matplotlib
diff --git a/‎lib/matplotlib/_mathtext.py
Lines changed: 15 additions & 3 deletions b/‎lib/matplotlib/_mathtext.py
Lines changed: 15 additions & 3 deletions
diff --git a/‎lib/matplotlib/tests/baseline_images/test_mathtext/mathtext1_dejavusans_07.png
4.82 KB b/‎lib/matplotlib/tests/baseline_images/test_mathtext/mathtext1_dejavusans_07.png
4.82 KB
diff --git a/‎lib/matplotlib/tests/baseline_images/test_mathtext/mathtext_cm_38.pdf
-22 Bytes b/‎lib/matplotlib/tests/baseline_images/test_mathtext/mathtext_cm_38.pdf
-22 Bytes
diff --git a/‎lib/matplotlib/tests/baseline_images/test_mathtext/mathtext_cm_38.png
83 Bytes b/‎lib/matplotlib/tests/baseline_images/test_mathtext/mathtext_cm_38.png
83 Bytes
@@ -1965,9 +1965,10 @@ def csnames(group, names):
             | p.boldsymbol
         )
 
+        mdelim = r"\middle" - (p.delim("mdelim") | Error("Expected a delimiter"))
         p.auto_delim    <<= (
             r"\left" - (p.delim("left") | Error("Expected a delimiter"))
-            + ZeroOrMore(p.simple | p.auto_delim)("mid")
+            + ZeroOrMore(p.simple | p.auto_delim | mdelim)("mid")
             + r"\right" - (p.delim("right") | Error("Expected a delimiter"))
         )
 
@@ -2586,13 +2587,24 @@ def overline(self, s, loc, toks):
     def _auto_sized_delimiter(self, front, middle, back):
         state = self.get_state()
         if len(middle):
-            height = max(x.height for x in middle)
-            depth = max(x.depth for x in middle)
+            height = max([x.height for x in middle if not isinstance(x, str)])
+            depth = max([x.depth for x in middle if not isinstance(x, str)])
             factor = None
         else:
             height = 0
             depth = 0
             factor = 1.0
+
+        for idx, el in enumerate(middle):
+            if isinstance(el, str) and el == '\\middle':
+                c = middle[idx + 1]
+                if c != '.':
+                    middle[idx + 1] = AutoHeightChar(
+                            c, height, depth, state, factor=factor)
+                else:
+                    middle.remove(c)
+                del middle[idx]
+
         parts = []
         # \left. and \right. aren't supposed to produce any symbols
         if front != '.':