lib/rubocop/cop/lint/literal_as_condition.rb
# frozen_string_literal: true
module RuboCop
module Cop
module Lint
# Checks for literals used as the conditions or as
# operands in and/or expressions serving as the conditions of
# if/while/until/case-when/case-in.
#
# NOTE: Literals in `case-in` condition where the match variable is used in
# `in` are accepted as a pattern matching.
#
# @example
#
# # bad
# if 20
# do_something
# end
#
# # bad
# if some_var && true
# do_something
# end
#
# # good
# if some_var && some_condition
# do_something
# end
#
# # good
# # When using a boolean value for an infinite loop.
# while true
# break if condition
# end
class LiteralAsCondition < Base
include RangeHelp
MSG = 'Literal `%<literal>s` appeared as a condition.'
def on_if(node)
check_for_literal(node)
end
def on_while(node)
return if condition(node).true_type?
check_for_literal(node)
end
alias on_while_post on_while
def on_until(node)
return if condition(node).false_type?
check_for_literal(node)
end
alias on_until_post on_until
def on_case(case_node)
if case_node.condition
check_case(case_node)
else
case_node.each_when do |when_node|
next unless when_node.conditions.all?(&:literal?)
range = when_conditions_range(when_node)
message = message(range)
add_offense(range, message: message)
end
end
end
def on_case_match(case_match_node)
if case_match_node.condition
return if case_match_node.descendants.any?(&:match_var_type?)
check_case(case_match_node)
else
case_match_node.each_in_pattern do |in_pattern_node|
next unless in_pattern_node.condition.literal?
add_offense(in_pattern_node)
end
end
end
def on_send(node)
return unless node.negation_method?
check_for_literal(node)
end
def message(node)
format(MSG, literal: node.source)
end
private
def check_for_literal(node)
cond = condition(node)
if cond.literal?
add_offense(cond)
else
check_node(cond)
end
end
def basic_literal?(node)
if node.array_type?
primitive_array?(node)
else
node.basic_literal?
end
end
def primitive_array?(node)
node.children.all? { |n| basic_literal?(n) }
end
def check_node(node)
if node.send_type? && node.prefix_bang?
handle_node(node.receiver)
elsif node.operator_keyword?
node.each_child_node { |op| handle_node(op) }
elsif node.begin_type? && node.children.one?
handle_node(node.children.first)
end
end
def handle_node(node)
if node.literal?
add_offense(node)
elsif %i[send and or begin].include?(node.type)
check_node(node)
end
end
def check_case(case_node)
condition = case_node.condition
return if condition.array_type? && !primitive_array?(condition)
return if condition.dstr_type?
handle_node(condition)
end
def condition(node)
if node.send_type?
node.receiver
else
node.condition
end
end
def when_conditions_range(when_node)
range_between(
when_node.conditions.first.source_range.begin_pos,
when_node.conditions.last.source_range.end_pos
)
end
end
end
end
end