class RuboCop::Cop::Style::DocumentDynamicEvalDefinition

When using ‘class_eval` (or other `eval`) with string interpolation, add a comment block showing its appearance if interpolated (a practice used in Rails code).

@example

# from activesupport/lib/active_support/core_ext/string/output_safety.rb

# bad
UNSAFE_STRING_METHODS.each do |unsafe_method|
  if 'String'.respond_to?(unsafe_method)
    class_eval <<-EOT, __FILE__, __LINE__ + 1
      def #{unsafe_method}(*params, &block)
        to_str.#{unsafe_method}(*params, &block)
      end

      def #{unsafe_method}!(*params)
        @dirty = true
        super
      end
    EOT
  end
end

# good, inline comments in heredoc
UNSAFE_STRING_METHODS.each do |unsafe_method|
  if 'String'.respond_to?(unsafe_method)
    class_eval <<-EOT, __FILE__, __LINE__ + 1
      def #{unsafe_method}(*params, &block)       # def capitalize(*params, &block)
        to_str.#{unsafe_method}(*params, &block)  #   to_str.capitalize(*params, &block)
      end                                         # end

      def #{unsafe_method}!(*params)              # def capitalize!(*params)
        @dirty = true                             #   @dirty = true
        super                                     #   super
      end                                         # end
    EOT
  end
end

# good, block comments in heredoc
class_eval <<-EOT, __FILE__, __LINE__ + 1
  # def capitalize!(*params)
  #   @dirty = true
  #   super
  # end

  def #{unsafe_method}!(*params)
    @dirty = true
    super
  end
EOT

# good, block comments before heredoc
class_eval(
  # def capitalize!(*params)
  #   @dirty = true
  #   super
  # end

  <<-EOT, __FILE__, __LINE__ + 1
    def #{unsafe_method}!(*params)
      @dirty = true
      super
    end
  EOT
)

# bad - interpolated string without comment
class_eval("def #{unsafe_method}!(*params); end")

# good - with inline comment or replace it with block comment using heredoc
class_eval("def #{unsafe_method}!(*params); end # def capitalize!(*params); end")

Constants

BLOCK_COMMENT_REGEXP
COMMENT_REGEXP
MSG
RESTRICT_ON_SEND

Public Instance Methods

on_send(node) click to toggle source
# File lib/rubocop/cop/style/document_dynamic_eval_definition.rb, line 84
def on_send(node)
  arg_node = node.first_argument

  return unless arg_node&.dstr_type? && interpolated?(arg_node)
  return if inline_comment_docs?(arg_node) ||
            (arg_node.heredoc? && comment_block_docs?(arg_node))

  add_offense(node.loc.selector)
end

Private Instance Methods

comment_block_docs?(arg_node) click to toggle source
# File lib/rubocop/cop/style/document_dynamic_eval_definition.rb, line 107
def comment_block_docs?(arg_node)
  comments = heredoc_comment_blocks(arg_node.loc.heredoc_body.line_span)
             .concat(preceding_comment_blocks(arg_node.parent))

  return false if comments.none?

  regexp = comment_regexp(arg_node)
  comments.any?(regexp) || regexp.match?(comments.join)
end
comment_regexp(arg_node) click to toggle source
# File lib/rubocop/cop/style/document_dynamic_eval_definition.rb, line 147
def comment_regexp(arg_node)
  # Replace the interpolations with wildcards
  regexp_parts = arg_node.child_nodes.map do |n|
    n.begin_type? ? /.+/ : source_to_regexp(n.source)
  end

  Regexp.new(regexp_parts.join)
end
heredoc_comment_blocks(heredoc_body) click to toggle source
# File lib/rubocop/cop/style/document_dynamic_eval_definition.rb, line 126
def heredoc_comment_blocks(heredoc_body)
  # Collect comments inside the heredoc
  line_range = (heredoc_body.begin - 1)..(heredoc_body.end - 1)
  lines = processed_source.lines[line_range]

  lines.each_with_object({}).with_index(line_range.begin) do |(line, hash), index|
    merge_adjacent_comments(line, index, hash)
  end.values
end
inline_comment_docs?(node) click to toggle source
# File lib/rubocop/cop/style/document_dynamic_eval_definition.rb, line 100
def inline_comment_docs?(node)
  node.each_child_node(:begin).all? do |begin_node|
    source_line = processed_source.lines[begin_node.first_line - 1]
    source_line.match?(COMMENT_REGEXP)
  end
end
interpolated?(arg_node) click to toggle source
# File lib/rubocop/cop/style/document_dynamic_eval_definition.rb, line 96
def interpolated?(arg_node)
  arg_node.each_child_node(:begin).any?
end
merge_adjacent_comments(line, index, hash) click to toggle source
# File lib/rubocop/cop/style/document_dynamic_eval_definition.rb, line 136
def merge_adjacent_comments(line, index, hash)
  # Combine adjacent comment lines into a single string
  return unless (line = line.dup.gsub!(BLOCK_COMMENT_REGEXP, ''))

  hash[index] = if hash.keys.last == index - 1
                  [hash.delete(index - 1), line].join("\n")
                else
                  line
                end
end
preceding_comment_blocks(node) click to toggle source
# File lib/rubocop/cop/style/document_dynamic_eval_definition.rb, line 117
def preceding_comment_blocks(node)
  # Collect comments in the method call, but outside the heredoc
  comments = processed_source.each_comment_in_lines(node.source_range.line_span)

  comments.each_with_object({}) do |comment, hash|
    merge_adjacent_comments(comment.text, comment.loc.line, hash)
  end.values
end
source_to_regexp(source) click to toggle source
# File lib/rubocop/cop/style/document_dynamic_eval_definition.rb, line 156
def source_to_regexp(source)
  # Get the source in the heredoc being `eval`ed, without any comments
  # and turn it into a regexp
  return /\s+/ if source.blank?

  source = source.gsub(COMMENT_REGEXP, '')
  return if source.blank?

  /\s*#{Regexp.escape(source.strip)}/
end