cpython/Lib/tokenize.py
Marta Gómez Macías 6715f91edc
gh-102856: Python tokenizer implementation for PEP 701 (#104323)
This commit replaces the Python implementation of the tokenize module with an implementation
that reuses the real C tokenizer via a private extension module. The tokenize module now implements
a compatibility layer that transforms tokens from the C tokenizer into Python tokenize tokens for backward
compatibility.

As the C tokenizer does not emit some tokens that the Python tokenizer provides (such as comments and non-semantic newlines), a new special mode has been added to the C tokenizer mode that currently is only used via
the extension module that exposes it to the Python layer. This new mode forces the C tokenizer to emit these new extra tokens and add the appropriate metadata that is needed to match the old Python implementation.

Co-authored-by: Pablo Galindo <pablogsal@gmail.com>
2023-05-21 01:03:02 +01:00

458 lines
16 KiB
Python

"""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
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"]
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
class TokenError(Exception): pass
class StopTokenizing(Exception): pass
class Untokenizer:
def __init__(self):
self.tokens = []
self.prev_row = 1
self.prev_col = 0
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 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:
end_line, end_col = end
end = (end_line, end_col + token.count('{') + token.count('}'))
token = re.sub('{', '{{', token)
token = re.sub('}', '}}', token)
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
return "".join(self.tokens)
def compat(self, token, iterable):
indents = []
toks_append = self.tokens.append
startline = token[0] in (NEWLINE, NL)
prevstring = False
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 == 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:
if '{' in tokval or '}' in tokval:
tokval = re.sub('{', '{{', tokval)
tokval = re.sub('}', '}}', tokval)
toks_append(tokval)
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 tokenizer.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 _tokenize(rl_gen, encoding)
def _tokenize(rl_gen, encoding):
source = b"".join(rl_gen).decode(encoding)
token = None
for token in _generate_tokens_from_c_tokenizer(source, extra_tokens=True):
# TODO: Marta -> limpiar esto
if 6 < token.type <= 54:
token = token._replace(type=OP)
if token.type in {ASYNC, AWAIT}:
token = token._replace(type=NAME)
if token.type == NEWLINE:
l_start, c_start = token.start
l_end, c_end = token.end
token = token._replace(string='\n', start=(l_start, c_start), end=(l_end, c_end+1))
yield token
if token is not None:
last_line, _ = token.start
yield TokenInfo(ENDMARKER, '', (last_line + 1, 0), (last_line + 1, 0), '')
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.
"""
def _gen():
while True:
try:
line = readline()
except StopIteration:
return
if not line:
return
yield line.encode()
return _tokenize(_gen(), 'utf-8')
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 = _tokenize(
(x.encode('utf-8') for x in iter(sys.stdin.readline, "")
), "utf-8")
# 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 _generate_tokens_from_c_tokenizer(source, extra_tokens=False):
"""Tokenize a source reading Python code as unicode strings using the internal C tokenizer"""
import _tokenize as c_tokenizer
for info in c_tokenizer.TokenizerIter(source, extra_tokens=extra_tokens):
tok, type, lineno, end_lineno, col_off, end_col_off, line = info
yield TokenInfo(type, tok, (lineno, col_off), (end_lineno, end_col_off), line)
if __name__ == "__main__":
main()