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## Unicode::DisplayWidth [![[version]](https://badge.fury.io/rb/unicode-display_width.svg)](https://badge.fury.io/rb/unicode-display_width) [<img src="https://travis-ci.org/janlelis/unicode-display_width.png" />](https://travis-ci.org/janlelis/unicode-display_width)
Determines the monospace display width of a string in Ruby. Implementation based on [EastAsianWidth.txt](https://www.unicode.org/Public/UNIDATA/EastAsianWidth.txt) and other data, 100% in Ruby. Other than [wcwidth()](https://github.com/janlelis/wcswidth-ruby), which fulfills a similar purpose, it does not rely on the OS vendor to provide an up-to-date method for measuring string width.
Unicode version: **12.1.0** (May 2019)
Supported Rubies: **2.7**, **2.6**, **2.5**, **2.4**
Old Rubies that might still work: **2.3**, **2.2**, **2.1**, **2.0**, **1.9**
## Introduction to Character Widths
Guessing the correct space a character will consume on terminals is not easy. There is no single standard. Most implementations combine data from [East Asian Width](https://www.unicode.org/reports/tr11/), some [General Categories](https://en.wikipedia.org/wiki/Unicode_character_property#General_Category), and hand-picked adjustments.
### How this Library Handles Widths
Further at the top means higher precedence. Please expect changes to this algorithm with every MINOR version update (the X in 1.X.0)!
Width | Characters | Comment
-------|------------------------------|--------------------------------------------------
X | (user defined) | Overwrites any other values
-1 | `"\b"` | Backspace (total width never below 0)
0 | `"\0"`, `"\x05"`, `"\a"`, `"\n"`, `"\v"`, `"\f"`, `"\r"`, `"\x0E"`, `"\x0F"` | [C0 control codes](https://en.wikipedia.org/wiki/C0_and_C1_control_codes#C0_.28ASCII_and_derivatives.29) that do not change horizontal width
1 | `"\u{00AD}"` | SOFT HYPHEN
2 | `"\u{2E3A}"` | TWO-EM DASH
3 | `"\u{2E3B}"` | THREE-EM DASH
0 | General Categories: Mn, Me, Cf (non-arabic) | Excludes ARABIC format characters
0 | `"\u{1160}".."\u{11FF}"` | HANGUL JUNGSEONG
0 | `"\u{2060}".."\u{206F}"`, `"\u{FFF0}".."\u{FFF8}"`, `"\u{E0000}".."\u{E0FFF}"` | Ignorable ranges
2 | East Asian Width: F, W | Full-width characters
2 | `"\u{3400}".."\u{4DBF}"`, `"\u{4E00}".."\u{9FFF}"`, `"\u{F900}".."\u{FAFF}"`, `"\u{20000}".."\u{2FFFD}"`, `"\u{30000}".."\u{3FFFD}"` | Full-width ranges
1 or 2 | East Asian Width: A | Ambiguous characters, user defined, default: 1
1 | All other codepoints | -
## Install
Install the gem with:
$ gem install unicode-display_width
Or add to your Gemfile:
gem 'unicode-display_width'
## Usage
```ruby
require 'unicode/display_width'
Unicode::DisplayWidth.of("⚀") # => 1
Unicode::DisplayWidth.of("一") # => 2
```
### Ambiguous Characters
The second parameter defines the value returned by characters defined as ambiguous:
```ruby
Unicode::DisplayWidth.of("·", 1) # => 1
Unicode::DisplayWidth.of("·", 2) # => 2
```
### Custom Overwrites
You can overwrite how to handle specific code points by passing a hash (or even a proc) as third parameter:
```ruby
Unicode::DisplayWidth.of("a\tb", 1, 0x09 => 10)) # => 12
```
### Emoji Support
Experimental emoji support is included. It will adjust the string's size for modifier and zero-width joiner sequences. You will need to add the [unicode-emoji](https://github.com/janlelis/unicode-emoji) gem to your Gemfile:
```ruby
gem 'unicode-display_width'
gem 'unicode-emoji'
```
You can then activate the emoji string width adjustments by passing `emoji: true` as fourth parameter:
```ruby
Unicode::DisplayWidth.of "🤾🏽♀️" # => 5
Unicode::DisplayWidth.of "🤾🏽♀️", 1, {}, emoji: true # => 2
```
### Usage with String Extension
Activated by default. Will be deactivated in version 2.0:
```ruby
require 'unicode/display_width/string_ext'
"⚀".display_width #=> 1
'一'.display_width #=> 2
```
You can actively opt-out from the string extension with: `require 'unicode/display_width/no_string_ext'`
### Usage From the CLI
Use this one-liner to print out display widths for strings from the command-line:
```
$ gem install unicode-display_width
$ ruby -r unicode/display_width -e 'puts Unicode::DisplayWidth.of $*[0]' -- "一"
```
Replace "一" with the actual string to measure
## Other Implementations & Discussion
- Python: https://github.com/jquast/wcwidth
- JavaScript: https://github.com/mycoboco/wcwidth.js
- C: https://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c
- C for Julia: https://github.com/JuliaLang/utf8proc/issues/2
See [unicode-x](https://github.com/janlelis/unicode-x) for more Unicode related micro libraries.
## Copyright & Info
- Copyright (c) 2011, 2015-2020 Jan Lelis, https://janlelis.com, released under the MIT
license
- Early versions based on runpaint's unicode-data interface: Copyright (c) 2009 Run Paint Run Run
- Unicode data: https://www.unicode.org/copyright.html#Exhibit1
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