class RuboCop::Cop::Performance::Casecmp
This cop identifies places where a case-insensitive string comparison can better be implemented using `casecmp`. This cop is unsafe because `String#casecmp` and `String#casecmp?` behave differently when using Non-ASCII characters.
@example
# bad str.downcase == 'abc' str.upcase.eql? 'ABC' 'abc' == str.downcase 'ABC'.eql? str.upcase str.downcase == str.downcase # good str.casecmp('ABC').zero? 'abc'.casecmp(str).zero?
Constants
- CASE_METHODS
- MSG
- RESTRICT_ON_SEND
Public Instance Methods
on_send(node)
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# File lib/rubocop/cop/performance/casecmp.rb, line 50 def on_send(node) return unless downcase_eq(node) || eq_downcase(node) return unless (parts = take_method_apart(node)) _receiver, method, arg, variable = parts good_method = build_good_method(arg, variable) message = format(MSG, good: good_method, bad: node.source) add_offense(node, message: message) do |corrector| correction(corrector, node, method, arg, variable) end end
Private Instance Methods
build_good_method(arg, variable)
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# File lib/rubocop/cop/performance/casecmp.rb, line 90 def build_good_method(arg, variable) # We want resulting call to be parenthesized # if arg already includes one or more sets of parens, don't add more # or if method call already used parens, again, don't add more if arg.send_type? || !parentheses?(arg) "#{variable.source}.casecmp(#{arg.source}).zero?" else "#{variable.source}.casecmp#{arg.source}.zero?" end end
correction(corrector, node, method, arg, variable)
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# File lib/rubocop/cop/performance/casecmp.rb, line 82 def correction(corrector, node, method, arg, variable) corrector.insert_before(node.loc.expression, '!') if method == :!= replacement = build_good_method(arg, variable) corrector.replace(node.loc.expression, replacement) end
take_method_apart(node)
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# File lib/rubocop/cop/performance/casecmp.rb, line 65 def take_method_apart(node) if downcase_downcase(node) receiver, method, rhs = *node arg, = *rhs elsif downcase_eq(node) receiver, method, arg = *node elsif eq_downcase(node) arg, method, receiver = *node else return end variable, = *receiver [receiver, method, arg, variable] end