Py3: Return bytes from FileGenerator

and use __getitem__ instead of __getslice__

pathod/language/generators.py

@@ -77,17 +77,17 @@ class FileGenerator(object):
 
     def __init__(self, path):
         self.path = path
-        self.fp = file(path, "rb")
+        self.fp = open(path, "rb")
         self.map = mmap.mmap(self.fp.fileno(), 0, access=mmap.ACCESS_READ)
 
     def __len__(self):
         return len(self.map)
 
     def __getitem__(self, x):
+        if isinstance(x, slice):
             return self.map.__getitem__(x)
-
-    def __getslice__(self, a, b):
-        return self.map.__getslice__(a, b)
+        # A slice of length 1 returns a byte object (not an integer)
+        return self.map.__getitem__(slice(x, x+1 or self.map.size()))
 
     def __repr__(self):
         return "<%s" % self.path

test/pathod/test_language_generators.py

@@ -19,13 +19,15 @@ def test_filegenerator():
     with tutils.tmpdir() as t:
         path = os.path.join(t, "foo")
         f = open(path, "wb")
-        f.write("x" * 10000)
+        f.write(b"x" * 10000)
         f.close()
         g = generators.FileGenerator(path)
         assert len(g) == 10000
-        assert g[0] == "x"
-        assert g[-1] == "x"
-        assert g[0:5] == "xxxxx"
+        assert g[0] == b"x"
+        assert g[-1] == b"x"
+        assert g[0:5] == b"xxxxx"
+        assert len(g[1:10]) == 9
+        assert len(g[10000:10001]) == 0
         assert repr(g)
         # remove all references to FileGenerator instance to close the file
         # handle.