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Contents
# frozen_string_literal: true
module RuboCop
module Cop
module Style
# This cop checks for accessing the first element of `String#unpack`
# which can be replaced with the shorter method `unpack1`.
#
# @example
#
# # bad
# 'foo'.unpack('h*').first
# 'foo'.unpack('h*')[0]
# 'foo'.unpack('h*').slice(0)
# 'foo'.unpack('h*').at(0)
#
# # good
# 'foo'.unpack1('h*')
#
class UnpackFirst < Cop
extend TargetRubyVersion
minimum_target_ruby_version 2.4
MSG = 'Use `%<receiver>s.unpack1(%<format>s)` instead of '\
'`%<receiver>s.unpack(%<format>s)%<method>s`.'.freeze
def_node_matcher :unpack_and_first_element?, <<-PATTERN
{
(send $(send (...) :unpack $(...)) :first)
(send $(send (...) :unpack $(...)) {:[] :slice :at} (int 0))
}
PATTERN
def on_send(node)
unpack_and_first_element?(node) do |unpack_call, unpack_arg|
range = first_element_range(node, unpack_call)
message = format(MSG,
receiver: unpack_call.receiver.source,
format: unpack_arg.source,
method: range.source)
add_offense(node, message: message)
end
end
def autocorrect(node)
unpack_and_first_element?(node) do |unpack_call, _unpack_arg|
lambda do |corrector|
corrector.remove(first_element_range(node, unpack_call))
corrector.replace(unpack_call.loc.selector, 'unpack1')
end
end
end
private
def first_element_range(node, unpack_call)
Parser::Source::Range.new(node.loc.expression.source_buffer,
unpack_call.loc.expression.end_pos,
node.loc.expression.end_pos)
end
end
end
end
end
Version data entries
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