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Class: RuboCop::Cop::Style::RedundantLineContinuation

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::AutoCorrector, ::RuboCop::Cop::Base, ::RuboCop::ExcludeLimit, NodePattern::Macros, RuboCop::AST::Sexp
Instance Chain:
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/redundant_line_continuation.rb

Overview

Check for redundant line continuation.

This cop marks a line continuation as redundant if removing the backslash does not result in a syntax error. However, a backslash at the end of a comment or for string concatenation is not redundant and is not considered an offense.

Examples:

# bad
foo. \
  bar
foo \
  &.bar \
    .baz

# good
foo.
  bar
foo
  &.bar
    .baz

# bad
[foo, \
  bar]
{foo: \
  bar}

# good
[foo,
  bar]
{foo:
  bar}

# bad
foo(bar, \
  baz)

# good
foo(bar,
  baz)

# also good - backslash in string concatenation is not redundant
foo('bar' \
  'baz')

# also good - backslash at the end of a comment is not redundant
foo(bar, # \
  baz)

# also good - backslash at the line following the newline begins with a + or -,
# it is not redundant
1 \
  + 2 \
    - 3

# also good - backslash with newline between the method name and its arguments,
# it is not redundant.
some_method \
  (argument)

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::RangeHelp - Included

BYTE_ORDER_MARK, NOT_GIVEN

Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

::RuboCop::Cop::Base - Inherited

.gem_requirements, .lint?,
.support_autocorrect?

Returns if class supports autocorrect.

.support_multiple_source?

Override if your cop should be called repeatedly for multiple investigations Between calls to on_new_investigation and on_investigation_end, the result of processed_source will remain constant.

Class Method Summary

::RuboCop::Cop::Base - Inherited

.autocorrect_incompatible_with

List of cops that should not try to autocorrect at the same time as this cop.

.badge

Naming.

.callbacks_needed, .cop_name, .department,
.documentation_url

Returns an url to view this cops documentation online.

.exclude_from_registry

Call for abstract Cop classes.

.inherited,
.joining_forces

Override and return the Force class(es) you need to join.

.match?

Returns true if the cop name or the cop namespace matches any of the given names.

.new,
.requires_gem

Register a version requirement for the given gem name.

.restrict_on_send

::RuboCop::ExcludeLimit - Extended

exclude_limit

Sets up a configuration option to have an exclude limit tracked.

transform

Instance Attribute Summary

Instance Method Summary

::RuboCop::Cop::MatchRange - Included

#each_match_range

Return a new Range covering the first matching group number for each match of regex inside range.

#match_range

For a match inside range, return a new Range covering the match.

::RuboCop::Cop::RangeHelp - Included

#add_range, #column_offset_between,
#contents_range

A range containing only the contents of a literal with delimiters (e.g.

#directions,
#effective_column

Returns the column attribute of the range, except if the range is on the first line and there’s a byte order mark at the beginning of that line, in which case 1 is subtracted from the column value.

#final_pos, #move_pos, #move_pos_str, #range_between, #range_by_whole_lines, #range_with_comments, #range_with_comments_and_lines, #range_with_surrounding_comma, #range_with_surrounding_space, #source_range

::RuboCop::Cop::Base - Inherited

#add_global_offense

Adds an offense that has no particular location.

#add_offense

Adds an offense on the specified range (or node with an expression) Unless that offense is disabled for this range, a corrector will be yielded to provide the cop the opportunity to autocorrect the offense.

#begin_investigation

Called before any investigation.

#callbacks_needed,
#cop_config

Configuration Helpers.

#cop_name, #excluded_file?,
#external_dependency_checksum

This method should be overridden when a cop’s behavior depends on state that lives outside of these locations:

#inspect
#message

Gets called if no message is specified when calling add_offense or add_global_offense Cops are discouraged to override this; instead pass your message directly.

#name

Alias for Base#cop_name.

#offenses,
#on_investigation_end

Called after all on_…​

#on_new_investigation

Called before all on_…​

#on_other_file

Called instead of all on_…​

#parse

There should be very limited reasons for a Cop to do it’s own parsing.

#parser_engine,
#ready

Called between investigations.

#relevant_file?, #target_rails_version, #target_ruby_version, #annotate, #apply_correction, #attempt_correction,
#callback_argument

Reserved for Cop::Cop.

#complete_investigation

Called to complete an investigation.

#correct, #current_corrector,
#current_offense_locations

Reserved for Commissioner:

#current_offenses, #currently_disabled_lines, #custom_severity, #default_severity, #disable_uncorrectable, #enabled_line?, #file_name_matches_any?, #find_message, #find_severity, #range_for_original, #range_from_node_or_range,
#reset_investigation

Actually private methods.

#use_corrector

::RuboCop::Cop::AutocorrectLogic - Included

::RuboCop::Cop::IgnoredNode - Included

Constructor Details

This class inherits a constructor from RuboCop::Cop::Base

Instance Method Details

#argument_is_method?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 183

def argument_is_method?(node)
  return false unless node.send_type?
  return false unless (first_argument = node.first_argument)

  method_call_with_arguments?(first_argument)
end

#argument_newline?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 147

def argument_newline?(node)
  node = node.to_a.last if node.assignment?
  return false if node.parenthesized_call?

  node = node.children.first if node.root? && node.begin_type?

  if argument_is_method?(node)
    argument_newline?(node.first_argument)
  else
    return false unless method_call_with_arguments?(node)

    node.loc.selector.line != node.first_argument.loc.line
  end
end

#ends_with_backslash_without_comment?(source_line) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 102

def ends_with_backslash_without_comment?(source_line)
  source_line.gsub(/#.+/, '').end_with?('\\')
end

#find_node_for_line(line) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 163

def find_node_for_line(line)
  processed_source.ast.each_node do |node|
    return node if same_line?(node, line)
  end
end

#inside_string_literal?(range, token) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 132

def inside_string_literal?(range, token)
  ALLOWED_STRING_TOKENS.include?(token.type) && token.pos.overlaps?(range)
end

#inside_string_literal_or_method_with_argument?(range) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 110

def inside_string_literal_or_method_with_argument?(range)
  processed_source.tokens.each_cons(2).any? do |token, next_token|
    next if token.line == next_token.line

    inside_string_literal?(range, token) || method_with_argument?(token, next_token)
  end
end

#leading_dot_method_chain_with_blank_line?(range) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 118

def leading_dot_method_chain_with_blank_line?(range)
  return false unless range.source_line.strip.start_with?('.', '&.')

  processed_source[range.line].strip.empty?
end

#method_call_with_arguments?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 190

def method_call_with_arguments?(node)
  node.call_type? && !node.arguments.empty?
end

#method_with_argument?(current_token, next_token) ⇒ Boolean (private)

A method call without parentheses such as the following cannot remove \:

do_something \
  argument
[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 140

def method_with_argument?(current_token, next_token)
  return false unless ARGUMENT_TAKING_FLOW_TOKEN_TYPES.include?(current_token.type)

  ARGUMENT_TYPES.include?(next_token.type)
end

#on_new_investigation

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 79

def on_new_investigation
  return unless processed_source.ast

  each_match_range(processed_source.ast.source_range, /(\\\n)/) do |range|
    next if require_line_continuation?(range)
    next unless redundant_line_continuation?(range)

    add_offense(range) do |corrector|
      corrector.remove_leading(range, 1)
    end
  end
end

#redundant_line_continuation?(range) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 124

def redundant_line_continuation?(range)
  return true unless (node = find_node_for_line(range.line))
  return false if argument_newline?(node)

  source = node.parent ? node.parent.source : node.source
  parse(source.gsub("\\\n", "\n")).valid_syntax?
end

#require_line_continuation?(range) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 94

def require_line_continuation?(range)
  !ends_with_backslash_without_comment?(range.source_line) ||
    string_concatenation?(range.source_line) ||
    start_with_arithmetic_operator?(processed_source[range.line]) ||
    inside_string_literal_or_method_with_argument?(range) ||
    leading_dot_method_chain_with_blank_line?(range)
end

#same_line?(node, line) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 169

def same_line?(node, line)
  return false unless (source_range = node.source_range)

  if node.is_a?(AST::StrNode)
    if node.heredoc?
      (node.loc.heredoc_body.line..node.loc.heredoc_body.last_line).cover?(line)
    else
      (source_range.line..source_range.last_line).cover?(line)
    end
  else
    source_range.line == line
  end
end

#start_with_arithmetic_operator?(source_line) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 194

def start_with_arithmetic_operator?(source_line)
  %r{\A\s*[+\-*/%]}.match?(source_line)
end

#string_concatenation?(source_line) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_line_continuation.rb', line 106

def string_concatenation?(source_line)
  /["']\s*\\\z/.match?(source_line)
end