mirror of
https://github.com/PyCQA/flake8.git
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408 lines
14 KiB
Python
408 lines
14 KiB
Python
"""Module containing our file processor that tokenizes a file for checks."""
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import contextlib
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import io
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import re
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import sys
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import tokenize
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import flake8
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from flake8 import defaults
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from flake8 import exceptions
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from flake8 import utils
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PyCF_ONLY_AST = 1024
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NEWLINE = frozenset([tokenize.NL, tokenize.NEWLINE])
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# Work around Python < 2.6 behaviour, which does not generate NL after
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# a comment which is on a line by itself.
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COMMENT_WITH_NL = tokenize.generate_tokens(['#\n'].pop).send(None)[1] == '#\n'
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SKIP_TOKENS = frozenset([tokenize.NL, tokenize.NEWLINE, tokenize.INDENT,
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tokenize.DEDENT])
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class FileProcessor(object):
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"""Processes a file and holdes state.
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This processes a file by generating tokens, logical and physical lines,
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and AST trees. This also provides a way of passing state about the file
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to checks expecting that state. Any public attribute on this object can
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be requested by a plugin. The known public attributes are:
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- blank_before
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- blank_lines
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- indect_char
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- indent_level
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- line_number
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- logical_line
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- max_line_length
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- multiline
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- noqa
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- previous_indent_level
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- previous_logical
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- tokens
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- total_lines
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- verbose
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"""
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NOQA_FILE = re.compile(r'\s*# flake8[:=]\s*noqa', re.I)
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def __init__(self, filename, options):
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"""Initialice our file processor.
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:param str filename:
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Name of the file to process
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"""
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self.filename = filename
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self.lines = self.read_lines()
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self.strip_utf_bom()
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self.options = options
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# Defaults for public attributes
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#: Number of preceding blank lines
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self.blank_before = 0
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#: Number of blank lines
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self.blank_lines = 0
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#: Checker states for each plugin?
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self._checker_states = {}
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#: Current checker state
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self.checker_state = None
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#: User provided option for hang closing
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self.hang_closing = options.hang_closing
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#: Character used for indentation
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self.indent_char = None
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#: Current level of indentation
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self.indent_level = 0
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#: Line number in the file
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self.line_number = 0
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#: Current logical line
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self.logical_line = ''
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#: Maximum line length as configured by the user
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self.max_line_length = options.max_line_length
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#: Whether the current physical line is multiline
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self.multiline = False
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#: Whether or not we're observing NoQA
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self.noqa = False
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#: Previous level of indentation
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self.previous_indent_level = 0
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#: Previous logical line
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self.previous_logical = ''
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#: Current set of tokens
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self.tokens = []
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#: Total number of lines in the file
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self.total_lines = len(self.lines)
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#: Verbosity level of Flake8
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self.verbose = options.verbose
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@contextlib.contextmanager
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def inside_multiline(self, line_number):
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"""Context-manager to toggle the multiline attribute."""
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self.line_number = line_number
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self.multiline = True
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yield
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self.multiline = False
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def reset_blank_before(self):
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"""Reset the blank_before attribute to zero."""
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self.blank_before = 0
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def delete_first_token(self):
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"""Delete the first token in the list of tokens."""
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del self.tokens[0]
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def visited_new_blank_line(self):
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"""Note that we visited a new blank line."""
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self.blank_lines += 1
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def update_state(self, mapping):
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"""Update the indent level based on the logical line mapping."""
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(start_row, start_col) = mapping[0][1]
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start_line = self.lines[start_row - 1]
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self.indent_level = expand_indent(start_line[:start_col])
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if self.blank_before < self.blank_lines:
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self.blank_before = self.blank_lines
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def update_checker_state_for(self, plugin):
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"""Update the checker_state attribute for the plugin."""
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if 'checker_state' in plugin.parameters:
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self.checker_state = self._checker_states.setdefault(
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plugin.name, {}
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)
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def next_logical_line(self):
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"""Record the previous logical line.
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This also resets the tokens list and the blank_lines count.
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"""
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if self.logical_line:
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self.previous_indent_level = self.indent_level
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self.previous_logical = self.logical_line
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self.blank_lines = 0
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self.tokens = []
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def build_logical_line_tokens(self):
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"""Build the mapping, comments, and logical line lists."""
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logical = []
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comments = []
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length = 0
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previous_row = previous_column = mapping = None
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for token_type, text, start, end, line in self.tokens:
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if token_type in SKIP_TOKENS:
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continue
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if not mapping:
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mapping = [(0, start)]
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if token_type == tokenize.COMMENT:
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comments.append(text)
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continue
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if token_type == tokenize.STRING:
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text = mutate_string(text)
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if previous_row:
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(start_row, start_column) = start
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if previous_row != start_row:
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row_index = previous_row - 1
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column_index = previous_column - 1
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previous_text = self.lines[row_index][column_index]
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if (previous_text == ',' or
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(previous_text not in '{[(' and
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text not in '}])')):
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text = ' ' + text
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elif previous_column != start_column:
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text = line[previous_column:start_column] + text
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logical.append(text)
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length += len(text)
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mapping.append((length, end))
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(previous_row, previous_column) = end
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return comments, logical, mapping
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def build_ast(self):
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"""Build an abstract syntax tree from the list of lines."""
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return compile(''.join(self.lines), '', 'exec', PyCF_ONLY_AST)
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def build_logical_line(self):
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"""Build a logical line from the current tokens list."""
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comments, logical, mapping_list = self.build_logical_line_tokens()
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self.logical_line = ''.join(logical)
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return ''.join(comments), self.logical_line, mapping_list
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def split_line(self, token):
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"""Split a physical line's line based on new-lines.
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This also auto-increments the line number for the caller.
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"""
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for line in token[1].split('\n')[:-1]:
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yield line
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self.line_number += 1
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def keyword_arguments_for(self, parameters, arguments=None):
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"""Generate the keyword arguments for a list of parameters."""
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if arguments is None:
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arguments = {}
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for param in parameters:
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if param not in arguments:
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arguments[param] = getattr(self, param)
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return arguments
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def check_physical_error(self, error_code, line):
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"""Update attributes based on error code and line."""
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if error_code == 'E101':
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self.indent_char = line[0]
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def generate_tokens(self):
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"""Tokenize the file and yield the tokens.
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:raises flake8.exceptions.InvalidSyntax:
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If a :class:`tokenize.TokenError` is raised while generating
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tokens.
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"""
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try:
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for token in tokenize.generate_tokens(self.next_line):
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if token[2][0] > self.total_lines:
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break
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self.tokens.append(token)
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yield token
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# NOTE(sigmavirus24): pycodestyle was catching both a SyntaxError
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# and a tokenize.TokenError. In looking a the source on Python 2 and
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# Python 3, the SyntaxError should never arise from generate_tokens.
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# If we were using tokenize.tokenize, we would have to catch that. Of
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# course, I'm going to be unsurprised to be proven wrong at a later
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# date.
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except tokenize.TokenError as exc:
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raise exceptions.InvalidSyntax(exc.message, exception=exc)
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def line_for(self, line_number):
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"""Retrieve the physical line at the specified line number."""
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return self.lines[line_number - 1]
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def next_line(self):
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"""Get the next line from the list."""
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if self.line_number >= self.total_lines:
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return ''
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line = self.lines[self.line_number]
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self.line_number += 1
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if self.indent_char is None and line[:1] in defaults.WHITESPACE:
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self.indent_char = line[0]
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return line
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def read_lines(self):
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# type: () -> List[str]
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"""Read the lines for this file checker."""
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if self.filename is None or self.filename == '-':
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self.filename = 'stdin'
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return self.read_lines_from_stdin()
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return self.read_lines_from_filename()
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def _readlines_py2(self):
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# type: () -> List[str]
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with open(self.filename, 'rU') as fd:
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return fd.readlines()
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def _readlines_py3(self):
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# type: () -> List[str]
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try:
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with open(self.filename, 'rb') as fd:
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(coding, lines) = tokenize.detect_encoding(fd.readline)
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textfd = io.TextIOWrapper(fd, coding, line_buffering=True)
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return ([l.decode(coding) for l in lines] +
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textfd.readlines())
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except (LookupError, SyntaxError, UnicodeError):
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# If we can't detect the codec with tokenize.detect_encoding, or
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# the detected encoding is incorrect, just fallback to latin-1.
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with open(self.filename, encoding='latin-1') as fd:
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return fd.readlines()
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def read_lines_from_filename(self):
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# type: () -> List[str]
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"""Read the lines for a file."""
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if (2, 6) <= sys.version_info < (3, 0):
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readlines = self._readlines_py2
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elif (3, 0) <= sys.version_info < (4, 0):
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readlines = self._readlines_py3
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return readlines()
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def read_lines_from_stdin(self):
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# type: () -> List[str]
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"""Read the lines from standard in."""
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return utils.stdin_get_value().splitlines(True)
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def should_ignore_file(self):
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# type: () -> bool
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"""Check if ``# flake8: noqa`` is in the file to be ignored.
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:returns:
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True if a line matches :attr:`FileProcessor.NOQA_FILE`,
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otherwise False
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:rtype:
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bool
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"""
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ignore_file = self.NOQA_FILE.search
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return any(ignore_file(line) for line in self.lines)
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def strip_utf_bom(self):
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# type: () -> NoneType
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"""Strip the UTF bom from the lines of the file."""
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if not self.lines:
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# If we have nothing to analyze quit early
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return
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first_byte = ord(self.lines[0][0])
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if first_byte not in (0xEF, 0xFEFF):
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return
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# If the first byte of the file is a UTF-8 BOM, strip it
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if first_byte == 0xFEFF:
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self.lines[0] = self.lines[0][1:]
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elif self.lines[0][:3] == '\xEF\xBB\xBF':
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self.lines[0] = self.lines[0][3:]
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def is_eol_token(token):
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"""Check if the token is an end-of-line token."""
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return token[0] in NEWLINE or token[4][token[3][1]:].lstrip() == '\\\n'
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if COMMENT_WITH_NL: # If on Python 2.6
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def is_eol_token(token, _is_eol_token=is_eol_token):
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"""Check if the token is an end-of-line token."""
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return (_is_eol_token(token) or
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(token[0] == tokenize.COMMENT and token[1] == token[4]))
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def is_multiline_string(token):
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"""Check if this is a multiline string."""
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return token[0] == tokenize.STRING and '\n' in token[1]
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def token_is_newline(token):
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"""Check if the token type is a newline token type."""
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return token[0] in NEWLINE
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def token_is_comment(token):
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"""Check if the token type is a comment."""
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return COMMENT_WITH_NL and token[0] == tokenize.COMMENT
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def count_parentheses(current_parentheses_count, token_text):
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"""Count the number of parentheses."""
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current_parentheses_count = current_parentheses_count or 0
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if token_text in '([{':
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return current_parentheses_count + 1
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elif token_text in '}])':
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return current_parentheses_count - 1
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return current_parentheses_count
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def log_token(log, token):
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"""Log a token to a provided logging object."""
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if token[2][0] == token[3][0]:
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pos = '[%s:%s]' % (token[2][1] or '', token[3][1])
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else:
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pos = 'l.%s' % token[3][0]
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log.log(flake8._EXTRA_VERBOSE, 'l.%s\t%s\t%s\t%r' %
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(token[2][0], pos, tokenize.tok_name[token[0]],
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token[1]))
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def expand_indent(line):
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r"""Return the amount of indentation.
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Tabs are expanded to the next multiple of 8.
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>>> expand_indent(' ')
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4
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>>> expand_indent('\t')
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8
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>>> expand_indent(' \t')
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8
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>>> expand_indent(' \t')
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16
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"""
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if '\t' not in line:
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return len(line) - len(line.lstrip())
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result = 0
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for char in line:
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if char == '\t':
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result = result // 8 * 8 + 8
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elif char == ' ':
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result += 1
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else:
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break
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return result
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def mutate_string(text):
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"""Replace contents with 'xxx' to prevent syntax matching.
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>>> mute_string('"abc"')
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'"xxx"'
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>>> mute_string("'''abc'''")
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"'''xxx'''"
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>>> mute_string("r'abc'")
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"r'xxx'"
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"""
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# String modifiers (e.g. u or r)
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start = text.index(text[-1]) + 1
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end = len(text) - 1
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# Triple quotes
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if text[-3:] in ('"""', "'''"):
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start += 2
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end -= 2
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return text[:start] + 'x' * (end - start) + text[end:]
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