Vendor

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

@@ -0,0 +1,586 @@
+package cascadia
+
+import (
+	"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, false)
+	})
+}
+
+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
+	insensitive         bool
+}
+
+// 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 matchInsensitiveValue(s, t.val, t.insensitive) })
+	case "!=":
+		return attributeNotEqualMatch(t.key, t.val, n, t.insensitive)
+	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, t.insensitive) })
+	case "|=":
+		return attributeDashMatch(t.key, t.val, n, t.insensitive)
+	case "^=":
+		return attributePrefixMatch(t.key, t.val, n, t.insensitive)
+	case "$=":
+		return attributeSuffixMatch(t.key, t.val, n, t.insensitive)
+	case "*=":
+		return attributeSubstringMatch(t.key, t.val, n, t.insensitive)
+	case "#=":
+		return attributeRegexMatch(t.key, t.regexp, n)
+	default:
+		panic(fmt.Sprintf("unsuported operation : %s", t.operation))
+	}
+}
+
+// matches elements where we ignore (or not) the case of the attribute value
+// the user attribute is the value set by the user to match elements
+// the real attribute is the attribute value found in the code parsed
+func matchInsensitiveValue(userAttr string, realAttr string, ignoreCase bool) bool {
+	if ignoreCase {
+		return strings.EqualFold(userAttr, realAttr)
+	}
+	return userAttr == realAttr
+
+}
+
+// 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, ignoreCase bool) bool {
+	if n.Type != html.ElementNode {
+		return false
+	}
+	for _, a := range n.Attr {
+		if a.Key == key && matchInsensitiveValue(a.Val, val, ignoreCase) {
+			return false
+		}
+	}
+	return true
+}
+
+// returns true if s is a whitespace-separated list that includes val.
+func matchInclude(val string, s string, ignoreCase bool) bool {
+	for s != "" {
+		i := strings.IndexAny(s, " \t\r\n\f")
+		if i == -1 {
+			return matchInsensitiveValue(s, val, ignoreCase)
+		}
+		if matchInsensitiveValue(s[:i], val, ignoreCase) {
+			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, ignoreCase bool) bool {
+	return matchAttribute(n, key,
+		func(s string) bool {
+			if matchInsensitiveValue(s, val, ignoreCase) {
+				return true
+			}
+			if len(s) <= len(val) {
+				return false
+			}
+			if matchInsensitiveValue(s[:len(val)], val, ignoreCase) && 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, ignoreCase bool) bool {
+	return matchAttribute(n, key,
+		func(s string) bool {
+			if strings.TrimSpace(s) == "" {
+				return false
+			}
+			if ignoreCase {
+				return strings.HasPrefix(strings.ToLower(s), strings.ToLower(val))
+			}
+			return strings.HasPrefix(s, val)
+		})
+}
+
+// attributeSuffixMatch matches elements where
+// the attribute named key ends with val.
+func attributeSuffixMatch(key, val string, n *html.Node, ignoreCase bool) bool {
+	return matchAttribute(n, key,
+		func(s string) bool {
+			if strings.TrimSpace(s) == "" {
+				return false
+			}
+			if ignoreCase {
+				return strings.HasSuffix(strings.ToLower(s), strings.ToLower(val))
+			}
+			return strings.HasSuffix(s, val)
+		})
+}
+
+// attributeSubstringMatch matches nodes where
+// the attribute named key contains val.
+func attributeSubstringMatch(key, val string, n *html.Node, ignoreCase bool) bool {
+	return matchAttribute(n, key,
+		func(s string) bool {
+			if strings.TrimSpace(s) == "" {
+				return false
+			}
+			if ignoreCase {
+				return strings.Contains(strings.ToLower(s), strings.ToLower(val))
+			}
+			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 ""
+}
+
+// see pseudo_classes.go for pseudo classes selectors
+
+// on a static context, some selectors can't match anything
+type neverMatchSelector struct {
+	value string
+}
+
+func (s neverMatchSelector) Match(n *html.Node) bool {
+	return false
+}
+
+func (s neverMatchSelector) Specificity() Specificity {
+	return Specificity{0, 0, 0}
+}
+
+func (c neverMatchSelector) 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
+}