Fix substack parsing

devRD · devRD · commit e93cc3af6327 · 2023-07-10T01:09:12.000+05:30
diff --git a/lib/matplotlib/_mathtext.py b/lib/matplotlib/_mathtext.py
@@ -1700,7 +1700,6 @@ def names(elt):
     csname = expr.split("{", 1)[0]
     err = (csname + "".join("{%s}" % name for name in names(args))
            if expr == csname else expr)
-    print(csname, args, err)
     return csname - (args | Error(f"Expected {err}"))
 
 
@@ -1871,7 +1870,6 @@ def csnames(group, names):
         p.required_group   = Forward()
         p.optional_group   = Forward()
         p.token            = Forward()
-        p.substack         = Forward()
 
         set_names_and_parse_actions()  # for mutually recursive definitions.
 
@@ -1917,6 +1915,10 @@ def csnames(group, names):
 
         p.text = cmd(r"\text", QuotedString('{', '\\', endQuoteChar="}"))
 
+        p.substack = cmd(r"\substack", "{" +
+                           delimited_list(OneOrMore(p.token), delim="\\",
+                                          combine=False)("parts") + "}")
+
         p.subsuper = (
             (Optional(p.placeable)("nucleus")
              + OneOrMore(oneOf(["_", "^"]) - p.placeable)("subsuper")
@@ -1935,9 +1937,6 @@ def csnames(group, names):
 
         p.operatorname = cmd(r"\operatorname", "{" + ZeroOrMore(p.simple)("name") + "}")
 
-        p.substack <<= cmd(
-            r"\substack", "{"+delimited_list(OneOrMore(p.token), delim="\\\\", combine=True)("parts")+"}")
-
         p.placeable     <<= (
             p.accent     # Must be before symbol as all accents are symbols
             | p.symbol   # Must be second to catch all named symbols and single
@@ -1953,8 +1952,8 @@ def csnames(group, names):
             | p.underset
             | p.sqrt
             | p.overline
-            | p.substack
             | p.text
+            | p.substack
         )
 
         p.auto_delim    <<= (
@@ -1977,7 +1976,6 @@ def csnames(group, names):
 
         # To add space to nucleus operators after sub/superscripts
         self._in_subscript_or_superscript = False
-        self.p = p
 
     def parse(self, s, fonts_object, fontsize, dpi):
         """
@@ -2606,17 +2604,24 @@ def auto_delim(self, s, loc, toks):
             toks["right"])
 
     def substack(self, s, loc, toks):
-        print(list(toks.keys()))
-        print(toks["parts"])
-        parts = toks["parts"].split("\\\\")
-        print(parts)
+        parts = toks["parts"]
         state = self.get_state()
         thickness = state.get_current_underline_thickness()
         vlist = []
 
-        max_width = max(map(lambda c: c.width, parts))
+        p = [[]]
+        # Checking idle kern value as whitespace to
+        # determine line break for multiple values
+        for b in parts:
+            if isinstance(b, Kern):
+                p.append([])
+            else:
+                p[-1].append(b)
+
+        hlist = [Hlist(k) for k in p]
+        max_width = max(map(lambda c: c.width, hlist))
 
-        for sub in parts:
+        for sub in hlist:
             cp = HCentered([sub])
             cp.hpack(max_width, 'exactly')
             vlist.append(cp)
diff --git a/lib/matplotlib/tests/baseline_images/test_mathtext/mathtext1_dejavusans_05.png b/lib/matplotlib/tests/baseline_images/test_mathtext/mathtext1_dejavusans_05.png
diff --git a/lib/matplotlib/tests/test_mathtext.py b/lib/matplotlib/tests/test_mathtext.py
@@ -134,7 +134,6 @@
     r'$\sum x\quad\sum^nx\quad\sum_nx\quad\sum_n^nx\quad\prod x\quad\prod^nx\quad\prod_nx\quad\prod_n^nx$',  # GitHub issue 18085
     r'$1.$ $2.$ $19680801.$ $a.$ $b.$ $mpl.$',
     r'$\text{text}_{\text{sub}}^{\text{sup}} + \text{\$foo\$} + \frac{\text{num}}{\mathbf{\text{den}}}\text{with space, curly brackets \{\}, and dash -}$',
-    r'$\sum_{\substack{k = 1}{k \neq \lfloor n/2\rfloor}}^{n}P(i,j) \sum_{\substack{i \neq 0}{-1 \leq i \leq 3}{1 \leq j \leq 5}} F^i(x,y) \sum_{\substack{\left \lfloor \frac{n}{2} \right\rfloor}} F(n)$',
 ]
 
 digits = "0123456789"
@@ -300,7 +299,7 @@ def test_fontinfo():
         (r'$\left(\right$', r'Expected a delimiter'),
         # PyParsing 2 uses double quotes, PyParsing 3 uses single quotes and an
         # extra backslash.
-        (r'$\left($', re.compile(r'Expected ("|\'\\)\\right["\']')),
+        (r'$\left($', re.compile(r'Expected (\"|\'\\)\right[\"\']')),
         (r'$\dfrac$', r'Expected \dfrac{num}{den}'),
         (r'$\dfrac{}{}$', r'Expected \dfrac{num}{den}'),
         (r'$\overset$', r'Expected \overset{annotation}{body}'),
