Add support for all valid string literals (#115)

black.py

@@ -1923,8 +1923,8 @@ def normalize_string_quotes(leaf: Leaf) -> None:
 
     prefix = leaf.value[:first_quote_pos]
     body = leaf.value[first_quote_pos + len(orig_quote):-len(orig_quote)]
-    unescaped_new_quote = re.compile(r"(([^\\]|^)(\\\\)*)" + new_quote)
+    unescaped_new_quote = re.compile(rf"(([^\\]|^)(\\\\)*){new_quote}")
-    escaped_orig_quote = re.compile(r"\\(\\\\)*" + orig_quote)
+    escaped_orig_quote = re.compile(rf"\\(\\\\)*{orig_quote}")
     if "r" in prefix.casefold():
         if unescaped_new_quote.search(body):
             # There's at least one unescaped new_quote in this raw string
@@ -1934,8 +1934,8 @@ def normalize_string_quotes(leaf: Leaf) -> None:
         # Do not introduce or remove backslashes in raw strings
         new_body = body
     else:
-        new_body = escaped_orig_quote.sub(f"\\1{orig_quote}", body)
+        new_body = escaped_orig_quote.sub(rf"\1{orig_quote}", body)
-        new_body = unescaped_new_quote.sub(f"\\1\\\\{new_quote}", new_body)
+        new_body = unescaped_new_quote.sub(rf"\1\\{new_quote}", new_body)
     if new_quote == '"""' and new_body[-1] == '"':
         # edge case:
         new_body = new_body[:-1] + '\\"'

blib2to3/README

@@ -7,6 +7,7 @@ Reasons for forking:
   *args and **kwargs
 - backport of GH-6143 that restores the ability to reformat legacy usage of
   `async`
+- support all types of string literals
 - better ability to debug (better reprs)
 - INDENT and DEDENT don't hold whitespace and comment prefixes
 - ability to Cythonize

blib2to3/pgen2/tokenize.py

@@ -48,6 +48,10 @@
 def group(*choices): return '(' + '|'.join(choices) + ')'
 def any(*choices): return group(*choices) + '*'
 def maybe(*choices): return group(*choices) + '?'
+def _combinations(*l):
+    return set(
+        x + y for x in l for y in l + ("",) if x.casefold() != y.casefold()
+    )
 
 Whitespace = r'[ \f\t]*'
 Comment = r'#[^\r\n]*'
@@ -74,7 +78,7 @@ def maybe(*choices): return group(*choices) + '?'
 Single3 = r"[^'\\]*(?:(?:\\.|'(?!''))[^'\\]*)*'''"
 # Tail end of """ string.
 Double3 = r'[^"\\]*(?:(?:\\.|"(?!""))[^"\\]*)*"""'
-_litprefix = r"(?:[uUrRbBfF]|[rR][bB]|[bBuU][rR])?"
+_litprefix = r"(?:[uUrRbBfF]|[rR][fFbB]|[fFbBuU][rR])?"
 Triple = group(_litprefix + "'''", _litprefix + '"""')
 # Single-line ' or " string.
 String = group(_litprefix + r"'[^\n'\\]*(?:\\.[^\n'\\]*)*'",
@@ -107,59 +111,29 @@ def maybe(*choices): return group(*choices) + '?'
 pseudoprog = re.compile(PseudoToken, re.UNICODE)
 single3prog = re.compile(Single3)
 double3prog = re.compile(Double3)
+
+_strprefixes = (
+    _combinations('r', 'R', 'f', 'F') |
+    _combinations('r', 'R', 'b', 'B') |
+    {'u', 'U', 'ur', 'uR', 'Ur', 'UR'}
+)
+
 endprogs = {"'": re.compile(Single), '"': re.compile(Double),
             "'''": single3prog, '"""': double3prog,
-            "r'''": single3prog, 'r"""': double3prog,
+            **{f"{prefix}'''": single3prog for prefix in _strprefixes},
-            "u'''": single3prog, 'u"""': double3prog,
+            **{f'{prefix}"""': double3prog for prefix in _strprefixes},
-            "b'''": single3prog, 'b"""': double3prog,
+            **{prefix: None for prefix in _strprefixes}}
-            "f'''": single3prog, 'f"""': double3prog,
-            "ur'''": single3prog, 'ur"""': double3prog,
-            "br'''": single3prog, 'br"""': double3prog,
-            "rb'''": single3prog, 'rb"""': double3prog,
-            "R'''": single3prog, 'R"""': double3prog,
-            "U'''": single3prog, 'U"""': double3prog,
-            "B'''": single3prog, 'B"""': double3prog,
-            "F'''": single3prog, 'F"""': double3prog,
-            "uR'''": single3prog, 'uR"""': double3prog,
-            "Ur'''": single3prog, 'Ur"""': double3prog,
-            "UR'''": single3prog, 'UR"""': double3prog,
-            "bR'''": single3prog, 'bR"""': double3prog,
-            "Br'''": single3prog, 'Br"""': double3prog,
-            "BR'''": single3prog, 'BR"""': double3prog,
-            "rB'''": single3prog, 'rB"""': double3prog,
-            "Rb'''": single3prog, 'Rb"""': double3prog,
-            "RB'''": single3prog, 'RB"""': double3prog,
-            'r': None, 'R': None,
-            'u': None, 'U': None,
-            'f': None, 'F': None,
-            'b': None, 'B': None}
 
-triple_quoted = {}
+triple_quoted = (
-for t in ("'''", '"""',
+    {"'''", '"""'} |
-          "r'''", 'r"""', "R'''", 'R"""',
+    {f"{prefix}'''" for prefix in _strprefixes} |
-          "u'''", 'u"""', "U'''", 'U"""',
+    {f'{prefix}"""' for prefix in _strprefixes}
-          "b'''", 'b"""', "B'''", 'B"""',
+)
-          "f'''", 'f"""', "F'''", 'F"""',
+single_quoted = (
-          "ur'''", 'ur"""', "Ur'''", 'Ur"""',
+    {"'", '"'} |
-          "uR'''", 'uR"""', "UR'''", 'UR"""',
+    {f"{prefix}'" for prefix in _strprefixes} |
-          "br'''", 'br"""', "Br'''", 'Br"""',
+    {f'{prefix}"' for prefix in _strprefixes}
-          "bR'''", 'bR"""', "BR'''", 'BR"""',
+)
-          "rb'''", 'rb"""', "Rb'''", 'Rb"""',
-          "rB'''", 'rB"""', "RB'''", 'RB"""',):
-    triple_quoted[t] = t
-single_quoted = {}
-for t in ("'", '"',
-          "r'", 'r"', "R'", 'R"',
-          "u'", 'u"', "U'", 'U"',
-          "b'", 'b"', "B'", 'B"',
-          "f'", 'f"', "F'", 'F"',
-          "ur'", 'ur"', "Ur'", 'Ur"',
-          "uR'", 'uR"', "UR'", 'UR"',
-          "br'", 'br"', "Br'", 'Br"',
-          "bR'", 'bR"', "BR'", 'BR"',
-          "rb'", 'rb"', "Rb'", 'Rb"',
-          "rB'", 'rB"', "RB'", 'RB"',):
-    single_quoted[t] = t
 
 tabsize = 8
 

tests/python2.py

@@ -8,7 +8,7 @@
 
 
 def function((_globals, _locals)):
-    exec "print 'hi from exec!'" in _globals, _locals
+    exec ur"print 'hi from exec!'" in _globals, _locals
 
 
 function((globals(), locals()))
@@ -27,7 +27,7 @@ def function((_globals, _locals)):
 
 
 def function((_globals, _locals)):
-    exec "print 'hi from exec!'" in _globals, _locals
+    exec ur"print 'hi from exec!'" in _globals, _locals
 
 
 function((globals(), locals()))

tests/string_quotes.py

@@ -22,6 +22,7 @@
 r'Date d\'expiration:(.*)'
 r'Tricky "quote'
 r'Not-so-tricky \"quote'
+rf'{yay}'
 '\n\
 The \"quick\"\n\
 brown fox\n\
@@ -56,6 +57,7 @@
 r"Date d\'expiration:(.*)"
 r'Tricky "quote'
 r"Not-so-tricky \"quote"
+rf"{yay}"
 "\n\
 The \"quick\"\n\
 brown fox\n\