class RuboCop::Cop::Style::RedundantInterpolation

Checks for strings that are just an interpolated expression.

@safety

Autocorrection is unsafe because when calling a destructive method to string,
the resulting string may have different behavior or raise `FrozenError`.

[source,ruby]
----
x = 'a'
y = "#{x}"
y << 'b'   # return 'ab'
x          # return 'a'
y = x.to_s
y << 'b'   # return 'ab'
x          # return 'ab'

x = 'a'.freeze
y = "#{x}"
y << 'b'   # return 'ab'.
y = x.to_s
y << 'b'   # raise `FrozenError`.
----

@example

# bad
"#{@var}"

# good
@var.to_s

# good if @var is already a String
@var

Constants

MSG

Public Class Methods

autocorrect_incompatible_with() click to toggle source
# File lib/rubocop/cop/style/redundant_interpolation.rb, line 45
def self.autocorrect_incompatible_with
  [Style::LineEndConcatenation]
end

Public Instance Methods

on_dstr(node) click to toggle source
# File lib/rubocop/cop/style/redundant_interpolation.rb, line 49
def on_dstr(node)
  return unless single_interpolation?(node)

  add_offense(node) do |corrector|
    embedded_node = node.children.first

    if variable_interpolation?(embedded_node)
      autocorrect_variable_interpolation(corrector, embedded_node, node)
    elsif single_variable_interpolation?(embedded_node)
      autocorrect_single_variable_interpolation(corrector, embedded_node, node)
    else
      autocorrect_other(corrector, embedded_node, node)
    end
  end
end

Private Instance Methods

autocorrect_other(corrector, embedded_node, node) click to toggle source
# File lib/rubocop/cop/style/redundant_interpolation.rb, line 122
def autocorrect_other(corrector, embedded_node, node)
  loc = node.loc
  embedded_loc = embedded_node.loc

  corrector.replace(loc.begin, '')
  corrector.replace(loc.end, '')
  corrector.replace(embedded_loc.begin, '(')
  corrector.replace(embedded_loc.end, ').to_s')
end
autocorrect_single_variable_interpolation(corrector, embedded_node, node) click to toggle source
# File lib/rubocop/cop/style/redundant_interpolation.rb, line 105
def autocorrect_single_variable_interpolation(corrector, embedded_node, node)
  embedded_var = embedded_node.children.first

  source = if require_parentheses?(embedded_var)
             receiver = range_between(
               embedded_var.source_range.begin_pos, embedded_var.loc.selector.end_pos
             )
             arguments = embedded_var.arguments.map(&:source).join(', ')

             "#{receiver.source}(#{arguments})"
           else
             embedded_var.source
           end

  corrector.replace(node, "#{source}.to_s")
end
autocorrect_variable_interpolation(corrector, embedded_node, node) click to toggle source
# File lib/rubocop/cop/style/redundant_interpolation.rb, line 99
def autocorrect_variable_interpolation(corrector, embedded_node, node)
  replacement = "#{embedded_node.source}.to_s"

  corrector.replace(node, replacement)
end
embedded_in_percent_array?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_interpolation.rb, line 95
def embedded_in_percent_array?(node)
  node.parent&.array_type? && percent_literal?(node.parent)
end
implicit_concatenation?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_interpolation.rb, line 91
def implicit_concatenation?(node)
  node.parent&.dstr_type?
end
interpolation?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_interpolation.rb, line 83
def interpolation?(node)
  variable_interpolation?(node) || node.begin_type?
end
require_parentheses?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_interpolation.rb, line 132
def require_parentheses?(node)
  node.send_type? && !node.arguments.count.zero? && !node.parenthesized_call?
end
single_interpolation?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_interpolation.rb, line 67
def single_interpolation?(node)
  node.children.one? &&
    interpolation?(node.children.first) &&
    !implicit_concatenation?(node) &&
    !embedded_in_percent_array?(node)
end
single_variable_interpolation?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_interpolation.rb, line 74
def single_variable_interpolation?(node)
  return false unless node.children.one?

  first_child = node.children.first

  variable_interpolation?(first_child) ||
    (first_child.send_type? && !first_child.operator_method?)
end
variable_interpolation?(node) click to toggle source
# File lib/rubocop/cop/style/redundant_interpolation.rb, line 87
def variable_interpolation?(node)
  node.variable? || node.reference?
end