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#!/usr/bin/env python
# - Check Python source code formatting, according to PEP 8
# Copyright (C) 2006-2009 Johann C. Rocholl <>
# Copyright (C) 2009-2014 Florent Xicluna <>
# Copyright (C) 2014-2015 Ian Lee <>
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation files
# (the "Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the Software,
# and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
Check Python source code formatting, according to PEP 8.
For usage and a list of options, try this:
$ python -h
This program and its regression test suite live here:
Groups of errors and warnings:
E errors
W warnings
100 indentation
200 whitespace
300 blank lines
400 imports
500 line length
600 deprecation
700 statements
900 syntax error
from __future__ import with_statement
import os
import sys
import re
import time
import inspect
import keyword
import tokenize
from optparse import OptionParser
from fnmatch import fnmatch
from configparser import RawConfigParser
from io import TextIOWrapper
except ImportError:
from ConfigParser import RawConfigParser
__version__ = '1.6.3a0'
DEFAULT_EXCLUDE = '.svn,CVS,.bzr,.hg,.git,__pycache__,.tox'
DEFAULT_IGNORE = 'E121,E123,E126,E226,E24,E704'
if sys.platform == 'win32':
USER_CONFIG = os.path.expanduser(r'~\.pep8')
USER_CONFIG = os.path.join(
os.getenv('XDG_CONFIG_HOME') or os.path.expanduser('~/.config'),
except ImportError:
PROJECT_CONFIG = ('setup.cfg', 'tox.ini', '.pep8')
TESTSUITE_PATH = os.path.join(os.path.dirname(__file__), 'testsuite')
'default': '%(path)s:%(row)d:%(col)d: %(code)s %(text)s',
'pylint': '%(path)s:%(row)d: [%(code)s] %(text)s',
PyCF_ONLY_AST = 1024
SINGLETONS = frozenset(['False', 'None', 'True'])
KEYWORDS = frozenset(keyword.kwlist + ['print']) - SINGLETONS
UNARY_OPERATORS = frozenset(['>>', '**', '*', '+', '-'])
ARITHMETIC_OP = frozenset(['**', '*', '/', '//', '+', '-'])
WS_OPTIONAL_OPERATORS = ARITHMETIC_OP.union(['^', '&', '|', '<<', '>>', '%'])
'**=', '*=', '/=', '//=', '+=', '-=', '!=', '<>', '<', '>',
'%=', '^=', '&=', '|=', '==', '<=', '>=', '<<=', '>>=', '='])
WHITESPACE = frozenset(' \t')
NEWLINE = frozenset([tokenize.NL, tokenize.NEWLINE])
SKIP_TOKENS = NEWLINE.union([tokenize.INDENT, tokenize.DEDENT])
# ERRORTOKEN is triggered by backticks in Python 3
BENCHMARK_KEYS = ['directories', 'files', 'logical lines', 'physical lines']
INDENT_REGEX = re.compile(r'([ \t]*)')
RAISE_COMMA_REGEX = re.compile(r'raise\s+\w+\s*,')
RERAISE_COMMA_REGEX = re.compile(r'raise\s+\w+\s*,.*,\s*\w+\s*$')
ERRORCODE_REGEX = re.compile(r'\b[A-Z]\d{3}\b')
DOCSTRING_REGEX = re.compile(r'u?r?["\']')
EXTRANEOUS_WHITESPACE_REGEX = re.compile(r'[[({] | []}),;:]')
WHITESPACE_AFTER_COMMA_REGEX = re.compile(r'[,;:]\s*(?: |\t)')
COMPARE_SINGLETON_REGEX = re.compile(r'(\bNone|\bFalse|\bTrue)?\s*([=!]=)'
COMPARE_NEGATIVE_REGEX = re.compile(r'\b(not)\s+[^][)(}{ ]+\s+(in|is)\s')
COMPARE_TYPE_REGEX = re.compile(r'(?:[=!]=|is(?:\s+not)?)\s*type(?:s.\w+Type'
r'|\s*\(\s*([^)]*[^ )])\s*\))')
KEYWORD_REGEX = re.compile(r'(\s*)\b(?:%s)\b(\s*)' % r'|'.join(KEYWORDS))
OPERATOR_REGEX = re.compile(r'(?:[^,\s])(\s*)(?:[-+*/|!<=>%&^]+)(\s*)')
LAMBDA_REGEX = re.compile(r'\blambda\b')
HUNK_REGEX = re.compile(r'^@@ -\d+(?:,\d+)? \+(\d+)(?:,(\d+))? @@.*$')
# Work around Python < 2.6 behaviour, which does not generate NL after
# a comment which is on a line by itself.
COMMENT_WITH_NL = tokenize.generate_tokens(['#\n'].pop).send(None)[1] == '#\n'
# Plugins (check functions) for physical lines
def tabs_or_spaces(physical_line, indent_char):
r"""Never mix tabs and spaces.
The most popular way of indenting Python is with spaces only. The
second-most popular way is with tabs only. Code indented with a mixture
of tabs and spaces should be converted to using spaces exclusively. When
invoking the Python command line interpreter with the -t option, it issues
warnings about code that illegally mixes tabs and spaces. When using -tt
these warnings become errors. These options are highly recommended!
Okay: if a == 0:\n a = 1\n b = 1
E101: if a == 0:\n a = 1\n\tb = 1
indent = INDENT_REGEX.match(physical_line).group(1)
for offset, char in enumerate(indent):
if char != indent_char:
return offset, "E101 indentation contains mixed spaces and tabs"
def tabs_obsolete(physical_line):
r"""For new projects, spaces-only are strongly recommended over tabs.
Okay: if True:\n return
W191: if True:\n\treturn
indent = INDENT_REGEX.match(physical_line).group(1)
if '\t' in indent:
return indent.index('\t'), "W191 indentation contains tabs"
def trailing_whitespace(physical_line):
r"""Trailing whitespace is superfluous.
The warning returned varies on whether the line itself is blank, for easier
filtering for those who want to indent their blank lines.
Okay: spam(1)\n#
W291: spam(1) \n#
W293: class Foo(object):\n \n bang = 12
physical_line = physical_line.rstrip('\n') # chr(10), newline
physical_line = physical_line.rstrip('\r') # chr(13), carriage return
physical_line = physical_line.rstrip('\x0c') # chr(12), form feed, ^L
stripped = physical_line.rstrip(' \t\v')
if physical_line != stripped:
if stripped:
return len(stripped), "W291 trailing whitespace"
return 0, "W293 blank line contains whitespace"
def trailing_blank_lines(physical_line, lines, line_number, total_lines):
r"""Trailing blank lines are superfluous.
Okay: spam(1)
W391: spam(1)\n
However the last line should end with a new line (warning W292).
if line_number == total_lines:
stripped_last_line = physical_line.rstrip()
if not stripped_last_line:
return 0, "W391 blank line at end of file"
if stripped_last_line == physical_line:
return len(physical_line), "W292 no newline at end of file"
def maximum_line_length(physical_line, max_line_length, multiline):
r"""Limit all lines to a maximum of 79 characters.
There are still many devices around that are limited to 80 character
lines; plus, limiting windows to 80 characters makes it possible to have
several windows side-by-side. The default wrapping on such devices looks
ugly. Therefore, please limit all lines to a maximum of 79 characters.
For flowing long blocks of text (docstrings or comments), limiting the
length to 72 characters is recommended.
Reports error E501.
line = physical_line.rstrip()
length = len(line)
if length > max_line_length and not noqa(line):
# Special case for long URLs in multi-line docstrings or comments,
# but still report the error when the 72 first chars are whitespaces.
chunks = line.split()
if ((len(chunks) == 1 and multiline) or
(len(chunks) == 2 and chunks[0] == '#')) and \
len(line) - len(chunks[-1]) < max_line_length - 7:
if hasattr(line, 'decode'): # Python 2
# The line could contain multi-byte characters
length = len(line.decode('utf-8'))
except UnicodeError:
if length > max_line_length:
return (max_line_length, "E501 line too long "
"(%d > %d characters)" % (length, max_line_length))
# Plugins (check functions) for logical lines
def blank_lines(logical_line, blank_lines, indent_level, line_number,
blank_before, previous_logical, previous_indent_level):
r"""Separate top-level function and class definitions with two blank lines.
Method definitions inside a class are separated by a single blank line.
Extra blank lines may be used (sparingly) to separate groups of related
functions. Blank lines may be omitted between a bunch of related
one-liners (e.g. a set of dummy implementations).
Use blank lines in functions, sparingly, to indicate logical sections.
Okay: def a():\n pass\n\n\ndef b():\n pass
Okay: def a():\n pass\n\n\n# Foo\n# Bar\n\ndef b():\n pass
E301: class Foo:\n b = 0\n def bar():\n pass
E302: def a():\n pass\n\ndef b(n):\n pass
E303: def a():\n pass\n\n\n\ndef b(n):\n pass
E303: def a():\n\n\n\n pass
E304: @decorator\n\ndef a():\n pass
if line_number < 3 and not previous_logical:
return # Don't expect blank lines before the first line
if previous_logical.startswith('@'):
if blank_lines:
yield 0, "E304 blank lines found after function decorator"
elif blank_lines > 2 or (indent_level and blank_lines == 2):
yield 0, "E303 too many blank lines (%d)" % blank_lines
elif logical_line.startswith(('def ', 'class ', '@')):
if indent_level:
if not (blank_before or previous_indent_level < indent_level or
yield 0, "E301 expected 1 blank line, found 0"
elif blank_before != 2:
yield 0, "E302 expected 2 blank lines, found %d" % blank_before
def extraneous_whitespace(logical_line):
r"""Avoid extraneous whitespace.
Avoid extraneous whitespace in these situations:
- Immediately inside parentheses, brackets or braces.
- Immediately before a comma, semicolon, or colon.
Okay: spam(ham[1], {eggs: 2})
E201: spam( ham[1], {eggs: 2})
E201: spam(ham[ 1], {eggs: 2})
E201: spam(ham[1], { eggs: 2})
E202: spam(ham[1], {eggs: 2} )
E202: spam(ham[1 ], {eggs: 2})
E202: spam(ham[1], {eggs: 2 })
E203: if x == 4: print x, y; x, y = y , x
E203: if x == 4: print x, y ; x, y = y, x
E203: if x == 4 : print x, y; x, y = y, x
line = logical_line
for match in EXTRANEOUS_WHITESPACE_REGEX.finditer(line):
text =
char = text.strip()
found = match.start()
if text == char + ' ':
# assert char in '([{'
yield found + 1, "E201 whitespace after '%s'" % char
elif line[found - 1] != ',':
code = ('E202' if char in '}])' else 'E203') # if char in ',;:'
yield found, "%s whitespace before '%s'" % (code, char)
def whitespace_around_keywords(logical_line):
r"""Avoid extraneous whitespace around keywords.
Okay: True and False
E271: True and False
E272: True and False
E273: True and\tFalse
E274: True\tand False
for match in KEYWORD_REGEX.finditer(logical_line):
before, after = match.groups()
if '\t' in before:
yield match.start(1), "E274 tab before keyword"
elif len(before) > 1:
yield match.start(1), "E272 multiple spaces before keyword"
if '\t' in after:
yield match.start(2), "E273 tab after keyword"
elif len(after) > 1:
yield match.start(2), "E271 multiple spaces after keyword"
def missing_whitespace(logical_line):
r"""Each comma, semicolon or colon should be followed by whitespace.
Okay: [a, b]
Okay: (3,)
Okay: a[1:4]
Okay: a[:4]
Okay: a[1:]
Okay: a[1:4:2]
E231: ['a','b']
E231: foo(bar,baz)
E231: [{'a':'b'}]
line = logical_line
for index in range(len(line) - 1):
char = line[index]
if char in ',;:' and line[index + 1] not in WHITESPACE:
before = line[:index]
if char == ':' and before.count('[') > before.count(']') and \
before.rfind('{') < before.rfind('['):
continue # Slice syntax, no space required
if char == ',' and line[index + 1] == ')':
continue # Allow tuple with only one element: (3,)
yield index, "E231 missing whitespace after '%s'" % char
def indentation(logical_line, previous_logical, indent_char,
indent_level, previous_indent_level):
r"""Use 4 spaces per indentation level.
For really old code that you don't want to mess up, you can continue to
use 8-space tabs.
Okay: a = 1
Okay: if a == 0:\n a = 1
E111: a = 1
E114: # a = 1
Okay: for item in items:\n pass
E112: for item in items:\npass
E115: for item in items:\n# Hi\n pass
Okay: a = 1\nb = 2
E113: a = 1\n b = 2
E116: a = 1\n # b = 2
c = 0 if logical_line else 3
tmpl = "E11%d %s" if logical_line else "E11%d %s (comment)"
if indent_level % 4:
yield 0, tmpl % (1 + c, "indentation is not a multiple of four")
indent_expect = previous_logical.endswith(':')
if indent_expect and indent_level <= previous_indent_level:
yield 0, tmpl % (2 + c, "expected an indented block")
elif not indent_expect and indent_level > previous_indent_level:
yield 0, tmpl % (3 + c, "unexpected indentation")
def continued_indentation(logical_line, tokens, indent_level, hang_closing,
indent_char, noqa, verbose):
r"""Continuation lines indentation.
Continuation lines should align wrapped elements either vertically
using Python's implicit line joining inside parentheses, brackets
and braces, or using a hanging indent.
When using a hanging indent these considerations should be applied:
- there should be no arguments on the first line, and
- further indentation should be used to clearly distinguish itself as a
continuation line.
Okay: a = (\n)
E123: a = (\n )
Okay: a = (\n 42)
E121: a = (\n 42)
E122: a = (\n42)
E123: a = (\n 42\n )
E124: a = (24,\n 42\n)
E125: if (\n b):\n pass
E126: a = (\n 42)
E127: a = (24,\n 42)
E128: a = (24,\n 42)
E129: if (a or\n b):\n pass
E131: a = (\n 42\n 24)
first_row = tokens[0][2][0]
nrows = 1 + tokens[-1][2][0] - first_row
if noqa or nrows == 1:
# indent_next tells us whether the next block is indented; assuming
# that it is indented by 4 spaces, then we should not allow 4-space
# indents on the final continuation line; in turn, some other
# indents are allowed to have an extra 4 spaces.
indent_next = logical_line.endswith(':')
row = depth = 0
valid_hangs = (4,) if indent_char != '\t' else (4, 8)
# remember how many brackets were opened on each line
parens = [0] * nrows
# relative indents of physical lines
rel_indent = [0] * nrows
# for each depth, collect a list of opening rows
open_rows = [[0]]
# for each depth, memorize the hanging indentation
hangs = [None]
# visual indents
indent_chances = {}
last_indent = tokens[0][2]
visual_indent = None
last_token_multiline = False
# for each depth, memorize the visual indent column
indent = [last_indent[1]]
if verbose >= 3:
print(">>> " + tokens[0][4].rstrip())
for token_type, text, start, end, line in tokens:
newline = row < start[0] - first_row
if newline:
row = start[0] - first_row
newline = not last_token_multiline and token_type not in NEWLINE
if newline:
# this is the beginning of a continuation line.
last_indent = start
if verbose >= 3:
print("... " + line.rstrip())
# record the initial indent.
rel_indent[row] = expand_indent(line) - indent_level
# identify closing bracket
close_bracket = (token_type == tokenize.OP and text in ']})')
# is the indent relative to an opening bracket line?
for open_row in reversed(open_rows[depth]):
hang = rel_indent[row] - rel_indent[open_row]
hanging_indent = hang in valid_hangs
if hanging_indent:
if hangs[depth]:
hanging_indent = (hang == hangs[depth])
# is there any chance of visual indent?
visual_indent = (not close_bracket and hang > 0 and
if close_bracket and indent[depth]:
# closing bracket for visual indent
if start[1] != indent[depth]:
yield (start, "E124 closing bracket does not match "
"visual indentation")
elif close_bracket and not hang:
# closing bracket matches indentation of opening bracket's line
if hang_closing:
yield start, "E133 closing bracket is missing indentation"
elif indent[depth] and start[1] < indent[depth]:
if visual_indent is not True:
# visual indent is broken
yield (start, "E128 continuation line "
"under-indented for visual indent")
elif hanging_indent or (indent_next and rel_indent[row] == 8):
# hanging indent is verified
if close_bracket and not hang_closing:
yield (start, "E123 closing bracket does not match "
"indentation of opening bracket's line")
hangs[depth] = hang
elif visual_indent is True:
# visual indent is verified
indent[depth] = start[1]
elif visual_indent in (text, str):
# ignore token lined up with matching one from a previous line
# indent is broken
if hang <= 0:
error = "E122", "missing indentation or outdented"
elif indent[depth]:
error = "E127", "over-indented for visual indent"
elif not close_bracket and hangs[depth]:
error = "E131", "unaligned for hanging indent"
hangs[depth] = hang
if hang > 4:
error = "E126", "over-indented for hanging indent"
error = "E121", "under-indented for hanging indent"
yield start, "%s continuation line %s" % error
# look for visual indenting
if (parens[row] and
token_type not in (tokenize.NL, tokenize.COMMENT) and
not indent[depth]):
indent[depth] = start[1]
indent_chances[start[1]] = True
if verbose >= 4:
print("bracket depth %s indent to %s" % (depth, start[1]))
# deal with implicit string concatenation
elif (token_type in (tokenize.STRING, tokenize.COMMENT) or
text in ('u', 'ur', 'b', 'br')):
indent_chances[start[1]] = str
# special case for the "if" statement because len("if (") == 4
elif not indent_chances and not row and not depth and text == 'if':
indent_chances[end[1] + 1] = True
elif text == ':' and line[end[1]:].isspace():
# keep track of bracket depth
if token_type == tokenize.OP:
if text in '([{':
depth += 1
if len(open_rows) == depth:
parens[row] += 1
if verbose >= 4:
print("bracket depth %s seen, col %s, visual min = %s" %
(depth, start[1], indent[depth]))
elif text in ')]}' and depth > 0:
# parent indents should not be more than this one
prev_indent = indent.pop() or last_indent[1]
for d in range(depth):
if indent[d] > prev_indent:
indent[d] = 0
for ind in list(indent_chances):
if ind >= prev_indent:
del indent_chances[ind]
del open_rows[depth + 1:]
depth -= 1
if depth:
indent_chances[indent[depth]] = True
for idx in range(row, -1, -1):
if parens[idx]:
parens[idx] -= 1
assert len(indent) == depth + 1
if start[1] not in indent_chances:
# allow to line up tokens
indent_chances[start[1]] = text
last_token_multiline = (start[0] != end[0])
if last_token_multiline:
rel_indent[end[0] - first_row] = rel_indent[row]
if indent_next and expand_indent(line) == indent_level + 4:
pos = (start[0], indent[0] + 4)
if visual_indent:
code = "E129 visually indented line"
code = "E125 continuation line"
yield pos, "%s with same indent as next logical line" % code
def whitespace_before_parameters(logical_line, tokens):
r"""Avoid extraneous whitespace.
Avoid extraneous whitespace in the following situations:
- before the open parenthesis that starts the argument list of a
function call.
- before the open parenthesis that starts an indexing or slicing.
Okay: spam(1)
E211: spam (1)
Okay: dict['key'] = list[index]
E211: dict ['key'] = list[index]
E211: dict['key'] = list [index]
prev_type, prev_text, __, prev_end, __ = tokens[0]
for index in range(1, len(tokens)):
token_type, text, start, end, __ = tokens[index]
if (token_type == tokenize.OP and
text in '([' and
start != prev_end and
(prev_type == tokenize.NAME or prev_text in '}])') and
# Syntax "class A (B):" is allowed, but avoid it
(index < 2 or tokens[index - 2][1] != 'class') and
# Allow "return ( for a in range(5))"
not keyword.iskeyword(prev_text)):
yield prev_end, "E211 whitespace before '%s'" % text
prev_type = token_type
prev_text = text
prev_end = end
def whitespace_around_operator(logical_line):
r"""Avoid extraneous whitespace around an operator.
Okay: a = 12 + 3
E221: a = 4 + 5
E222: a = 4 + 5
E223: a = 4\t+ 5
E224: a = 4 +\t5
for match in OPERATOR_REGEX.finditer(logical_line):
before, after = match.groups()
if '\t' in before:
yield match.start(1), "E223 tab before operator"
elif len(before) > 1:
yield match.start(1), "E221 multiple spaces before operator"
if '\t' in after:
yield match.start(2), "E224 tab after operator"
elif len(after) > 1:
yield match.start(2), "E222 multiple spaces after operator"
def missing_whitespace_around_operator(logical_line, tokens):
r"""Surround operators with a single space on either side.
- Always surround these binary operators with a single space on
either side: assignment (=), augmented assignment (+=, -= etc.),
comparisons (==, <, >, !=, <=, >=, in, not in, is, is not),
Booleans (and, or, not).
- If operators with different priorities are used, consider adding
whitespace around the operators with the lowest priorities.
Okay: i = i + 1
Okay: submitted += 1
Okay: x = x * 2 - 1
Okay: hypot2 = x * x + y * y
Okay: c = (a + b) * (a - b)
Okay: foo(bar, key='word', *args, **kwargs)
Okay: alpha[:-i]
E225: i=i+1
E225: submitted +=1
E225: x = x /2 - 1
E225: z = x **y
E226: c = (a+b) * (a-b)
E226: hypot2 = x*x + y*y
E227: c = a|b
E228: msg = fmt%(errno, errmsg)
parens = 0
need_space = False
prev_type = tokenize.OP
prev_text = prev_end = None
for token_type, text, start, end, line in tokens:
if token_type in SKIP_COMMENTS:
if text in ('(', 'lambda'):
parens += 1
elif text == ')':
parens -= 1
if need_space:
if start != prev_end:
# Found a (probably) needed space
if need_space is not True and not need_space[1]:
yield (need_space[0],
"E225 missing whitespace around operator")
need_space = False
elif text == '>' and prev_text in ('<', '-'):
# Tolerate the "<>" operator, even if running Python 3
# Deal with Python 3's annotated return value "->"
if need_space is True or need_space[1]:
# A needed trailing space was not found
yield prev_end, "E225 missing whitespace around operator"
elif prev_text != '**':
code, optype = 'E226', 'arithmetic'
if prev_text == '%':
code, optype = 'E228', 'modulo'
elif prev_text not in ARITHMETIC_OP:
code, optype = 'E227', 'bitwise or shift'
yield (need_space[0], "%s missing whitespace "
"around %s operator" % (code, optype))
need_space = False
elif token_type == tokenize.OP and prev_end is not None:
if text == '=' and parens:
# Allow keyword args or defaults: foo(bar=None).
need_space = True
elif text in UNARY_OPERATORS:
# Check if the operator is being used as a binary operator
# Allow unary operators: -123, -x, +1.
# Allow argument unpacking: foo(*args, **kwargs).
if (prev_text in '}])' if prev_type == tokenize.OP
else prev_text not in KEYWORDS):
need_space = None
need_space = None
if need_space is None:
# Surrounding space is optional, but ensure that
# trailing space matches opening space
need_space = (prev_end, start != prev_end)
elif need_space and start == prev_end:
# A needed opening space was not found
yield prev_end, "E225 missing whitespace around operator"
need_space = False
prev_type = token_type
prev_text = text
prev_end = end
def whitespace_around_comma(logical_line):
r"""Avoid extraneous whitespace after a comma or a colon.
Note: these checks are disabled by default
Okay: a = (1, 2)
E241: a = (1, 2)
E242: a = (1,\t2)
line = logical_line
for m in WHITESPACE_AFTER_COMMA_REGEX.finditer(line):
found = m.start() + 1
if '\t' in
yield found, "E242 tab after '%s'" %[0]
yield found, "E241 multiple spaces after '%s'" %[0]
def whitespace_around_named_parameter_equals(logical_line, tokens):
r"""Don't use spaces around the '=' sign in function arguments.
Don't use spaces around the '=' sign when used to indicate a
keyword argument or a default parameter value.
Okay: def complex(real, imag=0.0):
Okay: return magic(r=real, i=imag)
Okay: boolean(a == b)
Okay: boolean(a != b)
Okay: boolean(a <= b)
Okay: boolean(a >= b)
Okay: def foo(arg: int = 42):
E251: def complex(real, imag = 0.0):
E251: return magic(r = real, i = imag)
parens = 0
no_space = False
prev_end = None
annotated_func_arg = False
in_def = logical_line.startswith('def')
message = "E251 unexpected spaces around keyword / parameter equals"
for token_type, text, start, end, line in tokens:
if token_type == tokenize.NL:
if no_space:
no_space = False
if start != prev_end:
yield (prev_end, message)
if token_type == tokenize.OP:
if text == '(':
parens += 1
elif text == ')':
parens -= 1
elif in_def and text == ':' and parens == 1:
annotated_func_arg = True
elif parens and text == ',' and parens == 1:
annotated_func_arg = False
elif parens and text == '=' and not annotated_func_arg:
no_space = True
if start != prev_end:
yield (prev_end, message)
if not parens:
annotated_func_arg = False
prev_end = end
def whitespace_before_comment(logical_line, tokens):
r"""Separate inline comments by at least two spaces.
An inline comment is a comment on the same line as a statement. Inline
comments should be separated by at least two spaces from the statement.
They should start with a # and a single space.
Each line of a block comment starts with a # and a single space
(unless it is indented text inside the comment).
Okay: x = x + 1 # Increment x
Okay: x = x + 1 # Increment x
Okay: # Block comment
E261: x = x + 1 # Increment x
E262: x = x + 1 #Increment x
E262: x = x + 1 # Increment x
E265: #Block comment
E266: ### Block comment
prev_end = (0, 0)
for token_type, text, start, end, line in tokens:
if token_type == tokenize.COMMENT:
inline_comment = line[:start[1]].strip()
if inline_comment:
if prev_end[0] == start[0] and start[1] < prev_end[1] + 2:
yield (prev_end,
"E261 at least two spaces before inline comment")
symbol, sp, comment = text.partition(' ')
bad_prefix = symbol not in '#:' and (symbol.lstrip('#')[:1] or '#')
if inline_comment:
if bad_prefix or comment[:1] in WHITESPACE:
yield start, "E262 inline comment should start with '# '"
elif bad_prefix and (bad_prefix != '!' or start[0] > 1):
if bad_prefix != '#':
yield start, "E265 block comment should start with '# '"
elif comment:
yield start, "E266 too many leading '#' for block comment"
elif token_type != tokenize.NL:
prev_end = end
def imports_on_separate_lines(logical_line):
r"""Imports should usually be on separate lines.
Okay: import os\nimport sys
E401: import sys, os
Okay: from subprocess import Popen, PIPE
Okay: from myclas import MyClass
Okay: from import YourClass
Okay: import myclass
Okay: import
line = logical_line
if line.startswith('import '):
found = line.find(',')
if -1 < found and ';' not in line[:found]:
yield found, "E401 multiple imports on one line"
def module_imports_on_top_of_file(
logical_line, indent_level, checker_state, noqa):
r"""Imports are always put at the top of the file, just after any module
comments and docstrings, and before module globals and constants.
Okay: import os
Okay: # this is a comment\nimport os
Okay: '''this is a module docstring'''\nimport os
Okay: r'''this is a module docstring'''\nimport os
Okay: try:\n import x\nexcept:\n pass\nelse:\n pass\nimport y
Okay: try:\n import x\nexcept:\n pass\nfinally:\n pass\nimport y
E402: a=1\nimport os
E402: 'One string'\n"Two string"\nimport os
E402: a=1\nfrom sys import x
Okay: if x:\n import os
def is_string_literal(line):
if line[0] in 'uUbB':
line = line[1:]
if line and line[0] in 'rR':
line = line[1:]
return line and (line[0] == '"' or line[0] == "'")
allowed_try_keywords = ('try', 'except', 'else', 'finally')
if indent_level: # Allow imports in conditional statements or functions
if not logical_line: # Allow empty lines or comments
if noqa:
line = logical_line
if line.startswith('import ') or line.startswith('from '):
if checker_state.get('seen_non_imports', False):
yield 0, "E402 module level import not at top of file"
elif any(line.startswith(kw) for kw in allowed_try_keywords):
# Allow try, except, else, finally keywords intermixed with imports in
# order to support conditional importing
elif is_string_literal(line):
# The first literal is a docstring, allow it. Otherwise, report error.
if checker_state.get('seen_docstring', False):
checker_state['seen_non_imports'] = True
checker_state['seen_docstring'] = True
checker_state['seen_non_imports'] = True
def compound_statements(logical_line):
r"""Compound statements (on the same line) are generally discouraged.
While sometimes it's okay to put an if/for/while with a small body
on the same line, never do this for multi-clause statements.
Also avoid folding such long lines!
Always use a def statement instead of an assignment statement that
binds a lambda expression directly to a name.
Okay: if foo == 'blah':\n do_blah_thing()
Okay: do_one()
Okay: do_two()
Okay: do_three()
E701: if foo == 'blah': do_blah_thing()
E701: for x in lst: total += x
E701: while t < 10: t = delay()
E701: if foo == 'blah': do_blah_thing()
E701: else: do_non_blah_thing()
E701: try: something()
E701: finally: cleanup()
E701: if foo == 'blah': one(); two(); three()
E702: do_one(); do_two(); do_three()
E703: do_four(); # useless semicolon
E704: def f(x): return 2*x
E731: f = lambda x: 2*x
line = logical_line
last_char = len(line) - 1
found = line.find(':')
while -1 < found < last_char:
before = line[:found]
if ((before.count('{') <= before.count('}') and # {'a': 1} (dict)
before.count('[') <= before.count(']') and # [1:2] (slice)
before.count('(') <= before.count(')'))): # (annotation)
lambda_kw =
if lambda_kw:
before = line[:lambda_kw.start()].rstrip()
if before[-1:] == '=' and isidentifier(before[:-1].strip()):
yield 0, ("E731 do not assign a lambda expression, use a "
if before.startswith('def '):
yield 0, "E704 multiple statements on one line (def)"
yield found, "E701 multiple statements on one line (colon)"
found = line.find(':', found + 1)
found = line.find(';')
while -1 < found:
if found < last_char:
yield found, "E702 multiple statements on one line (semicolon)"
yield found, "E703 statement ends with a semicolon"
found = line.find(';', found + 1)
def explicit_line_join(logical_line, tokens):
r"""Avoid explicit line join between brackets.
The preferred way of wrapping long lines is by using Python's implied line
continuation inside parentheses, brackets and braces. Long lines can be
broken over multiple lines by wrapping expressions in parentheses. These
should be used in preference to using a backslash for line continuation.
E502: aaa = [123, \\n 123]
E502: aaa = ("bbb " \\n "ccc")
Okay: aaa = [123,\n 123]
Okay: aaa = ("bbb "\n "ccc")
Okay: aaa = "bbb " \\n "ccc"
Okay: aaa = 123 # \\
prev_start = prev_end = parens = 0
comment = False
backslash = None
for token_type, text, start, end, line in tokens:
if token_type == tokenize.COMMENT:
comment = True
if start[0] != prev_start and parens and backslash and not comment:
yield backslash, "E502 the backslash is redundant between brackets"
if end[0] != prev_end:
if line.rstrip('\r\n').endswith('\\'):
backslash = (end[0], len(line.splitlines()[-1]) - 1)
backslash = None
prev_start = prev_end = end[0]
prev_start = start[0]
if token_type == tokenize.OP:
if text in '([{':
parens += 1
elif text in ')]}':
parens -= 1
def break_around_binary_operator(logical_line, tokens):
Avoid breaks before binary operators.
The preferred place to break around a binary operator is after the
operator, not before it.
W503: (width == 0\n + height == 0)
W503: (width == 0\n and height == 0)
Okay: (width == 0 +\n height == 0)
Okay: foo(\n -x)
Okay: foo(x\n [])
Okay: x = '''\n''' + ''
Okay: foo(x,\n -y)
Okay: foo(x, # comment\n -y)
def is_binary_operator(token_type, text):
# The % character is strictly speaking a binary operator, but the
# common usage seems to be to put it next to the format parameters,
# after a line break.
return ((token_type == tokenize.OP or text in ['and', 'or']) and
text not in "()[]{},:.;@=%")
line_break = False
unary_context = True
for token_type, text, start, end, line in tokens:
if token_type == tokenize.COMMENT:
if ('\n' in text or '\r' in text) and token_type != tokenize.STRING:
line_break = True
if (is_binary_operator(token_type, text) and line_break and
not unary_context):
yield start, "W503 line break before binary operator"
unary_context = text in '([{,;'
line_break = False
def comparison_to_singleton(logical_line, noqa):
r"""Comparison to singletons should use "is" or "is not".
Comparisons to singletons like None should always be done
with "is" or "is not", never the equality operators.
Okay: if arg is not None:
E711: if arg != None:
E711: if None == arg:
E712: if arg == True:
E712: if False == arg:
Also, beware of writing if x when you really mean if x is not None --
e.g. when testing whether a variable or argument that defaults to None was
set to some other value. The other value might have a type (such as a
container) that could be false in a boolean context!
match = not noqa and
if match:
singleton = or
same = ( == '==')
msg = "'if cond is %s:'" % (('' if same else 'not ') + singleton)
if singleton in ('None',):
code = 'E711'
code = 'E712'
nonzero = ((singleton == 'True' and same) or
(singleton == 'False' and not same))
msg += " or 'if %scond:'" % ('' if nonzero else 'not ')
yield match.start(2), ("%s comparison to %s should be %s" %
(code, singleton, msg))
def comparison_negative(logical_line):
r"""Negative comparison should be done using "not in" and "is not".
Okay: if x not in y:\n pass
Okay: assert (X in Y or X is Z)
Okay: if not (X in Y):\n pass
Okay: zz = x is not y
E713: Z = not X in Y
E713: if not X.B in Y:\n pass
E714: if not X is Y:\n pass
E714: Z = not X.B is Y
match =
if match:
pos = match.start(1)
if == 'in':
yield pos, "E713 test for membership should be 'not in'"
yield pos, "E714 test for object identity should be 'is not'"
def comparison_type(logical_line, noqa):
r"""Object type comparisons should always use isinstance().
Do not compare types directly.
Okay: if isinstance(obj, int):
E721: if type(obj) is type(1):
When checking if an object is a string, keep in mind that it might be a
unicode string too! In Python 2.3, str and unicode have a common base
class, basestring, so you can do:
Okay: if isinstance(obj, basestring):
Okay: if type(a1) is type(b1):
match =
if match and not noqa:
inst =
if inst and isidentifier(inst) and inst not in SINGLETONS:
return # Allow comparison for types which are not obvious
yield match.start(), "E721 do not compare types, use 'isinstance()'"
def python_3000_has_key(logical_line, noqa):
r"""The {}.has_key() method is removed in Python 3: use the 'in' operator.
Okay: if "alph" in d:\n print d["alph"]
W601: assert d.has_key('alph')
pos = logical_line.find('.has_key(')
if pos > -1 and not noqa:
yield pos, "W601 .has_key() is deprecated, use 'in'"
def python_3000_raise_comma(logical_line):
r"""When raising an exception, use "raise ValueError('message')".
The older form is removed in Python 3.
Okay: raise DummyError("Message")
W602: raise DummyError, "Message"
match = RAISE_COMMA_REGEX.match(logical_line)
if match and not RERAISE_COMMA_REGEX.match(logical_line):
yield match.end() - 1, "W602 deprecated form of raising exception"
def python_3000_not_equal(logical_line):
r"""New code should always use != instead of <>.
The older syntax is removed in Python 3.
Okay: if a != 'no':
W603: if a <> 'no':
pos = logical_line.find('<>')
if pos > -1:
yield pos, "W603 '<>' is deprecated, use '!='"
def python_3000_backticks(logical_line):
r"""Backticks are removed in Python 3: use repr() instead.
Okay: val = repr(1 + 2)
W604: val = `1 + 2`
pos = logical_line.find('`')
if pos > -1:
yield pos, "W604 backticks are deprecated, use 'repr()'"
# Helper functions
if sys.version_info < (3,):
# Python 2: implicit encoding.
def readlines(filename):
"""Read the source code."""
with open(filename, 'rU') as f:
return f.readlines()
isidentifier = re.compile(r'[a-zA-Z_]\w*$').match
stdin_get_value =
# Python 3
def readlines(filename):
"""Read the source code."""
with open(filename, 'rb') as f:
(coding, lines) = tokenize.detect_encoding(f.readline)
f = TextIOWrapper(f, coding, line_buffering=True)
return [l.decode(coding) for l in lines] + f.readlines()
except (LookupError, SyntaxError, UnicodeError):
# Fall back if file encoding is improperly declared
with open(filename, encoding='latin-1') as f:
return f.readlines()
isidentifier = str.isidentifier
def stdin_get_value():
return TextIOWrapper(sys.stdin.buffer, errors='ignore').read()
noqa = re.compile(r'# no(?:qa|pep8)\b', re.I).search
def expand_indent(line):
r"""Return the amount of indentation.
Tabs are expanded to the next multiple of 8.
>>> expand_indent(' ')
>>> expand_indent('\t')
>>> expand_indent(' \t')
>>> expand_indent(' \t')
if '\t' not in line:
return len(line) - len(line.lstrip())
result = 0
for char in line:
if char == '\t':
result = result // 8 * 8 + 8
elif char == ' ':
result += 1
return result
def mute_string(text):
"""Replace contents with 'xxx' to prevent syntax matching.
>>> mute_string('"abc"')
>>> mute_string("'''abc'''")
>>> mute_string("r'abc'")
# String modifiers (e.g. u or r)
start = text.index(text[-1]) + 1
end = len(text) - 1
# Triple quotes
if text[-3:] in ('"""', "'''"):
start += 2
end -= 2
return text[:start] + 'x' * (end - start) + text[end:]
def parse_udiff(diff, patterns=None, parent='.'):
"""Return a dictionary of matching lines."""
# For each file of the diff, the entry key is the filename,
# and the value is a set of row numbers to consider.
rv = {}
path = nrows = None
for line in diff.splitlines():
if nrows:
if line[:1] != '-':
nrows -= 1
if line[:3] == '@@ ':
hunk_match = HUNK_REGEX.match(line)
(row, nrows) = [int(g or '1') for g in hunk_match.groups()]
rv[path].update(range(row, row + nrows))
elif line[:3] == '+++':
path = line[4:].split('\t', 1)[0]
if path[:2] == 'b/':
path = path[2:]
rv[path] = set()
return dict([(os.path.join(parent, path), rows)
for (path, rows) in rv.items()
if rows and filename_match(path, patterns)])
def normalize_paths(value, parent=os.curdir):
"""Parse a comma-separated list of paths.
Return a list of absolute paths.
if not value:
return []
if isinstance(value, list):
return value
paths = []
for path in value.split(','):
path = path.strip()
if '/' in path:
path = os.path.abspath(os.path.join(parent, path))
return paths
def filename_match(filename, patterns, default=True):
"""Check if patterns contains a pattern that matches filename.
If patterns is unspecified, this always returns True.
if not patterns:
return default
return any(fnmatch(filename, pattern) for pattern in patterns)
def _is_eol_token(token):
return token[0] in NEWLINE or token[4][token[3][1]:].lstrip() == '\\\n'
def _is_eol_token(token, _eol_token=_is_eol_token):
return _eol_token(token) or (token[0] == tokenize.COMMENT and
token[1] == token[4])
# Framework to run all checks
_checks = {'physical_line': {}, 'logical_line': {}, 'tree': {}}
def _get_parameters(function):
if sys.version_info >= (3, 3):
return [
for parameter
in inspect.signature(function).parameters.values()
if parameter.kind == parameter.POSITIONAL_OR_KEYWORD]
return inspect.getargspec(function)[0]
def register_check(check, codes=None):
"""Register a new check object."""
def _add_check(check, kind, codes, args):
if check in _checks[kind]:
_checks[kind][check][0].extend(codes or [])
_checks[kind][check] = (codes or [''], args)
if inspect.isfunction(check):
args = _get_parameters(check)
if args and args[0] in ('physical_line', 'logical_line'):
if codes is None:
codes = ERRORCODE_REGEX.findall(check.__doc__ or '')
_add_check(check, args[0], codes, args)
elif inspect.isclass(check):
if _get_parameters(check.__init__)[:2] == ['self', 'tree']:
_add_check(check, 'tree', codes, None)
def init_checks_registry():
"""Register all globally visible functions.
The first argument name is either 'physical_line' or 'logical_line'.
mod = inspect.getmodule(register_check)
for (name, function) in inspect.getmembers(mod, inspect.isfunction):
class Checker(object):
"""Load a Python source file, tokenize it, check coding style."""
def __init__(self, filename=None, lines=None,
options=None, report=None, **kwargs):
if options is None:
options = StyleGuide(kwargs).options
assert not kwargs
self._io_error = None
self._physical_checks = options.physical_checks
self._logical_checks = options.logical_checks
self._ast_checks = options.ast_checks
self.max_line_length = options.max_line_length
self.multiline = False # in a multiline string?
self.hang_closing = options.hang_closing
self.verbose = options.verbose
self.filename = filename
# Dictionary where a checker can store its custom state.
self._checker_states = {}
if filename is None:
self.filename = 'stdin'
self.lines = lines or []
elif filename == '-':
self.filename = 'stdin'
self.lines = stdin_get_value().splitlines(True)
elif lines is None:
self.lines = readlines(filename)
except IOError:
(exc_type, exc) = sys.exc_info()[:2]
self._io_error = '%s: %s' % (exc_type.__name__, exc)
self.lines = []
self.lines = lines
if self.lines:
ord0 = ord(self.lines[0][0])
if ord0 in (0xef, 0xfeff): # Strip the UTF-8 BOM
if ord0 == 0xfeff:
self.lines[0] = self.lines[0][1:]
elif self.lines[0][:3] == '\xef\xbb\xbf':
self.lines[0] = self.lines[0][3:] = report or
self.report_error =
def report_invalid_syntax(self):
"""Check if the syntax is valid."""
(exc_type, exc) = sys.exc_info()[:2]
if len(exc.args) > 1:
offset = exc.args[1]
if len(offset) > 2:
offset = offset[1:3]
offset = (1, 0)
self.report_error(offset[0], offset[1] or 0,
'E901 %s: %s' % (exc_type.__name__, exc.args[0]),
def readline(self):
"""Get the next line from the input buffer."""
if self.line_number >= self.total_lines:
return ''
line = self.lines[self.line_number]
self.line_number += 1
if self.indent_char is None and line[:1] in WHITESPACE:
self.indent_char = line[0]
return line
def run_check(self, check, argument_names):
"""Run a check plugin."""
arguments = []
for name in argument_names:
arguments.append(getattr(self, name))
return check(*arguments)
def init_checker_state(self, name, argument_names):
""" Prepares a custom state for the specific checker plugin."""
if 'checker_state' in argument_names:
self.checker_state = self._checker_states.setdefault(name, {})
def check_physical(self, line):
"""Run all physical checks on a raw input line."""
self.physical_line = line
for name, check, argument_names in self._physical_checks:
self.init_checker_state(name, argument_names)
result = self.run_check(check, argument_names)
if result is not None:
(offset, text) = result
self.report_error(self.line_number, offset, text, check)
if text[:4] == 'E101':
self.indent_char = line[0]
def build_tokens_line(self):
"""Build a logical line from tokens."""
logical = []
comments = []
length = 0
prev_row = prev_col = mapping = None
for token_type, text, start, end, line in self.tokens:
if token_type in SKIP_TOKENS:
if not mapping:
mapping = [(0, start)]
if token_type == tokenize.COMMENT:
if token_type == tokenize.STRING:
text = mute_string(text)
if prev_row:
(start_row, start_col) = start
if prev_row != start_row: # different row
prev_text = self.lines[prev_row - 1][prev_col - 1]
if prev_text == ',' or (prev_text not in '{[(' and
text not in '}])'):
text = ' ' + text
elif prev_col != start_col: # different column
text = line[prev_col:start_col] + text
length += len(text)
mapping.append((length, end))
(prev_row, prev_col) = end
self.logical_line = ''.join(logical)
self.noqa = comments and noqa(''.join(comments))
return mapping
def check_logical(self):
"""Build a line from tokens and run all logical checks on it."""
mapping = self.build_tokens_line()
if not mapping:
(start_row, start_col) = mapping[0][1]
start_line = self.lines[start_row - 1]
self.indent_level = expand_indent(start_line[:start_col])
if self.blank_before < self.blank_lines:
self.blank_before = self.blank_lines
if self.verbose >= 2:
for name, check, argument_names in self._logical_checks:
if self.verbose >= 4:
print(' ' + name)
self.init_checker_state(name, argument_names)
for offset, text in self.run_check(check, argument_names) or ():
if not isinstance(offset, tuple):
for token_offset, pos in mapping:
if offset <= token_offset:
offset = (pos[0], pos[1] + offset - token_offset)
self.report_error(offset[0], offset[1], text, check)
if self.logical_line:
self.previous_indent_level = self.indent_level
self.previous_logical = self.logical_line
self.blank_lines = 0
self.tokens = []
def check_ast(self):
"""Build the file's AST and run all AST checks."""
tree = compile(''.join(self.lines), '', 'exec', PyCF_ONLY_AST)
except (ValueError, SyntaxError, TypeError):
return self.report_invalid_syntax()
for name, cls, __ in self._ast_checks:
checker = cls(tree, self.filename)
for lineno, offset, text, check in
if not self.lines or not noqa(self.lines[lineno - 1]):
self.report_error(lineno, offset, text, check)
def generate_tokens(self):
"""Tokenize the file, run physical line checks and yield tokens."""
if self._io_error:
self.report_error(1, 0, 'E902 %s' % self._io_error, readlines)
tokengen = tokenize.generate_tokens(self.readline)
for token in tokengen:
if token[2][0] > self.total_lines:
yield token
except (SyntaxError, tokenize.TokenError):
def maybe_check_physical(self, token):
"""If appropriate (based on token), check current physical line(s)."""
# Called after every token, but act only on end of line.
if _is_eol_token(token):
# Obviously, a newline token ends a single physical line.
elif token[0] == tokenize.STRING and '\n' in token[1]:
# Less obviously, a string that contains newlines is a
# multiline string, either triple-quoted or with internal
# newlines backslash-escaped. Check every physical line in the
# string *except* for the last one: its newline is outside of
# the multiline string, so we consider it a regular physical
# line, and will check it like any other physical line.
# Subtleties:
# - we don't *completely* ignore the last line; if it contains
# the magical "# noqa" comment, we disable all physical
# checks for the entire multiline string
# - have to wind self.line_number back because initially it
# points to the last line of the string, and we want
# check_physical() to give accurate feedback
if noqa(token[4]):
self.multiline = True
self.line_number = token[2][0]
for line in token[1].split('\n')[:-1]:
self.check_physical(line + '\n')
self.line_number += 1
self.multiline = False
def check_all(self, expected=None, line_offset=0):
"""Run all checks on the input file.""", self.lines, expected, line_offset)
self.total_lines = len(self.lines)
if self._ast_checks:
self.line_number = 0
self.indent_char = None
self.indent_level = self.previous_indent_level = 0
self.previous_logical = ''
self.tokens = []
self.blank_lines = self.blank_before = 0
parens = 0
for token in self.generate_tokens():
token_type, text = token[0:2]
if self.verbose >= 3:
if token[2][0] == token[3][0]:
pos = '[%s:%s]' % (token[2][1] or '', token[3][1])
pos = 'l.%s' % token[3][0]
print('l.%s\t%s\t%s\t%r' %
(token[2][0], pos, tokenize.tok_name[token[0]], text))
if token_type == tokenize.OP:
if text in '([{':
parens += 1
elif text in '}])':
parens -= 1
elif not parens:
if token_type in NEWLINE:
if token_type == tokenize.NEWLINE:
self.blank_before = 0
elif len(self.tokens) == 1:
# The physical line contains only this token.
self.blank_lines += 1
del self.tokens[0]
elif COMMENT_WITH_NL and token_type == tokenize.COMMENT:
if len(self.tokens) == 1:
# The comment also ends a physical line
token = list(token)
token[1] = text.rstrip('\r\n')
token[3] = (token[2][0], token[2][1] + len(token[1]))
self.tokens = [tuple(token)]
if self.tokens:
class BaseReport(object):
"""Collect the results of the checks."""
print_filename = False
def __init__(self, options):
self._benchmark_keys = options.benchmark_keys
self._ignore_code = options.ignore_code
# Results
self.elapsed = 0
self.total_errors = 0
self.counters = dict.fromkeys(self._benchmark_keys, 0)
self.messages = {}
def start(self):
"""Start the timer."""
self._start_time = time.time()
def stop(self):
"""Stop the timer."""
self.elapsed = time.time() - self._start_time
def init_file(self, filename, lines, expected, line_offset):
"""Signal a new file."""
self.filename = filename
self.lines = lines
self.expected = expected or ()
self.line_offset = line_offset
self.file_errors = 0
self.counters['files'] += 1
self.counters['physical lines'] += len(lines)
def increment_logical_line(self):
"""Signal a new logical line."""
self.counters['logical lines'] += 1
def error(self, line_number, offset, text, check):
"""Report an error, according to options."""
code = text[:4]
if self._ignore_code(code):
if code in self.counters:
self.counters[code] += 1
self.counters[code] = 1
self.messages[code] = text[5:]
# Don't care about expected errors or warnings
if code in self.expected:
if self.print_filename and not self.file_errors:
self.file_errors += 1
self.total_errors += 1
return code
def get_file_results(self):
"""Return the count of errors and warnings for this file."""
return self.file_errors
def get_count(self, prefix=''):
"""Return the total count of errors and warnings."""
return sum([self.counters[key]
for key in self.messages if key.startswith(prefix)])
def get_statistics(self, prefix=''):
"""Get statistics for message codes that start with the prefix.
prefix='' matches all errors and warnings
prefix='E' matches all errors
prefix='W' matches all warnings
prefix='E4' matches all errors that have to do with imports
return ['%-7s %s %s' % (self.counters[key], key, self.messages[key])
for key in sorted(self.messages) if key.startswith(prefix)]
def print_statistics(self, prefix=''):
"""Print overall statistics (number of errors and warnings)."""
for line in self.get_statistics(prefix):
def print_benchmark(self):
"""Print benchmark numbers."""
print('%-7.2f %s' % (self.elapsed, 'seconds elapsed'))
if self.elapsed:
for key in self._benchmark_keys:
print('%-7d %s per second (%d total)' %
(self.counters[key] / self.elapsed, key,
class FileReport(BaseReport):
"""Collect the results of the checks and print only the filenames."""
print_filename = True
class StandardReport(BaseReport):
"""Collect and print the results of the checks."""
def __init__(self, options):
super(StandardReport, self).__init__(options)
self._fmt = REPORT_FORMAT.get(options.format.lower(),
self._repeat = options.repeat
self._show_source = options.show_source
self._show_pep8 = options.show_pep8
def init_file(self, filename, lines, expected, line_offset):
"""Signal a new file."""
self._deferred_print = []
return super(StandardReport, self).init_file(
filename, lines, expected, line_offset)
def error(self, line_number, offset, text, check):
"""Report an error, according to options."""
code = super(StandardReport, self).error(line_number, offset,
text, check)
if code and (self.counters[code] == 1 or self._repeat):
(line_number, offset, code, text[5:], check.__doc__))
return code
def get_file_results(self):
"""Print the result and return the overall count for this file."""
for line_number, offset, code, text, doc in self._deferred_print:
print(self._fmt % {
'path': self.filename,
'row': self.line_offset + line_number, 'col': offset + 1,
'code': code, 'text': text,
if self._show_source:
if line_number > len(self.lines):
line = ''
line = self.lines[line_number - 1]
print(re.sub(r'\S', ' ', line[:offset]) + '^')
if self._show_pep8 and doc:
print(' ' + doc.strip())
# stdout is block buffered when not stdout.isatty().
# line can be broken where buffer boundary since other processes
# write to same file.
# flush() after print() to avoid buffer boundary.
# Typical buffer size is 8192. line written safely when
# len(line) < 8192.
return self.file_errors
class DiffReport(StandardReport):
"""Collect and print the results for the changed lines only."""
def __init__(self, options):
super(DiffReport, self).__init__(options)
self._selected = options.selected_lines
def error(self, line_number, offset, text, check):
if line_number not in self._selected[self.filename]:
return super(DiffReport, self).error(line_number, offset, text, check)
class StyleGuide(object):
"""Initialize a PEP-8 instance with few options."""
def __init__(self, *args, **kwargs):
# build options from the command line
self.checker_class = kwargs.pop('checker_class', Checker)
parse_argv = kwargs.pop('parse_argv', False)
config_file = kwargs.pop('config_file', False)
parser = kwargs.pop('parser', None)
# build options from dict
options_dict = dict(*args, **kwargs)
arglist = None if parse_argv else options_dict.get('paths', None)
options, self.paths = process_options(
arglist, parse_argv, config_file, parser)
if options_dict:
if 'paths' in options_dict:
self.paths = options_dict['paths']
self.runner = self.input_file
self.options = options
if not options.reporter:
options.reporter = BaseReport if options.quiet else StandardReport = tuple( or ())
if not ( or options.ignore or
options.testsuite or options.doctest) and DEFAULT_IGNORE:
# The default choice: ignore controversial checks
options.ignore = tuple(DEFAULT_IGNORE.split(','))
# Ignore all checks which are not explicitly selected
options.ignore = ('',) if else tuple(options.ignore)
options.benchmark_keys = BENCHMARK_KEYS[:]
options.ignore_code = self.ignore_code
options.physical_checks = self.get_checks('physical_line')
options.logical_checks = self.get_checks('logical_line')
options.ast_checks = self.get_checks('tree')
def init_report(self, reporter=None):
"""Initialize the report instance.""" = (reporter or self.options.reporter)(self.options)
def check_files(self, paths=None):
"""Run all checks on the paths."""
if paths is None:
paths = self.paths
report =
runner = self.runner
for path in paths:
if os.path.isdir(path):
elif not self.excluded(path):
except KeyboardInterrupt:
print('... stopped')
return report
def input_file(self, filename, lines=None, expected=None, line_offset=0):
"""Run all checks on a Python source file."""
if self.options.verbose:
print('checking %s' % filename)
fchecker = self.checker_class(
filename, lines=lines, options=self.options)
return fchecker.check_all(expected=expected, line_offset=line_offset)
def input_dir(self, dirname):
"""Check all files in this directory and all subdirectories."""
dirname = dirname.rstrip('/')
if self.excluded(dirname):
return 0
counters =
verbose = self.options.verbose
filepatterns = self.options.filename
runner = self.runner
for root, dirs, files in os.walk(dirname):
if verbose:
print('directory ' + root)
counters['directories'] += 1
for subdir in sorted(dirs):
if self.excluded(subdir, root):
for filename in sorted(files):
# contain a pattern that matches?
if ((filename_match(filename, filepatterns) and
not self.excluded(filename, root))):
runner(os.path.join(root, filename))
def excluded(self, filename, parent=None):
"""Check if the file should be excluded.
Check if 'options.exclude' contains a pattern that matches filename.
if not self.options.exclude:
return False
basename = os.path.basename(filename)
if filename_match(basename, self.options.exclude):
return True
if parent:
filename = os.path.join(parent, filename)
filename = os.path.abspath(filename)
return filename_match(filename, self.options.exclude)
def ignore_code(self, code):
"""Check if the error code should be ignored.
If '' contains a prefix of the error code,
return False. Else, if 'options.ignore' contains a prefix of
the error code, return True.
if len(code) < 4 and any(s.startswith(code)
for s in
return False
return (code.startswith(self.options.ignore) and
not code.startswith(
def get_checks(self, argument_name):
"""Get all the checks for this category.
Find all globally visible functions where the first argument name
starts with argument_name and which contain selected tests.
checks = []
for check, attrs in _checks[argument_name].items():
(codes, args) = attrs
if any(not (code and self.ignore_code(code)) for code in codes):
checks.append((check.__name__, check, args))
return sorted(checks)
def get_parser(prog='pep8', version=__version__):
parser = OptionParser(prog=prog, version=version,
usage="%prog [options] input ...")
parser.config_options = [
'exclude', 'filename', 'select', 'ignore', 'max-line-length',
'hang-closing', 'count', 'format', 'quiet', 'show-pep8',
'show-source', 'statistics', 'verbose']
parser.add_option('-v', '--verbose', default=0, action='count',
help="print status messages, or debug with -vv")
parser.add_option('-q', '--quiet', default=0, action='count',
help="report only file names, or nothing with -qq")
parser.add_option('-r', '--repeat', default=True, action='store_true',
help="(obsolete) show all occurrences of the same error")
parser.add_option('--first', action='store_false', dest='repeat',
help="show first occurrence of each error")
parser.add_option('--exclude', metavar='patterns', default=DEFAULT_EXCLUDE,
help="exclude files or directories which match these "
"comma separated patterns (default: %default)")
parser.add_option('--filename', metavar='patterns', default='*.py',
help="when parsing directories, only check filenames "
"matching these comma separated patterns "
"(default: %default)")
parser.add_option('--select', metavar='errors', default='',
help="select errors and warnings (e.g. E,W6)")
parser.add_option('--ignore', metavar='errors', default='',
help="skip errors and warnings (e.g. E4,W) "
"(default: %s)" % DEFAULT_IGNORE)
parser.add_option('--show-source', action='store_true',
help="show source code for each error")
parser.add_option('--show-pep8', action='store_true',
help="show text of PEP 8 for each error "
"(implies --first)")
parser.add_option('--statistics', action='store_true',
help="count errors and warnings")
parser.add_option('--count', action='store_true',
help="print total number of errors and warnings "
"to standard error and set exit code to 1 if "
"total is not null")
parser.add_option('--max-line-length', type='int', metavar='n',
help="set maximum allowed line length "
"(default: %default)")
parser.add_option('--hang-closing', action='store_true',
help="hang closing bracket instead of matching "
"indentation of opening bracket's line")
parser.add_option('--format', metavar='format', default='default',
help="set the error format [default|pylint|<custom>]")
parser.add_option('--diff', action='store_true',
help="report changes only within line number ranges in "
"the unified diff received on STDIN")
group = parser.add_option_group("Testing Options")
if os.path.exists(TESTSUITE_PATH):
group.add_option('--testsuite', metavar='dir',
help="run regression tests from dir")
group.add_option('--doctest', action='store_true',
help="run doctest on myself")
group.add_option('--benchmark', action='store_true',
help="measure processing speed")
return parser
def read_config(options, args, arglist, parser):
"""Read and parse configurations
If a config file is specified on the command line with the "--config"
option, then only it is used for configuration.
Otherwise, the user configuration (~/.config/pep8) and any local
configurations in the current directory or above will be merged together
(in that order) using the read method of ConfigParser.
config = RawConfigParser()
cli_conf = options.config
local_dir = os.curdir
if USER_CONFIG and os.path.isfile(USER_CONFIG):
if options.verbose:
print('user configuration: %s' % USER_CONFIG)
parent = tail = args and os.path.abspath(os.path.commonprefix(args))
while tail:
if, fn) for fn in PROJECT_CONFIG):
local_dir = parent
if options.verbose:
print('local configuration: in %s' % parent)
(parent, tail) = os.path.split(parent)
if cli_conf and os.path.isfile(cli_conf):
if options.verbose:
print('cli configuration: %s' % cli_conf)
pep8_section = parser.prog
if config.has_section(pep8_section):
option_list = dict([(o.dest, o.type or o.action)
for o in parser.option_list])
# First, read the default values
(new_options, __) = parser.parse_args([])
# Second, parse the configuration
for opt in config.options(pep8_section):
if opt.replace('_', '-') not in parser.config_options:
print(" unknown option '%s' ignored" % opt)
if options.verbose > 1:
print(" %s = %s" % (opt, config.get(pep8_section, opt)))
normalized_opt = opt.replace('-', '_')
opt_type = option_list[normalized_opt]
if opt_type in ('int', 'count'):
value = config.getint(pep8_section, opt)
elif opt_type == 'string':
value = config.get(pep8_section, opt)
if normalized_opt == 'exclude':
value = normalize_paths(value, local_dir)
assert opt_type in ('store_true', 'store_false')
value = config.getboolean(pep8_section, opt)
setattr(new_options, normalized_opt, value)
# Third, overwrite with the command-line options
(options, __) = parser.parse_args(arglist, values=new_options)
options.doctest = options.testsuite = False
return options
def process_options(arglist=None, parse_argv=False, config_file=None,
"""Process options passed either via arglist or via command line args.
Passing in the ``config_file`` parameter allows other tools, such as flake8
to specify their own options to be processed in pep8.
if not parser:
parser = get_parser()
if not parser.has_option('--config'):
group = parser.add_option_group("Configuration", description=(
"The project options are read from the [%s] section of the "
"tox.ini file or the setup.cfg file located in any parent folder "
"of the path(s) being processed. Allowed options are: %s." %
(parser.prog, ', '.join(parser.config_options))))
group.add_option('--config', metavar='path', default=config_file,
help="user config file location")
# Don't read the command line if the module is used as a library.
if not arglist and not parse_argv:
arglist = []
# If parse_argv is True and arglist is None, arguments are
# parsed from the command line (sys.argv)
(options, args) = parser.parse_args(arglist)
options.reporter = None
if options.ensure_value('testsuite', False):
elif not options.ensure_value('doctest', False):
if parse_argv and not args:
if options.diff or any(os.path.exists(name)
for name in PROJECT_CONFIG):
args = ['.']
parser.error('input not specified')
options = read_config(options, args, arglist, parser)
options.reporter = parse_argv and options.quiet == 1 and FileReport
options.filename = _parse_multi_options(options.filename)
options.exclude = normalize_paths(options.exclude) = _parse_multi_options(
options.ignore = _parse_multi_options(options.ignore)
if options.diff:
options.reporter = DiffReport
stdin = stdin_get_value()
options.selected_lines = parse_udiff(stdin, options.filename, args[0])
args = sorted(options.selected_lines)
return options, args
def _parse_multi_options(options, split_token=','):
r"""Split and strip and discard empties.
Turns the following:
into ["A", "B"]
if options:
return [o.strip() for o in options.split(split_token) if o.strip()]
return options
def _main():
"""Parse options and run checks on Python source."""
import signal
# Handle "Broken pipe" gracefully
signal.signal(signal.SIGPIPE, lambda signum, frame: sys.exit(1))
except AttributeError:
pass # not supported on Windows
pep8style = StyleGuide(parse_argv=True)
options = pep8style.options
if options.doctest or options.testsuite:
from import run_tests
report = run_tests(pep8style)
report = pep8style.check_files()
if options.statistics:
if options.benchmark:
if options.testsuite and not options.quiet:
if report.total_errors:
if options.count:
sys.stderr.write(str(report.total_errors) + '\n')
if __name__ == '__main__':
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