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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
from io import TextIOWrapper
from itertools import chain
import re
import sys
from token import *
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__ + ["COMMENT", "tokenize", "detect_encoding",
"NL", "untokenize", "ENCODING", "TokenInfo"]
del token
COMMENT = N_TOKENS
tok_name[COMMENT] = 'COMMENT'
NL = N_TOKENS + 1
tok_name[NL] = 'NL'
ENCODING = N_TOKENS + 2
tok_name[ENCODING] = 'ENCODING'
N_TOKENS += 3
EXACT_TOKEN_TYPES = {
'(': LPAR,
')': RPAR,
'[': LSQB,
']': RSQB,
':': COLON,
',': COMMA,
';': SEMI,
'+': PLUS,
'-': MINUS,
'*': STAR,
'/': SLASH,
'|': VBAR,
'&': AMPER,
'<': LESS,
'>': GREATER,
'=': EQUAL,
'.': DOT,
'%': PERCENT,
'{': LBRACE,
'}': RBRACE,
'==': EQEQUAL,
'!=': NOTEQUAL,
'<=': LESSEQUAL,
'>=': GREATEREQUAL,
'~': TILDE,
'^': CIRCUMFLEX,
'<<': LEFTSHIFT,
'>>': RIGHTSHIFT,
'**': DOUBLESTAR,
'+=': PLUSEQUAL,
'-=': MINEQUAL,
'*=': STAREQUAL,
'/=': SLASHEQUAL,
'%=': PERCENTEQUAL,
'&=': AMPEREQUAL,
'|=': VBAREQUAL,
'^=': CIRCUMFLEXEQUAL,
'<<=': LEFTSHIFTEQUAL,
'>>=': RIGHTSHIFTEQUAL,
'**=': DOUBLESTAREQUAL,
'//': DOUBLESLASH,
'//=': DOUBLESLASHEQUAL,
'@': AT,
'@=': ATEQUAL,
}
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+|[1-9][0-9]*)'
Intnumber = group(Hexnumber, Binnumber, Octnumber, Decnumber)
Exponent = r'[eE][-+]?[0-9]+'
Pointfloat = group(r'[0-9]+\.[0-9]*', r'\.[0-9]+') + maybe(Exponent)
Expfloat = r'[0-9]+' + Exponent
Floatnumber = group(Pointfloat, Expfloat)
Imagnumber = group(r'[0-9]+[jJ]', Floatnumber + r'[jJ]')
Number = group(Imagnumber, Floatnumber, Intnumber)
StringPrefix = r'(?:[bB][rR]?|[rR][bB]?|[uU])?'
# 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"\\]*)*"')
# 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"~")
Bracket = '[][(){}]'
Special = group(r'\r?\n', r'\.\.\.', r'[:;.,@]')
Funny = group(Operator, Bracket, 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)
def _compile(expr):
return re.compile(expr, re.UNICODE)
endpats = {"'": Single, '"': Double,
"'''": Single3, '"""': Double3,
"r'''": Single3, 'r"""': Double3,
"b'''": Single3, 'b"""': Double3,
"R'''": Single3, 'R"""': Double3,
"B'''": Single3, 'B"""': Double3,
"br'''": Single3, 'br"""': Double3,
"bR'''": Single3, 'bR"""': Double3,
"Br'''": Single3, 'Br"""': Double3,
"BR'''": Single3, 'BR"""': Double3,
"rb'''": Single3, 'rb"""': Double3,
"Rb'''": Single3, 'Rb"""': Double3,
"rB'''": Single3, 'rB"""': Double3,
"RB'''": Single3, 'RB"""': Double3,
"u'''": Single3, 'u"""': Double3,
"U'''": Single3, 'U"""': Double3,
'r': None, 'R': None, 'b': None, 'B': None,
'u': None, 'U': None}
triple_quoted = {}
for t in ("'''", '"""',
"r'''", 'r"""', "R'''", 'R"""',
"b'''", 'b"""', "B'''", 'B"""',
"br'''", 'br"""', "Br'''", 'Br"""',
"bR'''", 'bR"""', "BR'''", 'BR"""',
"rb'''", 'rb"""', "rB'''", 'rB"""',
"Rb'''", 'Rb"""', "RB'''", 'RB"""',
"u'''", 'u"""', "U'''", 'U"""',
):
triple_quoted[t] = t
single_quoted = {}
for t in ("'", '"',
"r'", 'r"', "R'", 'R"',
"b'", 'b"', "B'", 'B"',
"br'", 'br"', "Br'", 'Br"',
"bR'", 'bR"', "BR'", 'BR"' ,
"rb'", 'rb"', "rB'", 'rB"',
"Rb'", 'Rb"', "RB'", 'RB"' ,
"u'", 'u"', "U'", 'U"',
):
single_quoted[t] = t
tabsize = 8
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)
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
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 chain([token], iterable):
toknum, tokval = tok[:2]
if toknum == ENCODING:
self.encoding = tokval
continue
if toknum in (NAME, NUMBER, ASYNC, AWAIT):
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
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 intput:
# Output bytes will tokenize the 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 argment, 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. Alternately, 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
logical line; continuation lines are included.
The first token sequence will always be an ENCODING token
which tells you which encoding was used to decode the bytes stream.
"""
# This import is here to avoid problems when the itertools module is not
# built yet and tokenize is imported.
from itertools import chain, repeat
encoding, consumed = detect_encoding(readline)
rl_gen = iter(readline, b"")
empty = repeat(b"")
return _tokenize(chain(consumed, rl_gen, empty).__next__, encoding)
def _tokenize(readline, encoding):
lnum = parenlev = continued = 0
numchars = '0123456789'
contstr, needcont = '', 0
contline = None
indents = [0]
# 'stashed' and 'ctx' are used for async/await parsing
stashed = None
ctx = [('sync', 0)]
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), '')
while True: # loop over lines in stream
try:
line = readline()
except StopIteration:
line = b''
if encoding is not None:
line = line.decode(encoding)
lnum += 1
pos, max = 0, len(line)
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)
yield TokenInfo(STRING, contstr + line[:end],
strstart, (lnum, end), contline + line)
contstr, needcont = '', 0
contline = None
elif needcont and line[-2:] != '\\\n' and line[-3:] != '\\\r\n':
yield TokenInfo(ERRORTOKEN, contstr + line,
strstart, (lnum, len(line)), contline)
contstr = ''
contline = None
continue
else:
contstr = contstr + line
contline = contline + line
continue
elif parenlev == 0 and not continued: # new statement
if not line: break
column = 0
while pos < max: # measure leading whitespace
if line[pos] == ' ':
column += 1
elif line[pos] == '\t':
column = (column//tabsize + 1)*tabsize
elif line[pos] == '\f':
column = 0
else:
break
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 TokenInfo(COMMENT, comment_token,
(lnum, pos), (lnum, pos + len(comment_token)), line)
yield TokenInfo(NL, line[nl_pos:],
(lnum, nl_pos), (lnum, len(line)), line)
else:
yield TokenInfo((NL, COMMENT)[line[pos] == '#'], line[pos:],
(lnum, pos), (lnum, len(line)), line)
continue
if column > indents[-1]: # count indents or dedents
indents.append(column)
yield TokenInfo(INDENT, line[:pos], (lnum, 0), (lnum, pos), line)
while column < indents[-1]:
if column not in indents:
raise IndentationError(
"unindent does not match any outer indentation level",
("<tokenize>", lnum, pos, line))
indents = indents[:-1]
cur_indent = indents[-1]
while len(ctx) > 1 and ctx[-1][1] >= cur_indent:
ctx.pop()
yield TokenInfo(DEDENT, '', (lnum, pos), (lnum, pos), line)
else: # continued statement
if not line:
raise TokenError("EOF in multi-line statement", (lnum, 0))
continued = 0
while pos < max:
pseudomatch = _compile(PseudoToken).match(line, pos)
if pseudomatch: # scan for tokens
start, end = pseudomatch.span(1)
spos, epos, pos = (lnum, start), (lnum, end), end
if start == end:
continue
token, initial = line[start:end], line[start]
if (initial in numchars or # ordinary number
(initial == '.' and token != '.' and token != '...')):
yield TokenInfo(NUMBER, token, spos, epos, line)
elif initial in '\r\n':
if stashed:
yield stashed
stashed = None
yield TokenInfo(NL if parenlev > 0 else NEWLINE,
token, spos, epos, line)
elif initial == '#':
assert not token.endswith("\n")
if stashed:
yield stashed
stashed = None
yield TokenInfo(COMMENT, token, spos, epos, line)
elif token in triple_quoted:
endprog = _compile(endpats[token])
endmatch = endprog.match(line, pos)
if endmatch: # all on one line
pos = endmatch.end(0)
token = line[start:pos]
yield TokenInfo(STRING, token, spos, (lnum, pos), line)
else:
strstart = (lnum, start) # multiple lines
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
strstart = (lnum, start)
endprog = _compile(endpats[initial] or
endpats[token[1]] or
endpats[token[2]])
contstr, needcont = line[start:], 1
contline = line
break
else: # ordinary string
yield TokenInfo(STRING, token, spos, epos, line)
elif initial.isidentifier(): # ordinary name
if token in ('async', 'await'):
if ctx[-1][0] == 'async' and ctx[-1][1] < indents[-1]:
yield TokenInfo(
ASYNC if token == 'async' else AWAIT,
token, spos, epos, line)
continue
tok = TokenInfo(NAME, token, spos, epos, line)
if token == 'async' and not stashed:
stashed = tok
continue
if token == 'def':
if (stashed
and stashed.type == NAME
and stashed.string == 'async'):
ctx.append(('async', indents[-1]))
yield TokenInfo(ASYNC, stashed.string,
stashed.start, stashed.end,
stashed.line)
stashed = None
else:
ctx.append(('sync', indents[-1]))
if stashed:
yield stashed
stashed = None
yield tok
elif initial == '\\': # continued stmt
continued = 1
else:
if initial in '([{':
parenlev += 1
elif initial in ')]}':
parenlev -= 1
if stashed:
yield stashed
stashed = None
yield TokenInfo(OP, token, spos, epos, line)
else:
yield TokenInfo(ERRORTOKEN, line[pos],
(lnum, pos), (lnum, pos+1), line)
pos += 1
if stashed:
yield stashed
stashed = None
for indent in indents[1:]: # pop remaining indent levels
yield TokenInfo(DEDENT, '', (lnum, 0), (lnum, 0), '')
yield TokenInfo(ENDMARKER, '', (lnum, 0), (lnum, 0), '')
# An undocumented, backwards compatible, API for all the places in the standard
# library that expect to be able to use tokenize with strings
def generate_tokens(readline):
return _tokenize(readline, None)
def main():
import argparse
# Helper error handling routines
def perror(message):
print(message, file=sys.stderr)
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(sys.stdin.readline, None)
# 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
if __name__ == "__main__":
main()
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