1 files changed, 622 insertions, 0 deletions
diff --git a/vendor/github.com/andybalholm/cascadia/selector.go b/vendor/github.com/andybalholm/cascadia/selector.go
new file mode 100644
index 0000000000..9fb05ccb77
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/selector.go
@@ -0,0 +1,622 @@
+package cascadia
+
+import (
+	"bytes"
+	"fmt"
+	"regexp"
+	"strings"
+
+	"golang.org/x/net/html"
+)
+
+// the Selector type, and functions for creating them
+
+// A Selector is a function which tells whether a node matches or not.
+type Selector func(*html.Node) bool
+
+// hasChildMatch returns whether n has any child that matches a.
+func hasChildMatch(n *html.Node, a Selector) bool {
+	for c := n.FirstChild; c != nil; c = c.NextSibling {
+		if a(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 Selector) bool {
+	for c := n.FirstChild; c != nil; c = c.NextSibling {
+		if a(c) || (c.Type == html.ElementNode && hasDescendantMatch(c, a)) {
+			return true
+		}
+	}
+	return false
+}
+
+// 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) {
+	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
+}
+
+// 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
+}
+
+// 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
+}
+
+// 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
+}
+
+// typeSelector returns a Selector that matches elements with a given tag name.
+func typeSelector(tag string) Selector {
+	tag = toLowerASCII(tag)
+	return func(n *html.Node) bool {
+		return n.Type == html.ElementNode && n.Data == tag
+	}
+}
+
+// toLowerASCII returns s with all ASCII capital letters lowercased.
+func toLowerASCII(s string) string {
+	var b []byte
+	for i := 0; i < len(s); i++ {
+		if c := s[i]; 'A' <= c && c <= 'Z' {
+			if b == nil {
+				b = make([]byte, len(s))
+				copy(b, s)
+			}
+			b[i] = s[i] + ('a' - 'A')
+		}
+	}
+
+	if b == nil {
+		return s
+	}
+
+	return string(b)
+}
+
+// attributeSelector returns a Selector that matches elements
+// where the attribute named key satisifes the function f.
+func attributeSelector(key string, f func(string) bool) Selector {
+	key = toLowerASCII(key)
+	return func(n *html.Node) bool {
+		if n.Type != html.ElementNode {
+			return false
+		}
+		for _, a := range n.Attr {
+			if a.Key == key && f(a.Val) {
+				return true
+			}
+		}
+		return false
+	}
+}
+
+// attributeExistsSelector returns a Selector that matches elements that have
+// an attribute named key.
+func attributeExistsSelector(key string) Selector {
+	return attributeSelector(key, func(string) bool { return true })
+}
+
+// attributeEqualsSelector returns a Selector that matches elements where
+// the attribute named key has the value val.
+func attributeEqualsSelector(key, val string) Selector {
+	return attributeSelector(key,
+		func(s string) bool {
+			return s == val
+		})
+}
+
+// attributeNotEqualSelector returns a Selector that matches elements where
+// the attribute named key does not have the value val.
+func attributeNotEqualSelector(key, val string) Selector {
+	key = toLowerASCII(key)
+	return func(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
+	}
+}
+
+// attributeIncludesSelector returns a Selector that matches elements where
+// the attribute named key is a whitespace-separated list that includes val.
+func attributeIncludesSelector(key, val string) Selector {
+	return attributeSelector(key,
+		func(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
+		})
+}
+
+// attributeDashmatchSelector returns a Selector that matches elements where
+// the attribute named key equals val or starts with val plus a hyphen.
+func attributeDashmatchSelector(key, val string) Selector {
+	return attributeSelector(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
+		})
+}
+
+// attributePrefixSelector returns a Selector that matches elements where
+// the attribute named key starts with val.
+func attributePrefixSelector(key, val string) Selector {
+	return attributeSelector(key,
+		func(s string) bool {
+			if strings.TrimSpace(s) == "" {
+				return false
+			}
+			return strings.HasPrefix(s, val)
+		})
+}
+
+// attributeSuffixSelector returns a Selector that matches elements where
+// the attribute named key ends with val.
+func attributeSuffixSelector(key, val string) Selector {
+	return attributeSelector(key,
+		func(s string) bool {
+			if strings.TrimSpace(s) == "" {
+				return false
+			}
+			return strings.HasSuffix(s, val)
+		})
+}
+
+// attributeSubstringSelector returns a Selector that matches nodes where
+// the attribute named key contains val.
+func attributeSubstringSelector(key, val string) Selector {
+	return attributeSelector(key,
+		func(s string) bool {
+			if strings.TrimSpace(s) == "" {
+				return false
+			}
+			return strings.Contains(s, val)
+		})
+}
+
+// attributeRegexSelector returns a Selector that matches nodes where
+// the attribute named key matches the regular expression rx
+func attributeRegexSelector(key string, rx *regexp.Regexp) Selector {
+	return attributeSelector(key,
+		func(s string) bool {
+			return rx.MatchString(s)
+		})
+}
+
+// intersectionSelector returns a selector that matches nodes that match
+// both a and b.
+func intersectionSelector(a, b Selector) Selector {
+	return func(n *html.Node) bool {
+		return a(n) && b(n)
+	}
+}
+
+// unionSelector returns a selector that matches elements that match
+// either a or b.
+func unionSelector(a, b Selector) Selector {
+	return func(n *html.Node) bool {
+		return a(n) || b(n)
+	}
+}
+
+// negatedSelector returns a selector that matches elements that do not match a.
+func negatedSelector(a Selector) Selector {
+	return func(n *html.Node) bool {
+		if n.Type != html.ElementNode {
+			return false
+		}
+		return !a(n)
+	}
+}
+
+// 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()
+}
+
+// textSubstrSelector returns a selector that matches nodes that
+// contain the given text.
+func textSubstrSelector(val string) Selector {
+	return func(n *html.Node) bool {
+		text := strings.ToLower(nodeText(n))
+		return strings.Contains(text, val)
+	}
+}
+
+// ownTextSubstrSelector returns a selector that matches nodes that
+// directly contain the given text
+func ownTextSubstrSelector(val string) Selector {
+	return func(n *html.Node) bool {
+		text := strings.ToLower(nodeOwnText(n))
+		return strings.Contains(text, val)
+	}
+}
+
+// textRegexSelector returns a selector that matches nodes whose text matches
+// the specified regular expression
+func textRegexSelector(rx *regexp.Regexp) Selector {
+	return func(n *html.Node) bool {
+		return rx.MatchString(nodeText(n))
+	}
+}
+
+// ownTextRegexSelector returns a selector that matches nodes whose text
+// directly matches the specified regular expression
+func ownTextRegexSelector(rx *regexp.Regexp) Selector {
+	return func(n *html.Node) bool {
+		return rx.MatchString(nodeOwnText(n))
+	}
+}
+
+// hasChildSelector returns a selector that matches elements
+// with a child that matches a.
+func hasChildSelector(a Selector) Selector {
+	return func(n *html.Node) bool {
+		if n.Type != html.ElementNode {
+			return false
+		}
+		return hasChildMatch(n, a)
+	}
+}
+
+// hasDescendantSelector returns a selector that matches elements
+// with any descendant that matches a.
+func hasDescendantSelector(a Selector) Selector {
+	return func(n *html.Node) bool {
+		if n.Type != html.ElementNode {
+			return false
+		}
+		return hasDescendantMatch(n, a)
+	}
+}
+
+// nthChildSelector returns a selector that implements :nth-child(an+b).
+// If last is true, implements :nth-last-child instead.
+// If ofType is true, implements :nth-of-type instead.
+func nthChildSelector(a, b int, last, ofType bool) Selector {
+	return func(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
+	}
+}
+
+// simpleNthChildSelector returns a selector that implements :nth-child(b).
+// If ofType is true, implements :nth-of-type instead.
+func simpleNthChildSelector(b int, ofType bool) Selector {
+	return func(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
+	}
+}
+
+// simpleNthLastChildSelector returns a selector that implements
+// :nth-last-child(b). If ofType is true, implements :nth-last-of-type
+// instead.
+func simpleNthLastChildSelector(b int, ofType bool) Selector {
+	return func(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
+	}
+}
+
+// onlyChildSelector returns a selector that implements :only-child.
+// If ofType is true, it implements :only-of-type instead.
+func onlyChildSelector(ofType bool) Selector {
+	return func(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 count > 1 {
+				return false
+			}
+		}
+
+		return count == 1
+	}
+}
+
+// inputSelector is a Selector that matches input, select, textarea and button elements.
+func inputSelector(n *html.Node) bool {
+	return n.Type == html.ElementNode && (n.Data == "input" || n.Data == "select" || n.Data == "textarea" || n.Data == "button")
+}
+
+// emptyElementSelector is a Selector that matches empty elements.
+func emptyElementSelector(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
+}
+
+// descendantSelector returns a Selector that matches an element if
+// it matches d and has an ancestor that matches a.
+func descendantSelector(a, d Selector) Selector {
+	return func(n *html.Node) bool {
+		if !d(n) {
+			return false
+		}
+
+		for p := n.Parent; p != nil; p = p.Parent {
+			if a(p) {
+				return true
+			}
+		}
+
+		return false
+	}
+}
+
+// childSelector returns a Selector that matches an element if
+// it matches d and its parent matches a.
+func childSelector(a, d Selector) Selector {
+	return func(n *html.Node) bool {
+		return d(n) && n.Parent != nil && a(n.Parent)
+	}
+}
+
+// siblingSelector returns a Selector that matches an element
+// if it matches s2 and in is preceded by an element that matches s1.
+// If adjacent is true, the sibling must be immediately before the element.
+func siblingSelector(s1, s2 Selector, adjacent bool) Selector {
+	return func(n *html.Node) bool {
+		if !s2(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(n)
+			}
+			return false
+		}
+
+		// Walk backwards looking for element that matches s1
+		for c := n.PrevSibling; c != nil; c = c.PrevSibling {
+			if s1(c) {
+				return true
+			}
+		}
+
+		return false
+	}
+}
+
+// rootSelector implements :root
+func rootSelector(n *html.Node) bool {
+	if n.Type != html.ElementNode {
+		return false
+	}
+	if n.Parent == nil {
+		return false
+	}
+	return n.Parent.Type == html.DocumentNode
+}