refactor: simplify code

Author: RanKKI

Lib/email/_policybase.py

@@ -307,29 +307,7 @@ def header_source_parse(self, sourcelines):
 
         """
         name, value = sourcelines[0].split(':', 1)
-
-        # Fixed: https://github.com/python/cpython/issues/124452
-        #
-        # Root cause: The function '_refold_parse_tree' in '_header_value_parse.py'.
-        # If there is no WSP, it can't figure out how to wrap the text.
-        # Therefore, it places the entire value directly after '\n', and because
-        # there is a WSP after '<HeaderName>:', the WSP will be moved to the front
-        # of the value according to RFC5322, section 2.2.3.
-        #
-        # However, the WSP is not part of the value; therefore, we must
-        # remove it.
-
-        no_first_value = value.strip() == '' and len(sourcelines) > 1
-
-        # When using the compat32 policy, the value is '\n'. Therefore,
-        # use an empty string if there is no value (without WSP and CRLF)
-        # on the first line
-        value = '' if no_first_value else value.lstrip(' \t')
-
-        if no_first_value and sourcelines[1][0] in ' \t':
-            sourcelines[1] = sourcelines[1][1:]
-
-        value += ''.join(sourcelines[1:])
+        value = ''.join((value, *sourcelines[1:])).lstrip(' \t\r\n')
         return (name, value.rstrip('\r\n'))
 
     def header_store_parse(self, name, value):

Lib/email/policy.py

@@ -125,14 +125,7 @@ def header_source_parse(self, sourcelines):
 
         """
         name, value = sourcelines[0].split(':', 1)
-        no_first_value = not value.strip() and len(sourcelines) > 1
-
-        value = '' if no_first_value else value.lstrip(' \t')
-
-        if no_first_value and sourcelines[1][0] in ' \t':
-            sourcelines[1] = sourcelines[1][1:]
-
-        value += ''.join(sourcelines[1:])
+        value = ''.join((value, *sourcelines[1:])).lstrip(' \t\r\n')
         return (name, value.rstrip('\r\n'))
 
     def header_store_parse(self, name, value):

Lib/test/test_email/test_message.py

@@ -958,15 +958,14 @@ def test_folding_with_utf8_encoding_8(self):
                          b'123456789-123456789\n 123456789 Hello '
                          b'=?utf-8?q?W=C3=B6rld!?= 123456789 123456789\n\n')
 
-
     def test_folding_with_short_nospace_1(self):
         # bpo-36520
         #
         # Fold a line that contains a long whitespace after
         # the fold point.
 
         m = EmailMessage(policy.default)
-        m['Message-ID'] = '12345678912345678123456789123456789123456789'
+        m['Message-ID'] = '123456789'*3
         parsed_msg = message_from_bytes(m.as_bytes(), policy=policy.default)
         self.assertEqual(parsed_msg['Message-ID'], m['Message-ID'])
 
@@ -977,12 +976,10 @@ def test_folding_with_long_nospace_default_policy_1(self):
         # to its original form without any modifications.
 
         m = EmailMessage(policy.default)
-        m['Message-ID'] = '12345678912345678123456789123456789123456789'\
-                        '12345678912345678123456789123456789123456789'
+        message = '123456789' * 10
+        m['Message-ID'] = message
         self.assertEqual(m.as_bytes(),
-                         b'Message-ID:\n 12345678912345678123456789123456'\
-                         b'78912345678912345678912345678123456789123456789'\
-                         b'123456789\n\n')
+                         f'Message-ID:\n {message}\n\n'.encode())
         parsed_msg = message_from_bytes(m.as_bytes(), policy=policy.default)
         self.assertEqual(parsed_msg['Message-ID'], m['Message-ID'])
 
@@ -993,8 +990,8 @@ def test_folding_with_long_nospace_compat32_policy_1(self):
         # to its original form without any modifications.
 
         m = EmailMessage(policy.compat32)
-        m['Message-ID'] = '12345678912345678123456789123456789123456789'\
-                        '12345678912345678123456789123456789123456789'
+        message = '123456789' * 10
+        m['Message-ID'] = message
         parsed_msg = message_from_bytes(m.as_bytes(), policy=policy.default)
         self.assertEqual(parsed_msg['Message-ID'], m['Message-ID'])