Convert non-breaking spaces to spaces in Ruby

Question

I have cases where user-entered data from an html textarea or input is sometimes sent with \u00a0 (non-breaking spaces) instead of spaces when encoded as utf-8 json.

I believe that to be a bug in Firefox, as I know that the user isn't intentionally putting in non-breaking spaces instead of spaces.

There are also two bugs in Ruby, one of which can be used to combat the other.

For whatever reason \s doesn't match \u00a0.

However [^[:print:]], which definitely should not match) and \xC2\xA0 both will match, but I consider those to be less-than-ideal ways to deal with the issue.

Are there other recommendations for getting around this issue?

Answer 1

Use /\u00a0/ to match non-breaking spaces. For instance s.gsub(/\u00a0/, ' ') converts all non-breaking spaces to regular spaces.

Use /[[:space:]]/ to match all whitespace, including Unicode whitespace like non-breaking spaces. This is unlike /\s/, which matches only ASCII whitespace.

See also: Ruby Regexp documentation

Answer 2

If you cannot use \s for Unicode whitespace, that’s a bug in the Ruby regex implementation, because according to UTS#18 “Unicode Regular Expressions” Annex C on Compatibility Properties a \s, is absolutely required to match any Unicode whitespace code point.

There is no wiggle-room allowed since the two columns detailing the Standard Recommendation and the POSIX Compatibility are the same for the \s case. You cannot document your way around this: you are out of compliance with The Unicode Standard, in particular, with UTS#18’s RL1.2a, if you do not do this.

If you do not meet RL1.2a, you do not meet the Level 1 requirements, which are the most basic and elementary functionality needed to use regular expressions on Unicode. Without that, you are pretty much lost. This is why standards exist. My recollection is that Ruby also fails to meet several other Level 1 requirements. You may therefore wish to use a programming language that meets at least Level 1 if you actually need to handle Unicode with regular expressions.

Note that you cannot use a Unicode General Category property like \p{Zs} to stand for \p{Whitespace}. That’s because the Whitespace property is a derived property, not a general category. There are also control characters included in it, not just separators.