pypy support

  * add to continuous build
  * exclude wsaccel dependency

Closes #119.

.travis.yml

@@ -1,4 +1,5 @@
 language: python
+dist: xenial
 
 git:
   depth: 1
@@ -7,8 +8,7 @@ matrix:
   include:
     - python: 3.6
     - python: 3.7
-      dist: xenial
-      sudo: true
+    - python: pypy3.6-7.1.1
 
 install:
   - pip install -e .

setup.py

@@ -31,6 +31,8 @@
         'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: Implementation :: CPython',
+        'Programming Language :: Python :: Implementation :: PyPy',
     ],
     python_requires=">=3.5",
     keywords='websocket client server trio',
@@ -39,7 +41,9 @@
         'async_generator>=1.10,<2',
         'ipaddress>=1.0.22,<2',
         'trio>=0.11',
-        'wsaccel>=0.6.2,<0.7',
+        # TODO: confirm whether wsaccel is relevant to performance
+        # Disabled on pypy: https://github.com/methane/wsaccel/issues/19
+        'wsaccel>=0.6.2,<0.7;implementation_name!="pypy"',
         'wsproto>=0.14,<0.15',
         'yarl>=1.2.6,<2'
     ],