class RuboCop::Cop::Style::MapIntoArray


dest
src.each { |e| dest << e * 2; puts e }
dest = []
# good - contains another operation
dest = src.map { |e| e * 2 }
# good
dest
src.each { |e| dest << e * 2 }
dest = []
# bad
@example
(e.g. ‘Enumerator::Lazy`).
with a block, not all objects that have a `map` method return an array
method also have a `map` method (e.g. `ENV`). Additionally, for calls
This cop is unsafe because not all objects that have an `each`
@safety
—-
src.each { |e| dest << transform(e, dest) } # `transform` method may mutate `dest`
dest = []
src.each { |e| ret << e * 2 } # `<<` method may mutate `ret`
ret = []
mapping destination variable remains an empty array:
This is because, if not, it’s challenging to statically guarantee that the
initialized as an empty array and referred to only by the pushing operation.
NOTE: It only detects when the mapping destination is a local variable
when a return value could be used because these types differ.
return value of ‘Enumerable#map` is an `Array`. They are not autocorrected
NOTE: The return value of `Enumerable#each` is `self`, whereas the
this cop uses the specified method for replacement.
If `PreferredMethods` is configured for `map` in `Style/CollectionMethods`,
can be replaced by `map`.
Checks for usages of `each` with `<<`, `push`, or `append` which

def self.joining_forces 

def self.joining_forces
  VariableForce
end

def after_leaving_scope(scope, _variable_table) 

def after_leaving_scope(scope, _variable_table)
  (@scopes ||= []) << scope
end

def correct_push_node(corrector, push_node) 

def correct_push_node(corrector, push_node)
  range = push_node.source_range
  arg_range = push_node.first_argument.source_range
  corrector.remove(range_between(range.begin_pos, arg_range.begin_pos))
  corrector.remove(range_between(arg_range.end_pos, range.end_pos))
end

def correct_return_value_handling(corrector, block, dest_var) 

def correct_return_value_handling(corrector, block, dest_var)
  next_node = block.right_sibling
  if lvar_ref?(next_node, dest_var.name)
    corrector.remove(range_with_surrounding_space(next_node.source_range, side: :left))
  end
  corrector.insert_before(block, "#{dest_var.name} = ")
end

def dest_used_only_for_mapping?(block, dest_var, asgn) 

def dest_used_only_for_mapping?(block, dest_var, asgn)
  range = asgn.source_range.join(block.source_range)
  asgn.parent.equal?(block.parent) &&
    dest_var.references.one? { |r| range.contains?(r.node.source_range) } &&
    dest_var.assignments.one? { |a| range.contains?(a.node.source_range) }
end

def find_closest_assignment(block, dest_var) 

def find_closest_assignment(block, dest_var)
  dest_var.assignments.reverse_each.lazy.map(&:node).find do |node|
    node.source_range.end_pos < block.source_range.begin_pos
  end
end

def find_dest_var(block) 

def find_dest_var(block)
  node = block.body.receiver
  name = node.children.first
  candidates = @scopes.lazy.filter_map { |s| s.variables[name] }
  candidates.find { |v| v.references.any? { |n| n.node.equal?(node) } }
end

def new_method_name 

def new_method_name
  default = 'map'
  alternative = config.for_cop('Style/CollectionMethods').dig('PreferredMethods', default)
  alternative || default
end

def on_block(node) 

def on_block(node)
  return unless each_block_with_push?(node)
  dest_var = find_dest_var(node)
  return unless (asgn = find_closest_assignment(node, dest_var))
  return unless empty_array_asgn?(asgn)
  return unless dest_used_only_for_mapping?(node, dest_var, asgn)
  register_offense(node, dest_var, asgn)
end

def register_offense(block, dest_var, asgn) 

def register_offense(block, dest_var, asgn)
  add_offense(block, message: format(MSG, new_method_name: new_method_name)) do |corrector|
    next if return_value_used?(block)
    corrector.replace(block.send_node.selector, new_method_name)
    remove_assignment(corrector, asgn)
    correct_push_node(corrector, block.body)
    correct_return_value_handling(corrector, block, dest_var)
  end
end

def remove_assignment(corrector, asgn) 

def remove_assignment(corrector, asgn)
  range = range_with_surrounding_space(asgn.source_range, side: :right)
  range = range_with_surrounding_space(range, side: :right, newlines: false)
  corrector.remove(range)
end

def return_value_used?(node) 

def return_value_used?(node)
  parent = node.parent
  case parent&.type
  when nil
    false
  when :begin, :kwbegin
    !node.right_sibling && return_value_used?(parent)
  else
    !parent.respond_to?(:void_context?) || !parent.void_context?
  end
end