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Ruby: Checking for East Asian Width (Unicode)

Using Ruby, I have to output strings in an columnar format to the terminal. Something like this:

| row 1     | a string here     | etc
| row 2     | another string    | etc

I can do this fine with Latin UTF8 characters using String#ljust and %s.

But a problem arises when the characters are Korean, Chinese, etc. The columns simply won't align when there are rows of English interspersed with rows containing Korean, etc.

How can I get column alignment here? Is there a way to output Asian characters in the equivalent of a fixed-width font? How about for documents that are meant to be displayed and edited in Vim?

Solution

  • Late to the party, but hopefully still helpful: In Ruby, you can use the unicode-display_width gem to check for a string's east-asian-width:

    require 'unicode/display_width'
"⚀".display_width #=> 1
'一'.display_width #=> 2