834 lines
19 KiB
Go
834 lines
19 KiB
Go
package cascadia
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import (
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"bytes"
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"fmt"
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"regexp"
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"strings"
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"golang.org/x/net/html"
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)
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// Matcher is the interface for basic selector functionality.
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// Match returns whether a selector matches n.
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type Matcher interface {
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Match(n *html.Node) bool
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}
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// Sel is the interface for all the functionality provided by selectors.
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// It is currently the same as Matcher, but other methods may be added in the
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// future.
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type Sel interface {
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Matcher
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Specificity() Specificity
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}
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// Parse parses a selector.
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func Parse(sel string) (Sel, error) {
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p := &parser{s: sel}
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compiled, err := p.parseSelector()
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if err != nil {
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return nil, err
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}
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if p.i < len(sel) {
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return nil, fmt.Errorf("parsing %q: %d bytes left over", sel, len(sel)-p.i)
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}
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return compiled, nil
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}
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// ParseGroup parses a selector, or a group of selectors separated by commas.
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func ParseGroup(sel string) (SelectorGroup, error) {
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p := &parser{s: sel}
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compiled, err := p.parseSelectorGroup()
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if err != nil {
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return nil, err
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}
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if p.i < len(sel) {
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return nil, fmt.Errorf("parsing %q: %d bytes left over", sel, len(sel)-p.i)
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}
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return compiled, nil
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}
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// A Selector is a function which tells whether a node matches or not.
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//
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// This type is maintained for compatibility; I recommend using the newer and
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// more idiomatic interfaces Sel and Matcher.
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type Selector func(*html.Node) bool
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// Compile parses a selector and returns, if successful, a Selector object
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// that can be used to match against html.Node objects.
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func Compile(sel string) (Selector, error) {
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compiled, err := ParseGroup(sel)
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if err != nil {
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return nil, err
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}
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return Selector(compiled.Match), nil
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}
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// MustCompile is like Compile, but panics instead of returning an error.
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func MustCompile(sel string) Selector {
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compiled, err := Compile(sel)
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if err != nil {
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panic(err)
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}
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return compiled
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}
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// MatchAll returns a slice of the nodes that match the selector,
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// from n and its children.
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func (s Selector) MatchAll(n *html.Node) []*html.Node {
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return s.matchAllInto(n, nil)
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}
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func (s Selector) matchAllInto(n *html.Node, storage []*html.Node) []*html.Node {
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if s(n) {
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storage = append(storage, n)
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}
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for child := n.FirstChild; child != nil; child = child.NextSibling {
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storage = s.matchAllInto(child, storage)
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}
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return storage
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}
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func queryInto(n *html.Node, m Matcher, storage []*html.Node) []*html.Node {
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for child := n.FirstChild; child != nil; child = child.NextSibling {
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if m.Match(child) {
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storage = append(storage, child)
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}
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storage = queryInto(child, m, storage)
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}
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return storage
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}
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// QueryAll returns a slice of all the nodes that match m, from the descendants
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// of n.
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func QueryAll(n *html.Node, m Matcher) []*html.Node {
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return queryInto(n, m, nil)
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}
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// Match returns true if the node matches the selector.
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func (s Selector) Match(n *html.Node) bool {
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return s(n)
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}
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// MatchFirst returns the first node that matches s, from n and its children.
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func (s Selector) MatchFirst(n *html.Node) *html.Node {
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if s.Match(n) {
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return n
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}
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for c := n.FirstChild; c != nil; c = c.NextSibling {
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m := s.MatchFirst(c)
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if m != nil {
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return m
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}
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}
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return nil
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}
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// Query returns the first node that matches m, from the descendants of n.
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// If none matches, it returns nil.
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func Query(n *html.Node, m Matcher) *html.Node {
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for c := n.FirstChild; c != nil; c = c.NextSibling {
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if m.Match(c) {
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return c
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}
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if matched := Query(c, m); matched != nil {
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return matched
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}
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}
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return nil
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}
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// Filter returns the nodes in nodes that match the selector.
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func (s Selector) Filter(nodes []*html.Node) (result []*html.Node) {
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for _, n := range nodes {
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if s(n) {
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result = append(result, n)
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}
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}
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return result
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}
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// Filter returns the nodes that match m.
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func Filter(nodes []*html.Node, m Matcher) (result []*html.Node) {
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for _, n := range nodes {
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if m.Match(n) {
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result = append(result, n)
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}
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}
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return result
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}
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type tagSelector struct {
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tag string
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}
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// Matches elements with a given tag name.
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func (t tagSelector) Match(n *html.Node) bool {
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return n.Type == html.ElementNode && n.Data == t.tag
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}
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func (c tagSelector) Specificity() Specificity {
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return Specificity{0, 0, 1}
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}
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type classSelector struct {
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class string
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}
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// Matches elements by class attribute.
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func (t classSelector) Match(n *html.Node) bool {
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return matchAttribute(n, "class", func(s string) bool {
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return matchInclude(t.class, s)
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})
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}
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func (c classSelector) Specificity() Specificity {
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return Specificity{0, 1, 0}
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}
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type idSelector struct {
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id string
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}
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// Matches elements by id attribute.
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func (t idSelector) Match(n *html.Node) bool {
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return matchAttribute(n, "id", func(s string) bool {
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return s == t.id
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})
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}
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func (c idSelector) Specificity() Specificity {
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return Specificity{1, 0, 0}
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}
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type attrSelector struct {
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key, val, operation string
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regexp *regexp.Regexp
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}
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// Matches elements by attribute value.
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func (t attrSelector) Match(n *html.Node) bool {
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switch t.operation {
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case "":
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return matchAttribute(n, t.key, func(string) bool { return true })
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case "=":
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return matchAttribute(n, t.key, func(s string) bool { return s == t.val })
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case "!=":
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return attributeNotEqualMatch(t.key, t.val, n)
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case "~=":
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// matches elements where the attribute named key is a whitespace-separated list that includes val.
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return matchAttribute(n, t.key, func(s string) bool { return matchInclude(t.val, s) })
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case "|=":
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return attributeDashMatch(t.key, t.val, n)
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case "^=":
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return attributePrefixMatch(t.key, t.val, n)
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case "$=":
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return attributeSuffixMatch(t.key, t.val, n)
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case "*=":
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return attributeSubstringMatch(t.key, t.val, n)
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case "#=":
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return attributeRegexMatch(t.key, t.regexp, n)
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default:
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panic(fmt.Sprintf("unsuported operation : %s", t.operation))
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}
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}
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// matches elements where the attribute named key satisifes the function f.
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func matchAttribute(n *html.Node, key string, f func(string) bool) bool {
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if n.Type != html.ElementNode {
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return false
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}
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for _, a := range n.Attr {
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if a.Key == key && f(a.Val) {
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return true
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}
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}
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return false
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}
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// attributeNotEqualMatch matches elements where
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// the attribute named key does not have the value val.
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func attributeNotEqualMatch(key, val string, n *html.Node) bool {
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if n.Type != html.ElementNode {
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return false
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}
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for _, a := range n.Attr {
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if a.Key == key && a.Val == val {
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return false
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}
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}
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return true
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}
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// returns true if s is a whitespace-separated list that includes val.
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func matchInclude(val, s string) bool {
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for s != "" {
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i := strings.IndexAny(s, " \t\r\n\f")
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if i == -1 {
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return s == val
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}
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if s[:i] == val {
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return true
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}
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s = s[i+1:]
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}
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return false
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}
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// matches elements where the attribute named key equals val or starts with val plus a hyphen.
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func attributeDashMatch(key, val string, n *html.Node) bool {
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return matchAttribute(n, key,
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func(s string) bool {
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if s == val {
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return true
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}
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if len(s) <= len(val) {
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return false
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}
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if s[:len(val)] == val && s[len(val)] == '-' {
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return true
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}
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return false
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})
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}
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// attributePrefixMatch returns a Selector that matches elements where
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// the attribute named key starts with val.
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func attributePrefixMatch(key, val string, n *html.Node) bool {
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return matchAttribute(n, key,
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func(s string) bool {
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if strings.TrimSpace(s) == "" {
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return false
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}
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return strings.HasPrefix(s, val)
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})
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}
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// attributeSuffixMatch matches elements where
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// the attribute named key ends with val.
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func attributeSuffixMatch(key, val string, n *html.Node) bool {
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return matchAttribute(n, key,
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func(s string) bool {
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if strings.TrimSpace(s) == "" {
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return false
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}
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return strings.HasSuffix(s, val)
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})
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}
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// attributeSubstringMatch matches nodes where
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// the attribute named key contains val.
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func attributeSubstringMatch(key, val string, n *html.Node) bool {
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return matchAttribute(n, key,
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func(s string) bool {
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if strings.TrimSpace(s) == "" {
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return false
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}
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return strings.Contains(s, val)
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})
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}
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// attributeRegexMatch matches nodes where
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// the attribute named key matches the regular expression rx
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func attributeRegexMatch(key string, rx *regexp.Regexp, n *html.Node) bool {
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return matchAttribute(n, key,
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func(s string) bool {
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return rx.MatchString(s)
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})
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}
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func (c attrSelector) Specificity() Specificity {
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return Specificity{0, 1, 0}
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}
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// ---------------- Pseudo class selectors ----------------
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// we use severals concrete types of pseudo-class selectors
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type relativePseudoClassSelector struct {
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name string // one of "not", "has", "haschild"
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match SelectorGroup
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}
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func (s relativePseudoClassSelector) Match(n *html.Node) bool {
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if n.Type != html.ElementNode {
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return false
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}
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switch s.name {
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case "not":
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// matches elements that do not match a.
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return !s.match.Match(n)
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case "has":
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// matches elements with any descendant that matches a.
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return hasDescendantMatch(n, s.match)
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case "haschild":
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// matches elements with a child that matches a.
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return hasChildMatch(n, s.match)
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default:
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panic(fmt.Sprintf("unsupported relative pseudo class selector : %s", s.name))
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}
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}
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// hasChildMatch returns whether n has any child that matches a.
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func hasChildMatch(n *html.Node, a Matcher) bool {
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for c := n.FirstChild; c != nil; c = c.NextSibling {
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if a.Match(c) {
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return true
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}
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}
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return false
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}
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// hasDescendantMatch performs a depth-first search of n's descendants,
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// testing whether any of them match a. It returns true as soon as a match is
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// found, or false if no match is found.
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func hasDescendantMatch(n *html.Node, a Matcher) bool {
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for c := n.FirstChild; c != nil; c = c.NextSibling {
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if a.Match(c) || (c.Type == html.ElementNode && hasDescendantMatch(c, a)) {
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return true
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}
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}
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return false
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}
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// Specificity returns the specificity of the most specific selectors
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// in the pseudo-class arguments.
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// See https://www.w3.org/TR/selectors/#specificity-rules
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func (s relativePseudoClassSelector) Specificity() Specificity {
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var max Specificity
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for _, sel := range s.match {
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newSpe := sel.Specificity()
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if max.Less(newSpe) {
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max = newSpe
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}
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}
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return max
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}
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type containsPseudoClassSelector struct {
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own bool
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value string
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}
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func (s containsPseudoClassSelector) Match(n *html.Node) bool {
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var text string
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if s.own {
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// matches nodes that directly contain the given text
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text = strings.ToLower(nodeOwnText(n))
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} else {
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// matches nodes that contain the given text.
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text = strings.ToLower(nodeText(n))
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}
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return strings.Contains(text, s.value)
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}
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func (s containsPseudoClassSelector) Specificity() Specificity {
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return Specificity{0, 1, 0}
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}
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type regexpPseudoClassSelector struct {
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own bool
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regexp *regexp.Regexp
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}
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func (s regexpPseudoClassSelector) Match(n *html.Node) bool {
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var text string
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if s.own {
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// matches nodes whose text directly matches the specified regular expression
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text = nodeOwnText(n)
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} else {
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// matches nodes whose text matches the specified regular expression
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text = nodeText(n)
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}
|
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return s.regexp.MatchString(text)
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}
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|
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// writeNodeText writes the text contained in n and its descendants to b.
|
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func writeNodeText(n *html.Node, b *bytes.Buffer) {
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switch n.Type {
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case html.TextNode:
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b.WriteString(n.Data)
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case html.ElementNode:
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for c := n.FirstChild; c != nil; c = c.NextSibling {
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writeNodeText(c, b)
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}
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}
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}
|
|
|
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// nodeText returns the text contained in n and its descendants.
|
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func nodeText(n *html.Node) string {
|
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var b bytes.Buffer
|
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writeNodeText(n, &b)
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return b.String()
|
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}
|
|
|
|
// nodeOwnText returns the contents of the text nodes that are direct
|
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// children of n.
|
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func nodeOwnText(n *html.Node) string {
|
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var b bytes.Buffer
|
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for c := n.FirstChild; c != nil; c = c.NextSibling {
|
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if c.Type == html.TextNode {
|
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b.WriteString(c.Data)
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}
|
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}
|
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return b.String()
|
|
}
|
|
|
|
func (s regexpPseudoClassSelector) Specificity() Specificity {
|
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return Specificity{0, 1, 0}
|
|
}
|
|
|
|
type nthPseudoClassSelector struct {
|
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a, b int
|
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last, ofType bool
|
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}
|
|
|
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func (s nthPseudoClassSelector) Match(n *html.Node) bool {
|
|
if s.a == 0 {
|
|
if s.last {
|
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return simpleNthLastChildMatch(s.b, s.ofType, n)
|
|
} else {
|
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return simpleNthChildMatch(s.b, s.ofType, n)
|
|
}
|
|
}
|
|
return nthChildMatch(s.a, s.b, s.last, s.ofType, n)
|
|
}
|
|
|
|
// nthChildMatch implements :nth-child(an+b).
|
|
// If last is true, implements :nth-last-child instead.
|
|
// If ofType is true, implements :nth-of-type instead.
|
|
func nthChildMatch(a, b int, last, ofType bool, n *html.Node) bool {
|
|
if n.Type != html.ElementNode {
|
|
return false
|
|
}
|
|
|
|
parent := n.Parent
|
|
if parent == nil {
|
|
return false
|
|
}
|
|
|
|
if parent.Type == html.DocumentNode {
|
|
return false
|
|
}
|
|
|
|
i := -1
|
|
count := 0
|
|
for c := parent.FirstChild; c != nil; c = c.NextSibling {
|
|
if (c.Type != html.ElementNode) || (ofType && c.Data != n.Data) {
|
|
continue
|
|
}
|
|
count++
|
|
if c == n {
|
|
i = count
|
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if !last {
|
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break
|
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}
|
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}
|
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}
|
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|
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if i == -1 {
|
|
// This shouldn't happen, since n should always be one of its parent's children.
|
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return false
|
|
}
|
|
|
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if last {
|
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i = count - i + 1
|
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}
|
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|
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i -= b
|
|
if a == 0 {
|
|
return i == 0
|
|
}
|
|
|
|
return i%a == 0 && i/a >= 0
|
|
}
|
|
|
|
// simpleNthChildMatch implements :nth-child(b).
|
|
// If ofType is true, implements :nth-of-type instead.
|
|
func simpleNthChildMatch(b int, ofType bool, n *html.Node) bool {
|
|
if n.Type != html.ElementNode {
|
|
return false
|
|
}
|
|
|
|
parent := n.Parent
|
|
if parent == nil {
|
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return false
|
|
}
|
|
|
|
if parent.Type == html.DocumentNode {
|
|
return false
|
|
}
|
|
|
|
count := 0
|
|
for c := parent.FirstChild; c != nil; c = c.NextSibling {
|
|
if c.Type != html.ElementNode || (ofType && c.Data != n.Data) {
|
|
continue
|
|
}
|
|
count++
|
|
if c == n {
|
|
return count == b
|
|
}
|
|
if count >= b {
|
|
return false
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
|
|
// simpleNthLastChildMatch implements :nth-last-child(b).
|
|
// If ofType is true, implements :nth-last-of-type instead.
|
|
func simpleNthLastChildMatch(b int, ofType bool, n *html.Node) bool {
|
|
if n.Type != html.ElementNode {
|
|
return false
|
|
}
|
|
|
|
parent := n.Parent
|
|
if parent == nil {
|
|
return false
|
|
}
|
|
|
|
if parent.Type == html.DocumentNode {
|
|
return false
|
|
}
|
|
|
|
count := 0
|
|
for c := parent.LastChild; c != nil; c = c.PrevSibling {
|
|
if c.Type != html.ElementNode || (ofType && c.Data != n.Data) {
|
|
continue
|
|
}
|
|
count++
|
|
if c == n {
|
|
return count == b
|
|
}
|
|
if count >= b {
|
|
return false
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
|
|
// Specificity for nth-child pseudo-class.
|
|
// Does not support a list of selectors
|
|
func (s nthPseudoClassSelector) Specificity() Specificity {
|
|
return Specificity{0, 1, 0}
|
|
}
|
|
|
|
type onlyChildPseudoClassSelector struct {
|
|
ofType bool
|
|
}
|
|
|
|
// Match implements :only-child.
|
|
// If `ofType` is true, it implements :only-of-type instead.
|
|
func (s onlyChildPseudoClassSelector) Match(n *html.Node) bool {
|
|
if n.Type != html.ElementNode {
|
|
return false
|
|
}
|
|
|
|
parent := n.Parent
|
|
if parent == nil {
|
|
return false
|
|
}
|
|
|
|
if parent.Type == html.DocumentNode {
|
|
return false
|
|
}
|
|
|
|
count := 0
|
|
for c := parent.FirstChild; c != nil; c = c.NextSibling {
|
|
if (c.Type != html.ElementNode) || (s.ofType && c.Data != n.Data) {
|
|
continue
|
|
}
|
|
count++
|
|
if count > 1 {
|
|
return false
|
|
}
|
|
}
|
|
|
|
return count == 1
|
|
}
|
|
|
|
func (s onlyChildPseudoClassSelector) Specificity() Specificity {
|
|
return Specificity{0, 1, 0}
|
|
}
|
|
|
|
type inputPseudoClassSelector struct{}
|
|
|
|
// Matches input, select, textarea and button elements.
|
|
func (s inputPseudoClassSelector) Match(n *html.Node) bool {
|
|
return n.Type == html.ElementNode && (n.Data == "input" || n.Data == "select" || n.Data == "textarea" || n.Data == "button")
|
|
}
|
|
|
|
func (s inputPseudoClassSelector) Specificity() Specificity {
|
|
return Specificity{0, 1, 0}
|
|
}
|
|
|
|
type emptyElementPseudoClassSelector struct{}
|
|
|
|
// Matches empty elements.
|
|
func (s emptyElementPseudoClassSelector) Match(n *html.Node) bool {
|
|
if n.Type != html.ElementNode {
|
|
return false
|
|
}
|
|
|
|
for c := n.FirstChild; c != nil; c = c.NextSibling {
|
|
switch c.Type {
|
|
case html.ElementNode, html.TextNode:
|
|
return false
|
|
}
|
|
}
|
|
|
|
return true
|
|
}
|
|
|
|
func (s emptyElementPseudoClassSelector) Specificity() Specificity {
|
|
return Specificity{0, 1, 0}
|
|
}
|
|
|
|
type rootPseudoClassSelector struct{}
|
|
|
|
// Match implements :root
|
|
func (s rootPseudoClassSelector) Match(n *html.Node) bool {
|
|
if n.Type != html.ElementNode {
|
|
return false
|
|
}
|
|
if n.Parent == nil {
|
|
return false
|
|
}
|
|
return n.Parent.Type == html.DocumentNode
|
|
}
|
|
|
|
func (s rootPseudoClassSelector) Specificity() Specificity {
|
|
return Specificity{0, 1, 0}
|
|
}
|
|
|
|
type compoundSelector struct {
|
|
selectors []Sel
|
|
}
|
|
|
|
// Matches elements if each sub-selectors matches.
|
|
func (t compoundSelector) Match(n *html.Node) bool {
|
|
if len(t.selectors) == 0 {
|
|
return n.Type == html.ElementNode
|
|
}
|
|
|
|
for _, sel := range t.selectors {
|
|
if !sel.Match(n) {
|
|
return false
|
|
}
|
|
}
|
|
return true
|
|
}
|
|
|
|
func (s compoundSelector) Specificity() Specificity {
|
|
var out Specificity
|
|
for _, sel := range s.selectors {
|
|
out = out.Add(sel.Specificity())
|
|
}
|
|
return out
|
|
}
|
|
|
|
type combinedSelector struct {
|
|
first Sel
|
|
combinator byte
|
|
second Sel
|
|
}
|
|
|
|
func (t combinedSelector) Match(n *html.Node) bool {
|
|
if t.first == nil {
|
|
return false // maybe we should panic
|
|
}
|
|
switch t.combinator {
|
|
case 0:
|
|
return t.first.Match(n)
|
|
case ' ':
|
|
return descendantMatch(t.first, t.second, n)
|
|
case '>':
|
|
return childMatch(t.first, t.second, n)
|
|
case '+':
|
|
return siblingMatch(t.first, t.second, true, n)
|
|
case '~':
|
|
return siblingMatch(t.first, t.second, false, n)
|
|
default:
|
|
panic("unknown combinator")
|
|
}
|
|
}
|
|
|
|
// matches an element if it matches d and has an ancestor that matches a.
|
|
func descendantMatch(a, d Matcher, n *html.Node) bool {
|
|
if !d.Match(n) {
|
|
return false
|
|
}
|
|
|
|
for p := n.Parent; p != nil; p = p.Parent {
|
|
if a.Match(p) {
|
|
return true
|
|
}
|
|
}
|
|
|
|
return false
|
|
}
|
|
|
|
// matches an element if it matches d and its parent matches a.
|
|
func childMatch(a, d Matcher, n *html.Node) bool {
|
|
return d.Match(n) && n.Parent != nil && a.Match(n.Parent)
|
|
}
|
|
|
|
// matches an element if it matches s2 and is preceded by an element that matches s1.
|
|
// If adjacent is true, the sibling must be immediately before the element.
|
|
func siblingMatch(s1, s2 Matcher, adjacent bool, n *html.Node) bool {
|
|
if !s2.Match(n) {
|
|
return false
|
|
}
|
|
|
|
if adjacent {
|
|
for n = n.PrevSibling; n != nil; n = n.PrevSibling {
|
|
if n.Type == html.TextNode || n.Type == html.CommentNode {
|
|
continue
|
|
}
|
|
return s1.Match(n)
|
|
}
|
|
return false
|
|
}
|
|
|
|
// Walk backwards looking for element that matches s1
|
|
for c := n.PrevSibling; c != nil; c = c.PrevSibling {
|
|
if s1.Match(c) {
|
|
return true
|
|
}
|
|
}
|
|
|
|
return false
|
|
}
|
|
|
|
func (s combinedSelector) Specificity() Specificity {
|
|
spec := s.first.Specificity()
|
|
if s.second != nil {
|
|
spec = spec.Add(s.second.Specificity())
|
|
}
|
|
return spec
|
|
}
|
|
|
|
// A SelectorGroup is a list of selectors, which matches if any of the
|
|
// individual selectors matches.
|
|
type SelectorGroup []Sel
|
|
|
|
// Match returns true if the node matches one of the single selectors.
|
|
func (s SelectorGroup) Match(n *html.Node) bool {
|
|
for _, sel := range s {
|
|
if sel.Match(n) {
|
|
return true
|
|
}
|
|
}
|
|
return false
|
|
}
|