class RuboCop::Cop::Performance::StartWith

‘abc’.start_with?(‘ab’)
# good
’abc’.match(/Aab/)
‘abc’ =~ /Aab/
‘abc’.match?(/Aab/)
# bad
@example
`String#start_with?‘ would suffice.
This cop identifies unnecessary use of a regex where

def autocorrect(node) 

def autocorrect(node)
  redundant_regex?(node) do |receiver, regex_str|
    receiver, regex_str = regex_str, receiver if receiver.is_a?(String)
    regex_str = regex_str[2..-1] # drop \A anchor
    regex_str = interpret_string_escapes(regex_str)
    lambda do |corrector|
      new_source = receiver.source + '.start_with?(' +
                   to_string_literal(regex_str) + ')'
      corrector.replace(node.source_range, new_source)
    end
  end
end

def literal_at_start?(regex_str) 

def literal_at_start?(regex_str)
  # is this regexp 'literal' in the sense of only matching literal
  # chars, rather than using metachars like `.` and `*` and so on?
  # also, is it anchored at the start of the string?
  # (tricky: \s, \d, and so on are metacharacters, but other characters
  #  escaped with a slash are just literals. LITERAL_REGEX takes all
  #  that into account.)
  regex_str =~ /\A\\A(?:#{LITERAL_REGEX})+\z/
end

def on_send(node) 

def on_send(node)
  return unless redundant_regex?(node)
  add_offense(node)
end