WIP: Use assign expr for match/group

Lib/_markupbase.py

@@ -378,8 +378,7 @@ def _scan_name(self, i, declstartpos):
         n = len(rawdata)
         if i == n:
             return None, -1
-        m = _declname_match(rawdata, i)
-        if m:
+        if (m := _declname_match(rawdata, i)):
             s = m.group()
             name = s.strip()
             if (i + len(s)) == n:

Lib/_osx_support.py

@@ -287,8 +287,7 @@ def _check_for_unavailable_sdk(_config_vars):
     # to /usr and /System/Library by either a standalone CLT
     # package or the CLT component within Xcode.
     cflags = _config_vars.get('CFLAGS', '')
-    m = re.search(r'-isysroot\s+(\S+)', cflags)
-    if m is not None:
+    if (m := re.search(r'-isysroot\s+(\S+)', cflags)) is not None:
         sdk = m.group(1)
         if not os.path.exists(sdk):
             for cv in _UNIVERSAL_CONFIG_VARS:

Lib/configparser.py

@@ -1059,8 +1059,7 @@ def _read(self, fp, fpname):
             else:
                 indent_level = cur_indent_level
                 # is it a section header?
-                mo = self.SECTCRE.match(value)
-                if mo:
+                if (mo := self.SECTCRE.match(value)):
                     sectname = mo.group('header')
                     if sectname in self._sections:
                         if self._strict and sectname in elements_added:
@@ -1082,8 +1081,7 @@ def _read(self, fp, fpname):
                     raise MissingSectionHeaderError(fpname, lineno, line)
                 # an option line?
                 else:
-                    mo = self._optcre.match(value)
-                    if mo:
+                    if (mo := self._optcre.match(value)):
                         optname, vi, optval = mo.group('option', 'vi', 'value')
                         if not optname:
                             e = self._handle_error(e, fpname, lineno, line)

Lib/dataclasses.py

@@ -599,8 +599,7 @@ def _is_type(annotation, cls, a_module, a_type, is_type_predicate):
     # a eval() penalty for every single field of every dataclass
     # that's defined.  It was judged not worth it.
 
-    match = _MODULE_IDENTIFIER_RE.match(annotation)
-    if match:
+    if (match := _MODULE_IDENTIFIER_RE.match(annotation)):
         ns = None
         module_name = match.group(1)
         if not module_name:

Lib/imaplib.py

@@ -1579,9 +1579,10 @@ def run(cmd, args):
             run(cmd, args)
 
         for ml in run('list', ('/tmp/', 'yy%')):
-            mo = re.match(r'.*"([^"]+)"$', ml)
-            if mo: path = mo.group(1)
-            else: path = ml.split()[-1]
+            if (mo := re.match(r'.*"([^"]+)"$', ml)):
+                path = mo.group(1)
+            else:
+                path = ml.split()[-1]
             run('delete', (path,))
 
         for cmd,args in test_seq2:

Lib/inspect.py

@@ -796,8 +796,7 @@ def findsource(object):
         # that's most probably not inside a function definition.
         candidates = []
         for i in range(len(lines)):
-            match = pat.match(lines[i])
-            if match:
+            if (match := pat.match(lines[i])):
                 # if it's at toplevel, it's already the best one
                 if lines[i][0] == 'c':
                     return lines, i

Lib/keyword.py

@@ -74,8 +74,7 @@ def main():
         lines = []
         for line in fp:
             if '{1, "' in line:
-                match = strprog.search(line)
-                if match:
+                if (match := strprog.search(line)):
                     lines.append("        '" + match.group(1) + "'," + nl)
     lines.sort()
 

Lib/nntplib.py

@@ -619,8 +619,7 @@ def _getdescriptions(self, group_pattern, return_all):
             resp, lines = self._longcmdstring('XGTITLE ' + group_pattern)
         groups = {}
         for raw_line in lines:
-            match = line_pat.search(raw_line.strip())
-            if match:
+            if (match := line_pat.search(raw_line.strip())):
                 name, desc = match.group(1, 2)
                 if not return_all:
                     return desc
@@ -845,8 +844,7 @@ def xgtitle(self, group, *, file=None):
         resp, raw_lines = self._longcmdstring('XGTITLE ' + group, file)
         lines = []
         for raw_line in raw_lines:
-            match = line_pat.search(raw_line.strip())
-            if match:
+            if (match := line_pat.search(raw_line.strip())):
                 lines.append(match.group(1, 2))
         return resp, lines
 

Lib/smtplib.py

@@ -471,8 +471,7 @@ def ehlo(self, name=''):
             # It's actually stricter, in that only spaces are allowed between
             # parameters, but were not going to check for that here.  Note
             # that the space isn't present if there are no parameters.
-            m = re.match(r'(?P<feature>[A-Za-z0-9][A-Za-z0-9\-]*) ?', each)
-            if m:
+            if (m := re.match(r'(?P<feature>[A-Za-z0-9][A-Za-z0-9\-]*) ?', each)):
                 feature = m.group("feature").lower()
                 params = m.string[m.end("feature"):].strip()
                 if feature == "auth":

Lib/string.py

@@ -120,8 +120,7 @@ def substitute(*args, **kws):
         # Helper function for .sub()
         def convert(mo):
             # Check the most common path first.
-            named = mo.group('named') or mo.group('braced')
-            if named is not None:
+            if (named := mo.group('named') or mo.group('braced')) is not None:
                 return str(mapping[named])
             if mo.group('escaped') is not None:
                 return self.delimiter

Lib/sysconfig.py

@@ -224,8 +224,7 @@ def _parse_makefile(filename, vars=None):
     for line in lines:
         if line.startswith('#') or line.strip() == '':
             continue
-        m = _variable_rx.match(line)
-        if m:
+        if (m := _variable_rx.match(line)):
             n, v = m.group(1, 2)
             v = v.strip()
             # `$$' is a literal `$' in make
@@ -449,18 +448,15 @@ def parse_config_h(fp, vars=None):
         line = fp.readline()
         if not line:
             break
-        m = define_rx.match(line)
-        if m:
+        if (m := define_rx.match(line)):
             n, v = m.group(1, 2)
             try:
                 v = int(v)
             except ValueError:
                 pass
             vars[n] = v
-        else:
-            m = undef_rx.match(line)
-            if m:
-                vars[m.group(1)] = 0
+        elif (m := undef_rx.match(line)):
+            vars[m.group(1)] = 0
     return vars
 
 
@@ -659,8 +655,7 @@ def get_platform():
         osname = "cygwin"
         import re
         rel_re = re.compile(r'[\d.]+')
-        m = rel_re.match(release)
-        if m:
+        if (m := rel_re.match(release)):
             release = m.group()
     elif osname[:6] == "darwin":
         import _osx_support

Lib/tarfile.py

@@ -1200,8 +1200,7 @@ def _proc_pax(self, tarfile):
         # these fields are UTF-8 encoded but since POSIX.1-2008 tar
         # implementations are allowed to store them as raw binary strings if
         # the translation to UTF-8 fails.
-        match = re.search(br"\d+ hdrcharset=([^\n]+)\n", buf)
-        if match is not None:
+        if (match := re.search(br"\d+ hdrcharset=([^\n]+)\n", buf)) is not None:
             pax_headers["hdrcharset"] = match.group(1).decode("utf-8")
 
         # For the time being, we don't care about anything other than "BINARY".

Lib/token.py

@@ -115,17 +115,15 @@ def _main():
     tokens = {}
     prev_val = None
     for line in lines:
-        match = prog.match(line)
-        if match:
+
+        if (match := prog.match(line)):
             name, val = match.group(1, 2)
             val = int(val)
             tokens[val] = {'token': name}          # reverse so we can sort them...
             prev_val = val
-        else:
-            comment_match = comment_regex.match(line)
-            if comment_match and prev_val is not None:
-                comment = comment_match.group(1)
-                tokens[prev_val]['comment'] = comment
+        elif (comment_match := comment_regex.match(line)) and prev_val is not None:
+            comment = comment_match.group(1)
+            tokens[prev_val]['comment'] = comment
     keys = sorted(tokens.keys())
     # load the output skeleton from the target:
     try: