Fix error when parsing values consisting of !important only

[leonid-shevtsov]

I haven't found a good justification for raising the error, and it helps a lot when parsing 3rd party CSS. It would still be raised when manually creating the declarations, and not parsing a block of CSS.

The performance impact is not noticable in my benchmarks... i also have a version that optimizes adding the declaration from parsed data, but it doesn't give any more than 3% speedup, so IMO the increased complexity wasn't worth it

Feel free to close if the error is valuable.

Coincidentally it also removes the sole use case for rule_set_exceptions, so i had to emulate the error in tests.

Pre-Merge Checklist

• CHANGELOG.md updated with short summary

[grosser]

color: !important; is technically valid but not useful right ?
... so the css that is being parsed is some auto-generated stuff that just happens to be valid and it should not blow up the parser is what you are saying ?

[leonid-shevtsov]

color: !important; is technically valid but not useful right ?

yes - technically valid in the sense that it does not break the overall CSS code and you would not typically notice its presence. It's certainly more valid than a missing closing brace which css_parser will silently allow: 😀

https://github.com/premailer/css_parser/blob/master/test/test_css_parser_basic.rb#L32

... so the css that is being parsed is some auto-generated stuff that just happens to be valid and it should not blow up the parser is what you are saying ?

Not really auto-generated, just some 3rd party CSS. Yeah, it was surprising that this benign mistake would cause an exception.

[grosser]

1.19.1