python: rename aux.py to aux_.py

Fixes #437, reporeted by Yann Thierry-Mieg.

* python/spot/aux.py: Rename as...
* python/spot/aux_.py: ... this.
* python/spot/__init__.py, python/Makefile.am: Adjust.
* NEWS: Mention the change.

python/spot/aux_.py

@@ -0,0 +1,122 @@
+# -*- coding: utf-8 -*-
+# Copyright (C) 2016, 2019-2020 Laboratoire de Recherche et
+# Développement de l'Epita (LRDE).
+#
+# This file is part of Spot, a model checking library.
+#
+# Spot is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# Spot is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file is named "aux_.py" for compatibility with Windows'
+# historical limitations, but should really be imported as "spot.aux".
+
+"""
+Auxiliary functions for Spot's Python bindings
+"""
+
+from functools import lru_cache
+import subprocess
+import sys
+import os
+import errno
+import contextlib
+import re
+
+
+def extend(*classes):
+    """
+    Decorator that extends all the given classes with the contents
+    of the class currently being defined.
+    """
+    def wrap(this):
+        for cls in classes:
+            for (name, val) in this.__dict__.items():
+                if name not in ('__dict__', '__weakref__') \
+                   and not (name == '__doc__' and val is None):
+                    setattr(cls, name, val)
+        return classes[0]
+    return wrap
+
+
+# Work around a bug introduced in GraphViz 2.42.x, where the scale
+# parameter is inverted.  https://gitlab.com/graphviz/graphviz/issues/1605
+# In our case, the scale parameters should both be <= 1, so we can
+# detect when that is not the case.
+svgscale_regex = re.compile('transform="scale\(([\d.]+) ([\d.]+)\) rotate')
+
+def _gvfix(matchobj):
+        xs = float(matchobj.group(1))
+        ys = float(matchobj.group(2))
+        if xs >= 1 and ys >= 1:
+            xs = 1/xs
+            ys = 1/ys
+        return 'transform="scale({} {}) rotate'.format(xs, ys)
+
+
+# Add a small LRU cache so that when we display automata into a
+# interactive widget, we avoid some repeated calls to dot for
+# identical inputs.
+@lru_cache(maxsize=64)
+def str_to_svg(str):
+    """
+    Send some text to dot for conversion to SVG.
+    """
+    try:
+        dot = subprocess.Popen(['dot', '-Tsvg'],
+                               stdin=subprocess.PIPE,
+                               stdout=subprocess.PIPE,
+                               stderr=subprocess.PIPE)
+    except FileNotFoundError:
+        print("The command 'dot' seems to be missing on your system.\n"
+              "Please install the GraphViz package "
+              "and make sure 'dot' is in your PATH.", file=sys.stderr)
+        raise
+
+    stdout, stderr = dot.communicate(str)
+    if stderr:
+        print("Calling 'dot' for the conversion to SVG produced the message:\n"
+              + stderr.decode('utf-8'), file=sys.stderr)
+    ret = dot.wait()
+    if ret:
+        raise subprocess.CalledProcessError(ret, 'dot')
+    out = stdout.decode('utf-8')
+    return svgscale_regex.sub(_gvfix, out)
+
+
+def ostream_to_svg(ostr):
+    """
+    Encode an ostringstream as utf-8 and send it to dot for cocnversion to SVG.
+    """
+    return str_to_svg(ostr.str().encode('utf-8'))
+
+
+def rm_f(filename):
+    """
+    Remove filename if it exists.
+    """
+    try:
+        os.remove(filename)
+    except OSError as e:
+        if e.errno != errno.ENOENT:
+            raise
+
+
+@contextlib.contextmanager
+def tmpdir():
+    cwd = os.getcwd()
+    tmpdir = os.environ.get('SPOT_TMPDIR') or os.environ.get('TMPDIR') or '.'
+    try:
+        os.chdir(tmpdir)
+        yield
+    finally:
+        os.chdir(cwd)