cpython/Lib/tokenize.py at 3.14 · python/cpython · GitHub

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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(br'^[ \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', 't', 'br', 'fr', 'tr']

# 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.prev_line = ""

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))

self.add_backslash_continuation(start)

col_offset = col - self.prev_col

if col_offset:

self.tokens.append(" " * col_offset)

def add_backslash_continuation(self, start):

"""Add backslash continuation characters if the row has increased

without encountering a newline token.

This also inserts the correct amount of whitespace before the backslash.

"""

row = start[0]

row_offset = row - self.prev_row

if row_offset == 0:

return

newline = '\r\n' if self.prev_line.endswith('\r\n') else '\n'

line = self.prev_line.rstrip('\\\r\n')

ws = ''.join(_itertools.takewhile(str.isspace, reversed(line)))

self.tokens.append(ws + f"\\{newline}" * row_offset)

self.prev_col = 0

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 or characters[-1] != "N":

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 in {FSTRING_MIDDLE, TSTRING_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)

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

self.prev_line = line

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_or_tstring = 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 in {FSTRING_START, TSTRING_START}:

in_fstring_or_tstring += 1

elif toknum in {FSTRING_END, TSTRING_END}:

in_fstring_or_tstring -= 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 in {FSTRING_MIDDLE, TSTRING_MIDDLE}:

tokval = self.escape_brackets(tokval)

# Insert a space between two consecutive brackets if we are in an f-string or t-string

if tokval in {"{", "}"} and self.tokens and self.tokens[-1] == tokval and in_fstring_or_tstring:

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.

The result is guaranteed to tokenize back to match the input so

that the conversion is lossless and round-trips are assured.

The guarantee applies only to the token type and token string as

the spacing between tokens (column positions) may change.

"""

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 check(line, encoding):

# Check if the line matches the encoding.

if 0 in line:

raise SyntaxError("source code cannot contain null bytes")

try:

line.decode(encoding)

except UnicodeDecodeError:

msg = "invalid or missing encoding declaration"

if filename is not None:

msg = '{} for {!r}'.format(msg, filename)

raise SyntaxError(msg)

def find_cookie(line):

match = cookie_re.match(line)

if not match:

return None

encoding = _get_normal_name(match.group(1).decode())

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:

check(first, encoding)

return encoding, [first]

if not blank_re.match(first):

check(first, default)

return default, [first]

second = read_or_stop()

if not second:

check(first, default)

return default, [first]

encoding = find_cookie(second)

if encoding:

check(first + second, encoding)

return encoding, [first, second]

check(first + second, default)

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(args=None):

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(color=True)

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(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()

cpython/Lib/tokenize.py at 3.14 · python/cpython · GitHub

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