# Characteristics [![[version]](https://badge.fury.io/rb/characteristics.svg)](https://badge.fury.io/rb/characteristics)  [![[ci]](https://github.com/janlelis/characteristics/workflows/Test/badge.svg)](https://github.com/janlelis/characteristics/actions?query=workflow%3ATest)

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](https://github.com/janlelis/unibits) and [uniscribe](https://github.com/janlelis/uniscribe) gems makes use of this data to visualize it accordingly.

¹ in the sense of [codepoints](https://en.wikipedia.org/wiki/Codepoint)

## Setup

Add to your `Gemfile`:

```ruby
gem 'characteristics'
```

## Usage

```ruby
# 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.

## Properties

### General

#### `valid?`

Validness is determined by Ruby's `String#valid_encoding?`

#### `unicode?`

**true** for Unicode encodings (`UTF-X`)

#### `control?`

Control characters are codepoints in the is [C0, delete or C1 control character range](https://en.wikipedia.org/wiki/C0_and_C1_control_codes). Characters in this range of [IBM codepage 437](https://en.wikipedia.org/wiki/Code_page_437) based encodings are always treated as control characters.

#### `assigned?`

- 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

#### `blank?`

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).

#### `separator?`

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)

#### `format?`

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

#### `variation_selector?`

**true** for [variation selectors](https://en.wikipedia.org/wiki/Variation_Selector).

#### `tag?`

**true** for [tags](https://en.wikipedia.org/wiki/Tags_(Unicode_block)).

#### `ignorable?`

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

#### `noncharacter?`

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

## Also See

- [Symbolify](https://github.com/janlelis/symbolify)

## MIT License

Copyright (C) 2017-2024 Jan Lelis <https://janlelis.com>. Released under the MIT license.