peridot/vendor/github.com/andybalholm/cascadia/selector.go

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2022-07-07 20:11:50 +00:00
package cascadia
import (
"bytes"
"fmt"
"regexp"
"strings"
"golang.org/x/net/html"
)
// Matcher is the interface for basic selector functionality.
// Match returns whether a selector matches n.
type Matcher interface {
Match(n *html.Node) bool
}
// Sel is the interface for all the functionality provided by selectors.
type Sel interface {
Matcher
Specificity() Specificity
// Returns a CSS input compiling to this selector.
String() string
// Returns a pseudo-element, or an empty string.
PseudoElement() string
}
// Parse parses a selector. Use `ParseWithPseudoElement`
// if you need support for pseudo-elements.
func Parse(sel string) (Sel, error) {
p := &parser{s: sel}
compiled, err := p.parseSelector()
if err != nil {
return nil, err
}
if p.i < len(sel) {
return nil, fmt.Errorf("parsing %q: %d bytes left over", sel, len(sel)-p.i)
}
return compiled, nil
}
// ParseWithPseudoElement parses a single selector,
// with support for pseudo-element.
func ParseWithPseudoElement(sel string) (Sel, error) {
p := &parser{s: sel, acceptPseudoElements: true}
compiled, err := p.parseSelector()
if err != nil {
return nil, err
}
if p.i < len(sel) {
return nil, fmt.Errorf("parsing %q: %d bytes left over", sel, len(sel)-p.i)
}
return compiled, nil
}
// ParseGroup parses a selector, or a group of selectors separated by commas.
// Use `ParseGroupWithPseudoElements`
// if you need support for pseudo-elements.
func ParseGroup(sel string) (SelectorGroup, error) {
p := &parser{s: sel}
compiled, err := p.parseSelectorGroup()
if err != nil {
return nil, err
}
if p.i < len(sel) {
return nil, fmt.Errorf("parsing %q: %d bytes left over", sel, len(sel)-p.i)
}
return compiled, nil
}
// ParseGroupWithPseudoElements parses a selector, or a group of selectors separated by commas.
// It supports pseudo-elements.
func ParseGroupWithPseudoElements(sel string) (SelectorGroup, error) {
p := &parser{s: sel, acceptPseudoElements: true}
compiled, err := p.parseSelectorGroup()
if err != nil {
return nil, err
}
if p.i < len(sel) {
return nil, fmt.Errorf("parsing %q: %d bytes left over", sel, len(sel)-p.i)
}
return compiled, nil
}
// A Selector is a function which tells whether a node matches or not.
//
// This type is maintained for compatibility; I recommend using the newer and
// more idiomatic interfaces Sel and Matcher.
type Selector func(*html.Node) bool
// Compile parses a selector and returns, if successful, a Selector object
// that can be used to match against html.Node objects.
func Compile(sel string) (Selector, error) {
compiled, err := ParseGroup(sel)
if err != nil {
return nil, err
}
return Selector(compiled.Match), nil
}
// MustCompile is like Compile, but panics instead of returning an error.
func MustCompile(sel string) Selector {
compiled, err := Compile(sel)
if err != nil {
panic(err)
}
return compiled
}
// MatchAll returns a slice of the nodes that match the selector,
// from n and its children.
func (s Selector) MatchAll(n *html.Node) []*html.Node {
return s.matchAllInto(n, nil)
}
func (s Selector) matchAllInto(n *html.Node, storage []*html.Node) []*html.Node {
if s(n) {
storage = append(storage, n)
}
for child := n.FirstChild; child != nil; child = child.NextSibling {
storage = s.matchAllInto(child, storage)
}
return storage
}
func queryInto(n *html.Node, m Matcher, storage []*html.Node) []*html.Node {
for child := n.FirstChild; child != nil; child = child.NextSibling {
if m.Match(child) {
storage = append(storage, child)
}
storage = queryInto(child, m, storage)
}
return storage
}
// QueryAll returns a slice of all the nodes that match m, from the descendants
// of n.
func QueryAll(n *html.Node, m Matcher) []*html.Node {
return queryInto(n, m, nil)
}
// Match returns true if the node matches the selector.
func (s Selector) Match(n *html.Node) bool {
return s(n)
}
// MatchFirst returns the first node that matches s, from n and its children.
func (s Selector) MatchFirst(n *html.Node) *html.Node {
if s.Match(n) {
return n
}
for c := n.FirstChild; c != nil; c = c.NextSibling {
m := s.MatchFirst(c)
if m != nil {
return m
}
}
return nil
}
// Query returns the first node that matches m, from the descendants of n.
// If none matches, it returns nil.
func Query(n *html.Node, m Matcher) *html.Node {
for c := n.FirstChild; c != nil; c = c.NextSibling {
if m.Match(c) {
return c
}
if matched := Query(c, m); matched != nil {
return matched
}
}
return nil
}
// Filter returns the nodes in nodes that match the selector.
func (s Selector) Filter(nodes []*html.Node) (result []*html.Node) {
for _, n := range nodes {
if s(n) {
result = append(result, n)
}
}
return result
}
// Filter returns the nodes that match m.
func Filter(nodes []*html.Node, m Matcher) (result []*html.Node) {
for _, n := range nodes {
if m.Match(n) {
result = append(result, n)
}
}
return result
}
type tagSelector struct {
tag string
}
// Matches elements with a given tag name.
func (t tagSelector) Match(n *html.Node) bool {
return n.Type == html.ElementNode && n.Data == t.tag
}
func (c tagSelector) Specificity() Specificity {
return Specificity{0, 0, 1}
}
func (c tagSelector) PseudoElement() string {
return ""
}
type classSelector struct {
class string
}
// Matches elements by class attribute.
func (t classSelector) Match(n *html.Node) bool {
return matchAttribute(n, "class", func(s string) bool {
return matchInclude(t.class, s)
})
}
func (c classSelector) Specificity() Specificity {
return Specificity{0, 1, 0}
}
func (c classSelector) PseudoElement() string {
return ""
}
type idSelector struct {
id string
}
// Matches elements by id attribute.
func (t idSelector) Match(n *html.Node) bool {
return matchAttribute(n, "id", func(s string) bool {
return s == t.id
})
}
func (c idSelector) Specificity() Specificity {
return Specificity{1, 0, 0}
}
func (c idSelector) PseudoElement() string {
return ""
}
type attrSelector struct {
key, val, operation string
regexp *regexp.Regexp
}
// Matches elements by attribute value.
func (t attrSelector) Match(n *html.Node) bool {
switch t.operation {
case "":
return matchAttribute(n, t.key, func(string) bool { return true })
case "=":
return matchAttribute(n, t.key, func(s string) bool { return s == t.val })
case "!=":
return attributeNotEqualMatch(t.key, t.val, n)
case "~=":
// matches elements where the attribute named key is a whitespace-separated list that includes val.
return matchAttribute(n, t.key, func(s string) bool { return matchInclude(t.val, s) })
case "|=":
return attributeDashMatch(t.key, t.val, n)
case "^=":
return attributePrefixMatch(t.key, t.val, n)
case "$=":
return attributeSuffixMatch(t.key, t.val, n)
case "*=":
return attributeSubstringMatch(t.key, t.val, n)
case "#=":
return attributeRegexMatch(t.key, t.regexp, n)
default:
panic(fmt.Sprintf("unsuported operation : %s", t.operation))
}
}
// matches elements where the attribute named key satisifes the function f.
func matchAttribute(n *html.Node, key string, f func(string) bool) bool {
if n.Type != html.ElementNode {
return false
}
for _, a := range n.Attr {
if a.Key == key && f(a.Val) {
return true
}
}
return false
}
// attributeNotEqualMatch matches elements where
// the attribute named key does not have the value val.
func attributeNotEqualMatch(key, val string, n *html.Node) bool {
if n.Type != html.ElementNode {
return false
}
for _, a := range n.Attr {
if a.Key == key && a.Val == val {
return false
}
}
return true
}
// returns true if s is a whitespace-separated list that includes val.
func matchInclude(val, s string) bool {
for s != "" {
i := strings.IndexAny(s, " \t\r\n\f")
if i == -1 {
return s == val
}
if s[:i] == val {
return true
}
s = s[i+1:]
}
return false
}
// matches elements where the attribute named key equals val or starts with val plus a hyphen.
func attributeDashMatch(key, val string, n *html.Node) bool {
return matchAttribute(n, key,
func(s string) bool {
if s == val {
return true
}
if len(s) <= len(val) {
return false
}
if s[:len(val)] == val && s[len(val)] == '-' {
return true
}
return false
})
}
// attributePrefixMatch returns a Selector that matches elements where
// the attribute named key starts with val.
func attributePrefixMatch(key, val string, n *html.Node) bool {
return matchAttribute(n, key,
func(s string) bool {
if strings.TrimSpace(s) == "" {
return false
}
return strings.HasPrefix(s, val)
})
}
// attributeSuffixMatch matches elements where
// the attribute named key ends with val.
func attributeSuffixMatch(key, val string, n *html.Node) bool {
return matchAttribute(n, key,
func(s string) bool {
if strings.TrimSpace(s) == "" {
return false
}
return strings.HasSuffix(s, val)
})
}
// attributeSubstringMatch matches nodes where
// the attribute named key contains val.
func attributeSubstringMatch(key, val string, n *html.Node) bool {
return matchAttribute(n, key,
func(s string) bool {
if strings.TrimSpace(s) == "" {
return false
}
return strings.Contains(s, val)
})
}
// attributeRegexMatch matches nodes where
// the attribute named key matches the regular expression rx
func attributeRegexMatch(key string, rx *regexp.Regexp, n *html.Node) bool {
return matchAttribute(n, key,
func(s string) bool {
return rx.MatchString(s)
})
}
func (c attrSelector) Specificity() Specificity {
return Specificity{0, 1, 0}
}
func (c attrSelector) PseudoElement() string {
return ""
}
// ---------------- Pseudo class selectors ----------------
// we use severals concrete types of pseudo-class selectors
type relativePseudoClassSelector struct {
name string // one of "not", "has", "haschild"
match SelectorGroup
}
func (s relativePseudoClassSelector) Match(n *html.Node) bool {
if n.Type != html.ElementNode {
return false
}
switch s.name {
case "not":
// matches elements that do not match a.
return !s.match.Match(n)
case "has":
// matches elements with any descendant that matches a.
return hasDescendantMatch(n, s.match)
case "haschild":
// matches elements with a child that matches a.
return hasChildMatch(n, s.match)
default:
panic(fmt.Sprintf("unsupported relative pseudo class selector : %s", s.name))
}
}
// hasChildMatch returns whether n has any child that matches a.
func hasChildMatch(n *html.Node, a Matcher) bool {
for c := n.FirstChild; c != nil; c = c.NextSibling {
if a.Match(c) {
return true
}
}
return false
}
// hasDescendantMatch performs a depth-first search of n's descendants,
// testing whether any of them match a. It returns true as soon as a match is
// found, or false if no match is found.
func hasDescendantMatch(n *html.Node, a Matcher) bool {
for c := n.FirstChild; c != nil; c = c.NextSibling {
if a.Match(c) || (c.Type == html.ElementNode && hasDescendantMatch(c, a)) {
return true
}
}
return false
}
// Specificity returns the specificity of the most specific selectors
// in the pseudo-class arguments.
// See https://www.w3.org/TR/selectors/#specificity-rules
func (s relativePseudoClassSelector) Specificity() Specificity {
var max Specificity
for _, sel := range s.match {
newSpe := sel.Specificity()
if max.Less(newSpe) {
max = newSpe
}
}
return max
}
func (c relativePseudoClassSelector) PseudoElement() string {
return ""
}
type containsPseudoClassSelector struct {
own bool
value string
}
func (s containsPseudoClassSelector) Match(n *html.Node) bool {
var text string
if s.own {
// matches nodes that directly contain the given text
text = strings.ToLower(nodeOwnText(n))
} else {
// matches nodes that contain the given text.
text = strings.ToLower(nodeText(n))
}
return strings.Contains(text, s.value)
}
func (s containsPseudoClassSelector) Specificity() Specificity {
return Specificity{0, 1, 0}
}
func (c containsPseudoClassSelector) PseudoElement() string {
return ""
}
type regexpPseudoClassSelector struct {
own bool
regexp *regexp.Regexp
}
func (s regexpPseudoClassSelector) Match(n *html.Node) bool {
var text string
if s.own {
// matches nodes whose text directly matches the specified regular expression
text = nodeOwnText(n)
} else {
// matches nodes whose text matches the specified regular expression
text = nodeText(n)
}
return s.regexp.MatchString(text)
}
// writeNodeText writes the text contained in n and its descendants to b.
func writeNodeText(n *html.Node, b *bytes.Buffer) {
switch n.Type {
case html.TextNode:
b.WriteString(n.Data)
case html.ElementNode:
for c := n.FirstChild; c != nil; c = c.NextSibling {
writeNodeText(c, b)
}
}
}
// nodeText returns the text contained in n and its descendants.
func nodeText(n *html.Node) string {
var b bytes.Buffer
writeNodeText(n, &b)
return b.String()
}
// nodeOwnText returns the contents of the text nodes that are direct
// children of n.
func nodeOwnText(n *html.Node) string {
var b bytes.Buffer
for c := n.FirstChild; c != nil; c = c.NextSibling {
if c.Type == html.TextNode {
b.WriteString(c.Data)
}
}
return b.String()
}
func (s regexpPseudoClassSelector) Specificity() Specificity {
return Specificity{0, 1, 0}
}
func (c regexpPseudoClassSelector) PseudoElement() string {
return ""
}
type nthPseudoClassSelector struct {
a, b int
last, ofType bool
}
func (s nthPseudoClassSelector) Match(n *html.Node) bool {
if s.a == 0 {
if s.last {
return simpleNthLastChildMatch(s.b, s.ofType, n)
} else {
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
if !last {
break
}
}
}
if i == -1 {
// This shouldn't happen, since n should always be one of its parent's children.
return false
}
if last {
i = count - i + 1
}
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 {
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}
}
func (c nthPseudoClassSelector) PseudoElement() string {
return ""
}
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}
}
func (c onlyChildPseudoClassSelector) PseudoElement() string {
return ""
}
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}
}
func (c inputPseudoClassSelector) PseudoElement() string {
return ""
}
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}
}
func (c emptyElementPseudoClassSelector) PseudoElement() string {
return ""
}
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}
}
func (c rootPseudoClassSelector) PseudoElement() string {
return ""
}
type compoundSelector struct {
selectors []Sel
pseudoElement string
}
// 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())
}
if s.pseudoElement != "" {
// https://drafts.csswg.org/selectors-3/#specificity
out = out.Add(Specificity{0, 0, 1})
}
return out
}
func (c compoundSelector) PseudoElement() string {
return c.pseudoElement
}
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
}
// on combinedSelector, a pseudo-element only makes sens on the last
// selector, although others increase specificity.
func (c combinedSelector) PseudoElement() string {
if c.second == nil {
return ""
}
return c.second.PseudoElement()
}
// 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
}