Set correct return statement for `is_type_comment` function (#929)

[etc/vim.git] / blib2to3 / pgen2 / tokenize.py

diff --git a/blib2to3/pgen2/tokenize.py b/blib2to3/pgen2/tokenize.py
index 14560e4fddff6224abbafd228229ed88605bd1a3..8c1c4cfac680a2f4815d880c989d6e3b3d115bb0 100644 (file)
--- a/blib2to3/pgen2/tokenize.py
+++ b/blib2to3/pgen2/tokenize.py
@@ -25,17 +25,20 @@ are the same, except instead of generating tokens, tokeneater is a callback
 function to which the 5 fields described above are passed as 5 arguments,
 each time a new token is found."""
 
 function to which the 5 fields described above are passed as 5 arguments,
 each time a new token is found."""
 

-__author__ = 'Ka-Ping Yee <ping@lfw.org>'
-__credits__ = \
-    'GvR, ESR, Tim Peters, Thomas Wouters, Fred Drake, Skip Montanaro'
+__author__ = "Ka-Ping Yee <ping@lfw.org>"
+__credits__ = "GvR, ESR, Tim Peters, Thomas Wouters, Fred Drake, Skip Montanaro"

 
 

-import string, re
+import regex as re

 from codecs import BOM_UTF8, lookup
 from codecs import BOM_UTF8, lookup

-from lib2to3.pgen2.token import *
+from blib2to3.pgen2.token import *

 
 from . import token
 
 from . import token

-__all__ = [x for x in dir(token) if x[0] != '_'] + ["tokenize",
-           "generate_tokens", "untokenize"]
+
+__all__ = [x for x in dir(token) if x[0] != "_"] + [
+    "tokenize",
+    "generate_tokens",
+    "untokenize",
+]

 del token
 
 try:
 del token
 
 try:


@@ -45,25 +48,40 @@ except NameError:
     # valid Python 3 code.
     bytes = str
 
     # valid Python 3 code.
     bytes = str
 

-def group(*choices): return '(' + '|'.join(choices) + ')'
-def any(*choices): return group(*choices) + '*'
-def maybe(*choices): return group(*choices) + '?'

 
 

-Whitespace = r'[ \f\t]*'
-Comment = r'#[^\r\n]*'
-Ignore = Whitespace + any(r'\\\r?\n' + Whitespace) + maybe(Comment)
-Name = r'[a-zA-Z_]\w*'
+def group(*choices):
+    return "(" + "|".join(choices) + ")"
+
+
+def any(*choices):
+    return group(*choices) + "*"
+
+
+def maybe(*choices):
+    return group(*choices) + "?"

 
 

-Binnumber = r'0[bB]_?[01]+(?:_[01]+)*'
-Hexnumber = r'0[xX]_?[\da-fA-F]+(?:_[\da-fA-F]+)*[lL]?'
-Octnumber = r'0[oO]?_?[0-7]+(?:_[0-7]+)*[lL]?'
-Decnumber = group(r'[1-9]\d*(?:_\d+)*[lL]?', '0[lL]?')
+
+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]*"
+Ignore = Whitespace + any(r"\\\r?\n" + Whitespace) + maybe(Comment)
+Name = r"\w+"  # this is invalid but it's fine because Name comes after Number in all groups
+
+Binnumber = r"0[bB]_?[01]+(?:_[01]+)*"
+Hexnumber = r"0[xX]_?[\da-fA-F]+(?:_[\da-fA-F]+)*[lL]?"
+Octnumber = r"0[oO]?_?[0-7]+(?:_[0-7]+)*[lL]?"
+Decnumber = group(r"[1-9]\d*(?:_\d+)*[lL]?", "0[lL]?")

 Intnumber = group(Binnumber, Hexnumber, Octnumber, Decnumber)
 Intnumber = group(Binnumber, Hexnumber, Octnumber, Decnumber)

-Exponent = r'[eE][-+]?\d+(?:_\d+)*'
-Pointfloat = group(r'\d+(?:_\d+)*\.(?:\d+(?:_\d+)*)?', r'\.\d+(?:_\d+)*') + maybe(Exponent)
-Expfloat = r'\d+(?:_\d+)*' + Exponent
+Exponent = r"[eE][-+]?\d+(?:_\d+)*"
+Pointfloat = group(r"\d+(?:_\d+)*\.(?:\d+(?:_\d+)*)?", r"\.\d+(?:_\d+)*") + maybe(
+    Exponent
+)
+Expfloat = r"\d+(?:_\d+)*" + Exponent

 Floatnumber = group(Pointfloat, Expfloat)
 Floatnumber = group(Pointfloat, Expfloat)

-Imagnumber = group(r'\d+(?:_\d+)*[jJ]', Floatnumber + r'[jJ]')
+Imagnumber = group(r"\d+(?:_\d+)*[jJ]", Floatnumber + r"[jJ]")

 Number = group(Imagnumber, Floatnumber, Intnumber)
 
 # Tail end of ' string.
 Number = group(Imagnumber, Floatnumber, Intnumber)
 
 # Tail end of ' string.


@@ -74,102 +92,94 @@ Double = r'[^"\\]*(?:\\.[^"\\]*)*"'
 Single3 = r"[^'\\]*(?:(?:\\.|'(?!''))[^'\\]*)*'''"
 # Tail end of """ string.
 Double3 = r'[^"\\]*(?:(?:\\.|"(?!""))[^"\\]*)*"""'
 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.
 Triple = group(_litprefix + "'''", _litprefix + '"""')
 # Single-line ' or " string.

-String = group(_litprefix + r"'[^\n'\\]*(?:\\.[^\n'\\]*)*'",
-               _litprefix + r'"[^\n"\\]*(?:\\.[^\n"\\]*)*"')
+String = group(
+    _litprefix + r"'[^\n'\\]*(?:\\.[^\n'\\]*)*'",
+    _litprefix + r'"[^\n"\\]*(?:\\.[^\n"\\]*)*"',
+)

 
 # Because of leftmost-then-longest match semantics, be sure to put the
 # longest operators first (e.g., if = came before ==, == would get
 # recognized as two instances of =).
 
 # Because of leftmost-then-longest match semantics, be sure to put the
 # longest operators first (e.g., if = came before ==, == would get
 # recognized as two instances of =).

-Operator = group(r"\*\*=?", r">>=?", r"<<=?", r"<>", r"!=",
-                 r"//=?", r"->",
-                 r"[+\-*/%&@|^=<>]=?",
-                 r"~")
-
-Bracket = '[][(){}]'
-Special = group(r'\r?\n', r'[:;.,`@]')
+Operator = group(
+    r"\*\*=?",
+    r">>=?",
+    r"<<=?",
+    r"<>",
+    r"!=",
+    r"//=?",
+    r"->",
+    r"[+\-*/%&@|^=<>:]=?",
+    r"~",
+)
+
+Bracket = "[][(){}]"
+Special = group(r"\r?\n", r"[:;.,`@]")

 Funny = group(Operator, Bracket, Special)
 
 PlainToken = group(Number, Funny, String, Name)
 Token = Ignore + PlainToken
 
 # First (or only) line of ' or " string.
 Funny = group(Operator, Bracket, Special)
 
 PlainToken = group(Number, Funny, String, Name)
 Token = Ignore + PlainToken
 
 # First (or only) line of ' or " string.

-ContStr = group(_litprefix + r"'[^\n'\\]*(?:\\.[^\n'\\]*)*" +
-                group("'", r'\\\r?\n'),
-                _litprefix + r'"[^\n"\\]*(?:\\.[^\n"\\]*)*' +
-                group('"', r'\\\r?\n'))
-PseudoExtras = group(r'\\\r?\n', Comment, Triple)
+ContStr = group(
+    _litprefix + r"'[^\n'\\]*(?:\\.[^\n'\\]*)*" + group("'", r"\\\r?\n"),
+    _litprefix + r'"[^\n"\\]*(?:\\.[^\n"\\]*)*' + group('"', r"\\\r?\n"),
+)
+PseudoExtras = group(r"\\\r?\n", Comment, Triple)

 PseudoToken = Whitespace + group(PseudoExtras, Number, Funny, ContStr, Name)
 
 PseudoToken = Whitespace + group(PseudoExtras, Number, Funny, ContStr, Name)
 

-tokenprog, pseudoprog, single3prog, double3prog = list(map(
-    re.compile, (Token, PseudoToken, Single3, Double3)))
-endprogs = {"'": re.compile(Single), '"': re.compile(Double),
-            "'''": single3prog, '"""': double3prog,
-            "r'''": single3prog, 'r"""': double3prog,
-            "u'''": single3prog, 'u"""': double3prog,
-            "b'''": single3prog, 'b"""': double3prog,
-            "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 = {}
-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"""',):
-    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
+tokenprog = re.compile(Token, re.UNICODE)
+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,
+    **{f"{prefix}'''": single3prog for prefix in _strprefixes},
+    **{f'{prefix}"""': double3prog for prefix in _strprefixes},
+    **{prefix: None for prefix in _strprefixes},
+}
+
+triple_quoted = (
+    {"'''", '"""'}
+    | {f"{prefix}'''" for prefix in _strprefixes}
+    | {f'{prefix}"""' for prefix in _strprefixes}
+)
+single_quoted = (
+    {"'", '"'}
+    | {f"{prefix}'" for prefix in _strprefixes}
+    | {f'{prefix}"' for prefix in _strprefixes}
+)

 
 tabsize = 8
 
 
 tabsize = 8
 

-class TokenError(Exception): pass

 
 

-class StopTokenizing(Exception): pass
+class TokenError(Exception):
+    pass

 
 

-def printtoken(type, token, xxx_todo_changeme, xxx_todo_changeme1, line): # for testing
+
+class StopTokenizing(Exception):
+    pass
+
+
+def printtoken(type, token, xxx_todo_changeme, xxx_todo_changeme1, line):  # for testing

     (srow, scol) = xxx_todo_changeme
     (erow, ecol) = xxx_todo_changeme1
     (srow, scol) = xxx_todo_changeme
     (erow, ecol) = xxx_todo_changeme1

-    print("%d,%d-%d,%d:\t%s\t%s" % \
-        (srow, scol, erow, ecol, tok_name[type], repr(token)))
+    print(
+        "%d,%d-%d,%d:\t%s\t%s" % (srow, scol, erow, ecol, tok_name[type], repr(token))
+    )
+

 
 def tokenize(readline, tokeneater=printtoken):
     """
 
 def tokenize(readline, tokeneater=printtoken):
     """


@@ -189,13 +199,14 @@ def tokenize(readline, tokeneater=printtoken):
     except StopTokenizing:
         pass
 
     except StopTokenizing:
         pass
 

+

 # backwards compatible interface
 def tokenize_loop(readline, tokeneater):
     for token_info in generate_tokens(readline):
         tokeneater(*token_info)
 
 # backwards compatible interface
 def tokenize_loop(readline, tokeneater):
     for token_info in generate_tokens(readline):
         tokeneater(*token_info)
 

-class Untokenizer:

 
 

+class Untokenizer:

     def __init__(self):
         self.tokens = []
         self.prev_row = 1
     def __init__(self):
         self.tokens = []
         self.prev_row = 1


@@ -228,14 +239,14 @@ class Untokenizer:
         toks_append = self.tokens.append
         toknum, tokval = token
         if toknum in (NAME, NUMBER):
         toks_append = self.tokens.append
         toknum, tokval = token
         if toknum in (NAME, NUMBER):

-            tokval += ' '
+            tokval += " "

         if toknum in (NEWLINE, NL):
             startline = True
         for tok in iterable:
             toknum, tokval = tok[:2]
 
         if toknum in (NEWLINE, NL):
             startline = True
         for tok in iterable:
             toknum, tokval = tok[:2]
 

-            if toknum in (NAME, NUMBER):
-                tokval += ' '
+            if toknum in (NAME, NUMBER, ASYNC, AWAIT):
+                tokval += " "

 
             if toknum == INDENT:
                 indents.append(tokval)
 
             if toknum == INDENT:
                 indents.append(tokval)


@@ -250,8 +261,10 @@ class Untokenizer:
                 startline = False
             toks_append(tokval)
 
                 startline = False
             toks_append(tokval)
 

-cookie_re = re.compile(r'^[ \t\f]*#.*?coding[:=][ \t]*([-\w.]+)', re.ASCII)
-blank_re = re.compile(br'^[ \t\f]*(?:[#\r\n]|$)', re.ASCII)
+
+cookie_re = re.compile(r"^[ \t\f]*#.*?coding[:=][ \t]*([-\w.]+)", re.ASCII)
+blank_re = re.compile(br"^[ \t\f]*(?:[#\r\n]|$)", re.ASCII)
+

 
 def _get_normal_name(orig_enc):
     """Imitates get_normal_name in tokenizer.c."""
 
 def _get_normal_name(orig_enc):
     """Imitates get_normal_name in tokenizer.c."""


@@ -259,11 +272,13 @@ def _get_normal_name(orig_enc):
     enc = orig_enc[:12].lower().replace("_", "-")
     if enc == "utf-8" or enc.startswith("utf-8-"):
         return "utf-8"
     enc = orig_enc[:12].lower().replace("_", "-")
     if enc == "utf-8" or enc.startswith("utf-8-"):
         return "utf-8"

-    if enc in ("latin-1", "iso-8859-1", "iso-latin-1") or \
-       enc.startswith(("latin-1-", "iso-8859-1-", "iso-latin-1-")):
+    if enc in ("latin-1", "iso-8859-1", "iso-latin-1") or enc.startswith(
+        ("latin-1-", "iso-8859-1-", "iso-latin-1-")
+    ):

         return "iso-8859-1"
     return orig_enc
 
         return "iso-8859-1"
     return orig_enc
 

+

 def detect_encoding(readline):
     """
     The detect_encoding() function is used to detect the encoding that should
 def detect_encoding(readline):
     """
     The detect_encoding() function is used to detect the encoding that should


@@ -284,7 +299,8 @@ def detect_encoding(readline):
     """
     bom_found = False
     encoding = None
     """
     bom_found = False
     encoding = None

-    default = 'utf-8'
+    default = "utf-8"
+

     def read_or_stop():
         try:
             return readline()
     def read_or_stop():
         try:
             return readline()


@@ -293,7 +309,7 @@ def detect_encoding(readline):
 
     def find_cookie(line):
         try:
 
     def find_cookie(line):
         try:

-            line_string = line.decode('ascii')
+            line_string = line.decode("ascii")

         except UnicodeDecodeError:
             return None
         match = cookie_re.match(line_string)
         except UnicodeDecodeError:
             return None
         match = cookie_re.match(line_string)


@@ -307,17 +323,17 @@ def detect_encoding(readline):
             raise SyntaxError("unknown encoding: " + encoding)
 
         if bom_found:
             raise SyntaxError("unknown encoding: " + encoding)
 
         if bom_found:

-            if codec.name != 'utf-8':
+            if codec.name != "utf-8":

                 # This behaviour mimics the Python interpreter
                 # This behaviour mimics the Python interpreter

-                raise SyntaxError('encoding problem: utf-8')
-            encoding += '-sig'
+                raise SyntaxError("encoding problem: utf-8")
+            encoding += "-sig"

         return encoding
 
     first = read_or_stop()
     if first.startswith(BOM_UTF8):
         bom_found = True
         first = first[3:]
         return encoding
 
     first = read_or_stop()
     if first.startswith(BOM_UTF8):
         bom_found = True
         first = first[3:]

-        default = 'utf-8-sig'
+        default = "utf-8-sig"

     if not first:
         return default, []
 
     if not first:
         return default, []
 


@@ -337,6 +353,7 @@ def detect_encoding(readline):
 
     return default, [first, second]
 
 
     return default, [first, second]
 

+

 def untokenize(iterable):
     """Transform tokens back into Python source code.
 
 def untokenize(iterable):
     """Transform tokens back into Python source code.
 


@@ -358,7 +375,8 @@ def untokenize(iterable):
     ut = Untokenizer()
     return ut.untokenize(iterable)
 
     ut = Untokenizer()
     return ut.untokenize(iterable)
 

-def generate_tokens(readline):
+
+def generate_tokens(readline, grammar=None):

     """
     The generate_tokens() generator requires one argument, readline, which
     must be a callable object which provides the same interface as the
     """
     The generate_tokens() generator requires one argument, readline, which
     must be a callable object which provides the same interface as the


@@ -375,33 +393,52 @@ def generate_tokens(readline):
     logical line; continuation lines are included.
     """
     lnum = parenlev = continued = 0
     logical line; continuation lines are included.
     """
     lnum = parenlev = continued = 0

-    namechars, numchars = string.ascii_letters + '_', '0123456789'
-    contstr, needcont = '', 0
+    numchars = "0123456789"
+    contstr, needcont = "", 0

     contline = None
     indents = [0]
 
     contline = None
     indents = [0]
 

-    while 1:                                   # loop over lines in stream
+    # If we know we're parsing 3.7+, we can unconditionally parse `async` and
+    # `await` as keywords.
+    async_keywords = False if grammar is None else grammar.async_keywords
+    # 'stashed' and 'async_*' are used for async/await parsing
+    stashed = None
+    async_def = False
+    async_def_indent = 0
+    async_def_nl = False
+
+    while 1:  # loop over lines in stream

         try:
             line = readline()
         except StopIteration:
         try:
             line = readline()
         except StopIteration:

-            line = ''
+            line = ""

         lnum = lnum + 1
         pos, max = 0, len(line)
 
         lnum = lnum + 1
         pos, max = 0, len(line)
 

-        if contstr:                            # continued string
+        if contstr:  # continued string

             if not line:
                 raise TokenError("EOF in multi-line string", strstart)
             endmatch = endprog.match(line)
             if endmatch:
                 pos = end = endmatch.end(0)
             if not line:
                 raise TokenError("EOF in multi-line string", strstart)
             endmatch = endprog.match(line)
             if endmatch:
                 pos = end = endmatch.end(0)

-                yield (STRING, contstr + line[:end],
-                       strstart, (lnum, end), contline + line)
-                contstr, needcont = '', 0
+                yield (
+                    STRING,
+                    contstr + line[:end],
+                    strstart,
+                    (lnum, end),
+                    contline + line,
+                )
+                contstr, needcont = "", 0

                 contline = None
                 contline = None

-            elif needcont and line[-2:] != '\\\n' and line[-3:] != '\\\r\n':
-                yield (ERRORTOKEN, contstr + line,
-                           strstart, (lnum, len(line)), contline)
-                contstr = ''
+            elif needcont and line[-2:] != "\\\n" and line[-3:] != "\\\r\n":
+                yield (
+                    ERRORTOKEN,
+                    contstr + line,
+                    strstart,
+                    (lnum, len(line)),
+                    contline,
+                )
+                contstr = ""

                 contline = None
                 continue
             else:
                 contline = None
                 continue
             else:


@@ -410,109 +447,206 @@ def generate_tokens(readline):
                 continue
 
         elif parenlev == 0 and not continued:  # new statement
                 continue
 
         elif parenlev == 0 and not continued:  # new statement

-            if not line: break
+            if not line:
+                break

             column = 0
             column = 0

-            while pos < max:                   # measure leading whitespace
-                if line[pos] == ' ': column = column + 1
-                elif line[pos] == '\t': column = (column//tabsize + 1)*tabsize
-                elif line[pos] == '\f': column = 0
-                else: break
-                pos = pos + 1
-            if pos == max: break
-
-            if line[pos] in '#\r\n':           # skip comments or blank lines
-                if line[pos] == '#':
-                    comment_token = line[pos:].rstrip('\r\n')
-                    nl_pos = pos + len(comment_token)
-                    yield (COMMENT, comment_token,
-                           (lnum, pos), (lnum, pos + len(comment_token)), line)
-                    yield (NL, line[nl_pos:],
-                           (lnum, nl_pos), (lnum, len(line)), line)
+            while pos < max:  # measure leading whitespace
+                if line[pos] == " ":
+                    column = column + 1
+                elif line[pos] == "\t":
+                    column = (column // tabsize + 1) * tabsize
+                elif line[pos] == "\f":
+                    column = 0

                 else:
                 else:

-                    yield ((NL, COMMENT)[line[pos] == '#'], line[pos:],
-                           (lnum, pos), (lnum, len(line)), line)
+                    break
+                pos = pos + 1
+            if pos == max:
+                break
+
+            if stashed:
+                yield stashed
+                stashed = None
+
+            if line[pos] in "\r\n":  # skip blank lines
+                yield (NL, line[pos:], (lnum, pos), (lnum, len(line)), line)
+                continue
+
+            if line[pos] == "#":  # skip comments
+                comment_token = line[pos:].rstrip("\r\n")
+                nl_pos = pos + len(comment_token)
+                yield (
+                    COMMENT,
+                    comment_token,
+                    (lnum, pos),
+                    (lnum, pos + len(comment_token)),
+                    line,
+                )
+                yield (NL, line[nl_pos:], (lnum, nl_pos), (lnum, len(line)), line)

                 continue
 
                 continue
 

-            if column > indents[-1]:           # count indents or dedents
+            if column > indents[-1]:  # count indents

                 indents.append(column)
                 yield (INDENT, line[:pos], (lnum, 0), (lnum, pos), line)
                 indents.append(column)
                 yield (INDENT, line[:pos], (lnum, 0), (lnum, pos), line)

-            while column < indents[-1]:
+
+            while column < indents[-1]:  # count dedents

                 if column not in indents:
                     raise IndentationError(
                         "unindent does not match any outer indentation level",
                 if column not in indents:
                     raise IndentationError(
                         "unindent does not match any outer indentation level",

-                        ("<tokenize>", lnum, pos, line))
+                        ("<tokenize>", lnum, pos, line),
+                    )

                 indents = indents[:-1]
 
                 indents = indents[:-1]
 

-                yield (DEDENT, '', (lnum, pos), (lnum, pos), line)
+                if async_def and async_def_indent >= indents[-1]:
+                    async_def = False
+                    async_def_nl = False
+                    async_def_indent = 0
+
+                yield (DEDENT, "", (lnum, pos), (lnum, pos), line)

 
 

-        else:                                  # continued statement
+            if async_def and async_def_nl and async_def_indent >= indents[-1]:
+                async_def = False
+                async_def_nl = False
+                async_def_indent = 0
+
+        else:  # continued statement

             if not line:
                 raise TokenError("EOF in multi-line statement", (lnum, 0))
             continued = 0
 
         while pos < max:
             pseudomatch = pseudoprog.match(line, pos)
             if not line:
                 raise TokenError("EOF in multi-line statement", (lnum, 0))
             continued = 0
 
         while pos < max:
             pseudomatch = pseudoprog.match(line, pos)

-            if pseudomatch:                                # scan for tokens
+            if pseudomatch:  # scan for tokens

                 start, end = pseudomatch.span(1)
                 spos, epos, pos = (lnum, start), (lnum, end), end
                 token, initial = line[start:end], line[start]
 
                 start, end = pseudomatch.span(1)
                 spos, epos, pos = (lnum, start), (lnum, end), end
                 token, initial = line[start:end], line[start]
 

-                if initial in numchars or \
-                   (initial == '.' and token != '.'):      # ordinary number
+                if initial in numchars or (
+                    initial == "." and token != "."
+                ):  # ordinary number

                     yield (NUMBER, token, spos, epos, line)
                     yield (NUMBER, token, spos, epos, line)

-                elif initial in '\r\n':
+                elif initial in "\r\n":

                     newline = NEWLINE
                     if parenlev > 0:
                         newline = NL
                     newline = NEWLINE
                     if parenlev > 0:
                         newline = NL

+                    elif async_def:
+                        async_def_nl = True
+                    if stashed:
+                        yield stashed
+                        stashed = None

                     yield (newline, token, spos, epos, line)
 
                     yield (newline, token, spos, epos, line)
 

-                elif initial == '#':
+                elif initial == "#":

                     assert not token.endswith("\n")
                     assert not token.endswith("\n")

+                    if stashed:
+                        yield stashed
+                        stashed = None

                     yield (COMMENT, token, spos, epos, line)
                 elif token in triple_quoted:
                     endprog = endprogs[token]
                     endmatch = endprog.match(line, pos)
                     yield (COMMENT, token, spos, epos, line)
                 elif token in triple_quoted:
                     endprog = endprogs[token]
                     endmatch = endprog.match(line, pos)

-                    if endmatch:                           # all on one line
+                    if endmatch:  # all on one line

                         pos = endmatch.end(0)
                         token = line[start:pos]
                         pos = endmatch.end(0)
                         token = line[start:pos]

+                        if stashed:
+                            yield stashed
+                            stashed = None

                         yield (STRING, token, spos, (lnum, pos), line)
                     else:
                         yield (STRING, token, spos, (lnum, pos), line)
                     else:

-                        strstart = (lnum, start)           # multiple lines
+                        strstart = (lnum, start)  # multiple lines

                         contstr = line[start:]
                         contline = line
                         break
                         contstr = line[start:]
                         contline = line
                         break

-                elif initial in single_quoted or \
-                    token[:2] in single_quoted or \
-                    token[:3] in single_quoted:
-                    if token[-1] == '\n':                  # continued string
+                elif (
+                    initial in single_quoted
+                    or token[:2] in single_quoted
+                    or token[:3] in single_quoted
+                ):
+                    if token[-1] == "\n":  # continued string

                         strstart = (lnum, start)
                         strstart = (lnum, start)

-                        endprog = (endprogs[initial] or endprogs[token[1]] or
-                                   endprogs[token[2]])
+                        endprog = (
+                            endprogs[initial]
+                            or endprogs[token[1]]
+                            or endprogs[token[2]]
+                        )

                         contstr, needcont = line[start:], 1
                         contline = line
                         break
                         contstr, needcont = line[start:], 1
                         contline = line
                         break

-                    else:                                  # ordinary string
+                    else:  # ordinary string
+                        if stashed:
+                            yield stashed
+                            stashed = None

                         yield (STRING, token, spos, epos, line)
                         yield (STRING, token, spos, epos, line)

-                elif initial in namechars:                 # ordinary name
-                    yield (NAME, token, spos, epos, line)
-                elif initial == '\\':                      # continued stmt
+                elif initial.isidentifier():  # ordinary name
+                    if token in ("async", "await"):
+                        if async_keywords or async_def:
+                            yield (
+                                ASYNC if token == "async" else AWAIT,
+                                token,
+                                spos,
+                                epos,
+                                line,
+                            )
+                            continue
+
+                    tok = (NAME, token, spos, epos, line)
+                    if token == "async" and not stashed:
+                        stashed = tok
+                        continue
+
+                    if token in ("def", "for"):
+                        if stashed and stashed[0] == NAME and stashed[1] == "async":
+
+                            if token == "def":
+                                async_def = True
+                                async_def_indent = indents[-1]
+
+                            yield (
+                                ASYNC,
+                                stashed[1],
+                                stashed[2],
+                                stashed[3],
+                                stashed[4],
+                            )
+                            stashed = None
+
+                    if stashed:
+                        yield stashed
+                        stashed = None
+
+                    yield tok
+                elif initial == "\\":  # continued stmt

                     # This yield is new; needed for better idempotency:
                     # This yield is new; needed for better idempotency:

+                    if stashed:
+                        yield stashed
+                        stashed = None

                     yield (NL, token, spos, (lnum, pos), line)
                     continued = 1
                 else:
                     yield (NL, token, spos, (lnum, pos), line)
                     continued = 1
                 else:

-                    if initial in '([{': parenlev = parenlev + 1
-                    elif initial in ')]}': parenlev = parenlev - 1
+                    if initial in "([{":
+                        parenlev = parenlev + 1
+                    elif initial in ")]}":
+                        parenlev = parenlev - 1
+                    if stashed:
+                        yield stashed
+                        stashed = None

                     yield (OP, token, spos, epos, line)
             else:
                     yield (OP, token, spos, epos, line)
             else:

-                yield (ERRORTOKEN, line[pos],
-                           (lnum, pos), (lnum, pos+1), line)
+                yield (ERRORTOKEN, line[pos], (lnum, pos), (lnum, pos + 1), line)

                 pos = pos + 1
 
                 pos = pos + 1
 

-    for indent in indents[1:]:                 # pop remaining indent levels
-        yield (DEDENT, '', (lnum, 0), (lnum, 0), '')
-    yield (ENDMARKER, '', (lnum, 0), (lnum, 0), '')
+    if stashed:
+        yield stashed
+        stashed = None
+
+    for indent in indents[1:]:  # pop remaining indent levels
+        yield (DEDENT, "", (lnum, 0), (lnum, 0), "")
+    yield (ENDMARKER, "", (lnum, 0), (lnum, 0), "")

 
 

-if __name__ == '__main__':                     # testing
+
+if __name__ == "__main__":  # testing

     import sys
     import sys

-    if len(sys.argv) > 1: tokenize(open(sys.argv[1]).readline)
-    else: tokenize(sys.stdin.readline)
+
+    if len(sys.argv) > 1:
+        tokenize(open(sys.argv[1]).readline)
+    else:
+        tokenize(sys.stdin.readline)