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vendor/github.com/tdewolff/parse/css/README.md

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+# CSS [![GoDoc](http://godoc.org/github.com/tdewolff/parse/css?status.svg)](http://godoc.org/github.com/tdewolff/parse/css) [![GoCover](http://gocover.io/_badge/github.com/tdewolff/parse/css)](http://gocover.io/github.com/tdewolff/parse/css)
+
+This package is a CSS3 lexer and parser written in [Go][1]. Both follow the specification at [CSS Syntax Module Level 3](http://www.w3.org/TR/css-syntax-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.
+
+## Installation
+Run the following command
+
+	go get github.com/tdewolff/parse/css
+
+or add the following import and run project with `go get`
+
+	import "github.com/tdewolff/parse/css"
+
+## Lexer
+### Usage
+The following initializes a new Lexer with io.Reader `r`:
+``` go
+l := css.NewLexer(r)
+```
+
+To tokenize until EOF an error, use:
+``` go
+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](http://www.w3.org/TR/css3-syntax/)):
+``` go
+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 token
+```
+
+### Examples
+``` go
+package main
+
+import (
+	"os"
+
+	"github.com/tdewolff/parse/css"
+)
+
+// Tokenize CSS3 from stdin.
+func main() {
+	l := css.NewLexer(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))
+		// ...
+		}
+	}
+}
+```
+
+## Parser
+### Usage
+The following creates a new Parser.
+``` go
+// true because this is the content of an inline style attribute
+p := css.NewParser(bytes.NewBufferString("color: red;"), true)
+```
+
+To iterate over the stylesheet, use:
+``` go
+for {
+    gt, _, data := p.Next()
+    if gt == css.ErrorGrammar {
+        break
+    }
+    // ...
+}
+```
+
+All grammar units returned by `Next`:
+``` go
+ErrorGrammar
+AtRuleGrammar
+EndAtRuleGrammar
+RulesetGrammar
+EndRulesetGrammar
+DeclarationGrammar
+TokenGrammar
+```
+
+### Examples
+``` go
+package main
+
+import (
+	"bytes"
+	"fmt"
+
+	"github.com/tdewolff/parse/css"
+)
+
+func main() {
+	// true because this is the content of an inline style attribute
+	p := css.NewParser(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)
+}
+
+```
+
+## License
+Released under the [MIT license](https://github.com/tdewolff/parse/blob/master/LICENSE.md).
+
+[1]: http://golang.org/ "Go Language"