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Class: RuboCop::Cop::Style::FormatString

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/format_string.rb

Overview

Enforces the use of a single string formatting utility. Valid options include Kernel#format, Kernel#sprintf, and String#%.

The detection of String#% cannot be implemented in a reliable manner for all cases, so only two scenarios are considered - if the first argument is a string literal and if the second argument is an array literal.

Autocorrection will be applied when using argument is a literal or known built-in conversion methods such as to_d, to_f, to_h, to_i, to_r, to_s, and to_sym on variables, provided that their return value is not an array. For example, when using to_s, '%s' % [1, 2, 3].to_s can be autocorrected without any incompatibility:

'%s' % [1, 2, 3]        #=> '1'
format('%s', [1, 2, 3]) #=> '[1, 2, 3]'
'%s' % [1, 2, 3].to_s   #=> '[1, 2, 3]'

Examples:

EnforcedStyle: format (default)

# bad
puts sprintf('%10s', 'foo')
puts '%10s' % 'foo'

# good
puts format('%10s', 'foo')

EnforcedStyle: sprintf

# bad
puts format('%10s', 'foo')
puts '%10s' % 'foo'

# good
puts sprintf('%10s', 'foo')

EnforcedStyle: percent

# bad
puts format('%10s', 'foo')
puts sprintf('%10s', 'foo')

# good
puts '%10s' % 'foo'

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

SYMBOL_TO_STRING_CACHE

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::ConfigurableEnforcedStyle - Included

::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

#autocorrect(corrector, node) (private)

[ GitHub ]

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

def autocorrect(corrector, node)
  return if variable_argument?(node)

  case node.method_name
  when :%
    autocorrect_from_percent(corrector, node)
  when :format, :sprintf
    case style
    when :percent
      autocorrect_to_percent(corrector, node)
    when :format, :sprintf
      corrector.replace(node.loc.selector, style.to_s)
    end
  end
end

#autocorrect_from_percent(corrector, node) (private)

[ GitHub ]

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

def autocorrect_from_percent(corrector, node)
  percent_rhs = node.first_argument
  args = case percent_rhs.type
         when :array, :hash
           percent_rhs.children.map(&:source).join(', ')
         else
           percent_rhs.source
         end

  corrected = "#{style}(#{node.receiver.source}, #{args})"

  corrector.replace(node, corrected)
end

#autocorrect_to_percent(corrector, node) (private)

[ GitHub ]

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

def autocorrect_to_percent(corrector, node)
  format_arg, *param_args = node.arguments
  format = format_arg.source

  args = if param_args.one?
           format_single_parameter(param_args.last)
         else
           "[#{param_args.map(&:source).join(', ')}]"
         end

  corrector.replace(node, "#{format} % #{args}")
end

#autocorrectable?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/format_string.rb', line 88

def autocorrectable?(node)
  return true if node.lvar_type?

  node.send_type? && !AUTOCORRECTABLE_METHODS.include?(node.method_name)
end

#format_single_parameter(arg) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/format_string.rb', line 145

def format_single_parameter(arg)
  source = arg.source
  return "{ #{source} }" if arg.hash_type?

  arg.send_type? && arg.operator_method? && !arg.parenthesized? ? "(#{source})" : source
end

#formatter(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/format_string.rb', line 61

def_node_matcher :formatter, <<~PATTERN
  {
    (send nil? ${:sprintf :format} _ _ ...)
    (send {str dstr} $:% ... )
    (send !nil? $:% {array hash})
  }
PATTERN

#message(detected_style) (private)

[ GitHub ]

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

def message(detected_style)
  format(MSG, prefer: method_name(style), current: method_name(detected_style))
end

#method_name(style_name) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/format_string.rb', line 98

def method_name(style_name)
  style_name == :percent ? 'String#%' : style_name
end

#on_send(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/format_string.rb', line 74

def on_send(node)
  formatter(node) do |selector|
    detected_style = selector == :% ? :percent : selector

    return if detected_style == style

    add_offense(node.loc.selector, message: message(detected_style)) do |corrector|
      autocorrect(corrector, node)
    end
  end
end

#variable_argument?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/format_string.rb', line 70

def_node_matcher :variable_argument?, <<~PATTERN
  (send {str dstr} :% #autocorrectable?)
PATTERN