Vendor

vendor/github.com/andybalholm/cascadia/pseudo_classes.go

@@ -0,0 +1,458 @@
+package cascadia
+
+import (
+	"bytes"
+	"fmt"
+	"regexp"
+	"strings"
+
+	"golang.org/x/net/html"
+	"golang.org/x/net/html/atom"
+)
+
+// This file implements the pseudo classes selectors,
+// which share the implementation of PseudoElement() and Specificity()
+
+type abstractPseudoClass struct{}
+
+func (s abstractPseudoClass) Specificity() Specificity {
+	return Specificity{0, 1, 0}
+}
+
+func (c abstractPseudoClass) PseudoElement() string {
+	return ""
+}
+
+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 {
+	abstractPseudoClass
+	value string
+	own   bool
+}
+
+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)
+}
+
+type regexpPseudoClassSelector struct {
+	abstractPseudoClass
+	regexp *regexp.Regexp
+	own    bool
+}
+
+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()
+}
+
+type nthPseudoClassSelector struct {
+	abstractPseudoClass
+	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
+	}
+
+	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
+	}
+
+	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
+	}
+
+	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
+}
+
+type onlyChildPseudoClassSelector struct {
+	abstractPseudoClass
+	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
+	}
+
+	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
+}
+
+type inputPseudoClassSelector struct {
+	abstractPseudoClass
+}
+
+// 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")
+}
+
+type emptyElementPseudoClassSelector struct {
+	abstractPseudoClass
+}
+
+// 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:
+			return false
+		case html.TextNode:
+			if strings.TrimSpace(nodeText(c)) == "" {
+				continue
+			} else {
+				return false
+			}
+		}
+	}
+
+	return true
+}
+
+type rootPseudoClassSelector struct {
+	abstractPseudoClass
+}
+
+// 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 hasAttr(n *html.Node, attr string) bool {
+	return matchAttribute(n, attr, func(string) bool { return true })
+}
+
+type linkPseudoClassSelector struct {
+	abstractPseudoClass
+}
+
+// Match implements :link
+func (s linkPseudoClassSelector) Match(n *html.Node) bool {
+	return (n.DataAtom == atom.A || n.DataAtom == atom.Area || n.DataAtom == atom.Link) && hasAttr(n, "href")
+}
+
+type langPseudoClassSelector struct {
+	abstractPseudoClass
+	lang string
+}
+
+func (s langPseudoClassSelector) Match(n *html.Node) bool {
+	own := matchAttribute(n, "lang", func(val string) bool {
+		return val == s.lang || strings.HasPrefix(val, s.lang+"-")
+	})
+	if n.Parent == nil {
+		return own
+	}
+	return own || s.Match(n.Parent)
+}
+
+type enabledPseudoClassSelector struct {
+	abstractPseudoClass
+}
+
+func (s enabledPseudoClassSelector) Match(n *html.Node) bool {
+	if n.Type != html.ElementNode {
+		return false
+	}
+	switch n.DataAtom {
+	case atom.A, atom.Area, atom.Link:
+		return hasAttr(n, "href")
+	case atom.Optgroup, atom.Menuitem, atom.Fieldset:
+		return !hasAttr(n, "disabled")
+	case atom.Button, atom.Input, atom.Select, atom.Textarea, atom.Option:
+		return !hasAttr(n, "disabled") && !inDisabledFieldset(n)
+	}
+	return false
+}
+
+type disabledPseudoClassSelector struct {
+	abstractPseudoClass
+}
+
+func (s disabledPseudoClassSelector) Match(n *html.Node) bool {
+	if n.Type != html.ElementNode {
+		return false
+	}
+	switch n.DataAtom {
+	case atom.Optgroup, atom.Menuitem, atom.Fieldset:
+		return hasAttr(n, "disabled")
+	case atom.Button, atom.Input, atom.Select, atom.Textarea, atom.Option:
+		return hasAttr(n, "disabled") || inDisabledFieldset(n)
+	}
+	return false
+}
+
+func hasLegendInPreviousSiblings(n *html.Node) bool {
+	for s := n.PrevSibling; s != nil; s = s.PrevSibling {
+		if s.DataAtom == atom.Legend {
+			return true
+		}
+	}
+	return false
+}
+
+func inDisabledFieldset(n *html.Node) bool {
+	if n.Parent == nil {
+		return false
+	}
+	if n.Parent.DataAtom == atom.Fieldset && hasAttr(n.Parent, "disabled") &&
+		(n.DataAtom != atom.Legend || hasLegendInPreviousSiblings(n)) {
+		return true
+	}
+	return inDisabledFieldset(n.Parent)
+}
+
+type checkedPseudoClassSelector struct {
+	abstractPseudoClass
+}
+
+func (s checkedPseudoClassSelector) Match(n *html.Node) bool {
+	if n.Type != html.ElementNode {
+		return false
+	}
+	switch n.DataAtom {
+	case atom.Input, atom.Menuitem:
+		return hasAttr(n, "checked") && matchAttribute(n, "type", func(val string) bool {
+			t := toLowerASCII(val)
+			return t == "checkbox" || t == "radio"
+		})
+	case atom.Option:
+		return hasAttr(n, "selected")
+	}
+	return false
+}