Cache pandoc result

gapic/utils/rst.py

@@ -20,6 +20,13 @@
 from gapic.utils.lines import wrap
 
 
+import functools
+
+@functools.lru_cache(maxsize=None)
+def _p(t, c, f):
+    return pypandoc.convert_text(t, "rst", format=f, verify_format=False, extra_args=["--columns=%d" % c]).strip()
+
+
 def rst(
     text: str,
     width: int = 72,
@@ -55,18 +62,12 @@ def rst(
             width=width - indent,
         )
     else:
-        # Convert from CommonMark to ReStructured Text.
-        answer = (
-            pypandoc.convert_text(
-                text,
-                "rst",
-                format=source_format,
-                verify_format=False,
-                extra_args=["--columns=%d" % (width - indent)],
-            )
-            .strip()
-            .replace("\n", f"\n{' ' * indent}")
-        )
+        # Fast path for snake_case and other simple symbols
+        if not re.search(r"[*`]|(?<!\w)_|_(?!\w)|\[.*\]\s*[(\[]|^\||^\s*([-+*]|\d+\.)\s+", text, re.M):
+            answer = wrap(re.sub(r"[ \t]+", " ", text).replace("|", "\\|"), indent=indent, width=width - indent)
+        else:
+            # Convert from CommonMark to ReStructured Text (cached).
+            answer = _p(str(text), width - indent, str(source_format)).replace("\n", f"\n{' ' * indent}")
 
     # Add a newline to the end of the document if any line breaks are
     # already present.

tests/unit/utils/test_rst.py

@@ -32,6 +32,14 @@ def test_rst_formatted():
         assert convert_text.call_count == 1
         assert convert_text.mock_calls[0][1][1] == "rst"
         assert convert_text.mock_calls[0][2]["format"] == "commonmark"
+        assert convert_text.mock_calls[0][2]["verify_format"] is False
+
+
+def test_rst_snake_case():
+    with mock.patch.object(pypandoc, "convert_text") as convert_text:
+        s = "some_variable_name"
+        assert utils.rst(s) == s
+        assert convert_text.call_count == 0
 
 
 def test_rst_add_newline():