Simplify psfonts.map parsing further

Combine the word splitting and classification in one regex so we only have to scan each line once. Add some quotation marks in the test case to check that we are handling quoted words correctly (the behavior should always have matched this test case).
matplotlib · QuLogic · Feb 26, 2017 · Aug 25, 2016 · Aug 25, 2016 · Aug 25, 2016
commit 254e3dffe13ae2da29e7a1e54fe7c9bbe0edf5f2
diff --git a/lib/matplotlib/dviread.py b/lib/matplotlib/dviread.py
@@ -868,16 +868,8 @@ def __getitem__(self, texname):
         return result._replace(filename=fn, encoding=enc)
 
     def _parse(self, file):
-        for line in file:
-            line = line.strip()
-            if line == b'' or line.startswith(b'%'):
-                continue
-            words = [word.strip(b'"') for word in
-                     re.findall(b'("[^"]*"|[^ ]+)', line)]
-            self._register(words)
-
-    def _register(self, words):
-        """Register a font described by "words", a sequence of bytestrings.
+        """
+        Parse the font mapping file.
 
         The format is, AFAIK: texname fontname [effects and filenames]
         Effects are PostScript snippets like ".177 SlantFont",
@@ -889,52 +881,68 @@ def _register(self, words):
         There is some difference between <foo.pfb and <<bar.pfb in
         subsetting, but I have no example of << in my TeX installation.
         """
-
         # If the map file specifies multiple encodings for a font, we
         # follow pdfTeX in choosing the last one specified. Such
         # entries are probably mistakes but they have occurred.
         # http://tex.stackexchange.com/questions/10826/
         # http://article.gmane.org/gmane.comp.tex.pdftex/4914
 
-        texname, psname = words[:2]
-        words = words[2:]
-        effects, encoding, filename = b'', None, None
+        empty_re = re.compile(br'%|\s*$')
+        word_re = re.compile(
+            br'''(?x) (?:
+                 "<\[ (?P<enc1>  [^"]+    )" | # quoted encoding marked by [
+                 "<   (?P<enc2>  [^"]+.enc)" | # quoted encoding, ends in .enc
+                 "<<? (?P<file1> [^"]+    )" | # quoted font file name
+                 "    (?P<eff1>  [^"]+    )" | # quoted effects or font name
+                 <\[  (?P<enc3>  \S+      )  | # encoding marked by [
+                 <    (?P<enc4>  \S+  .enc)  | # encoding, ends in .enc
+                 <<?  (?P<file2> \S+      )  | # font file name
+                      (?P<eff2>  \S+      )    # effects or font name
+            )''')
+        effects_re = re.compile(
+            br'''(?x) (?P<slant> -?[0-9]*(?:\.[0-9]+)) \s* SlantFont
+                    | (?P<extend>-?[0-9]*(?:\.[0-9]+)) \s* ExtendFont''')
+
+        lines = (line.strip()
+                 for line in file
+                 if not empty_re.match(line))
+        for line in lines:
+            effects, encoding, filename = b'', None, None
+            words = word_re.finditer(line)
+
+            w = next(words)
+            texname = w.group('eff2') or w.group('eff1')
+            w = next(words)
+            psname = w.group('eff2') or w.group('eff1')
+
+            for w in words:
+                eff = w.group('eff1') or w.group('eff2')
+                if eff:
+                    effects = eff
+                    continue
+                enc = (w.group('enc4') or w.group('enc3') or
+                       w.group('enc2') or w.group('enc1'))
+                if enc:
+                    if encoding is not None:
+                        matplotlib.verbose.report(
+                            'Multiple encodings for %s = %s'
+                            % (texname, psname),
+                            'debug')
+                    encoding = enc
+                    continue
+                filename = w.group('file2') or w.group('file1')
 
-        # pick the last non-filename word for effects
-        effects_words = [word for word in words if not word.startswith(b'<')]
-        if effects_words:
-            effects = effects_words[-1]
+            effects_dict = {}
+            for match in effects_re.finditer(effects):
+                slant = match.group('slant')
+                if slant:
+                    effects_dict['slant'] = float(slant)
+                else:
+                    effects_dict['extend'] = float(match.group('extend'))
 
-        encoding_re = br'<<?(\[.*|.*\.enc)'
-        encoding_files = [word.lstrip(b'<').lstrip(b'[')
-                          for word in words
-                          if re.match(encoding_re, word)]
-        if len(encoding_files) > 1:
-            matplotlib.verbose.report(
-                'Multiple encodings for %s = %s' % (texname, psname), 'debug')
-        if encoding_files:
-            encoding = encoding_files[-1]
-
-        font_files = [word.lstrip(b'<')
-                      for word in words
-                      if word.startswith(b'<')
-                      and not re.match(encoding_re, word)]
-        if font_files:
-            filename = font_files[-1]
-
-        eff = {}
-        for psword, keyword in ((b'SlantFont', 'slant'),
-                                (b'ExtendFont', 'extend')):
-            match = re.search(b'([^ ]+) +' + psword, effects)
-            if match:
-                try:
-                    eff[keyword] = float(match.group(1))
-                except ValueError:
-                    pass
-
-        self._font[texname] = PsFont(
-            texname=texname, psname=psname, effects=eff,
-            encoding=encoding, filename=filename)
+            self._font[texname] = PsFont(
+                texname=texname, psname=psname, effects=effects_dict,
+                encoding=encoding, filename=filename)
 
 
 class Encoding(object):

diff --git a/lib/matplotlib/tests/baseline_images/dviread/test.map b/lib/matplotlib/tests/baseline_images/dviread/test.map
@@ -1,9 +1,9 @@
 % used by test_dviread.py
-TeXfont1 PSfont1 <font1.pfb <font1.enc
-TeXfont2 PSfont2 <font2.enc <font2.pfa
-TeXfont3 PSfont3 "1.23 UnknownEffect" <[enc3.foo <font3.pfa
+TeXfont1 PSfont1 <font1.pfb "<font1.enc"
+TeXfont2 PSfont2 <font2.enc "<font2.pfa"
+"TeXfont3" PSfont3 "1.23 UnknownEffect" <[enc3.foo <font3.pfa
 TeXfont4 PSfont4 "-0.1 SlantFont 2.2 ExtendFont" <font4.enc <font4.pfa
-TeXfont5 PSfont5 <encoding1.enc <encoding2.enc <font5.pfb
+TeXfont5 "PSfont5" <encoding1.enc <encoding2.enc <font5.pfb
 TeXfont6 PSfont6
 TeXfont7 PSfont7 <font7.enc
 TeXfont8 PSfont8 <font8.pfb