[ANN] ruby_parser 3.13.1 Released

ruby_parser version 3.13.1 has been released!

* home: <https://github.com/seattlerb/ruby_parser>
* bugs: <https://github.com/seattlerb/ruby_parser/issues>
* rdoc: <http://docs.seattlerb.org/ruby_parser>

ruby_parser (RP) is a ruby parser written in pure ruby (utilizing
racc--which does by default use a C extension). RP's output is
the same as ParseTree's output: s-expressions using ruby's arrays and
base types.

As an example:

    def conditional1 arg1
      return 1 if arg1 == 0
      return 0
    end

becomes:

    s(:defn, :conditional1, s(:args, :arg1),
      s(:if,
        s(:call, s(:lvar, :arg1), :==, s(:lit, 0)),
        s(:return, s(:lit, 1)),
        nil),
      s(:return, s(:lit, 0)))

Tested against 801,039 files from the latest of all rubygems (as of 2013-05):

* 1.8 parser is at 99.9739% accuracy, 3.651 sigma
* 1.9 parser is at 99.9940% accuracy, 4.013 sigma
* 2.0 parser is at 99.9939% accuracy, 4.008 sigma

Changes:

### 3.13.1 / 2019-03-25

* 1 major enhancement:

  * Overhauled RubyLexer#lex_state to allow for multi-state value.

* 5 minor enhancements:

  * Added RubyParser#current so scripts can poke around inside.
  * Cleaned up and modernized bin/ruby_parse_extract_error.
  * Removed RubyLexer#in_lex_state? in favor of State#=~ and #==.
  * Renamed RubyLexer#in_arg_state? to is_after_operator?.
  * Replaced all use of :expr_<*> symbols w/ bitfields.

* 15 bug fixes:

  * Added tests to show #233 already fixed.
  * Fixed a lexer state bug dealing with complex edge case in hash key w/ interpolated symbol and an array value. Not a great fix. (presidentbeef)
  * Fixed a number of lex_state check problems.
  * Fixed alias and undef keyword data.
  * Fixed bug normalizing to utf-8 on tail of dstr (post-interpolation). (mvz)
  * Fixed handling of hex chars for bare unicode escape. (mvz)
  * Fixed handling of invalid string octals more gracefully. Needs generalization.
  * Fixed lexing of regexps w/ backslashed unicode. I hope.
  * Fixed parse_percent for EXPR_FITEM edge cases. Fixed bug #125.
  * Fixed parsing of op_asgn on constants (eg ::X ||= 1).
  * Fixed precedence of rescue modifier on assignments. (mvz/whitequark)
  * Fixed some EXPR_FNAME edge cases.
  * Fixed using unicode in gvars. Fixed bug 202. (331299)
  * Handle invalid string literals more gracefully.
  * Minor fix lexing %s[]