class RuboCop::Cop::Lint::Void

Checks for operators, variables, literals, lambda, proc and nonmutating methods used in void context.

@example CheckForMethodsWithNoSideEffects: false (default)

# bad
def some_method
  some_num * 10
  do_something
end

def some_method(some_var)
  some_var
  do_something
end

@example CheckForMethodsWithNoSideEffects: true

# bad
def some_method(some_array)
  some_array.sort
  do_something(some_array)
end

# good
def some_method
  do_something
  some_num * 10
end

def some_method(some_var)
  do_something
  some_var
end

def some_method(some_array)
  some_array.sort!
  do_something(some_array)
end

Constants

BINARY_OPERATORS
EXPRESSION_MSG
LIT_MSG
METHODS_REPLACEABLE_BY_EACH
NONMUTATING_METHODS
NONMUTATING_METHODS_WITH_BANG_VERSION
NONMUTATING_MSG
OPERATORS
OP_MSG
SELF_MSG
UNARY_OPERATORS
VAR_MSG
VOID_CONTEXT_TYPES

Public Instance Methods

on_begin(node) click to toggle source

# File lib/rubocop/cop/lint/void.rb, line 80
def on_begin(node)
  check_begin(node)
end

Also aliased as: on_kwbegin

on_block(node) click to toggle source

# File lib/rubocop/cop/lint/void.rb, line 71
def on_block(node)
  return unless node.body && !node.body.begin_type?
  return unless in_void_context?(node.body)

  check_expression(node.body)
end

Also aliased as: on_numblock

on_kwbegin(node)

Alias for: on_begin

on_numblock(node)

Alias for: on_block

Private Instance Methods

autocorrect_nonmutating_send(corrector, node, suggestion) click to toggle source

# File lib/rubocop/cop/lint/void.rb, line 194
def autocorrect_nonmutating_send(corrector, node, suggestion)
  send_node = if node.send_type?
                node
              else
                node.send_node
              end
  corrector.replace(send_node.loc.selector, suggestion)
end

autocorrect_void_expression(corrector, node) click to toggle source

# File lib/rubocop/cop/lint/void.rb, line 190
def autocorrect_void_expression(corrector, node)
  corrector.remove(range_with_surrounding_space(range: node.source_range, side: :left))
end

autocorrect_void_op(corrector, node) click to toggle source

# File lib/rubocop/cop/lint/void.rb, line 178
def autocorrect_void_op(corrector, node)
  if node.arguments.empty?
    corrector.replace(node, node.receiver.source)
  else
    corrector.replace(
      range_with_surrounding_space(range: node.loc.selector, side: :both,
                                   newlines: false),
      "\n"
    )
  end
end

check_begin(node) click to toggle source

# File lib/rubocop/cop/lint/void.rb, line 87
def check_begin(node)
  expressions = *node
  expressions.pop unless in_void_context?(node)
  expressions.each { |expr| check_expression(expr) }
end

check_expression(expr) click to toggle source

# File lib/rubocop/cop/lint/void.rb, line 93
def check_expression(expr)
  check_void_op(expr)
  check_literal(expr)
  check_var(expr)
  check_self(expr)
  check_void_expression(expr)
  return unless cop_config['CheckForMethodsWithNoSideEffects']

  check_nonmutating(expr)
end

check_literal(node) click to toggle source

# File lib/rubocop/cop/lint/void.rb, line 128
def check_literal(node)
  return if !node.literal? || node.xstr_type? || node.range_type?

  add_offense(node, message: format(LIT_MSG, lit: node.source)) do |corrector|
    autocorrect_void_expression(corrector, node)
  end
end

check_nonmutating(node) click to toggle source

# File lib/rubocop/cop/lint/void.rb, line 152
def check_nonmutating(node)
  return if !node.send_type? && !node.block_type? && !node.numblock_type?

  method_name = node.method_name
  return unless NONMUTATING_METHODS.include?(method_name)

  suggestion = if METHODS_REPLACEABLE_BY_EACH.include?(method_name)
                 'each'
               else
                 "#{method_name}!"
               end
  add_offense(node,
              message: format(NONMUTATING_MSG, method: method_name,
                                               suggest: suggestion)) do |corrector|
    autocorrect_nonmutating_send(corrector, node, suggestion)
  end
end

check_self(node) click to toggle source

# File lib/rubocop/cop/lint/void.rb, line 136
def check_self(node)
  return unless node.self_type?

  add_offense(node, message: SELF_MSG) do |corrector|
    autocorrect_void_expression(corrector, node)
  end
end

check_var(node) click to toggle source

# File lib/rubocop/cop/lint/void.rb, line 113
def check_var(node)
  return unless node.variable? || node.const_type?

  if node.const_type? && node.special_keyword?
    add_offense(node, message: format(VAR_MSG, var: node.source)) do |corrector|
      autocorrect_void_expression(corrector, node)
    end
  else
    add_offense(node.loc.name,
                message: format(VAR_MSG, var: node.loc.name.source)) do |corrector|
      autocorrect_void_expression(corrector, node)
    end
  end
end

check_void_expression(node) click to toggle source

# File lib/rubocop/cop/lint/void.rb, line 144
def check_void_expression(node)
  return unless node.defined_type? || node.lambda_or_proc?

  add_offense(node, message: format(EXPRESSION_MSG, expression: node.source)) do |corrector|
    autocorrect_void_expression(corrector, node)
  end
end

check_void_op(node) click to toggle source

# File lib/rubocop/cop/lint/void.rb, line 104
def check_void_op(node)
  return unless node.send_type? && OPERATORS.include?(node.method_name)

  add_offense(node.loc.selector,
              message: format(OP_MSG, op: node.method_name)) do |corrector|
    autocorrect_void_op(corrector, node)
  end
end

in_void_context?(node) click to toggle source

# File lib/rubocop/cop/lint/void.rb, line 170
def in_void_context?(node)
  parent = node.parent

  return false unless parent && parent.children.last == node

  VOID_CONTEXT_TYPES.include?(parent.type) && parent.void_context?
end