/
redundant_regexp_escape.rb
113 lines (97 loc) · 3.18 KB
/
redundant_regexp_escape.rb
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# frozen_string_literal: true
module RuboCop
module Cop
module Style
# This cop checks for redundant escapes inside Regexp literals.
#
# @example
# # bad
# %r{foo\/bar}
#
# # good
# %r{foo/bar}
#
# # good
# /foo\/bar/
#
# # good
# %r/foo\/bar/
#
# # good
# %r!foo\!bar!
#
# # bad
# /a\-b/
#
# # good
# /a-b/
#
# # bad
# /[\+\-]\d/
#
# # good
# /[+\-]\d/
#
# @api private
class RedundantRegexpEscape < Base
include RangeHelp
include RegexpLiteralHelp
extend AutoCorrector
MSG_REDUNDANT_ESCAPE = 'Redundant escape inside regexp literal'
ALLOWED_ALWAYS_ESCAPES = " \n[]^\\#".chars.freeze
ALLOWED_WITHIN_CHAR_CLASS_METACHAR_ESCAPES = '-'.chars.freeze
ALLOWED_OUTSIDE_CHAR_CLASS_METACHAR_ESCAPES = '.*+?{}()|$'.chars.freeze
def on_regexp(node)
each_escape(node) do |char, index, within_character_class|
next if allowed_escape?(node, char, within_character_class)
location = escape_range_at_index(node, index)
add_offense(location, message: MSG_REDUNDANT_ESCAPE) do |corrector|
corrector.remove_leading(escape_range_at_index(node, index), 1)
end
end
end
private
def allowed_escape?(node, char, within_character_class)
# Strictly speaking a few single-letter metachars are currently
# unnecessary to "escape", e.g. i, E, F, but enumerating them is
# rather difficult, and their behaviour could change over time with
# different versions of Ruby so that e.g. /\i/ != /i/
return true if /[[:alnum:]]/.match?(char)
return true if ALLOWED_ALWAYS_ESCAPES.include?(char) || delimiter?(node, char)
if within_character_class
ALLOWED_WITHIN_CHAR_CLASS_METACHAR_ESCAPES.include?(char)
else
ALLOWED_OUTSIDE_CHAR_CLASS_METACHAR_ESCAPES.include?(char)
end
end
def delimiter?(node, char)
delimiters = [
node.loc.begin.source[-1],
node.loc.end.source[0]
]
delimiters.include?(char)
end
def each_escape(node)
Regexp::Parser.parse(
pattern_source(node)
).traverse.reduce(0) do |char_class_depth, (event, expr)|
yield(expr.text[1], expr.ts, !char_class_depth.zero?) if expr.type == :escape
if expr.type == :set
char_class_depth + (event == :enter ? 1 : -1)
else
char_class_depth
end
end
rescue Regexp::Scanner::ScannerError
# Handle malformed patterns that are accepted by Ruby but cause the regexp_parser gem to
# error, see https://github.com/rubocop-hq/rubocop/issues/8083 for details
end
def escape_range_at_index(node, index)
regexp_begin = node.loc.begin.end_pos
start = regexp_begin + index
range_between(start, start + 2)
end
end
end
end
end