module RuboCop::Cop::CheckLineBreakable

This mixin detects collections that are safe to “break” by inserting new lines. This is useful for breaking up long lines.

Let’s look at hashes as an example:

We know hash keys are safe to break across lines. We can add linebreaks into hashes on lines longer than the specified maximum. Then in further passes cops can clean up the multi-line hash. For example, say the maximum line length is as indicated below:

|
v

{foo: “0000000000”, bar: “0000000000”, baz: “0000000000”}

In a LineLength autocorrection pass, a line is added before the first key that exceeds the column limit:

{foo: “0000000000”, bar: “0000000000”, baz: “0000000000”}

In a MultilineHashKeyLineBreaks pass, lines are inserted before all keys:

{foo: “0000000000”, bar: “0000000000”, baz: “0000000000”}

Then in future passes FirstHashElementLineBreak, MultilineHashBraceLayout, and TrailingCommaInHashLiteral will manipulate as well until we get:

{

foo: "0000000000",
bar: "0000000000",
baz: "0000000000",

}

(Note: Passes may not happen exactly in this sequence.)

Public Instance Methods

extract_breakable_node(node, max) click to toggle source
# File lib/rubocop/cop/mixin/check_line_breakable.rb, line 45
def extract_breakable_node(node, max)
  if node.send_type?
    args = process_args(node.arguments)
    return extract_breakable_node_from_elements(node, args, max)
  elsif node.def_type?
    return extract_breakable_node_from_elements(node, node.arguments, max)
  elsif node.array_type? || node.hash_type?
    return extract_breakable_node_from_elements(node, node.children, max)
  end
  nil
end

Private Instance Methods

all_on_same_line?(nodes) click to toggle source

@api private

# File lib/rubocop/cop/mixin/check_line_breakable.rb, line 200
def all_on_same_line?(nodes)
  return true if nodes.empty?

  nodes.first.first_line == nodes.last.last_line
end
already_on_multiple_lines?(node) click to toggle source

@api private

# File lib/rubocop/cop/mixin/check_line_breakable.rb, line 220
def already_on_multiple_lines?(node)
  return node.first_line != node.arguments.last.last_line if node.def_type?

  !node.single_line?
end
breakable_collection?(node, elements) click to toggle source

@api private

# File lib/rubocop/cop/mixin/check_line_breakable.rb, line 133
def breakable_collection?(node, elements)
  # For simplicity we only want to insert breaks in normal
  # hashes wrapped in a set of curly braces like {foo: 1}.
  # That is, not a kwargs hash. For method calls, this ensures
  # the method call is made with parens.
  starts_with_bracket = !node.hash_type? || node.loc.begin

  # If the call has a second argument, we can insert a line
  # break before the second argument and the rest of the
  # argument will get auto-formatted onto separate lines
  # by other cops.
  has_second_element = elements.length >= 2

  starts_with_bracket && has_second_element
end
children_could_be_broken_up?(children) click to toggle source

@api private

# File lib/rubocop/cop/mixin/check_line_breakable.rb, line 187
def children_could_be_broken_up?(children)
  return false if all_on_same_line?(children)

  last_seen_line = -1
  children.each do |child|
    return true if last_seen_line >= child.first_line

    last_seen_line = child.last_line
  end
  false
end
contained_by_breakable_collection_on_same_line?(node) click to toggle source

@api private

# File lib/rubocop/cop/mixin/check_line_breakable.rb, line 150
def contained_by_breakable_collection_on_same_line?(node)
  node.each_ancestor.find do |ancestor|
    # Ignore ancestors on different lines.
    break if ancestor.first_line != node.first_line

    if ancestor.hash_type? || ancestor.array_type?
      elements = ancestor.children
    elsif ancestor.send_type?
      elements = process_args(ancestor.arguments)
    else
      next
    end

    return true if breakable_collection?(ancestor, elements)
  end

  false
end
contained_by_multiline_collection_that_could_be_broken_up?(node) click to toggle source

@api private

# File lib/rubocop/cop/mixin/check_line_breakable.rb, line 170
def contained_by_multiline_collection_that_could_be_broken_up?(node)
  node.each_ancestor.find do |ancestor|
    if (ancestor.hash_type? || ancestor.array_type?) &&
       breakable_collection?(ancestor, ancestor.children)
      return children_could_be_broken_up?(ancestor.children)
    end

    next unless ancestor.send_type?

    args = process_args(ancestor.arguments)
    return children_could_be_broken_up?(args) if breakable_collection?(ancestor, args)
  end

  false
end
extract_breakable_node_from_elements(node, elements, max) click to toggle source

@api private

# File lib/rubocop/cop/mixin/check_line_breakable.rb, line 60
def extract_breakable_node_from_elements(node, elements, max)
  return unless breakable_collection?(node, elements)
  return if safe_to_ignore?(node)

  line = processed_source.lines[node.first_line - 1]
  return if processed_source.line_with_comment?(node.loc.line)
  return if line.length <= max

  extract_first_element_over_column_limit(node, elements, max)
end
extract_first_element_over_column_limit(node, elements, max) click to toggle source

@api private

# File lib/rubocop/cop/mixin/check_line_breakable.rb, line 72
def extract_first_element_over_column_limit(node, elements, max)
  line = node.first_line

  # If a `send` node is not parenthesized, don't move the first element, because it
  # can result in changed behavior or a syntax error.
  if node.send_type? && !node.parenthesized? && !first_argument_is_heredoc?(node)
    elements = elements.drop(1)
  end

  i = 0
  i += 1 while within_column_limit?(elements[i], max, line)
  i = shift_elements_for_heredoc_arg(node, elements, i)

  return if i.nil?
  return elements.first if i.zero?

  elements[i - 1]
end
first_argument_is_heredoc?(node) click to toggle source

@api private

# File lib/rubocop/cop/mixin/check_line_breakable.rb, line 92
def first_argument_is_heredoc?(node)
  first_argument = node.first_argument

  first_argument.respond_to?(:heredoc?) && first_argument.heredoc?
end
process_args(args) click to toggle source

@api private

# File lib/rubocop/cop/mixin/check_line_breakable.rb, line 207
def process_args(args)
  # If there is a trailing hash arg without explicit braces, like this:
  #
  #    method(1, 'key1' => value1, 'key2' => value2)
  #
  # ...then each key/value pair is treated as a method 'argument'
  # when determining where line breaks should appear.
  last_arg = args.last
  args = args[0...-1] + last_arg.children if last_arg&.hash_type? && !last_arg&.braces?
  args
end
safe_to_ignore?(node) click to toggle source

@api private

# File lib/rubocop/cop/mixin/check_line_breakable.rb, line 117
def safe_to_ignore?(node)
  return true unless max
  return true if already_on_multiple_lines?(node)

  # If there's a containing breakable collection on the same
  # line, we let that one get broken first. In a separate pass,
  # this one might get broken as well, but to avoid conflicting
  # or redundant edits, we only mark one offense at a time.
  return true if contained_by_breakable_collection_on_same_line?(node)

  return true if contained_by_multiline_collection_that_could_be_broken_up?(node)

  false
end
shift_elements_for_heredoc_arg(node, elements, index) click to toggle source

@api private If a send node contains a heredoc argument, splitting cannot happen after the heredoc or else it will cause a syntax error.

# File lib/rubocop/cop/mixin/check_line_breakable.rb, line 101
def shift_elements_for_heredoc_arg(node, elements, index)
  return index unless node.send_type? || node.array_type?

  heredoc_index = elements.index { |arg| arg.respond_to?(:heredoc?) && arg.heredoc? }
  return index unless heredoc_index
  return nil if heredoc_index.zero?

  heredoc_index >= index ? index : heredoc_index + 1
end
within_column_limit?(element, max, line) click to toggle source

@api private

# File lib/rubocop/cop/mixin/check_line_breakable.rb, line 112
def within_column_limit?(element, max, line)
  element && element.loc.column <= max && element.loc.line == line
end