class RuboCop::Cop::Style::ZeroLengthPredicate
Checks for numeric comparisons that can be replaced by a predicate method, such as receiver.length == 0, receiver.length > 0, receiver.length != 0, receiver.length < 1 and receiver.size == 0 that can be replaced by receiver.empty? and !receiver.empty?.
@safety
This cop is unsafe because it cannot be guaranteed that the receiver has an `empty?` method that is defined in terms of `length`. If there is a non-standard class that redefines `length` or `empty?`, the cop may register a false positive.
@example
# bad [1, 2, 3].length == 0 0 == "foobar".length array.length < 1 {a: 1, b: 2}.length != 0 string.length > 0 hash.size > 0 # good [1, 2, 3].empty? "foobar".empty? array.empty? !{a: 1, b: 2}.empty? !string.empty? !hash.empty?
Constants
- NONZERO_MSG
- RESTRICT_ON_SEND
- ZERO_MSG
Public Instance Methods
on_send(node)
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# File lib/rubocop/cop/style/zero_length_predicate.rb, line 42 def on_send(node) check_zero_length_predicate(node) check_nonzero_length_predicate(node) end
Private Instance Methods
check_nonzero_length_predicate(node)
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# File lib/rubocop/cop/style/zero_length_predicate.rb, line 64 def check_nonzero_length_predicate(node) nonzero_length_predicate = nonzero_length_predicate(node.parent) return unless nonzero_length_predicate lhs, opr, rhs = nonzero_length_predicate return if non_polymorphic_collection?(node.parent) add_offense( node.parent, message: format(NONZERO_MSG, lhs: lhs, opr: opr, rhs: rhs) ) do |corrector| corrector.replace(node.parent, replacement(node.parent)) end end
check_zero_length_predicate(node)
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# File lib/rubocop/cop/style/zero_length_predicate.rb, line 49 def check_zero_length_predicate(node) zero_length_predicate = zero_length_predicate(node.parent) return unless zero_length_predicate lhs, opr, rhs = zero_length_predicate return if non_polymorphic_collection?(node.parent) add_offense( node.parent, message: format(ZERO_MSG, lhs: lhs, opr: opr, rhs: rhs) ) do |corrector| corrector.replace(node.parent, replacement(node.parent)) end end
replacement(node)
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# File lib/rubocop/cop/style/zero_length_predicate.rb, line 93 def replacement(node) receiver = zero_length_receiver(node) return "#{receiver.source}.empty?" if receiver "!#{other_receiver(node).source}.empty?" end