This package is a CSS3 lexer and parser written in Go. Both follow the specification at CSS Syntax Module Level 3. The lexer takes an io.Reader and converts it into tokens until the EOF. The parser returns a parse tree of the full io.Reader input stream, but the low-level Next function can be used for stream parsing to returns grammar units until the EOF.
Run the following command
go get -u github.com/tdewolff/parse/v2/css or add the following import and run project with go get
import "github.com/tdewolff/parse/v2/css" The following initializes a new Lexer with io.Reader r:
l := css.NewLexer(parse.NewInput(r))To tokenize until EOF an error, use:
for { tt, text := l.Next() switch tt { case css.ErrorToken: // error or EOF set in l.Err() return // ... } }All tokens (see CSS Syntax Module Level 3):
ErrorToken// non-official token, returned when errors occur IdentToken FunctionToken// rgb( rgba( ... AtKeywordToken// @abc HashToken// #abc StringToken BadStringToken URLToken// url( BadURLToken DelimToken// any unmatched character NumberToken// 5 PercentageToken// 5% DimensionToken// 5em UnicodeRangeToken IncludeMatchToken// ~= DashMatchToken// |= PrefixMatchToken// ^= SuffixMatchToken// $= SubstringMatchToken // *= ColumnToken// || WhitespaceToken CDOToken // <!-- CDCToken // --> ColonToken SemicolonToken CommaToken BracketToken // ( ) [ ] { }, all bracket tokens use this, Data() can distinguish between the brackets CommentToken// non-official tokenpackage main import ( "os" "github.com/tdewolff/parse/v2/css" ) // Tokenize CSS3 from stdin. func main() { l := css.NewLexer(parse.NewInput(os.Stdin)) for { tt, text := l.Next() switch tt { case css.ErrorToken: if l.Err() != io.EOF { fmt.Println("Error on line", l.Line(), ":", l.Err()) } return case css.IdentToken: fmt.Println("Identifier", string(text)) case css.NumberToken: fmt.Println("Number", string(text)) // ... } } }The following creates a new Parser.
// true because this is the content of an inline style attribute p := css.NewParser(parse.NewInput(bytes.NewBufferString("color: red;")), true)To iterate over the stylesheet, use:
for { gt, _, data := p.Next() if gt == css.ErrorGrammar { break } // ... }All grammar units returned by Next:
ErrorGrammar AtRuleGrammar EndAtRuleGrammar RulesetGrammar EndRulesetGrammar DeclarationGrammar TokenGrammarpackage main import ( "bytes" "fmt" "github.com/tdewolff/parse/v2/css" ) func main() { // true because this is the content of an inline style attribute p := css.NewParser(parse.NewInput(bytes.NewBufferString("color: red;")), true) out := "" for { gt, _, data := p.Next() if gt == css.ErrorGrammar { break } else if gt == css.AtRuleGrammar || gt == css.BeginAtRuleGrammar || gt == css.BeginRulesetGrammar || gt == css.DeclarationGrammar { out += string(data) if gt == css.DeclarationGrammar { out += ":" } for _, val := range p.Values() { out += string(val.Data) } if gt == css.BeginAtRuleGrammar || gt == css.BeginRulesetGrammar { out += "{" } else if gt == css.AtRuleGrammar || gt == css.DeclarationGrammar { out += ";" } } else { out += string(data) } } fmt.Println(out) }Released under the MIT license.