particle-iot/ruby-unicode-display-width

Name: ruby-unicode-display-width

Owner: Particle

Description: Debian package for Ruby gem unicode-display-width

Created: 2016-10-27 21:59:06.0

Updated: 2016-10-27 22:01:34.0

Pushed: 2018-01-03 18:43:54.0

Homepage: null

Size: 13

Language: Ruby

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README

Unicode::DisplayWidth

Determines the monospace display width of a string in Ruby. Implementation based on EastAsianWidth.txt and other data, 100% in Ruby. Other than wcwidth(), 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: 9.0.0

Introduction to Character Widths

Guesing 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, some General Categories, 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 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 2 | East Asian Width: F, W | Full-width characters 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

ire 'unicode/display_width'

ode::DisplayWidth.of("?") # => 1
ode::DisplayWidth.of("?") # => 2

Ambiguous Characters

The second parameter defines the value returned by characterrs defined as ambiguous:

ode::DisplayWidth.of("·", 1) # => 1
ode::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:

ode::DisplayWidth.of("a\tb", 1, 0x09 => 10)) # => 12

Usage with String Extension

Activated by default. Will be deactivated in version 2.0:

ire 'unicode/display_width/string_ext'

display_width #=> 1
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:

m install unicode-display_width
by -r unicode/display_width -e 'puts Unicode::DisplayWidth.of $*[0]' -- "?"

Replace “?” with the actual string to measure

Other Implementations & Discussion

• Python: https://github.com/jquast/wcwidth
• JavaScript: https://github.com/mycoboco/wcwidth.js
• C: http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c
• C for Julia: https://github.com/JuliaLang/utf8proc/issues/2

See unicode-x for more Unicode related micro libraries.

Copyright & Info

• Copyright (c) 2011, 2015-2016 Jan Lelis, http://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: http://www.unicode.org/copyright.html#Exhibit1