require 'strscan'
scanner = StringScanner.new('r|abc|  ')
 
puts "pre-regex: #{scanner.inspect}"
puts "got a char: #{scanner.getch} (res: #{scanner.inspect})"
divider = scanner.getch
puts "got divider: #{divider.inspect}"
puts "mid-regex: #{scanner.inspect}"
# this bit still fails even if you replace `#{divider}' with `|'
res = scanner.scan_until(/(?<![^\\]\\)#{divider}[a-z]*/)
puts "post-regex: #{scanner.inspect}"
 
if scanner.skip(/\s+/)# || scanner.skip(/;-.*?-;/m)
  puts "Success! #{res}"
else
  puts "Fail. Ended at: #{scanner.inspect}"
  puts "(res was #{res.inspect})"
end

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