Skip to content


Repository files navigation

Characteristics [version] [ci]

A Ruby library that provides additional info about characters:¹

  • Could a character be invisible (blank)?
  • Is a character assigned?
  • Is a character a special control character?

Extra data is available for Unicode characters (see below).

The unibits and uniscribe gems makes use of this data to visualize it accordingly.

¹ in the sense of codepoints


Add to your Gemfile:

gem 'characteristics'


# All supported encodings
char_info = Characteristics.create(character)
char_info.valid? # => true / false
char_info.unicode? # => true / false
char_info.assigned? # => true / false
char_info.control? # => true / false
char_info.blank? # => true / false
char_info.separator? # => true / false
char_info.format? # => true / false

# Unicode characters
char_info = Characteristics.create(character)
char_info.variation_selector? # => true / false
char_info.tag? # => true / false
char_info.ignorable? # => true / false
char_info.noncharacter? # => true / false

Types of Encodings

This library knows of four different kinds of encodings:

  • :unicode Unicode familiy of multi-byte encodings
    • UTF-X
  • :byte Known single-byte encoding
    • ISO-8859-X, Windows-125X, IBMX, CP85X, macX, TIS-620, Windows-874, KOI-X
  • :ascii 7-Bit ASCII
    • US-ASCII, GB1988
  • :binary Arbitrary string
    • ASCII-8BIT

Other encodings are currently not supported.




Validness is determined by Ruby's String#valid_encoding?


true for Unicode encodings (UTF-X)


Control characters are codepoints in the is C0, delete or C1 control character range. Characters in this range of IBM codepage 437 based encodings are always treated as control characters.


  • All valid ASCII and BINARY characters are considered assigned
  • For other byte based encodings, a character is considered assigned if it is not on the exception list included in this library. C0 control characters (and \x7F) are always considered assigned. C1 control characters are treated as assigned, if the encoding generally does not assign characters in the C1 region.
  • For Unicode, the general category is considered


The library includes a list of characters that might not be rendered visually. This list does not include unassigned codepoints, control characters (except for \t, \n, \v, \f, \r, and \u{85} in Unicode), or special formatting characters (right-to-left markers, variation selectors, etc).


Returns true if character is considered a separator. All separators also return true for the blank? check. In Unicode, the following characters are separators: \n, \v, \f, \r, \u{85} (next line), \u{2028} (line separator), and \u{2029} (paragraph separator)


This flag is true only for special formatting characters, which are not control characters, like right-to-left marks. In Unicode, this means codepoints with the General Category of Cf.

Additional Unicode Properties


true for variation selectors.


true for tags.


true for characters which might not be implemented, and thus, might render no visible glyph.


true if codepoint will never be assigned in a future standard of Unicode.


  • Support all non-dummy encodings that Ruby supports

Also See

MIT License

Copyright (C) 2017-2022 Jan Lelis Released under the MIT license.