Deprecate dviread.Encoding.

anntzer · anntzer · commit 533b8750f92c · 2018-12-07T13:47:29.000+01:00
In backend_pdf, it previously worked coincidentally because it would
create a list of glyph names with a "single" name of the form
``/foo/bar/baz/...`` which gets correctly interpreted as ``/foo /bar
/baz``, but we may as well use the correct parser there too.
diff --git a/doc/api/next_api_changes/2018-12-07-AL-removals.rst b/doc/api/next_api_changes/2018-12-07-AL-removals.rst
@@ -0,0 +1,4 @@
+Deprecations
+````````````
+The ``dviread.Encoding`` class, which failed to split lists of glyph names
+properly, is deprecated.
diff --git a/lib/matplotlib/backends/backend_pdf.py b/lib/matplotlib/backends/backend_pdf.py
@@ -745,12 +745,11 @@ def _embedTeXFont(self, fontinfo):
 
         # Encoding (if needed)
         if fontinfo.encodingfile is not None:
-            enc = dviread.Encoding(fontinfo.encodingfile)
-            differencesArray = [Name(ch) for ch in enc]
-            differencesArray = [0] + differencesArray
-            fontdict['Encoding'] = \
-                {'Type': Name('Encoding'),
-                 'Differences': differencesArray}
+            enc = dviread._parse_enc(fontinfo.encodingfile)
+            fontdict['Encoding'] = {
+                'Type': Name('Encoding'),
+                'Differences':  [0, *map(Name, enc)],
+            }
 
         # If no file is specified, stop short
         if fontinfo.fontfile is None:
diff --git a/lib/matplotlib/dviread.py b/lib/matplotlib/dviread.py
@@ -923,6 +923,7 @@ def _parse(self, file):
                 encoding=encoding, filename=filename)
 
 
+@cbook.deprecated("3.1")
 class Encoding(object):
     r"""
     Parses a \*.enc file referenced from a psfonts.map style file.
@@ -971,12 +972,7 @@ def _parse(file):
         return re.findall(br'/([^][{}<>\s]+)', data)
 
 
-# Note: this function should ultimately replace the Encoding class, which
-# appears to be mostly broken: because it uses b''.join(), there is no
-# whitespace left between glyph names (only slashes) so the final re.findall
-# returns a single string with all glyph names.  However this does not appear
-# to bother backend_pdf, so that needs to be investigated more.  (The fixed
-# version below is necessary for textpath/backend_svg, though.)
+@lru_cache()
 def _parse_enc(path):
     r"""
     Parses a \*.enc file referenced from a psfonts.map style file.
