perf: translate for canonicalize_name (#1030)

* perf: use translate

Signed-off-by: Henry Schreiner <[email protected]>

perf: use translate and replace

Signed-off-by: Henry Schreiner <[email protected]>

perf: also translate letters

Signed-off-by: Henry Schreiner <[email protected]>

* Update src/packaging/utils.py

---------

Signed-off-by: Henry Schreiner <[email protected]>

Author: henryiii

src/packaging/utils.py

@@ -34,7 +34,8 @@ class InvalidSdistFilename(ValueError):
 
 # Core metadata spec for `Name`
 _validate_regex = re.compile(r"[A-Z0-9]|[A-Z0-9][A-Z0-9._-]*[A-Z0-9]", re.IGNORECASE)
-_canonicalize_regex = re.compile(r"[-_.]+")
+_letters_translate = {c: c.lower() for c in "ABCDEFGHIJKLMNOPQRSTUVWXYZ"}
+_canonicalize_table = str.maketrans({"_": "-", ".": "-", **_letters_translate})
 _normalized_regex = re.compile(r"[a-z0-9]|[a-z0-9]([a-z0-9-](?!--))*[a-z0-9]")
 # PEP 427: The build number must start with a digit.
 _build_tag_regex = re.compile(r"(\d+)(.*)")
@@ -43,8 +44,13 @@ class InvalidSdistFilename(ValueError):
 def canonicalize_name(name: str, *, validate: bool = False) -> NormalizedName:
     if validate and not _validate_regex.fullmatch(name):
         raise InvalidName(f"name is invalid: {name!r}")
-    # This is taken from PEP 503.
-    value = _canonicalize_regex.sub("-", name).lower()
+    # Ensure all ``.`` and ``_`` are ``-``
+    # Emulates ``re.sub(r"[-_.]+", "-", name).lower()`` from PEP 503
+    # About 2x faster, safe since packages only support alphanumeric characters
+    value = name.translate(_canonicalize_table)
+    # Condense repeats (faster than regex)
+    while "--" in value:
+        value = value.replace("--", "-")
     return cast("NormalizedName", value)