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Class: RuboCop::Cop::Style::MapCompactWithConditionalBlock

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/map_compact_with_conditional_block.rb

Overview

Prefer select or reject over map { …​ }.compact. This cop also handles filter_map { …​ }, similar to map { …​ }.compact.

Examples:

# bad
array.map { |e| some_condition? ? e : next }.compact

# bad
array.filter_map { |e| some_condition? ? e : next }

# bad
array.map do |e|
  if some_condition?
    e
  else
    next
  end
end.compact

# bad
array.map do |e|
  next if some_condition?

  e
end.compact

# bad
array.map do |e|
  e if some_condition?
end.compact

# good
array.select { |e| some_condition? }

# good
array.reject { |e| some_condition? }

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

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::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

#conditional_block(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/map_compact_with_conditional_block.rb', line 51

def_node_matcher :conditional_block, <<~RUBY
  (block
    (call _ {:map :filter_map})
    (args
      $(arg _))
    {
      (if $_ $(lvar _) {next nil?})
      (if $_ {next nil?} $(lvar _))
      (if $_ (next $(lvar _)) {next nil nil?})
      (if $_ {next nil nil?} (next $(lvar _)))
      (begin
        {
          (if $_ next nil?)
          (if $_ nil? next)
        }
        $(lvar _))
      (begin
        {
          (if $_ (next $(lvar _)) nil?)
          (if $_ nil? (next $(lvar _)))
        }
        (nil))
    })
RUBY

#current(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/map_compact_with_conditional_block.rb', line 148

def current(node)
  if node.method?(:compact)
    map_or_filter_map_method = node.children.first

    "#{map_or_filter_map_method.method_name} { ... }.compact"
  else
    'filter_map { ... }'
  end
end

#filter_map_range(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/map_compact_with_conditional_block.rb', line 162

def filter_map_range(node)
  node.loc.selector.join(node.parent.source_range.end)
end

#inspect(node, block_argument_node, condition_node, return_value_node, range) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/map_compact_with_conditional_block.rb', line 96

def inspect(node, block_argument_node, condition_node, return_value_node, range)
  return unless returns_block_argument?(block_argument_node, return_value_node)
  return if condition_node.parent.elsif?

  method = truthy_branch?(return_value_node) ? 'select' : 'reject'
  current = current(node)

  add_offense(range, message: format(MSG, current: current, method: method)) do |corrector|
    return if part_of_ignored_node?(node) || ignored_node?(node)

    corrector.replace(
      range, "#{method} { |#{block_argument_node.source}| #{condition_node.source} }"
    )

    ignore_node(node)
  end
end

#map_with_compact_range(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/map_compact_with_conditional_block.rb', line 158

def map_with_compact_range(node)
  node.receiver.send_node.loc.selector.begin.join(node.source_range.end)
end

#on_csend(node)

Alias for #on_send.

[ GitHub ]

  
# File 'lib/rubocop/cop/style/map_compact_with_conditional_block.rb', line 92

alias on_csend on_send

#on_send(node) Also known as: #on_csend

[ GitHub ]

  
# File 'lib/rubocop/cop/style/map_compact_with_conditional_block.rb', line 76

def on_send(node)
  map_candidate = node.children.first
  if (block_argument, condition, return_value = conditional_block(map_candidate))
    return unless node.method?(:compact) && node.arguments.empty?

    range = map_with_compact_range(node)
  elsif (block_argument, condition, return_value = conditional_block(node.parent))
    return unless node.method?(:filter_map)

    range = filter_map_range(node)
  else
    return
  end

  inspect(node, block_argument, condition, return_value, range)
end

#returns_block_argument?(block_argument_node, return_value_node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/map_compact_with_conditional_block.rb', line 114

def returns_block_argument?(block_argument_node, return_value_node)
  block_argument_node.name == return_value_node.children.first
end

#truthy_branch?(node) ⇒ Boolean (private)

[ GitHub ]

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

def truthy_branch?(node)
  if node.parent.begin_type?
    truthy_branch_for_guard?(node)
  elsif node.parent.next_type?
    truthy_branch_for_if?(node.parent)
  else
    truthy_branch_for_if?(node)
  end
end

#truthy_branch_for_guard?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/map_compact_with_conditional_block.rb', line 138

def truthy_branch_for_guard?(node)
  if_node = node.left_sibling

  if if_node.if?
    if_node.if_branch.arguments.any?
  else
    if_node.if_branch.arguments.none?
  end
end

#truthy_branch_for_if?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/map_compact_with_conditional_block.rb', line 128

def truthy_branch_for_if?(node)
  if_node = node.parent

  if if_node.if? || if_node.ternary?
    if_node.if_branch == node
  elsif if_node.unless?
    if_node.else_branch == node
  end
end