Package filter implements a [transform.Transformer] that performs the Unicode code point filtering preprocessing step defined in [CSS Syntax Module Level 3, section 3.3]: "To filter code points from a stream of (unfiltered) code points input: "Replace any U+000D CARRIAGE RETURN (CR) code points, U+000C FORM FEED (FF) code points, or pairs of U+000D CARRIAGE RETURN (CR) followed by U+000A LINE FEED (LF) in input by a single U+000A LINE FEED (LF) code point.

Package token defines CSS tokens produced by a tokenizer.

ConsumeBadUrl consumes the remnants of a bad url from a stream of code points, "cleaning up" after the tokenizer realizes that it’s in the middle of a <bad-url-token> rather than a <url-token>.

ConsumeComments consumes zero or more CSS comments.

ConsumeEscapedCodepoint consumes an escaped code point.

ConsumeIdentLikeToken consumes an ident-like token from a stream of code points.

ConsumeIdentSequence consumes an ident sequence from a stream of code points.

ConsumeNumber consumes a number from a stream of code points.

ConsumeNumericToken consumes a numeric token from a stream of code points.

ConsumeString consumes a string token.

ConsumeUrlToken describes how to consume a url token from a stream of code points.

ConsumeWhitespace consumes as much whitespace as possible and returns a <whitespace-token>.

StringToNumber describes how to convert a string to a number according to the CSS specification.