Execute ( SpaceVim api: vim#key ):
  let regex = SpaceVim#api#import('vim#regex')
  AssertEqual regex.parser('(?i)abc', 0), '\v\cabc'
  AssertEqual regex.parser('(?-i)abc', 0), '\v\Cabc'
  AssertEqual regex.parser('(?:exp)', 0), '\v%(exp)'
  AssertEqual regex.parser('\a\f\v', 0), '\v%x07%x0C%x0B'
  AssertEqual regex.parser('[:word:]', 0), '\v[0-9A-Za-z_]'
  AssertEqual regex.parser('\bspace\b', 0), '\v<space>'
  AssertEqual regex.parser('\bspace', 0), '\v<space'
  AssertEqual regex.parser('space\b', 0), '\vspace>'
  AssertEqual regex.parser('if%@&ab', 0), '\vif\%\@\&ab'
  AssertEqual regex.parser('(?P<name>exp)', 0), '\v(exp)'

