Drop Python 2 legacy code

docs/source/installing.rst

@@ -31,17 +31,14 @@ For manual registration see :doc:`extensions`.
 Dependencies
 ------------
 
-nbdime requires Python version 3.3 or higher. If you are using Python 2,
-nbdime requires 2.7.1 or higher.
+nbdime requires Python version 3.6 or higher.
 
 nbdime depends on the following Python packages,
 which will be installed by :command:`pip`:
 
-  - six
   - nbformat
   - tornado
   - colorama
-  - backports.shutil_which (on python 2.7)
 
 and nbdime's web-based viewers depend on the following Node.js packages:
 

docs/source/nodevenv.rst

@@ -27,27 +27,3 @@ For example with Python 3.5, the steps with output are::
      * Install prebuilt node (7.2.0) ..... done.
      * Appending data to /Users/username/myenv/bin/activate
     (myenv) $
-
-Using Python 2.7, the steps with output are (note: you may need to install
-virtualenv as shown here)::
-
-    $ python2 -m pip install virtualenv
-    Collecting virtualenv
-      Downloading virtualenv-15.1.0-py2.py3-none-any.whl (1.8MB)
-        100% |████████████████████████████████| 1.8MB 600kB/s
-    Installing collected packages: virtualenv
-    Successfully installed virtualenv-15.1.0
-    $ python2 -m virtualenv myenv
-    New python executable in /Users/username/myenv/bin/python
-    Installing setuptools, pip, wheel...done.
-    $ source myenv/bin/activate
-    (myenv) $ pip install nodeenv
-    Collecting nodeenv
-      Downloading nodeenv-1.0.0.tar.gz
-    Installing collected packages: nodeenv
-      Running setup.py install for nodeenv ... done
-    Successfully installed nodeenv-1.0.0
-    (myenv) $ nodeenv -p
-     * Install prebuilt node (7.2.0) ..... done.
-     * Appending data to /Users/username/myenv/bin/activate
-    (myenv) $

nbdime/__init__.py

@@ -3,8 +3,6 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import unicode_literals
-
 from ._version import __version__
 
 from .diffing import diff, diff_notebooks

nbdime/__main__.py

@@ -3,19 +3,13 @@
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import unicode_literals
-from __future__ import print_function
-
 import sys
 from subprocess import call
 
 import nbdime
 from ._version import __version__
 
-try:
-    from shutil import which
-except ImportError:
-    from backports.shutil_which import which
+from shutil import which
 
 COMMANDS = ["show", "diff", "merge", "diff-web", "merge-web", "mergetool",
             "config-git", "extensions"]

nbdime/config.py

@@ -1,6 +1,5 @@
 
 import os
-from six import string_types
 
 from ipython_genutils import py3compat
 from jupyter_core.paths import jupyter_config_path
@@ -161,7 +160,7 @@ def validate_elements(self, obj, value):
                 raise TraitError('ignore config paths need to start with `/`')
             if not (v in (True, False) or
                     (isinstance(v, (tuple, list, set)) and
-                     all(isinstance(i, string_types) for i in v)
+                     all(isinstance(i, str) for i in v)
                     )):
                 raise TraitError('ignore config value needs to be True, False or a list of strings')
         return self.klass(value)

nbdime/diff_format.py

@@ -3,10 +3,6 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import unicode_literals
-
-from six import string_types
-
 from .log import NBDiffFormatError
 
 
@@ -195,7 +191,7 @@ def validate_diff(diff, deep=False):
         validate_diff_entry(e, deep=deep)
 
 
-sequence_types = string_types + (list,)
+sequence_types = (str, list)
 
 
 def validate_diff_entry(e, deep=False):
@@ -230,7 +226,7 @@ def validate_diff_entry(e, deep=False):
                 validate_diff(e.diff, deep=deep)
         else:
             raise NBDiffFormatError("Unknown diff op '{}'.".format(op))
-    elif isinstance(key, string_types) and op in MappingDiffBuilder.OPS:
+    elif isinstance(key, str) and op in MappingDiffBuilder.OPS:
         if op == DiffOp.ADD:
             pass  # e.value is a single value to insert at key
         elif op == DiffOp.REMOVE:

nbdime/diff_utils.py

@@ -6,9 +6,6 @@
 import itertools
 import copy
 
-from six import string_types
-from six.moves import xrange as range
-
 from .diff_format import DiffOp, DiffEntry, op_addrange, op_removerange
 from .log import NBDiffFormatError
 
@@ -50,7 +47,7 @@ def source_as_string(source):
     """Return source as a single string, joined as lines if it's a list."""
     if isinstance(source, list):
         source = "\n".join(line.strip("\n") for line in source)
-    if not isinstance(source, string_types):
+    if not isinstance(source, str):
         raise TypeError("Invalid argument type. Should be string or sequence of strings."
                         "Got %r" % source)
     return source
@@ -94,7 +91,7 @@ def _combine_ops(existing, new):
         if new.op == DiffOp.ADDRANGE:
             d.valuelist += new.valuelist
         else:
-            if isinstance(d.valuelist, string_types):
+            if isinstance(d.valuelist, str):
                 d.valuelist += new.value
             else:
                 d.valuelist.append(new.value)
@@ -108,7 +105,7 @@ def flatten_list_of_string_diff(a, linebased_diff):
     """Translates a diff of strings split by str.splitlines(True) to a diff of
     the joined multiline string.
     """
-    if isinstance(a, string_types):
+    if isinstance(a, str):
         a = a.splitlines(True)
 
     line_to_char = [0] + list(_accum(len(ia) for ia in a))
@@ -196,15 +193,15 @@ def to_json_patch(d, path=""):
     for e in d:
         op = e.op
         if op == DiffOp.ADD:
-            assert isinstance(e.key, string_types), "'add' diff op needs string key"
+            assert isinstance(e.key, str), "'add' diff op needs string key"
             p = "/".join([path, e.key])
             jp.append({"op": "add", "path": p, "value": e.value})
         elif op == DiffOp.REPLACE:
-            assert isinstance(e.key, string_types), "'replace' diff op needs string key"
+            assert isinstance(e.key, str), "'replace' diff op needs string key"
             p = "/".join([path, e.key])
             jp.append({"op": "replace", "path": p, "value": e.value})
         elif op == DiffOp.REMOVE:
-            assert isinstance(e.key, string_types), "'remove' diff op needs string key"
+            assert isinstance(e.key, str), "'remove' diff op needs string key"
             p = "/".join([path, e.key])
             jp.append({"op": "remove", "path": p})
         elif op == DiffOp.ADDRANGE:

nbdime/diffing/__init__.py

@@ -3,8 +3,6 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import unicode_literals
-
 from .generic import diff
 from .notebooks import diff_notebooks
 

nbdime/diffing/generic.py

@@ -3,10 +3,6 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import unicode_literals
-
-from six import string_types
-from six.moves import xrange as range
 import operator
 from collections import defaultdict
 import difflib
@@ -22,7 +18,7 @@
 
 def is_atomic(x):
     "Return True for values that diff should treat as a single atomic value."
-    return not isinstance(x, string_types + (list, dict))
+    return not isinstance(x, (str, list, dict))
 
 
 def default_predicates():
@@ -90,7 +86,7 @@ def diff(a, b, path="", predicates=None, differs=None):
         d = diff_lists(a, b, path=path, predicates=predicates, differs=differs)
     elif isinstance(a, dict) and isinstance(b, dict):
         d = diff_dicts(a, b, path=path, predicates=predicates, differs=differs)
-    elif isinstance(a, string_types) and isinstance(b, string_types):
+    elif isinstance(a, str) and isinstance(b, str):
         # Don't pass differs/predicates as the only possible use case is to
         # use a different character differ within each line or predicates
         # for comparing lines

nbdime/diffing/lcs.py

@@ -3,10 +3,6 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import unicode_literals
-
-from six.moves import xrange as range
-
 from ..diff_format import SequenceDiffBuilder
 
 

nbdime/diffing/notebooks.py

@@ -10,17 +10,10 @@
 Up- and down-conversion is handled by nbformat.
 """
 
-from __future__ import unicode_literals
-
 import operator
 import re
 import copy
-from six import string_types
-from six.moves import zip
-try:
-    from functools import lru_cache
-except ImportError:
-    from backports.functools_lru_cache import lru_cache
+from functools import lru_cache
 
 from ..diff_format import MappingDiffBuilder, DiffOp
 from ..utils import defaultdict2
@@ -139,7 +132,7 @@ def _compare_mimedata(mimetype, x, y, comp_text, comp_base64):
 
     # TODO: Compare binary images?
     #if mimetype.startswith("image/"):
-    if isinstance(x, string_types) and isinstance(y, string_types):
+    if isinstance(x, str) and isinstance(y, str):
         return _compare_mimedata_strings(x, y, comp_text, comp_base64)
     # Fallback to exactly equal
     return x == y

nbdime/diffing/seq_bruteforce.py

@@ -3,9 +3,6 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import unicode_literals
-
-from six.moves import xrange as range
 import operator
 from .lcs import diff_from_lcs
 

nbdime/diffing/seq_difflib.py

@@ -3,8 +3,6 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import unicode_literals
-
 from difflib import SequenceMatcher
 from ..diff_format import SequenceDiffBuilder
 

nbdime/diffing/seq_myers.py

@@ -3,8 +3,6 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import unicode_literals
-
 import operator
 
 __all__ = ["diff_sequence_myers"]

nbdime/diffing/sequences.py

@@ -3,10 +3,7 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import unicode_literals
-
 import operator
-from six import string_types
 from collections import defaultdict
 
 from .seq_difflib import diff_sequence_difflib
@@ -42,7 +39,7 @@ def diff_sequence(a, b, compare=operator.__eq__):
 
 def diff_strings_by_char(a, b, path="", predicates=None, differs=None):
     "Compute char-based diff of two strings."
-    assert isinstance(a, string_types) and isinstance(b, string_types), (
+    assert isinstance(a, str) and isinstance(b, str), (
         'Arguments need to be string types. Got %r and %r' % (a, b))
     if a == b:
         return []
@@ -53,7 +50,7 @@ def diff_strings_by_char(a, b, path="", predicates=None, differs=None):
 def diff_strings_linewise(a, b):
     """Do a line-wise diff of two strings
     """
-    assert isinstance(a, string_types) and isinstance(b, string_types), (
+    assert isinstance(a, str) and isinstance(b, str), (
         'Arguments need to be string types. Got %r and %r' % (a, b))
     lines_a = a.splitlines(True)
     lines_b = b.splitlines(True)

nbdime/diffing/snakes.py

@@ -7,8 +7,6 @@
 Utilities for computing 'snakes', or contiguous sequences of equal elements of two sequences.
 """
 
-from __future__ import unicode_literals
-
 from ..diff_format import SequenceDiffBuilder
 from .seq_bruteforce import bruteforce_compute_snakes
 

nbdime/gitfiles.py

@@ -5,8 +5,6 @@
 import os
 from collections import deque
 
-from six import string_types
-
 os.environ['GIT_PYTHON_REFRESH'] = 'quiet'
 from git import (
     Repo, InvalidGitRepositoryError, BadName, NoSuchPathError,
@@ -153,7 +151,7 @@ def changed_notebooks(ref_base, ref_remote, paths=None, repo_dir=None):
     repo, popped = get_repo(repo_dir or os.curdir)
     if repo_dir is None:
         repo_dir = os.path.relpath(repo.working_tree_dir, os.curdir)
-    if isinstance(paths, string_types):
+    if isinstance(paths, str):
         paths = (paths,)
     if paths and popped:
         # All paths need to be prepended by popped

nbdime/ignorables.py

@@ -3,6 +3,4 @@
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import unicode_literals
-
 diff_ignorables = ('sources', 'outputs', 'attachments', 'metadata', 'id', 'details')

nbdime/log.py

@@ -3,8 +3,6 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import unicode_literals
-
 import logging
 
 

nbdime/merging/__init__.py

@@ -3,8 +3,6 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import unicode_literals
-
 from .generic import decide_merge
 from .decisions import apply_decisions
 from .notebooks import merge_notebooks

nbdime/merging/autoresolve.py

@@ -3,8 +3,6 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import print_function, unicode_literals
-
 from ..diff_format import DiffOp, Deleted
 from ..patching import patch
 from ..utils import split_path, resolve_path

nbdime/merging/chunks.py

@@ -3,10 +3,6 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from __future__ import unicode_literals
-
-from six.moves import xrange as range
-
 from ..diff_format import DiffOp, SequenceDiffBuilder