css

README

CSS selectors in Go

This library is a fork of github.com/ericchiang/css fixing issues experienced using Gost-DOM.

Note. This fork starts at version 0.1.0, as I imagine adding significant chagnes to the public API, allowing it consume an interface; rather than the specific golang.org/x/net/html

---

This package implements a CSS selector compiler for Go's HTML parsing package golang.org/x/net/html.

package main

import (
	"fmt"
	"os"
	"strings"

	"github.com/ericchiang/css"
	"golang.org/x/net/html"
)

var data = `
<p>
  <h2 id="foo">a header</h2>
  <h2 id="bar">another header</h2>
</p>`

func main() {
	sel, err := css.Parse("h2#foo")
	if err != nil {
		panic(err)
	}
	node, err := html.Parse(strings.NewReader(data))
	if err != nil {
		panic(err)
	}
	for _, ele := range sel.Select(node) {
		html.Render(os.Stdout, ele)
	}
	fmt.Println()
}

$ go run example/css.go
<h2 id="foo">a header</h2>

Documentation

Overview

Package css implements CSS selector HTML search.

Selectors compiled by this package search through golang.org/x/net/html nodes and should be used in conjunction with that package.

data := `<p>
	<h2 id="foo">a header</h2>
	<h2 id="bar">another header</h2>
</p>`

sel, err := css.Parse("h2#foo")
if err != nil {
	// handle error
}
node, err := html.Parse(strings.NewReader(data))
if err != nil {
	// handle error
}
elements := sel.Select(node)

This package aims to support Selectors Level 4 https://www.w3.org/TR/selectors-4/.

The universal selector (*) is supported, along with:

a                       // Type selector
ns|a                    // Type selector with namespace
.red                    // Class selector
#demo                   // ID selector
[attr]                  // Attribute selector
[attr=value]            // Attribute selector value
[attr~=value]           // Attribute selector element of list
[attr|=value]           // Attribute selector value or "{value}-" prefix
[attr^=value]           // Attribute selector prefix
[attr$=value]           // Attribute selector suffix
[attr*=value]           // Attribute selector contains value
[attr=value i]          // Attribute selector case insensitive modifier
foo, bar                // Selector list
foo bar                 // Descendant combinator
foo > bar               // Child combinator
foo ~ bar               // General sibling combinator
foo + bar               // Adjacent sibling combinator
:empty                  // Element with no children
:first-child            // First child of parent
:first-of-type          // First child of its type of parent
:last-child             // Last child of parent
:last-of-type           // Last child of its type of parent
:only-child             // Only child of parent
:only-of-type           // Only child of its type parent
:root                   // Root element
:nth-child(An+B)        // Positional child matcher
:nth-last-child(An+B)   // Reverse positional child matcher
:nth-last-of-type(An+B) // Reverse positional child matcher of type
:nth-of-type(An+B)      // Positional child matcher of type

Index

• type ParseError
  • func (p *ParseError) Error() string
• type Selector
  • func MustParse(s string) *Selector
  • func Parse(s string) (*Selector, error)
  • func (s *Selector) Select(n *html.Node) []*html.Node

Types

type ParseError

type ParseError struct {
	Pos int
	Msg string
}

ParseError is returned indicating an lex, parse, or compilation error with the associated position in the string the error occurred.

func (*ParseError) Error

func (p *ParseError) Error() string

Error returns a formatted version of the error.

type Selector

type Selector struct {
	// contains filtered or unexported fields
}

Selector is a compiled CSS selector.

func MustParse

func MustParse(s string) *Selector

MustParse is like Parse but panics on errors.

func Parse

func Parse(s string) (*Selector, error)

Parse compiles a complex selector list from a string. The parser supports Selectors Level 4.

Multiple selectors are supported through comma separated values. For example "h1, h2".

Parse reports the first error hit when compiling.

func (*Selector) Select

func (s *Selector) Select(n *html.Node) []*html.Node

Select returns any matches from a parsed HTML document.