Add whitespace checks for match and case

Author: cdce8p

pycodestyle.py

@@ -163,6 +163,7 @@ def lru_cache(maxsize=128):  # noqa as it's a fake implementation.
     )))
 )
 DUNDER_REGEX = re.compile(r'^__([^\s]+)__ = ')
+MATCH_CASE_REGEX = re.compile(r'^\s*\b(?:match|case)(\s*)(?=.*\:)')
 
 _checks = {'physical_line': {}, 'logical_line': {}, 'tree': {}}
 
@@ -512,6 +513,32 @@ def missing_whitespace_after_import_keyword(logical_line):
             yield pos, "E275 missing whitespace after keyword"
 
 
+@register_check
+def missing_whitespace_after_match_case(logical_line):
+    r"""Check whitespace after 'match' and 'case'.
+
+    Python 3.10
+    Okay: match status:
+    E271: match  status:
+    E271: case\tstatus:
+    E271: case   _:
+    E275: matchstatus:
+    E275: casestatus:
+    E275: case_:
+    """
+    if sys.version_info < (3, 10):
+        return
+    match = MATCH_CASE_REGEX.match(logical_line)
+    if match:
+        whitespace = match.groups()[0]
+        if whitespace == ' ':
+            return
+        if whitespace == '':
+            yield match.start(1), "E275 missing whitespace after keyword"
+        else:
+            yield match.start(1), "E271 multiple spaces after keyword"
+
+
 @register_check
 def missing_whitespace(logical_line):
     r"""Each comma, semicolon or colon should be followed by whitespace.

testsuite/python310.py

@@ -7,3 +7,21 @@
         pass
     case _:
         print("Default")
+#: E271:2:6 E271:3:9 E271:5:9 E271:7:9
+var = 1
+match  var:
+    case  1:
+        pass
+    case	2:
+        pass
+    case  (
+        3
+    ):
+        pass
+#: E275:2:6 E275:3:9 E275:5:9
+var = 1
+match(var):
+    case(1):
+        pass
+    case_:
+        pass

testsuite/support.py

@@ -6,6 +6,7 @@
 from pycodestyle import Checker, BaseReport, StandardReport, readlines
 
 SELFTEST_REGEX = re.compile(r'\b(Okay|[EW]\d{3}):\s(.*)')
+SELFTEST_PY_REGEX = re.compile(r'\bPython (\d).(\d+)')
 ROOT_DIR = os.path.dirname(os.path.dirname(__file__))
 
 
@@ -112,8 +113,14 @@ def selftest(options):
     counters = report.counters
     checks = options.physical_checks + options.logical_checks
     for name, check, argument_names in checks:
+        python_version = None
         for line in check.__doc__.splitlines():
             line = line.lstrip()
+            match = SELFTEST_PY_REGEX.match(line)
+            if match:
+                python_version = tuple(map(int, match.groups()))
+            if python_version and sys.version_info < python_version:
+                continue
             match = SELFTEST_REGEX.match(line)
             if match is None:
                 continue