`Context` and contains
     all the resources that can be found when the endpoint gets accessed as a
@@ -185,12 +189,34 @@ def needs_blockwise_assembly(self, request):
 
     @asyncio.coroutine
     def render(self, request):
-        try:
-            child = self._resources[request.opt.uri_path]
-        except KeyError:
+        path = tuple(request.opt.uri_path)
+        # Only compare against resources with the same number of path components
+        matches = [(key, res) for key, res in self._resources.items() if len(key) == len(path)]
+        # Filter routes matching the path, one level at a time
+        for level in range(len(path)):
+            # Try to find exact string matches
+            string_matches = [
+                (key, res) for key, res in matches \
+                if not isinstance(key[level], PathRegex) and \
+                key[level] == path[level]
+                ]
+            if string_matches:
+                # string matches have a higher priority than regex matches
+                matches = string_matches
+                continue
+            # Try to find any regex matches
+            matches = [
+                (key, res) for key, res in matches \
+                if isinstance(key[level], PathRegex) and \
+                re.fullmatch(key[level], path[level])
+                ]
+        if len(matches) == 0:
             raise error.NoResource()
-        else:
-            return child.render(request)
+        elif len(matches) > 1:
+            raise error.RenderableError(
+                "Ambiguous matches: {} = {}".format(repr(path), repr(matches)))
+        child = matches[0][1]
+        return child.render(request)
 
     @asyncio.coroutine
     def add_observation(self, request, serverobservation):

server.py

@@ -13,6 +13,7 @@
 
 import asyncio
 
+from aiocoap.resource import PathRegex
 import aiocoap.resource as resource
 import aiocoap
 
@@ -90,6 +91,15 @@ def render_get(self, request):
         payload = datetime.datetime.now().strftime("%Y-%m-%d %H:%M").encode('ascii')
         return aiocoap.Message(code=aiocoap.CONTENT, payload=payload)
 
+class RegexResource(resource.Resource):
+    """Example wildcard matching resource, use request.opt.uri_path to find the
+    actual target of the request"""
+
+    @asyncio.coroutine
+    def render_get(self, request):
+        payload = 'Regular expression match example\nrequest.opt.uri_path = {}'.format(repr(request.opt.uri_path))
+        return aiocoap.Message(code=aiocoap.CONTENT, payload=payload.encode('utf-8'))
+
 #class CoreResource(resource.Resource):
 #    """
 #    Example Resource that provides list of links hosted by a server.
@@ -129,6 +139,10 @@ def main():
 
     root.add_resource(('other', 'separate'), SeparateLargeResource())
 
+    root.add_resource(('regex', 'anything', PathRegex(r'.*')), RegexResource())
+    root.add_resource(('regex', 'numbers', PathRegex(r'[0-9]*')), RegexResource())
+    root.add_resource(('regex', 'pattern', PathRegex(r'[a-zA-Z][0-9]')), RegexResource())
+
     asyncio.async(aiocoap.Context.create_server_context(root))
 
     asyncio.get_event_loop().run_forever()

tests/server.py

@@ -77,6 +77,12 @@ def render_post(self, request):
         response = request.payload.replace(b'0', b'O')
         return aiocoap.Message(code=aiocoap.CONTENT, payload=response)
 
+class PathResource(aiocoap.resource.Resource):
+    @asyncio.coroutine
+    def render_get(self, request):
+        payload = repr(request.opt.uri_path).encode('utf-8')
+        return aiocoap.Message(code=aiocoap.CONTENT, payload=payload)
+
 class TestingSite(aiocoap.resource.Site):
     def __init__(self):
         super(TestingSite, self).__init__()
@@ -86,6 +92,8 @@ def __init__(self):
         self.add_resource(('big',), BigResource())
         self.add_resource(('slowbig',), SlowBigResource())
         self.add_resource(('replacing',), ReplacingResource())
+        self.add_resource(('wildcard', aiocoap.resource.PathRegex('.*')), PathResource())
+        self.add_resource(('4digits', aiocoap.resource.PathRegex('[0-9]{4}')), PathResource())
 
 # helpers