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I have the regex that matches any kind of emoji (taken from here):

val EMOJI_REGEX = "(?:[\u2700-\u27bf]|(?:[\ud83c\udde6-\ud83c\uddff]){2}|[\ud800\udc00-\uDBFF\uDFFF]|[\u2600-\u26FF])[\ufe0e\ufe0f]?(?:[\u0300-\u036f\ufe20-\ufe23\u20d0-\u20f0]|[\ud83c\udffb-\ud83c\udfff])?(?:\u200d(?:[^\ud800-\udfff]|(?:[\ud83c\udde6-\ud83c\uddff]){2}|[\ud800\udc00-\uDBFF\uDFFF]|[\u2600-\u26FF])[\ufe0e\ufe0f]?(?:[\u0300-\u036f\ufe20-\ufe23\u20d0-\u20f0]|[\ud83c\udffb-\ud83c\udfff])?)*|[\u0023-\u0039]\ufe0f?\u20e3|\u3299|\u3297|\u303d|\u3030|\u24c2|[\ud83c\udd70-\ud83c\udd71]|[\ud83c\udd7e-\ud83c\udd7f]|\ud83c\udd8e|[\ud83c\udd91-\ud83c\udd9a]|[\ud83c\udde6-\ud83c\uddff]|[\ud83c\ude01-\ud83c\ude02]|\ud83c\ude1a|\ud83c\ude2f|[\ud83c\ude32-\ud83c\ude3a]|[\ud83c\ude50-\ud83c\ude51]|\u203c|\u2049|[\u25aa-\u25ab]|\u25b6|\u25c0|[\u25fb-\u25fe]|\u00a9|\u00ae|\u2122|\u2139|\ud83c\udc04|[\u2600-\u26FF]|\u2b05|\u2b06|\u2b07|\u2b1b|\u2b1c|\u2b50|\u2b55|\u231a|\u231b|\u2328|\u23cf|[\u23e9-\u23f3]|[\u23f8-\u23fa]|\ud83c\udccf|\u2934|\u2935|[\u2190-\u21ff]".toRegex()

if I try to match it with Emojis it works perfectly :

"‍‍".contains(EMOJI_REGEX)    ==> true ( as expected )
".".contains(EMOJI_REGEX)    ==> false ( as expected )
"yady".contains(EMOJI_REGEX)    ==> false ( as expected )

However if I want to negate the Regex : add [^ ...] before the whole expression : 

val NEGATED_EMOJI_REGEX = "[^(?:[\u2700-\u27bf]|(?:[\ud83c\udde6-\ud83c\uddff]){2}|[\ud800\udc00-\uDBFF\uDFFF]|[\u2600-\u26FF])[\ufe0e\ufe0f]?(?:[\u0300-\u036f\ufe20-\ufe23\u20d0-\u20f0]|[\ud83c\udffb-\ud83c\udfff])?(?:\u200d(?:[^\ud800-\udfff]|(?:[\ud83c\udde6-\ud83c\uddff]){2}|[\ud800\udc00-\uDBFF\uDFFF]|[\u2600-\u26FF])[\ufe0e\ufe0f]?(?:[\u0300-\u036f\ufe20-\ufe23\u20d0-\u20f0]|[\ud83c\udffb-\ud83c\udfff])?)*|[\u0023-\u0039]\ufe0f?\u20e3|\u3299|\u3297|\u303d|\u3030|\u24c2|[\ud83c\udd70-\ud83c\udd71]|[\ud83c\udd7e-\ud83c\udd7f]|\ud83c\udd8e|[\ud83c\udd91-\ud83c\udd9a]|[\ud83c\udde6-\ud83c\uddff]|[\ud83c\ude01-\ud83c\ude02]|\ud83c\ude1a|\ud83c\ude2f|[\ud83c\ude32-\ud83c\ude3a]|[\ud83c\ude50-\ud83c\ude51]|\u203c|\u2049|[\u25aa-\u25ab]|\u25b6|\u25c0|[\u25fb-\u25fe]|\u00a9|\u00ae|\u2122|\u2139|\ud83c\udc04|[\u2600-\u26FF]|\u2b05|\u2b06|\u2b07|\u2b1b|\u2b1c|\u2b50|\u2b55|\u231a|\u231b|\u2328|\u23cf|[\u23e9-\u23f3]|[\u23f8-\u23fa]|\ud83c\udccf|\u2934|\u2935|[\u2190-\u21ff]]".toRegex()

, it won't work as expected. It will always return false, whereas it should return false for emojis and true for any other characters.

"‍‍".contains(NEGATED_EMOJI_REGEX)    ==> false ( correct )
    ".".contains(NEGATED_EMOJI_REGEX)    ==> false ( wrong )
    "yady".contains(NEGATED_EMOJI_REGEX)    ==> false ( wrong )

If I want to negate a basic expression like: [^a-zA-z] it works just fine.

Any ideea what could be the issue?

biafas
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  • `[^.....]` doesn't negate an expression, it matches all characters that are not in the character class. – Toto Jun 04 '20 at 14:02

1 Answers1

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Anything inside [] is considered as a character, not an expression.

whereas it should return false for emojis and true for any other characters.

This can be done by matching the only non-Unicode characters 

[^\u0000-\u007F]+

The whole regex expression cannot be negated through can try negative look-ahead ?!

 ^(?!(?:[\u2700-\u27bf]...[\u2190-\u21ff])

or simply use negation with your initial result value as !resultOfRegexMatch

Pavneet_Singh
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