mathtext now supports text

oscargus · oscargus · commit 7c6ac68f45c0 · 2022-01-09T16:51:00.000+01:00
diff --git a/doc/users/next_whats_new/mathtext_supports_text.rst b/doc/users/next_whats_new/mathtext_supports_text.rst
@@ -0,0 +1,10 @@
+``mathtext`` now supports ``\text``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+``\text`` can be used to obtain upright text within an equation.
+
+.. code-block:: python
+
+import matplotlib.pyplot as plt
+plt.text(0.1, 0.5, r"$a = \sin(\phi) \text{ such that } \phi = \frac{x}{y}$")
+plt.draw()
diff --git a/lib/matplotlib/_mathtext.py b/lib/matplotlib/_mathtext.py
@@ -1993,6 +1993,7 @@ def __init__(self):
         p.subsuperop       = Forward()
         p.symbol           = Forward()
         p.symbol_name      = Forward()
+        p.text             = Forward()
         p.token            = Forward()
         p.underset         = Forward()
         p.unknown_symbol   = Forward()
@@ -2132,6 +2133,11 @@ def __init__(self):
                | Error("Expected \\operatorname{value}"))
         )
 
+        p.text <<= Group(
+            Suppress(Literal(r"\text"))
+            - QuotedString('{', '\\', endQuoteChar="}")
+        )
+
         p.placeable     <<= (
             p.accentprefixed  # Must be before accent so named symbols that are
                               # prefixed with an accent name work
@@ -2150,6 +2156,7 @@ def __init__(self):
             | p.sqrt
             | p.overline
             | p.operatorname
+            | p.text
         )
 
         p.simple        <<= (
@@ -2294,6 +2301,18 @@ def non_math(self, s, loc, toks):
         self.get_state().font = mpl.rcParams['mathtext.default']
         return [hlist]
 
+    def text(self, s, loc, toks):
+        self.pop_state()
+        s = toks[0][0].replace(r'\$', '$')
+        s = s.replace(r'\{', '{')
+        s = s.replace(r'\}', '}')
+        symbols = [Char(c, self.get_state(), math=False) for c in s]
+        hlist = Hlist(symbols)
+        # We're going into math now, so set font to 'it'
+        self.push_state()
+        self.get_state().font = mpl.rcParams['mathtext.default']
+        return [hlist]
+
     def _make_space(self, percentage):
         # All spaces are relative to em width
         state = self.get_state()
