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cpython/Lib/tokenize.py

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"""Tokenization help for Python programs.
tokenize(readline) is a generator that breaks a stream of bytes into
Python tokens. It decodes the bytes according to PEP-0263 for
determining source file encoding.
It accepts a readline-like method which is called repeatedly to get the
next line of input (or b"" for EOF). It generates 5-tuples with these
members:
the token type (see token.py)
the token (a string)
the starting (row, column) indices of the token (a 2-tuple of ints)
the ending (row, column) indices of the token (a 2-tuple of ints)
the original line (string)
It is designed to match the working of the Python tokenizer exactly, except
that it produces COMMENT tokens for comments and gives type OP for all
operators. Additionally, all token lists start with an ENCODING token
which tells you which encoding was used to decode the bytes stream.
"""
__author__ = 'Ka-Ping Yee <ping@lfw.org>'
__credits__ = ('GvR, ESR, Tim Peters, Thomas Wouters, Fred Drake, '
'Skip Montanaro, Raymond Hettinger, Trent Nelson, '
'Michael Foord')
from builtins import open as _builtin_open
from codecs import lookup, BOM_UTF8
import collections
import functools
from io import TextIOWrapper
import itertools as _itertools
import re
import sys
from token import *
from token import EXACT_TOKEN_TYPES
import _tokenize
cookie_re = re.compile(r'^[ \t\f]*#.*?coding[:=][ \t]*([-\w.]+)', re.ASCII)
blank_re = re.compile(br'^[ \t\f]*(?:[#\r\n]|$)', re.ASCII)
import token
__all__ = token.__all__ + ["tokenize", "generate_tokens", "detect_encoding",
"untokenize", "TokenInfo", "open", "TokenError"]
del token
class TokenInfo(collections.namedtuple('TokenInfo', 'type string start end line')):
def __repr__(self):
annotated_type = '%d (%s)' % (self.type, tok_name[self.type])
return ('TokenInfo(type=%s, string=%r, start=%r, end=%r, line=%r)' %
self._replace(type=annotated_type))
@property
def exact_type(self):
if self.type == OP and self.string in EXACT_TOKEN_TYPES:
return EXACT_TOKEN_TYPES[self.string]
else:
return self.type
def group(*choices): return '(' + '|'.join(choices) + ')'
def any(*choices): return group(*choices) + '*'
def maybe(*choices): return group(*choices) + '?'
# Note: we use unicode matching for names ("\w") but ascii matching for
# number literals.
Whitespace = r'[ \f\t]*'
Comment = r'#[^\r\n]*'
Ignore = Whitespace + any(r'\\\r?\n' + Whitespace) + maybe(Comment)
Name = r'\w+'
Hexnumber = r'0[xX](?:_?[0-9a-fA-F])+'
Binnumber = r'0[bB](?:_?[01])+'
Octnumber = r'0[oO](?:_?[0-7])+'
Decnumber = r'(?:0(?:_?0)*|[1-9](?:_?[0-9])*)'
Intnumber = group(Hexnumber, Binnumber, Octnumber, Decnumber)
Exponent = r'[eE][-+]?[0-9](?:_?[0-9])*'
Pointfloat = group(r'[0-9](?:_?[0-9])*\.(?:[0-9](?:_?[0-9])*)?',
r'\.[0-9](?:_?[0-9])*') + maybe(Exponent)
Expfloat = r'[0-9](?:_?[0-9])*' + Exponent
Floatnumber = group(Pointfloat, Expfloat)
Imagnumber = group(r'[0-9](?:_?[0-9])*[jJ]', Floatnumber + r'[jJ]')
Number = group(Imagnumber, Floatnumber, Intnumber)
# Return the empty string, plus all of the valid string prefixes.
def _all_string_prefixes():
# The valid string prefixes. Only contain the lower case versions,
# and don't contain any permutations (include 'fr', but not
# 'rf'). The various permutations will be generated.
_valid_string_prefixes = ['b', 'r', 'u', 'f', 'br', 'fr']
# if we add binary f-strings, add: ['fb', 'fbr']
result = {''}
for prefix in _valid_string_prefixes:
for t in _itertools.permutations(prefix):
# create a list with upper and lower versions of each
# character
for u in _itertools.product(*[(c, c.upper()) for c in t]):
result.add(''.join(u))
return result
@functools.lru_cache
def _compile(expr):
return re.compile(expr, re.UNICODE)
# Note that since _all_string_prefixes includes the empty string,
# StringPrefix can be the empty string (making it optional).
StringPrefix = group(*_all_string_prefixes())
# Tail end of ' string.
Single = r"[^'\\]*(?:\\.[^'\\]*)*'"
# Tail end of " string.
Double = r'[^"\\]*(?:\\.[^"\\]*)*"'
# Tail end of ''' string.
Single3 = r"[^'\\]*(?:(?:\\.|'(?!''))[^'\\]*)*'''"
# Tail end of """ string.
Double3 = r'[^"\\]*(?:(?:\\.|"(?!""))[^"\\]*)*"""'
Triple = group(StringPrefix + "'''", StringPrefix + '"""')
# Single-line ' or " string.
String = group(StringPrefix + r"'[^\n'\\]*(?:\\.[^\n'\\]*)*'",
StringPrefix + r'"[^\n"\\]*(?:\\.[^\n"\\]*)*"')
# Sorting in reverse order puts the long operators before their prefixes.
# Otherwise if = came before ==, == would get recognized as two instances
# of =.
Special = group(*map(re.escape, sorted(EXACT_TOKEN_TYPES, reverse=True)))
Funny = group(r'\r?\n', Special)
PlainToken = group(Number, Funny, String, Name)
Token = Ignore + PlainToken
# First (or only) line of ' or " string.
ContStr = group(StringPrefix + r"'[^\n'\\]*(?:\\.[^\n'\\]*)*" +
group("'", r'\\\r?\n'),
StringPrefix + r'"[^\n"\\]*(?:\\.[^\n"\\]*)*' +
group('"', r'\\\r?\n'))
PseudoExtras = group(r'\\\r?\n|\Z', Comment, Triple)
PseudoToken = Whitespace + group(PseudoExtras, Number, Funny, ContStr, Name)
# For a given string prefix plus quotes, endpats maps it to a regex
# to match the remainder of that string. _prefix can be empty, for
# a normal single or triple quoted string (with no prefix).
endpats = {}
for _prefix in _all_string_prefixes():
endpats[_prefix + "'"] = Single
endpats[_prefix + '"'] = Double
endpats[_prefix + "'''"] = Single3
endpats[_prefix + '"""'] = Double3
del _prefix
# A set of all of the single and triple quoted string prefixes,
# including the opening quotes.
single_quoted = set()
triple_quoted = set()
for t in _all_string_prefixes():
for u in (t + '"', t + "'"):
single_quoted.add(u)
for u in (t + '"""', t + "'''"):
triple_quoted.add(u)
del t, u
tabsize = 8
class TokenError(Exception): pass
class Untokenizer:
def __init__(self):
self.tokens = []
self.prev_row = 1
self.prev_col = 0
self.prev_type = None
self.encoding = None
def add_whitespace(self, start):
row, col = start
if row < self.prev_row or row == self.prev_row and col < self.prev_col:
raise ValueError("start ({},{}) precedes previous end ({},{})"
.format(row, col, self.prev_row, self.prev_col))
row_offset = row - self.prev_row
if row_offset:
self.tokens.append("\\\n" * row_offset)
self.prev_col = 0
col_offset = col - self.prev_col
if col_offset:
self.tokens.append(" " * col_offset)
def escape_brackets(self, token):
characters = []
consume_until_next_bracket = False
for character in token:
if character == "}":
if consume_until_next_bracket:
consume_until_next_bracket = False
else:
characters.append(character)
if character == "{":
n_backslashes = sum(
1 for char in _itertools.takewhile(
"\\".__eq__,
characters[-2::-1]
)
)
if n_backslashes % 2 == 0:
characters.append(character)
else:
consume_until_next_bracket = True
characters.append(character)
return "".join(characters)
def untokenize(self, iterable):
it = iter(iterable)
indents = []
startline = False
for t in it:
if len(t) == 2:
self.compat(t, it)
break
tok_type, token, start, end, line = t
if tok_type == ENCODING:
self.encoding = token
continue
if tok_type == ENDMARKER:
break
if tok_type == INDENT:
indents.append(token)
continue
elif tok_type == DEDENT:
indents.pop()
self.prev_row, self.prev_col = end
continue
elif tok_type in (NEWLINE, NL):
startline = True
elif startline and indents:
indent = indents[-1]
if start[1] >= len(indent):
self.tokens.append(indent)
self.prev_col = len(indent)
startline = False
elif tok_type == FSTRING_MIDDLE:
if '{' in token or '}' in token:
token = self.escape_brackets(token)
last_line = token.splitlines()[-1]
end_line, end_col = end
extra_chars = last_line.count("{{") + last_line.count("}}")
end = (end_line, end_col + extra_chars)
elif tok_type in (STRING, FSTRING_START) and self.prev_type in (STRING, FSTRING_END):
self.tokens.append(" ")
self.add_whitespace(start)
self.tokens.append(token)
self.prev_row, self.prev_col = end
if tok_type in (NEWLINE, NL):
self.prev_row += 1
self.prev_col = 0
self.prev_type = tok_type
return "".join(self.tokens)
def compat(self, token, iterable):
indents = []
toks_append = self.tokens.append
startline = token[0] in (NEWLINE, NL)
prevstring = False
in_fstring = 0
for tok in _itertools.chain([token], iterable):
toknum, tokval = tok[:2]
if toknum == ENCODING:
self.encoding = tokval
continue
if toknum in (NAME, NUMBER):
tokval += ' '
# Insert a space between two consecutive strings
if toknum == STRING:
if prevstring:
tokval = ' ' + tokval
prevstring = True
else:
prevstring = False
if toknum == FSTRING_START:
in_fstring += 1
elif toknum == FSTRING_END:
in_fstring -= 1
if toknum == INDENT:
indents.append(tokval)
continue
elif toknum == DEDENT:
indents.pop()
continue
elif toknum in (NEWLINE, NL):
startline = True
elif startline and indents:
toks_append(indents[-1])
startline = False
elif toknum == FSTRING_MIDDLE:
tokval = self.escape_brackets(tokval)
# Insert a space between two consecutive brackets if we are in an f-string
if tokval in {"{", "}"} and self.tokens and self.tokens[-1] == tokval and in_fstring:
tokval = ' ' + tokval
# Insert a space between two consecutive f-strings
if toknum in (STRING, FSTRING_START) and self.prev_type in (STRING, FSTRING_END):
self.tokens.append(" ")
toks_append(tokval)
self.prev_type = toknum
def untokenize(iterable):
"""Transform tokens back into Python source code.
It returns a bytes object, encoded using the ENCODING
token, which is the first token sequence output by tokenize.
Each element returned by the iterable must be a token sequence
with at least two elements, a token number and token value. If
only two tokens are passed, the resulting output is poor.
Round-trip invariant for full input:
Untokenized source will match input source exactly
Round-trip invariant for limited input:
# Output bytes will tokenize back to the input
t1 = [tok[:2] for tok in tokenize(f.readline)]
newcode = untokenize(t1)
readline = BytesIO(newcode).readline
t2 = [tok[:2] for tok in tokenize(readline)]
assert t1 == t2
"""
ut = Untokenizer()
out = ut.untokenize(iterable)
if ut.encoding is not None:
out = out.encode(ut.encoding)
return out
def _get_normal_name(orig_enc):
"""Imitates get_normal_name in Parser/tokenizer/helpers.c."""
# Only care about the first 12 characters.
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-")):
return "iso-8859-1"
return orig_enc
def detect_encoding(readline):
"""
The detect_encoding() function is used to detect the encoding that should
be used to decode a Python source file. It requires one argument, readline,
in the same way as the tokenize() generator.
It will call readline a maximum of twice, and return the encoding used
(as a string) and a list of any lines (left as bytes) it has read in.
It detects the encoding from the presence of a utf-8 bom or an encoding
cookie as specified in pep-0263. If both a bom and a cookie are present,
but disagree, a SyntaxError will be raised. If the encoding cookie is an
invalid charset, raise a SyntaxError. Note that if a utf-8 bom is found,
'utf-8-sig' is returned.
If no encoding is specified, then the default of 'utf-8' will be returned.
"""
try:
filename = readline.__self__.name
except AttributeError:
filename = None
bom_found = False
encoding = None
default = 'utf-8'
def read_or_stop():
try:
return readline()
except StopIteration:
return b''
def find_cookie(line):
try:
# Decode as UTF-8. Either the line is an encoding declaration,
# in which case it should be pure ASCII, or it must be UTF-8
# per default encoding.
line_string = line.decode('utf-8')
except UnicodeDecodeError:
msg = "invalid or missing encoding declaration"
if filename is not None:
msg = '{} for {!r}'.format(msg, filename)
raise SyntaxError(msg)
match = cookie_re.match(line_string)
if not match:
return None
encoding = _get_normal_name(match.group(1))
try:
codec = lookup(encoding)
except LookupError:
# This behaviour mimics the Python interpreter
if filename is None:
msg = "unknown encoding: " + encoding
else:
msg = "unknown encoding for {!r}: {}".format(filename,
encoding)
raise SyntaxError(msg)
if bom_found:
if encoding != 'utf-8':
# This behaviour mimics the Python interpreter
if filename is None:
msg = 'encoding problem: utf-8'
else:
msg = 'encoding problem for {!r}: utf-8'.format(filename)
raise SyntaxError(msg)
encoding += '-sig'
return encoding
first = read_or_stop()
if first.startswith(BOM_UTF8):
bom_found = True
first = first[3:]
default = 'utf-8-sig'
if not first:
return default, []
encoding = find_cookie(first)
if encoding:
return encoding, [first]
if not blank_re.match(first):
return default, [first]
second = read_or_stop()
if not second:
return default, [first]
encoding = find_cookie(second)
if encoding:
return encoding, [first, second]
return default, [first, second]
def open(filename):
"""Open a file in read only mode using the encoding detected by
detect_encoding().
"""
buffer = _builtin_open(filename, 'rb')
try:
encoding, lines = detect_encoding(buffer.readline)
buffer.seek(0)
text = TextIOWrapper(buffer, encoding, line_buffering=True)
text.mode = 'r'
return text
except:
buffer.close()
raise
def tokenize(readline):
"""
The tokenize() generator requires one argument, readline, which
must be a callable object which provides the same interface as the
readline() method of built-in file objects. Each call to the function
should return one line of input as bytes. Alternatively, readline
can be a callable function terminating with StopIteration:
readline = open(myfile, 'rb').__next__ # Example of alternate readline
The generator produces 5-tuples with these members: the token type; the
token string; a 2-tuple (srow, scol) of ints specifying the row and
column where the token begins in the source; a 2-tuple (erow, ecol) of
ints specifying the row and column where the token ends in the source;
and the line on which the token was found. The line passed is the
physical line.
The first token sequence will always be an ENCODING token
which tells you which encoding was used to decode the bytes stream.
"""
encoding, consumed = detect_encoding(readline)
rl_gen = _itertools.chain(consumed, iter(readline, b""))
if encoding is not None:
if encoding == "utf-8-sig":
# BOM will already have been stripped.
encoding = "utf-8"
yield TokenInfo(ENCODING, encoding, (0, 0), (0, 0), '')
yield from _generate_tokens_from_c_tokenizer(rl_gen.__next__, encoding, extra_tokens=True)
def generate_tokens(readline):
"""Tokenize a source reading Python code as unicode strings.
This has the same API as tokenize(), except that it expects the *readline*
callable to return str objects instead of bytes.
"""
return _generate_tokens_from_c_tokenizer(readline, extra_tokens=True)
def main():
import argparse
# Helper error handling routines
def perror(message):
sys.stderr.write(message)
sys.stderr.write('\n')
def error(message, filename=None, location=None):
if location:
args = (filename,) + location + (message,)
perror("%s:%d:%d: error: %s" % args)
elif filename:
perror("%s: error: %s" % (filename, message))
else:
perror("error: %s" % message)
sys.exit(1)
# Parse the arguments and options
parser = argparse.ArgumentParser(prog='python -m tokenize')
parser.add_argument(dest='filename', nargs='?',
metavar='filename.py',
help='the file to tokenize; defaults to stdin')
parser.add_argument('-e', '--exact', dest='exact', action='store_true',
help='display token names using the exact type')
args = parser.parse_args()
try:
# Tokenize the input
if args.filename:
filename = args.filename
with _builtin_open(filename, 'rb') as f:
tokens = list(tokenize(f.readline))
else:
filename = "<stdin>"
tokens = _generate_tokens_from_c_tokenizer(
sys.stdin.readline, extra_tokens=True)
# Output the tokenization
for token in tokens:
token_type = token.type
if args.exact:
token_type = token.exact_type
token_range = "%d,%d-%d,%d:" % (token.start + token.end)
print("%-20s%-15s%-15r" %
(token_range, tok_name[token_type], token.string))
except IndentationError as err:
line, column = err.args[1][1:3]
error(err.args[0], filename, (line, column))
except TokenError as err:
line, column = err.args[1]
error(err.args[0], filename, (line, column))
except SyntaxError as err:
error(err, filename)
except OSError as err:
error(err)
except KeyboardInterrupt:
print("interrupted\n")
except Exception as err:
perror("unexpected error: %s" % err)
raise
def _transform_msg(msg):
"""Transform error messages from the C tokenizer into the Python tokenize
The C tokenizer is more picky than the Python one, so we need to massage
the error messages a bit for backwards compatibility.
"""
if "unterminated triple-quoted string literal" in msg:
return "EOF in multi-line string"
return msg
def _generate_tokens_from_c_tokenizer(source, encoding=None, extra_tokens=False):
"""Tokenize a source reading Python code as unicode strings using the internal C tokenizer"""
if encoding is None:
it = _tokenize.TokenizerIter(source, extra_tokens=extra_tokens)
else:
it = _tokenize.TokenizerIter(source, encoding=encoding, extra_tokens=extra_tokens)
try:
for info in it:
yield TokenInfo._make(info)
except SyntaxError as e:
if type(e) != SyntaxError:
raise e from None
msg = _transform_msg(e.msg)
raise TokenError(msg, (e.lineno, e.offset)) from None
if __name__ == "__main__":
main()
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