class RuboCop::Cop::Performance::RegexpMatch

In Ruby 2.4, `String#match?`, `Regexp#match?`, and `Symbol#match?` have been added. The methods are faster than `match`. Because the methods avoid creating a `MatchData` object or saving backref. So, when `MatchData` is not used, use `match?` instead of `match`.

@example

# bad
def foo
  if x =~ /re/
    do_something
  end
end

# bad
def foo
  if x !~ /re/
    do_something
  end
end

# bad
def foo
  if x.match(/re/)
    do_something
  end
end

# bad
def foo
  if /re/ === x
    do_something
  end
end

# good
def foo
  if x.match?(/re/)
    do_something
  end
end

# good
def foo
  if !x.match?(/re/)
    do_something
  end
end

# good
def foo
  if x =~ /re/
    do_something(Regexp.last_match)
  end
end

# good
def foo
  if x.match(/re/)
    do_something($~)
  end
end

# good
def foo
  if /re/ === x
    do_something($~)
  end
end

Constants

MATCH_NODE_PATTERN
MSG
TYPES_IMPLEMENTING_MATCH

Constants are included in this list because it is unlikely that someone will store `nil` as a constant and then use it for comparison

Public Instance Methods

match_with_lvasgn?(node) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 102
def match_with_lvasgn?(node)
  return false unless node.match_with_lvasgn_type?

  regexp, _rhs = *node
  regexp.to_regexp.named_captures.empty?
end
on_case(node) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 135
def on_case(node)
  return if node.condition

  node.each_when do |when_node|
    when_node.each_condition do |condition|
      check_condition(condition)
    end
  end
end
on_if(node) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 131
def on_if(node)
  check_condition(node.condition)
end

Private Instance Methods

autocorrect(corrector, node) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 158
def autocorrect(corrector, node)
  if match_method?(node) || match_with_int_arg_method?(node)
    corrector.replace(node.loc.selector, 'match?')
  elsif match_operator?(node) || match_threequals?(node)
    recv, oper, arg = *node
    correct_operator(corrector, recv, arg, oper)
  elsif match_with_lvasgn?(node)
    recv, arg = *node
    correct_operator(corrector, recv, arg)
  end
end
check_condition(cond) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 147
def check_condition(cond)
  match_node?(cond) do
    return if last_match_used?(cond)

    message = message(cond)
    add_offense(cond, message: message) do |corrector|
      autocorrect(corrector, cond)
    end
  end
end
correct_operator(corrector, recv, arg, oper = nil) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 251
def correct_operator(corrector, recv, arg, oper = nil)
  op_range = correction_range(recv, arg)

  replace_with_match_predicate_method(corrector, recv, arg, op_range)

  corrector.insert_after(arg.loc.expression, ')') unless op_range.source.end_with?('(')
  corrector.insert_before(recv.loc.expression, '!') if oper == :!~
end
correction_range(recv, arg) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 276
def correction_range(recv, arg)
  buffer = processed_source.buffer
  op_begin_pos = recv.loc.expression.end_pos
  op_end_pos = arg.loc.expression.begin_pos
  Parser::Source::Range.new(buffer, op_begin_pos, op_end_pos)
end
find_last_match(body, range, scope_root) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 214
def find_last_match(body, range, scope_root)
  last_matches(body).find do |ref|
    ref_pos = ref.loc.expression.begin_pos
    range.cover?(ref_pos) &&
      scope_root(ref) == scope_root
  end
end
last_match_used?(match_node) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 174
def last_match_used?(match_node)
  scope_root = scope_root(match_node)
  body = scope_root ? scope_body(scope_root) : match_node.ancestors.last

  range = range_to_search_for_last_matches(match_node, body, scope_root)

  find_last_match(body, range, scope_root)
end
match_gvar?(sym) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 240
def match_gvar?(sym)
  %i[
    $~
    $MATCH
    $PREMATCH
    $POSTMATCH
    $LAST_PAREN_MATCH
    $LAST_MATCH_INFO
  ].include?(sym)
end
message(node) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 170
def message(node)
  format(MSG, current: node.loc.selector.source)
end
modifier_form?(match_node) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 210
def modifier_form?(match_node)
  match_node.parent.if_type? && match_node.parent.modifier_form?
end
next_match_pos(body, match_node_pos, scope_root) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 196
def next_match_pos(body, match_node_pos, scope_root)
  node = search_match_nodes(body).find do |match|
    begin_pos = if modifier_form?(match)
                  match.parent.if_branch.loc.expression.begin_pos
                else
                  match.loc.expression.begin_pos
                end

    begin_pos > match_node_pos && scope_root(match) == scope_root
  end

  node ? node.loc.expression.begin_pos : Float::INFINITY
end
range_to_search_for_last_matches(match_node, body, scope_root) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 183
def range_to_search_for_last_matches(match_node, body, scope_root)
  expression = if modifier_form?(match_node)
                 match_node.parent.if_branch.loc.expression
               else
                 match_node.loc.expression
               end

  match_node_pos = expression.begin_pos
  next_match_pos = next_match_pos(body, match_node_pos, scope_root)

  match_node_pos..next_match_pos
end
replace_with_match_predicate_method(corrector, recv, arg, op_range) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 260
def replace_with_match_predicate_method(corrector, recv, arg, op_range)
  if TYPES_IMPLEMENTING_MATCH.include?(recv.type)
    corrector.replace(op_range, '.match?(')
  elsif TYPES_IMPLEMENTING_MATCH.include?(arg.type)
    corrector.replace(op_range, '.match?(')
    swap_receiver_and_arg(corrector, recv, arg)
  else
    corrector.replace(op_range, '&.match?(')
  end
end
scope_body(node) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 222
def scope_body(node)
  children = node.children
  case node.type
  when :module
    children[1]
  when :defs
    children[3]
  else
    children[2]
  end
end
scope_root(node) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 234
def scope_root(node)
  node.each_ancestor.find do |ancestor|
    ancestor.def_type? || ancestor.defs_type? || ancestor.class_type? || ancestor.module_type?
  end
end
swap_receiver_and_arg(corrector, recv, arg) click to toggle source
# File lib/rubocop/cop/performance/regexp_match.rb, line 271
def swap_receiver_and_arg(corrector, recv, arg)
  corrector.replace(recv.loc.expression, arg.source)
  corrector.replace(arg.loc.expression, recv.source)
end