Colorize error part

lib/irb/color.rb

@@ -7,6 +7,7 @@ module IRB # :nodoc:
     CLEAR     = 0
     BOLD      = 1
     UNDERLINE = 4
+    REVERSE   = 7
     RED       = 31
     GREEN     = 32
     YELLOW    = 33
@@ -55,6 +56,7 @@ module IRB # :nodoc:
         on_tstring_content: [[RED],                   ALL],
         on_tstring_end:     [[RED],                   ALL],
         on_words_beg:       [[RED],                   ALL],
+        on_parse_error:     [[RED, REVERSE],          ALL],
       }
     rescue NameError
       # Give up highlighting Ripper-incompatible older Ruby
@@ -62,6 +64,14 @@ module IRB # :nodoc:
     end
     private_constant :TOKEN_SEQ_EXPRS
 
+    class Lexer < Ripper::Lexer
+      if method_defined?(:token)
+        def on_parse_error(mesg)
+          @buf.push Elem.new([lineno(), column()], __callee__, token(), state())
+        end
+      end
+    end
+
     class << self
       def colorable?
         $stdout.tty? && (/mswin|mingw/ =~ RUBY_PLATFORM || (ENV.key?('TERM') && ENV['TERM'] != 'dumb'))
@@ -101,11 +111,15 @@ module IRB # :nodoc:
         colored = +''
         length = 0
 
-        Ripper.lex(code).each do |(_line, _col), token, str, expr|
+        Lexer.new(code).parse.sort_by(&:pos).each do |elem|
+          token = elem.event
+          str = elem.tok
+          expr = elem.state
           in_symbol = symbol_state.scan_token(token)
           if seq = dispatch_seq(token, expr, str, in_symbol: in_symbol)
             Reline::Unicode.escape_for_print(str).each_line do |line|
-              colored << "#{seq.map { |s| "\e[#{s}m" }.join('')}#{line.sub(/\n?\z/, "#{clear}\\0")}"
+              colored << seq.map { |s| "\e[#{s}m" }.join('')
+              colored << line.sub(/\Z/, clear)
             end
           else
             colored << Reline::Unicode.escape_for_print(str)

test/irb/test_color.rb

@@ -9,6 +9,7 @@ module TestIRB
     CLEAR     = "\e[0m"
     BOLD      = "\e[1m"
     UNDERLINE = "\e[4m"
+    REVERSE   = "\e[7m"
     RED       = "\e[31m"
     GREEN     = "\e[32m"
     YELLOW    = "\e[33m"
@@ -37,7 +38,7 @@ module TestIRB
         '"foo#{a} #{b}"' => "#{RED}\"#{CLEAR}#{RED}foo#{CLEAR}#{RED}\#{#{CLEAR}a#{RED}}#{CLEAR}#{RED} #{CLEAR}#{RED}\#{#{CLEAR}b#{RED}}#{CLEAR}#{RED}\"#{CLEAR}",
         '/r#{e}g/' => "#{RED}#{BOLD}/#{CLEAR}#{RED}r#{CLEAR}#{RED}\#{#{CLEAR}e#{RED}}#{CLEAR}#{RED}g#{CLEAR}#{RED}#{BOLD}/#{CLEAR}",
         "'a\nb'" => "#{RED}'#{CLEAR}#{RED}a#{CLEAR}\n#{RED}b#{CLEAR}#{RED}'#{CLEAR}",
-        "4.5.6" => "4.5.6",
+        "4.5.6" => "#{MAGENTA}#{BOLD}4.5#{CLEAR}#{RED}#{REVERSE}.6#{CLEAR}",
         "[1]]]" => "[1]]]",
         "\e[0m\n" => "^[[#{BLUE}#{BOLD}0#{CLEAR}m\n",
         "%w[a b]" => "#{RED}%w[#{CLEAR}#{RED}a#{CLEAR} #{RED}b#{CLEAR}#{RED}]#{CLEAR}",
@@ -111,6 +112,7 @@ module TestIRB
         .gsub(CLEAR, '@@@{CLEAR}')
         .gsub(BOLD, '@@@{BOLD}')
         .gsub(UNDERLINE, '@@@{UNDERLINE}')
+        .gsub(REVERSE, '@@@{REVERSE}')
         .gsub(RED, '@@@{RED}')
         .gsub(GREEN, '@@@{GREEN}')
         .gsub(YELLOW, '@@@{YELLOW}')