Add initial Microsoft Teams support

Documentation on https://github.com/42wim/matterbridge/wiki/MS-Teams-setup

1 files changed, 2425 insertions, 0 deletions

diff --git a/vendor/golang.org/x/net/html/parse.go b/vendor/golang.org/x/net/html/parse.go
new file mode 100644
index 00000000..2cd12fc8
--- /dev/null
+++ b/vendor/golang.org/x/net/html/parse.go
@@ -0,0 +1,2425 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package html
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+
+	a "golang.org/x/net/html/atom"
+)
+
+// A parser implements the HTML5 parsing algorithm:
+// https://html.spec.whatwg.org/multipage/syntax.html#tree-construction
+type parser struct {
+	// tokenizer provides the tokens for the parser.
+	tokenizer *Tokenizer
+	// tok is the most recently read token.
+	tok Token
+	// Self-closing tags like <hr/> are treated as start tags, except that
+	// hasSelfClosingToken is set while they are being processed.
+	hasSelfClosingToken bool
+	// doc is the document root element.
+	doc *Node
+	// The stack of open elements (section 12.2.4.2) and active formatting
+	// elements (section 12.2.4.3).
+	oe, afe nodeStack
+	// Element pointers (section 12.2.4.4).
+	head, form *Node
+	// Other parsing state flags (section 12.2.4.5).
+	scripting, framesetOK bool
+	// The stack of template insertion modes
+	templateStack insertionModeStack
+	// im is the current insertion mode.
+	im insertionMode
+	// originalIM is the insertion mode to go back to after completing a text
+	// or inTableText insertion mode.
+	originalIM insertionMode
+	// fosterParenting is whether new elements should be inserted according to
+	// the foster parenting rules (section 12.2.6.1).
+	fosterParenting bool
+	// quirks is whether the parser is operating in "quirks mode."
+	quirks bool
+	// fragment is whether the parser is parsing an HTML fragment.
+	fragment bool
+	// context is the context element when parsing an HTML fragment
+	// (section 12.4).
+	context *Node
+}
+
+func (p *parser) top() *Node {
+	if n := p.oe.top(); n != nil {
+		return n
+	}
+	return p.doc
+}
+
+// Stop tags for use in popUntil. These come from section 12.2.4.2.
+var (
+	defaultScopeStopTags = map[string][]a.Atom{
+		"":     {a.Applet, a.Caption, a.Html, a.Table, a.Td, a.Th, a.Marquee, a.Object, a.Template},
+		"math": {a.AnnotationXml, a.Mi, a.Mn, a.Mo, a.Ms, a.Mtext},
+		"svg":  {a.Desc, a.ForeignObject, a.Title},
+	}
+)
+
+type scope int
+
+const (
+	defaultScope scope = iota
+	listItemScope
+	buttonScope
+	tableScope
+	tableRowScope
+	tableBodyScope
+	selectScope
+)
+
+// popUntil pops the stack of open elements at the highest element whose tag
+// is in matchTags, provided there is no higher element in the scope's stop
+// tags (as defined in section 12.2.4.2). It returns whether or not there was
+// such an element. If there was not, popUntil leaves the stack unchanged.
+//
+// For example, the set of stop tags for table scope is: "html", "table". If
+// the stack was:
+// ["html", "body", "font", "table", "b", "i", "u"]
+// then popUntil(tableScope, "font") would return false, but
+// popUntil(tableScope, "i") would return true and the stack would become:
+// ["html", "body", "font", "table", "b"]
+//
+// If an element's tag is in both the stop tags and matchTags, then the stack
+// will be popped and the function returns true (provided, of course, there was
+// no higher element in the stack that was also in the stop tags). For example,
+// popUntil(tableScope, "table") returns true and leaves:
+// ["html", "body", "font"]
+func (p *parser) popUntil(s scope, matchTags ...a.Atom) bool {
+	if i := p.indexOfElementInScope(s, matchTags...); i != -1 {
+		p.oe = p.oe[:i]
+		return true
+	}
+	return false
+}
+
+// indexOfElementInScope returns the index in p.oe of the highest element whose
+// tag is in matchTags that is in scope. If no matching element is in scope, it
+// returns -1.
+func (p *parser) indexOfElementInScope(s scope, matchTags ...a.Atom) int {
+	for i := len(p.oe) - 1; i >= 0; i-- {
+		tagAtom := p.oe[i].DataAtom
+		if p.oe[i].Namespace == "" {
+			for _, t := range matchTags {
+				if t == tagAtom {
+					return i
+				}
+			}
+			switch s {
+			case defaultScope:
+				// No-op.
+			case listItemScope:
+				if tagAtom == a.Ol || tagAtom == a.Ul {
+					return -1
+				}
+			case buttonScope:
+				if tagAtom == a.Button {
+					return -1
+				}
+			case tableScope:
+				if tagAtom == a.Html || tagAtom == a.Table || tagAtom == a.Template {
+					return -1
+				}
+			case selectScope:
+				if tagAtom != a.Optgroup && tagAtom != a.Option {
+					return -1
+				}
+			default:
+				panic("unreachable")
+			}
+		}
+		switch s {
+		case defaultScope, listItemScope, buttonScope:
+			for _, t := range defaultScopeStopTags[p.oe[i].Namespace] {
+				if t == tagAtom {
+					return -1
+				}
+			}
+		}
+	}
+	return -1
+}
+
+// elementInScope is like popUntil, except that it doesn't modify the stack of
+// open elements.
+func (p *parser) elementInScope(s scope, matchTags ...a.Atom) bool {
+	return p.indexOfElementInScope(s, matchTags...) != -1
+}
+
+// clearStackToContext pops elements off the stack of open elements until a
+// scope-defined element is found.
+func (p *parser) clearStackToContext(s scope) {
+	for i := len(p.oe) - 1; i >= 0; i-- {
+		tagAtom := p.oe[i].DataAtom
+		switch s {
+		case tableScope:
+			if tagAtom == a.Html || tagAtom == a.Table || tagAtom == a.Template {
+				p.oe = p.oe[:i+1]
+				return
+			}
+		case tableRowScope:
+			if tagAtom == a.Html || tagAtom == a.Tr || tagAtom == a.Template {
+				p.oe = p.oe[:i+1]
+				return
+			}
+		case tableBodyScope:
+			if tagAtom == a.Html || tagAtom == a.Tbody || tagAtom == a.Tfoot || tagAtom == a.Thead || tagAtom == a.Template {
+				p.oe = p.oe[:i+1]
+				return
+			}
+		default:
+			panic("unreachable")
+		}
+	}
+}
+
+// parseGenericRawTextElements implements the generic raw text element parsing
+// algorithm defined in 12.2.6.2.
+// https://html.spec.whatwg.org/multipage/parsing.html#parsing-elements-that-contain-only-text
+// TODO: Since both RAWTEXT and RCDATA states are treated as tokenizer's part
+// officially, need to make tokenizer consider both states.
+func (p *parser) parseGenericRawTextElement() {
+	p.addElement()
+	p.originalIM = p.im
+	p.im = textIM
+}
+
+// generateImpliedEndTags pops nodes off the stack of open elements as long as
+// the top node has a tag name of dd, dt, li, optgroup, option, p, rb, rp, rt or rtc.
+// If exceptions are specified, nodes with that name will not be popped off.
+func (p *parser) generateImpliedEndTags(exceptions ...string) {
+	var i int
+loop:
+	for i = len(p.oe) - 1; i >= 0; i-- {
+		n := p.oe[i]
+		if n.Type != ElementNode {
+			break
+		}
+		switch n.DataAtom {
+		case a.Dd, a.Dt, a.Li, a.Optgroup, a.Option, a.P, a.Rb, a.Rp, a.Rt, a.Rtc:
+			for _, except := range exceptions {
+				if n.Data == except {
+					break loop
+				}
+			}
+			continue
+		}
+		break
+	}
+
+	p.oe = p.oe[:i+1]
+}
+
+// addChild adds a child node n to the top element, and pushes n onto the stack
+// of open elements if it is an element node.
+func (p *parser) addChild(n *Node) {
+	if p.shouldFosterParent() {
+		p.fosterParent(n)
+	} else {
+		p.top().AppendChild(n)
+	}
+
+	if n.Type == ElementNode {
+		p.oe = append(p.oe, n)
+	}
+}
+
+// shouldFosterParent returns whether the next node to be added should be
+// foster parented.
+func (p *parser) shouldFosterParent() bool {
+	if p.fosterParenting {
+		switch p.top().DataAtom {
+		case a.Table, a.Tbody, a.Tfoot, a.Thead, a.Tr:
+			return true
+		}
+	}
+	return false
+}
+
+// fosterParent adds a child node according to the foster parenting rules.
+// Section 12.2.6.1, "foster parenting".
+func (p *parser) fosterParent(n *Node) {
+	var table, parent, prev, template *Node
+	var i int
+	for i = len(p.oe) - 1; i >= 0; i-- {
+		if p.oe[i].DataAtom == a.Table {
+			table = p.oe[i]
+			break
+		}
+	}
+
+	var j int
+	for j = len(p.oe) - 1; j >= 0; j-- {
+		if p.oe[j].DataAtom == a.Template {
+			template = p.oe[j]
+			break
+		}
+	}
+
+	if template != nil && (table == nil || j > i) {
+		template.AppendChild(n)
+		return
+	}
+
+	if table == nil {
+		// The foster parent is the html element.
+		parent = p.oe[0]
+	} else {
+		parent = table.Parent
+	}
+	if parent == nil {
+		parent = p.oe[i-1]
+	}
+
+	if table != nil {
+		prev = table.PrevSibling
+	} else {
+		prev = parent.LastChild
+	}
+	if prev != nil && prev.Type == TextNode && n.Type == TextNode {
+		prev.Data += n.Data
+		return
+	}
+
+	parent.InsertBefore(n, table)
+}
+
+// addText adds text to the preceding node if it is a text node, or else it
+// calls addChild with a new text node.
+func (p *parser) addText(text string) {
+	if text == "" {
+		return
+	}
+
+	if p.shouldFosterParent() {
+		p.fosterParent(&Node{
+			Type: TextNode,
+			Data: text,
+		})
+		return
+	}
+
+	t := p.top()
+	if n := t.LastChild; n != nil && n.Type == TextNode {
+		n.Data += text
+		return
+	}
+	p.addChild(&Node{
+		Type: TextNode,
+		Data: text,
+	})
+}
+
+// addElement adds a child element based on the current token.
+func (p *parser) addElement() {
+	p.addChild(&Node{
+		Type:     ElementNode,
+		DataAtom: p.tok.DataAtom,
+		Data:     p.tok.Data,
+		Attr:     p.tok.Attr,
+	})
+}
+
+// Section 12.2.4.3.
+func (p *parser) addFormattingElement() {
+	tagAtom, attr := p.tok.DataAtom, p.tok.Attr
+	p.addElement()
+
+	// Implement the Noah's Ark clause, but with three per family instead of two.
+	identicalElements := 0
+findIdenticalElements:
+	for i := len(p.afe) - 1; i >= 0; i-- {
+		n := p.afe[i]
+		if n.Type == scopeMarkerNode {
+			break
+		}
+		if n.Type != ElementNode {
+			continue
+		}
+		if n.Namespace != "" {
+			continue
+		}
+		if n.DataAtom != tagAtom {
+			continue
+		}
+		if len(n.Attr) != len(attr) {
+			continue
+		}
+	compareAttributes:
+		for _, t0 := range n.Attr {
+			for _, t1 := range attr {
+				if t0.Key == t1.Key && t0.Namespace == t1.Namespace && t0.Val == t1.Val {
+					// Found a match for this attribute, continue with the next attribute.
+					continue compareAttributes
+				}
+			}
+			// If we get here, there is no attribute that matches a.
+			// Therefore the element is not identical to the new one.
+			continue findIdenticalElements
+		}
+
+		identicalElements++
+		if identicalElements >= 3 {
+			p.afe.remove(n)
+		}
+	}
+
+	p.afe = append(p.afe, p.top())
+}
+
+// Section 12.2.4.3.
+func (p *parser) clearActiveFormattingElements() {
+	for {
+		if n := p.afe.pop(); len(p.afe) == 0 || n.Type == scopeMarkerNode {
+			return
+		}
+	}
+}
+
+// Section 12.2.4.3.
+func (p *parser) reconstructActiveFormattingElements() {
+	n := p.afe.top()
+	if n == nil {
+		return
+	}
+	if n.Type == scopeMarkerNode || p.oe.index(n) != -1 {
+		return
+	}
+	i := len(p.afe) - 1
+	for n.Type != scopeMarkerNode && p.oe.index(n) == -1 {
+		if i == 0 {
+			i = -1
+			break
+		}
+		i--
+		n = p.afe[i]
+	}
+	for {
+		i++
+		clone := p.afe[i].clone()
+		p.addChild(clone)
+		p.afe[i] = clone
+		if i == len(p.afe)-1 {
+			break
+		}
+	}
+}
+
+// Section 12.2.5.
+func (p *parser) acknowledgeSelfClosingTag() {
+	p.hasSelfClosingToken = false
+}
+
+// An insertion mode (section 12.2.4.1) is the state transition function from
+// a particular state in the HTML5 parser's state machine. It updates the
+// parser's fields depending on parser.tok (where ErrorToken means EOF).
+// It returns whether the token was consumed.
+type insertionMode func(*parser) bool
+
+// setOriginalIM sets the insertion mode to return to after completing a text or
+// inTableText insertion mode.
+// Section 12.2.4.1, "using the rules for".
+func (p *parser) setOriginalIM() {
+	if p.originalIM != nil {
+		panic("html: bad parser state: originalIM was set twice")
+	}
+	p.originalIM = p.im
+}
+
+// Section 12.2.4.1, "reset the insertion mode".
+func (p *parser) resetInsertionMode() {
+	for i := len(p.oe) - 1; i >= 0; i-- {
+		n := p.oe[i]
+		last := i == 0
+		if last && p.context != nil {
+			n = p.context
+		}
+
+		switch n.DataAtom {
+		case a.Select:
+			if !last {
+				for ancestor, first := n, p.oe[0]; ancestor != first; {
+					ancestor = p.oe[p.oe.index(ancestor)-1]
+					switch ancestor.DataAtom {
+					case a.Template:
+						p.im = inSelectIM
+						return
+					case a.Table:
+						p.im = inSelectInTableIM
+						return
+					}
+				}
+			}
+			p.im = inSelectIM
+		case a.Td, a.Th:
+			// TODO: remove this divergence from the HTML5 spec.
+			//
+			// See https://bugs.chromium.org/p/chromium/issues/detail?id=829668
+			p.im = inCellIM
+		case a.Tr:
+			p.im = inRowIM
+		case a.Tbody, a.Thead, a.Tfoot:
+			p.im = inTableBodyIM
+		case a.Caption:
+			p.im = inCaptionIM
+		case a.Colgroup:
+			p.im = inColumnGroupIM
+		case a.Table:
+			p.im = inTableIM
+		case a.Template:
+			// TODO: remove this divergence from the HTML5 spec.
+			if n.Namespace != "" {
+				continue
+			}
+			p.im = p.templateStack.top()
+		case a.Head:
+			// TODO: remove this divergence from the HTML5 spec.
+			//
+			// See https://bugs.chromium.org/p/chromium/issues/detail?id=829668
+			p.im = inHeadIM
+		case a.Body:
+			p.im = inBodyIM
+		case a.Frameset:
+			p.im = inFramesetIM
+		case a.Html:
+			if p.head == nil {
+				p.im = beforeHeadIM
+			} else {
+				p.im = afterHeadIM
+			}
+		default:
+			if last {
+				p.im = inBodyIM
+				return
+			}
+			continue
+		}
+		return
+	}
+}
+
+const whitespace = " \t\r\n\f"
+
+// Section 12.2.6.4.1.
+func initialIM(p *parser) bool {
+	switch p.tok.Type {
+	case TextToken:
+		p.tok.Data = strings.TrimLeft(p.tok.Data, whitespace)
+		if len(p.tok.Data) == 0 {
+			// It was all whitespace, so ignore it.
+			return true
+		}
+	case CommentToken:
+		p.doc.AppendChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+		return true
+	case DoctypeToken:
+		n, quirks := parseDoctype(p.tok.Data)
+		p.doc.AppendChild(n)
+		p.quirks = quirks
+		p.im = beforeHTMLIM
+		return true
+	}
+	p.quirks = true
+	p.im = beforeHTMLIM
+	return false
+}
+
+// Section 12.2.6.4.2.
+func beforeHTMLIM(p *parser) bool {
+	switch p.tok.Type {
+	case DoctypeToken:
+		// Ignore the token.
+		return true
+	case TextToken:
+		p.tok.Data = strings.TrimLeft(p.tok.Data, whitespace)
+		if len(p.tok.Data) == 0 {
+			// It was all whitespace, so ignore it.
+			return true
+		}
+	case StartTagToken:
+		if p.tok.DataAtom == a.Html {
+			p.addElement()
+			p.im = beforeHeadIM
+			return true
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Head, a.Body, a.Html, a.Br:
+			p.parseImpliedToken(StartTagToken, a.Html, a.Html.String())
+			return false
+		default:
+			// Ignore the token.
+			return true
+		}
+	case CommentToken:
+		p.doc.AppendChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+		return true
+	}
+	p.parseImpliedToken(StartTagToken, a.Html, a.Html.String())
+	return false
+}
+
+// Section 12.2.6.4.3.
+func beforeHeadIM(p *parser) bool {
+	switch p.tok.Type {
+	case TextToken:
+		p.tok.Data = strings.TrimLeft(p.tok.Data, whitespace)
+		if len(p.tok.Data) == 0 {
+			// It was all whitespace, so ignore it.
+			return true
+		}
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Head:
+			p.addElement()
+			p.head = p.top()
+			p.im = inHeadIM
+			return true
+		case a.Html:
+			return inBodyIM(p)
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Head, a.Body, a.Html, a.Br:
+			p.parseImpliedToken(StartTagToken, a.Head, a.Head.String())
+			return false
+		default:
+			// Ignore the token.
+			return true
+		}
+	case CommentToken:
+		p.addChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+		return true
+	case DoctypeToken:
+		// Ignore the token.
+		return true
+	}
+
+	p.parseImpliedToken(StartTagToken, a.Head, a.Head.String())
+	return false
+}
+
+// Section 12.2.6.4.4.
+func inHeadIM(p *parser) bool {
+	switch p.tok.Type {
+	case TextToken:
+		s := strings.TrimLeft(p.tok.Data, whitespace)
+		if len(s) < len(p.tok.Data) {
+			// Add the initial whitespace to the current node.
+			p.addText(p.tok.Data[:len(p.tok.Data)-len(s)])
+			if s == "" {
+				return true
+			}
+			p.tok.Data = s
+		}
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Html:
+			return inBodyIM(p)
+		case a.Base, a.Basefont, a.Bgsound, a.Link, a.Meta:
+			p.addElement()
+			p.oe.pop()
+			p.acknowledgeSelfClosingTag()
+			return true
+		case a.Noscript:
+			if p.scripting {
+				p.parseGenericRawTextElement()
+				return true
+			}
+			p.addElement()
+			p.im = inHeadNoscriptIM
+			// Don't let the tokenizer go into raw text mode when scripting is disabled.
+			p.tokenizer.NextIsNotRawText()
+			return true
+		case a.Script, a.Title:
+			p.addElement()
+			p.setOriginalIM()
+			p.im = textIM
+			return true
+		case a.Noframes, a.Style:
+			p.parseGenericRawTextElement()
+			return true
+		case a.Head:
+			// Ignore the token.
+			return true
+		case a.Template:
+			p.addElement()
+			p.afe = append(p.afe, &scopeMarker)
+			p.framesetOK = false
+			p.im = inTemplateIM
+			p.templateStack = append(p.templateStack, inTemplateIM)
+			return true
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Head:
+			p.oe.pop()
+			p.im = afterHeadIM
+			return true
+		case a.Body, a.Html, a.Br:
+			p.parseImpliedToken(EndTagToken, a.Head, a.Head.String())
+			return false
+		case a.Template:
+			if !p.oe.contains(a.Template) {
+				return true
+			}
+			// TODO: remove this divergence from the HTML5 spec.
+			//
+			// See https://bugs.chromium.org/p/chromium/issues/detail?id=829668
+			p.generateImpliedEndTags()
+			for i := len(p.oe) - 1; i >= 0; i-- {
+				if n := p.oe[i]; n.Namespace == "" && n.DataAtom == a.Template {
+					p.oe = p.oe[:i]
+					break
+				}
+			}
+			p.clearActiveFormattingElements()
+			p.templateStack.pop()
+			p.resetInsertionMode()
+			return true
+		default:
+			// Ignore the token.
+			return true
+		}
+	case CommentToken:
+		p.addChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+		return true
+	case DoctypeToken:
+		// Ignore the token.
+		return true
+	}
+
+	p.parseImpliedToken(EndTagToken, a.Head, a.Head.String())
+	return false
+}
+
+// 12.2.6.4.5.
+func inHeadNoscriptIM(p *parser) bool {
+	switch p.tok.Type {
+	case DoctypeToken:
+		// Ignore the token.
+		return true
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Html:
+			return inBodyIM(p)
+		case a.Basefont, a.Bgsound, a.Link, a.Meta, a.Noframes, a.Style:
+			return inHeadIM(p)
+		case a.Head, a.Noscript:
+			// Ignore the token.
+			return true
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Noscript, a.Br:
+		default:
+			// Ignore the token.
+			return true
+		}
+	case TextToken:
+		s := strings.TrimLeft(p.tok.Data, whitespace)
+		if len(s) == 0 {
+			// It was all whitespace.
+			return inHeadIM(p)
+		}
+	case CommentToken:
+		return inHeadIM(p)
+	}
+	p.oe.pop()
+	if p.top().DataAtom != a.Head {
+		panic("html: the new current node will be a head element.")
+	}
+	p.im = inHeadIM
+	if p.tok.DataAtom == a.Noscript {
+		return true
+	}
+	return false
+}
+
+// Section 12.2.6.4.6.
+func afterHeadIM(p *parser) bool {
+	switch p.tok.Type {
+	case TextToken:
+		s := strings.TrimLeft(p.tok.Data, whitespace)
+		if len(s) < len(p.tok.Data) {
+			// Add the initial whitespace to the current node.
+			p.addText(p.tok.Data[:len(p.tok.Data)-len(s)])
+			if s == "" {
+				return true
+			}
+			p.tok.Data = s
+		}
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Html:
+			return inBodyIM(p)
+		case a.Body:
+			p.addElement()
+			p.framesetOK = false
+			p.im = inBodyIM
+			return true
+		case a.Frameset:
+			p.addElement()
+			p.im = inFramesetIM
+			return true
+		case a.Base, a.Basefont, a.Bgsound, a.Link, a.Meta, a.Noframes, a.Script, a.Style, a.Template, a.Title:
+			p.oe = append(p.oe, p.head)
+			defer p.oe.remove(p.head)
+			return inHeadIM(p)
+		case a.Head:
+			// Ignore the token.
+			return true
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Body, a.Html, a.Br:
+			// Drop down to creating an implied <body> tag.
+		case a.Template:
+			return inHeadIM(p)
+		default:
+			// Ignore the token.
+			return true
+		}
+	case CommentToken:
+		p.addChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+		return true
+	case DoctypeToken:
+		// Ignore the token.
+		return true
+	}
+
+	p.parseImpliedToken(StartTagToken, a.Body, a.Body.String())
+	p.framesetOK = true
+	return false
+}
+
+// copyAttributes copies attributes of src not found on dst to dst.
+func copyAttributes(dst *Node, src Token) {
+	if len(src.Attr) == 0 {
+		return
+	}
+	attr := map[string]string{}
+	for _, t := range dst.Attr {
+		attr[t.Key] = t.Val
+	}
+	for _, t := range src.Attr {
+		if _, ok := attr[t.Key]; !ok {
+			dst.Attr = append(dst.Attr, t)
+			attr[t.Key] = t.Val
+		}
+	}
+}
+
+// Section 12.2.6.4.7.
+func inBodyIM(p *parser) bool {
+	switch p.tok.Type {
+	case TextToken:
+		d := p.tok.Data
+		switch n := p.oe.top(); n.DataAtom {
+		case a.Pre, a.Listing:
+			if n.FirstChild == nil {
+				// Ignore a newline at the start of a <pre> block.
+				if d != "" && d[0] == '\r' {
+					d = d[1:]
+				}
+				if d != "" && d[0] == '\n' {
+					d = d[1:]
+				}
+			}
+		}
+		d = strings.Replace(d, "\x00", "", -1)
+		if d == "" {
+			return true
+		}
+		p.reconstructActiveFormattingElements()
+		p.addText(d)
+		if p.framesetOK && strings.TrimLeft(d, whitespace) != "" {
+			// There were non-whitespace characters inserted.
+			p.framesetOK = false
+		}
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Html:
+			if p.oe.contains(a.Template) {
+				return true
+			}
+			copyAttributes(p.oe[0], p.tok)
+		case a.Base, a.Basefont, a.Bgsound, a.Link, a.Meta, a.Noframes, a.Script, a.Style, a.Template, a.Title:
+			return inHeadIM(p)
+		case a.Body:
+			if p.oe.contains(a.Template) {
+				return true
+			}
+			if len(p.oe) >= 2 {
+				body := p.oe[1]
+				if body.Type == ElementNode && body.DataAtom == a.Body {
+					p.framesetOK = false
+					copyAttributes(body, p.tok)
+				}
+			}
+		case a.Frameset:
+			if !p.framesetOK || len(p.oe) < 2 || p.oe[1].DataAtom != a.Body {
+				// Ignore the token.
+				return true
+			}
+			body := p.oe[1]
+			if body.Parent != nil {
+				body.Parent.RemoveChild(body)
+			}
+			p.oe = p.oe[:1]
+			p.addElement()
+			p.im = inFramesetIM
+			return true
+		case a.Address, a.Article, a.Aside, a.Blockquote, a.Center, a.Details, a.Dialog, a.Dir, a.Div, a.Dl, a.Fieldset, a.Figcaption, a.Figure, a.Footer, a.Header, a.Hgroup, a.Main, a.Menu, a.Nav, a.Ol, a.P, a.Section, a.Summary, a.Ul:
+			p.popUntil(buttonScope, a.P)
+			p.addElement()
+		case a.H1, a.H2, a.H3, a.H4, a.H5, a.H6:
+			p.popUntil(buttonScope, a.P)
+			switch n := p.top(); n.DataAtom {
+			case a.H1, a.H2, a.H3, a.H4, a.H5, a.H6:
+				p.oe.pop()
+			}
+			p.addElement()
+		case a.Pre, a.Listing:
+			p.popUntil(buttonScope, a.P)
+			p.addElement()
+			// The newline, if any, will be dealt with by the TextToken case.
+			p.framesetOK = false
+		case a.Form:
+			if p.form != nil && !p.oe.contains(a.Template) {
+				// Ignore the token
+				return true
+			}
+			p.popUntil(buttonScope, a.P)
+			p.addElement()
+			if !p.oe.contains(a.Template) {
+				p.form = p.top()
+			}
+		case a.Li:
+			p.framesetOK = false
+			for i := len(p.oe) - 1; i >= 0; i-- {
+				node := p.oe[i]
+				switch node.DataAtom {
+				case a.Li:
+					p.oe = p.oe[:i]
+				case a.Address, a.Div, a.P:
+					continue
+				default:
+					if !isSpecialElement(node) {
+						continue
+					}
+				}
+				break
+			}
+			p.popUntil(buttonScope, a.P)
+			p.addElement()
+		case a.Dd, a.Dt:
+			p.framesetOK = false
+			for i := len(p.oe) - 1; i >= 0; i-- {
+				node := p.oe[i]
+				switch node.DataAtom {
+				case a.Dd, a.Dt:
+					p.oe = p.oe[:i]
+				case a.Address, a.Div, a.P:
+					continue
+				default:
+					if !isSpecialElement(node) {
+						continue
+					}
+				}
+				break
+			}
+			p.popUntil(buttonScope, a.P)
+			p.addElement()
+		case a.Plaintext:
+			p.popUntil(buttonScope, a.P)
+			p.addElement()
+		case a.Button:
+			p.popUntil(defaultScope, a.Button)
+			p.reconstructActiveFormattingElements()
+			p.addElement()
+			p.framesetOK = false
+		case a.A:
+			for i := len(p.afe) - 1; i >= 0 && p.afe[i].Type != scopeMarkerNode; i-- {
+				if n := p.afe[i]; n.Type == ElementNode && n.DataAtom == a.A {
+					p.inBodyEndTagFormatting(a.A, "a")
+					p.oe.remove(n)
+					p.afe.remove(n)
+					break
+				}
+			}
+			p.reconstructActiveFormattingElements()
+			p.addFormattingElement()
+		case a.B, a.Big, a.Code, a.Em, a.Font, a.I, a.S, a.Small, a.Strike, a.Strong, a.Tt, a.U:
+			p.reconstructActiveFormattingElements()
+			p.addFormattingElement()
+		case a.Nobr:
+			p.reconstructActiveFormattingElements()
+			if p.elementInScope(defaultScope, a.Nobr) {
+				p.inBodyEndTagFormatting(a.Nobr, "nobr")
+				p.reconstructActiveFormattingElements()
+			}
+			p.addFormattingElement()
+		case a.Applet, a.Marquee, a.Object:
+			p.reconstructActiveFormattingElements()
+			p.addElement()
+			p.afe = append(p.afe, &scopeMarker)
+			p.framesetOK = false
+		case a.Table:
+			if !p.quirks {
+				p.popUntil(buttonScope, a.P)
+			}
+			p.addElement()
+			p.framesetOK = false
+			p.im = inTableIM
+			return true
+		case a.Area, a.Br, a.Embed, a.Img, a.Input, a.Keygen, a.Wbr:
+			p.reconstructActiveFormattingElements()
+			p.addElement()
+			p.oe.pop()
+			p.acknowledgeSelfClosingTag()
+			if p.tok.DataAtom == a.Input {
+				for _, t := range p.tok.Attr {
+					if t.Key == "type" {
+						if strings.ToLower(t.Val) == "hidden" {
+							// Skip setting framesetOK = false
+							return true
+						}
+					}
+				}
+			}
+			p.framesetOK = false
+		case a.Param, a.Source, a.Track:
+			p.addElement()
+			p.oe.pop()
+			p.acknowledgeSelfClosingTag()
+		case a.Hr:
+			p.popUntil(buttonScope, a.P)
+			p.addElement()
+			p.oe.pop()
+			p.acknowledgeSelfClosingTag()
+			p.framesetOK = false
+		case a.Image:
+			p.tok.DataAtom = a.Img
+			p.tok.Data = a.Img.String()
+			return false
+		case a.Textarea:
+			p.addElement()
+			p.setOriginalIM()
+			p.framesetOK = false
+			p.im = textIM
+		case a.Xmp:
+			p.popUntil(buttonScope, a.P)
+			p.reconstructActiveFormattingElements()
+			p.framesetOK = false
+			p.parseGenericRawTextElement()
+		case a.Iframe:
+			p.framesetOK = false
+			p.parseGenericRawTextElement()
+		case a.Noembed:
+			p.parseGenericRawTextElement()
+		case a.Noscript:
+			if p.scripting {
+				p.parseGenericRawTextElement()
+				return true
+			}
+			p.reconstructActiveFormattingElements()
+			p.addElement()
+			// Don't let the tokenizer go into raw text mode when scripting is disabled.
+			p.tokenizer.NextIsNotRawText()
+		case a.Select:
+			p.reconstructActiveFormattingElements()
+			p.addElement()
+			p.framesetOK = false
+			p.im = inSelectIM
+			return true
+		case a.Optgroup, a.Option:
+			if p.top().DataAtom == a.Option {
+				p.oe.pop()
+			}
+			p.reconstructActiveFormattingElements()
+			p.addElement()
+		case a.Rb, a.Rtc:
+			if p.elementInScope(defaultScope, a.Ruby) {
+				p.generateImpliedEndTags()
+			}
+			p.addElement()
+		case a.Rp, a.Rt:
+			if p.elementInScope(defaultScope, a.Ruby) {
+				p.generateImpliedEndTags("rtc")
+			}
+			p.addElement()
+		case a.Math, a.Svg:
+			p.reconstructActiveFormattingElements()
+			if p.tok.DataAtom == a.Math {
+				adjustAttributeNames(p.tok.Attr, mathMLAttributeAdjustments)
+			} else {
+				adjustAttributeNames(p.tok.Attr, svgAttributeAdjustments)
+			}
+			adjustForeignAttributes(p.tok.Attr)
+			p.addElement()
+			p.top().Namespace = p.tok.Data
+			if p.hasSelfClosingToken {
+				p.oe.pop()
+				p.acknowledgeSelfClosingTag()
+			}
+			return true
+		case a.Caption, a.Col, a.Colgroup, a.Frame, a.Head, a.Tbody, a.Td, a.Tfoot, a.Th, a.Thead, a.Tr:
+			// Ignore the token.
+		default:
+			p.reconstructActiveFormattingElements()
+			p.addElement()
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Body:
+			if p.elementInScope(defaultScope, a.Body) {
+				p.im = afterBodyIM
+			}
+		case a.Html:
+			if p.elementInScope(defaultScope, a.Body) {
+				p.parseImpliedToken(EndTagToken, a.Body, a.Body.String())
+				return false
+			}
+			return true
+		case a.Address, a.Article, a.Aside, a.Blockquote, a.Button, a.Center, a.Details, a.Dialog, a.Dir, a.Div, a.Dl, a.Fieldset, a.Figcaption, a.Figure, a.Footer, a.Header, a.Hgroup, a.Listing, a.Main, a.Menu, a.Nav, a.Ol, a.Pre, a.Section, a.Summary, a.Ul:
+			p.popUntil(defaultScope, p.tok.DataAtom)
+		case a.Form:
+			if p.oe.contains(a.Template) {
+				i := p.indexOfElementInScope(defaultScope, a.Form)
+				if i == -1 {
+					// Ignore the token.
+					return true
+				}
+				p.generateImpliedEndTags()
+				if p.oe[i].DataAtom != a.Form {
+					// Ignore the token.
+					return true
+				}
+				p.popUntil(defaultScope, a.Form)
+			} else {
+				node := p.form
+				p.form = nil
+				i := p.indexOfElementInScope(defaultScope, a.Form)
+				if node == nil || i == -1 || p.oe[i] != node {
+					// Ignore the token.
+					return true
+				}
+				p.generateImpliedEndTags()
+				p.oe.remove(node)
+			}
+		case a.P:
+			if !p.elementInScope(buttonScope, a.P) {
+				p.parseImpliedToken(StartTagToken, a.P, a.P.String())
+			}
+			p.popUntil(buttonScope, a.P)
+		case a.Li:
+			p.popUntil(listItemScope, a.Li)
+		case a.Dd, a.Dt:
+			p.popUntil(defaultScope, p.tok.DataAtom)
+		case a.H1, a.H2, a.H3, a.H4, a.H5, a.H6:
+			p.popUntil(defaultScope, a.H1, a.H2, a.H3, a.H4, a.H5, a.H6)
+		case a.A, a.B, a.Big, a.Code, a.Em, a.Font, a.I, a.Nobr, a.S, a.Small, a.Strike, a.Strong, a.Tt, a.U:
+			p.inBodyEndTagFormatting(p.tok.DataAtom, p.tok.Data)
+		case a.Applet, a.Marquee, a.Object:
+			if p.popUntil(defaultScope, p.tok.DataAtom) {
+				p.clearActiveFormattingElements()
+			}
+		case a.Br:
+			p.tok.Type = StartTagToken
+			return false
+		case a.Template:
+			return inHeadIM(p)
+		default:
+			p.inBodyEndTagOther(p.tok.DataAtom, p.tok.Data)
+		}
+	case CommentToken:
+		p.addChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+	case ErrorToken:
+		// TODO: remove this divergence from the HTML5 spec.
+		if len(p.templateStack) > 0 {
+			p.im = inTemplateIM
+			return false
+		}
+		for _, e := range p.oe {
+			switch e.DataAtom {
+			case a.Dd, a.Dt, a.Li, a.Optgroup, a.Option, a.P, a.Rb, a.Rp, a.Rt, a.Rtc, a.Tbody, a.Td, a.Tfoot, a.Th,
+				a.Thead, a.Tr, a.Body, a.Html:
+			default:
+				return true
+			}
+		}
+	}
+
+	return true
+}
+
+func (p *parser) inBodyEndTagFormatting(tagAtom a.Atom, tagName string) {
+	// This is the "adoption agency" algorithm, described at
+	// https://html.spec.whatwg.org/multipage/syntax.html#adoptionAgency
+
+	// TODO: this is a fairly literal line-by-line translation of that algorithm.
+	// Once the code successfully parses the comprehensive test suite, we should
+	// refactor this code to be more idiomatic.
+
+	// Steps 1-2
+	if current := p.oe.top(); current.Data == tagName && p.afe.index(current) == -1 {
+		p.oe.pop()
+		return
+	}
+
+	// Steps 3-5. The outer loop.
+	for i := 0; i < 8; i++ {
+		// Step 6. Find the formatting element.
+		var formattingElement *Node
+		for j := len(p.afe) - 1; j >= 0; j-- {
+			if p.afe[j].Type == scopeMarkerNode {
+				break
+			}
+			if p.afe[j].DataAtom == tagAtom {
+				formattingElement = p.afe[j]
+				break
+			}
+		}
+		if formattingElement == nil {
+			p.inBodyEndTagOther(tagAtom, tagName)
+			return
+		}
+
+		// Step 7. Ignore the tag if formatting element is not in the stack of open elements.
+		feIndex := p.oe.index(formattingElement)
+		if feIndex == -1 {
+			p.afe.remove(formattingElement)
+			return
+		}
+		// Step 8. Ignore the tag if formatting element is not in the scope.
+		if !p.elementInScope(defaultScope, tagAtom) {
+			// Ignore the tag.
+			return
+		}
+
+		// Step 9. This step is omitted because it's just a parse error but no need to return.
+
+		// Steps 10-11. Find the furthest block.
+		var furthestBlock *Node
+		for _, e := range p.oe[feIndex:] {
+			if isSpecialElement(e) {
+				furthestBlock = e
+				break
+			}
+		}
+		if furthestBlock == nil {
+			e := p.oe.pop()
+			for e != formattingElement {
+				e = p.oe.pop()
+			}
+			p.afe.remove(e)
+			return
+		}
+
+		// Steps 12-13. Find the common ancestor and bookmark node.
+		commonAncestor := p.oe[feIndex-1]
+		bookmark := p.afe.index(formattingElement)
+
+		// Step 14. The inner loop. Find the lastNode to reparent.
+		lastNode := furthestBlock
+		node := furthestBlock
+		x := p.oe.index(node)
+		// Step 14.1.
+		j := 0
+		for {
+			// Step 14.2.
+			j++
+			// Step. 14.3.
+			x--
+			node = p.oe[x]
+			// Step 14.4. Go to the next step if node is formatting element.
+			if node == formattingElement {
+				break
+			}
+			// Step 14.5. Remove node from the list of active formatting elements if
+			// inner loop counter is greater than three and node is in the list of
+			// active formatting elements.
+			if ni := p.afe.index(node); j > 3 && ni > -1 {
+				p.afe.remove(node)
+				// If any element of the list of active formatting elements is removed,
+				// we need to take care whether bookmark should be decremented or not.
+				// This is because the value of bookmark may exceed the size of the
+				// list by removing elements from the list.
+				if ni <= bookmark {
+					bookmark--
+				}
+				continue
+			}
+			// Step 14.6. Continue the next inner loop if node is not in the list of
+			// active formatting elements.
+			if p.afe.index(node) == -1 {
+				p.oe.remove(node)
+				continue
+			}
+			// Step 14.7.
+			clone := node.clone()
+			p.afe[p.afe.index(node)] = clone
+			p.oe[p.oe.index(node)] = clone
+			node = clone
+			// Step 14.8.
+			if lastNode == furthestBlock {
+				bookmark = p.afe.index(node) + 1
+			}
+			// Step 14.9.
+			if lastNode.Parent != nil {
+				lastNode.Parent.RemoveChild(lastNode)
+			}
+			node.AppendChild(lastNode)
+			// Step 14.10.
+			lastNode = node
+		}
+
+		// Step 15. Reparent lastNode to the common ancestor,
+		// or for misnested table nodes, to the foster parent.
+		if lastNode.Parent != nil {
+			lastNode.Parent.RemoveChild(lastNode)
+		}
+		switch commonAncestor.DataAtom {
+		case a.Table, a.Tbody, a.Tfoot, a.Thead, a.Tr:
+			p.fosterParent(lastNode)
+		default:
+			commonAncestor.AppendChild(lastNode)
+		}
+
+		// Steps 16-18. Reparent nodes from the furthest block's children
+		// to a clone of the formatting element.
+		clone := formattingElement.clone()
+		reparentChildren(clone, furthestBlock)
+		furthestBlock.AppendChild(clone)
+
+		// Step 19. Fix up the list of active formatting elements.
+		if oldLoc := p.afe.index(formattingElement); oldLoc != -1 && oldLoc < bookmark {
+			// Move the bookmark with the rest of the list.
+			bookmark--
+		}
+		p.afe.remove(formattingElement)
+		p.afe.insert(bookmark, clone)
+
+		// Step 20. Fix up the stack of open elements.
+		p.oe.remove(formattingElement)
+		p.oe.insert(p.oe.index(furthestBlock)+1, clone)
+	}
+}
+
+// inBodyEndTagOther performs the "any other end tag" algorithm for inBodyIM.
+// "Any other end tag" handling from 12.2.6.5 The rules for parsing tokens in foreign content
+// https://html.spec.whatwg.org/multipage/syntax.html#parsing-main-inforeign
+func (p *parser) inBodyEndTagOther(tagAtom a.Atom, tagName string) {
+	for i := len(p.oe) - 1; i >= 0; i-- {
+		// Two element nodes have the same tag if they have the same Data (a
+		// string-typed field). As an optimization, for common HTML tags, each
+		// Data string is assigned a unique, non-zero DataAtom (a uint32-typed
+		// field), since integer comparison is faster than string comparison.
+		// Uncommon (custom) tags get a zero DataAtom.
+		//
+		// The if condition here is equivalent to (p.oe[i].Data == tagName).
+		if (p.oe[i].DataAtom == tagAtom) &&
+			((tagAtom != 0) || (p.oe[i].Data == tagName)) {
+			p.oe = p.oe[:i]
+			break
+		}
+		if isSpecialElement(p.oe[i]) {
+			break
+		}
+	}
+}
+
+// Section 12.2.6.4.8.
+func textIM(p *parser) bool {
+	switch p.tok.Type {
+	case ErrorToken:
+		p.oe.pop()
+	case TextToken:
+		d := p.tok.Data
+		if n := p.oe.top(); n.DataAtom == a.Textarea && n.FirstChild == nil {
+			// Ignore a newline at the start of a <textarea> block.
+			if d != "" && d[0] == '\r' {
+				d = d[1:]
+			}
+			if d != "" && d[0] == '\n' {
+				d = d[1:]
+			}
+		}
+		if d == "" {
+			return true
+		}
+		p.addText(d)
+		return true
+	case EndTagToken:
+		p.oe.pop()
+	}
+	p.im = p.originalIM
+	p.originalIM = nil
+	return p.tok.Type == EndTagToken
+}
+
+// Section 12.2.6.4.9.
+func inTableIM(p *parser) bool {
+	switch p.tok.Type {
+	case TextToken:
+		p.tok.Data = strings.Replace(p.tok.Data, "\x00", "", -1)
+		switch p.oe.top().DataAtom {
+		case a.Table, a.Tbody, a.Tfoot, a.Thead, a.Tr:
+			if strings.Trim(p.tok.Data, whitespace) == "" {
+				p.addText(p.tok.Data)
+				return true
+			}
+		}
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Caption:
+			p.clearStackToContext(tableScope)
+			p.afe = append(p.afe, &scopeMarker)
+			p.addElement()
+			p.im = inCaptionIM
+			return true
+		case a.Colgroup:
+			p.clearStackToContext(tableScope)
+			p.addElement()
+			p.im = inColumnGroupIM
+			return true
+		case a.Col:
+			p.parseImpliedToken(StartTagToken, a.Colgroup, a.Colgroup.String())
+			return false
+		case a.Tbody, a.Tfoot, a.Thead:
+			p.clearStackToContext(tableScope)
+			p.addElement()
+			p.im = inTableBodyIM
+			return true
+		case a.Td, a.Th, a.Tr:
+			p.parseImpliedToken(StartTagToken, a.Tbody, a.Tbody.String())
+			return false
+		case a.Table:
+			if p.popUntil(tableScope, a.Table) {
+				p.resetInsertionMode()
+				return false
+			}
+			// Ignore the token.
+			return true
+		case a.Style, a.Script, a.Template:
+			return inHeadIM(p)
+		case a.Input:
+			for _, t := range p.tok.Attr {
+				if t.Key == "type" && strings.ToLower(t.Val) == "hidden" {
+					p.addElement()
+					p.oe.pop()
+					return true
+				}
+			}
+			// Otherwise drop down to the default action.
+		case a.Form:
+			if p.oe.contains(a.Template) || p.form != nil {
+				// Ignore the token.
+				return true
+			}
+			p.addElement()
+			p.form = p.oe.pop()
+		case a.Select:
+			p.reconstructActiveFormattingElements()
+			switch p.top().DataAtom {
+			case a.Table, a.Tbody, a.Tfoot, a.Thead, a.Tr:
+				p.fosterParenting = true
+			}
+			p.addElement()
+			p.fosterParenting = false
+			p.framesetOK = false
+			p.im = inSelectInTableIM
+			return true
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Table:
+			if p.popUntil(tableScope, a.Table) {
+				p.resetInsertionMode()
+				return true
+			}
+			// Ignore the token.
+			return true
+		case a.Body, a.Caption, a.Col, a.Colgroup, a.Html, a.Tbody, a.Td, a.Tfoot, a.Th, a.Thead, a.Tr:
+			// Ignore the token.
+			return true
+		case a.Template:
+			return inHeadIM(p)
+		}
+	case CommentToken:
+		p.addChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+		return true
+	case DoctypeToken:
+		// Ignore the token.
+		return true
+	case ErrorToken:
+		return inBodyIM(p)
+	}
+
+	p.fosterParenting = true
+	defer func() { p.fosterParenting = false }()
+
+	return inBodyIM(p)
+}
+
+// Section 12.2.6.4.11.
+func inCaptionIM(p *parser) bool {
+	switch p.tok.Type {
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Caption, a.Col, a.Colgroup, a.Tbody, a.Td, a.Tfoot, a.Thead, a.Tr:
+			if !p.popUntil(tableScope, a.Caption) {
+				// Ignore the token.
+				return true
+			}
+			p.clearActiveFormattingElements()
+			p.im = inTableIM
+			return false
+		case a.Select:
+			p.reconstructActiveFormattingElements()
+			p.addElement()
+			p.framesetOK = false
+			p.im = inSelectInTableIM
+			return true
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Caption:
+			if p.popUntil(tableScope, a.Caption) {
+				p.clearActiveFormattingElements()
+				p.im = inTableIM
+			}
+			return true
+		case a.Table:
+			if !p.popUntil(tableScope, a.Caption) {
+				// Ignore the token.
+				return true
+			}
+			p.clearActiveFormattingElements()
+			p.im = inTableIM
+			return false
+		case a.Body, a.Col, a.Colgroup, a.Html, a.Tbody, a.Td, a.Tfoot, a.Th, a.Thead, a.Tr:
+			// Ignore the token.
+			return true
+		}
+	}
+	return inBodyIM(p)
+}
+
+// Section 12.2.6.4.12.
+func inColumnGroupIM(p *parser) bool {
+	switch p.tok.Type {
+	case TextToken:
+		s := strings.TrimLeft(p.tok.Data, whitespace)
+		if len(s) < len(p.tok.Data) {
+			// Add the initial whitespace to the current node.
+			p.addText(p.tok.Data[:len(p.tok.Data)-len(s)])
+			if s == "" {
+				return true
+			}
+			p.tok.Data = s
+		}
+	case CommentToken:
+		p.addChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+		return true
+	case DoctypeToken:
+		// Ignore the token.
+		return true
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Html:
+			return inBodyIM(p)
+		case a.Col:
+			p.addElement()
+			p.oe.pop()
+			p.acknowledgeSelfClosingTag()
+			return true
+		case a.Template:
+			return inHeadIM(p)
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Colgroup:
+			if p.oe.top().DataAtom == a.Colgroup {
+				p.oe.pop()
+				p.im = inTableIM
+			}
+			return true
+		case a.Col:
+			// Ignore the token.
+			return true
+		case a.Template:
+			return inHeadIM(p)
+		}
+	case ErrorToken:
+		return inBodyIM(p)
+	}
+	if p.oe.top().DataAtom != a.Colgroup {
+		return true
+	}
+	p.oe.pop()
+	p.im = inTableIM
+	return false
+}
+
+// Section 12.2.6.4.13.
+func inTableBodyIM(p *parser) bool {
+	switch p.tok.Type {
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Tr:
+			p.clearStackToContext(tableBodyScope)
+			p.addElement()
+			p.im = inRowIM
+			return true
+		case a.Td, a.Th:
+			p.parseImpliedToken(StartTagToken, a.Tr, a.Tr.String())
+			return false
+		case a.Caption, a.Col, a.Colgroup, a.Tbody, a.Tfoot, a.Thead:
+			if p.popUntil(tableScope, a.Tbody, a.Thead, a.Tfoot) {
+				p.im = inTableIM
+				return false
+			}
+			// Ignore the token.
+			return true
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Tbody, a.Tfoot, a.Thead:
+			if p.elementInScope(tableScope, p.tok.DataAtom) {
+				p.clearStackToContext(tableBodyScope)
+				p.oe.pop()
+				p.im = inTableIM
+			}
+			return true
+		case a.Table:
+			if p.popUntil(tableScope, a.Tbody, a.Thead, a.Tfoot) {
+				p.im = inTableIM
+				return false
+			}
+			// Ignore the token.
+			return true
+		case a.Body, a.Caption, a.Col, a.Colgroup, a.Html, a.Td, a.Th, a.Tr:
+			// Ignore the token.
+			return true
+		}
+	case CommentToken:
+		p.addChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+		return true
+	}
+
+	return inTableIM(p)
+}
+
+// Section 12.2.6.4.14.
+func inRowIM(p *parser) bool {
+	switch p.tok.Type {
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Td, a.Th:
+			p.clearStackToContext(tableRowScope)
+			p.addElement()
+			p.afe = append(p.afe, &scopeMarker)
+			p.im = inCellIM
+			return true
+		case a.Caption, a.Col, a.Colgroup, a.Tbody, a.Tfoot, a.Thead, a.Tr:
+			if p.popUntil(tableScope, a.Tr) {
+				p.im = inTableBodyIM
+				return false
+			}
+			// Ignore the token.
+			return true
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Tr:
+			if p.popUntil(tableScope, a.Tr) {
+				p.im = inTableBodyIM
+				return true
+			}
+			// Ignore the token.
+			return true
+		case a.Table:
+			if p.popUntil(tableScope, a.Tr) {
+				p.im = inTableBodyIM
+				return false
+			}
+			// Ignore the token.
+			return true
+		case a.Tbody, a.Tfoot, a.Thead:
+			if p.elementInScope(tableScope, p.tok.DataAtom) {
+				p.parseImpliedToken(EndTagToken, a.Tr, a.Tr.String())
+				return false
+			}
+			// Ignore the token.
+			return true
+		case a.Body, a.Caption, a.Col, a.Colgroup, a.Html, a.Td, a.Th:
+			// Ignore the token.
+			return true
+		}
+	}
+
+	return inTableIM(p)
+}
+
+// Section 12.2.6.4.15.
+func inCellIM(p *parser) bool {
+	switch p.tok.Type {
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Caption, a.Col, a.Colgroup, a.Tbody, a.Td, a.Tfoot, a.Th, a.Thead, a.Tr:
+			if p.popUntil(tableScope, a.Td, a.Th) {
+				// Close the cell and reprocess.
+				p.clearActiveFormattingElements()
+				p.im = inRowIM
+				return false
+			}
+			// Ignore the token.
+			return true
+		case a.Select:
+			p.reconstructActiveFormattingElements()
+			p.addElement()
+			p.framesetOK = false
+			p.im = inSelectInTableIM
+			return true
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Td, a.Th:
+			if !p.popUntil(tableScope, p.tok.DataAtom) {
+				// Ignore the token.
+				return true
+			}
+			p.clearActiveFormattingElements()
+			p.im = inRowIM
+			return true
+		case a.Body, a.Caption, a.Col, a.Colgroup, a.Html:
+			// Ignore the token.
+			return true
+		case a.Table, a.Tbody, a.Tfoot, a.Thead, a.Tr:
+			if !p.elementInScope(tableScope, p.tok.DataAtom) {
+				// Ignore the token.
+				return true
+			}
+			// Close the cell and reprocess.
+			if p.popUntil(tableScope, a.Td, a.Th) {
+				p.clearActiveFormattingElements()
+			}
+			p.im = inRowIM
+			return false
+		}
+	}
+	return inBodyIM(p)
+}
+
+// Section 12.2.6.4.16.
+func inSelectIM(p *parser) bool {
+	switch p.tok.Type {
+	case TextToken:
+		p.addText(strings.Replace(p.tok.Data, "\x00", "", -1))
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Html:
+			return inBodyIM(p)
+		case a.Option:
+			if p.top().DataAtom == a.Option {
+				p.oe.pop()
+			}
+			p.addElement()
+		case a.Optgroup:
+			if p.top().DataAtom == a.Option {
+				p.oe.pop()
+			}
+			if p.top().DataAtom == a.Optgroup {
+				p.oe.pop()
+			}
+			p.addElement()
+		case a.Select:
+			if !p.popUntil(selectScope, a.Select) {
+				// Ignore the token.
+				return true
+			}
+			p.resetInsertionMode()
+		case a.Input, a.Keygen, a.Textarea:
+			if p.elementInScope(selectScope, a.Select) {
+				p.parseImpliedToken(EndTagToken, a.Select, a.Select.String())
+				return false
+			}
+			// In order to properly ignore <textarea>, we need to change the tokenizer mode.
+			p.tokenizer.NextIsNotRawText()
+			// Ignore the token.
+			return true
+		case a.Script, a.Template:
+			return inHeadIM(p)
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Option:
+			if p.top().DataAtom == a.Option {
+				p.oe.pop()
+			}
+		case a.Optgroup:
+			i := len(p.oe) - 1
+			if p.oe[i].DataAtom == a.Option {
+				i--
+			}
+			if p.oe[i].DataAtom == a.Optgroup {
+				p.oe = p.oe[:i]
+			}
+		case a.Select:
+			if !p.popUntil(selectScope, a.Select) {
+				// Ignore the token.
+				return true
+			}
+			p.resetInsertionMode()
+		case a.Template:
+			return inHeadIM(p)
+		}
+	case CommentToken:
+		p.addChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+	case DoctypeToken:
+		// Ignore the token.
+		return true
+	case ErrorToken:
+		return inBodyIM(p)
+	}
+
+	return true
+}
+
+// Section 12.2.6.4.17.
+func inSelectInTableIM(p *parser) bool {
+	switch p.tok.Type {
+	case StartTagToken, EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Caption, a.Table, a.Tbody, a.Tfoot, a.Thead, a.Tr, a.Td, a.Th:
+			if p.tok.Type == EndTagToken && !p.elementInScope(tableScope, p.tok.DataAtom) {
+				// Ignore the token.
+				return true
+			}
+			// This is like p.popUntil(selectScope, a.Select), but it also
+			// matches <math select>, not just <select>. Matching the MathML
+			// tag is arguably incorrect (conceptually), but it mimics what
+			// Chromium does.
+			for i := len(p.oe) - 1; i >= 0; i-- {
+				if n := p.oe[i]; n.DataAtom == a.Select {
+					p.oe = p.oe[:i]
+					break
+				}
+			}
+			p.resetInsertionMode()
+			return false
+		}
+	}
+	return inSelectIM(p)
+}
+
+// Section 12.2.6.4.18.
+func inTemplateIM(p *parser) bool {
+	switch p.tok.Type {
+	case TextToken, CommentToken, DoctypeToken:
+		return inBodyIM(p)
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Base, a.Basefont, a.Bgsound, a.Link, a.Meta, a.Noframes, a.Script, a.Style, a.Template, a.Title:
+			return inHeadIM(p)
+		case a.Caption, a.Colgroup, a.Tbody, a.Tfoot, a.Thead:
+			p.templateStack.pop()
+			p.templateStack = append(p.templateStack, inTableIM)
+			p.im = inTableIM
+			return false
+		case a.Col:
+			p.templateStack.pop()
+			p.templateStack = append(p.templateStack, inColumnGroupIM)
+			p.im = inColumnGroupIM
+			return false
+		case a.Tr:
+			p.templateStack.pop()
+			p.templateStack = append(p.templateStack, inTableBodyIM)
+			p.im = inTableBodyIM
+			return false
+		case a.Td, a.Th:
+			p.templateStack.pop()
+			p.templateStack = append(p.templateStack, inRowIM)
+			p.im = inRowIM
+			return false
+		default:
+			p.templateStack.pop()
+			p.templateStack = append(p.templateStack, inBodyIM)
+			p.im = inBodyIM
+			return false
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Template:
+			return inHeadIM(p)
+		default:
+			// Ignore the token.
+			return true
+		}
+	case ErrorToken:
+		if !p.oe.contains(a.Template) {
+			// Ignore the token.
+			return true
+		}
+		// TODO: remove this divergence from the HTML5 spec.
+		//
+		// See https://bugs.chromium.org/p/chromium/issues/detail?id=829668
+		p.generateImpliedEndTags()
+		for i := len(p.oe) - 1; i >= 0; i-- {
+			if n := p.oe[i]; n.Namespace == "" && n.DataAtom == a.Template {
+				p.oe = p.oe[:i]
+				break
+			}
+		}
+		p.clearActiveFormattingElements()
+		p.templateStack.pop()
+		p.resetInsertionMode()
+		return false
+	}
+	return false
+}
+
+// Section 12.2.6.4.19.
+func afterBodyIM(p *parser) bool {
+	switch p.tok.Type {
+	case ErrorToken:
+		// Stop parsing.
+		return true
+	case TextToken:
+		s := strings.TrimLeft(p.tok.Data, whitespace)
+		if len(s) == 0 {
+			// It was all whitespace.
+			return inBodyIM(p)
+		}
+	case StartTagToken:
+		if p.tok.DataAtom == a.Html {
+			return inBodyIM(p)
+		}
+	case EndTagToken:
+		if p.tok.DataAtom == a.Html {
+			if !p.fragment {
+				p.im = afterAfterBodyIM
+			}
+			return true
+		}
+	case CommentToken:
+		// The comment is attached to the <html> element.
+		if len(p.oe) < 1 || p.oe[0].DataAtom != a.Html {
+			panic("html: bad parser state: <html> element not found, in the after-body insertion mode")
+		}
+		p.oe[0].AppendChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+		return true
+	}
+	p.im = inBodyIM
+	return false
+}
+
+// Section 12.2.6.4.20.
+func inFramesetIM(p *parser) bool {
+	switch p.tok.Type {
+	case CommentToken:
+		p.addChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+	case TextToken:
+		// Ignore all text but whitespace.
+		s := strings.Map(func(c rune) rune {
+			switch c {
+			case ' ', '\t', '\n', '\f', '\r':
+				return c
+			}
+			return -1
+		}, p.tok.Data)
+		if s != "" {
+			p.addText(s)
+		}
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Html:
+			return inBodyIM(p)
+		case a.Frameset:
+			p.addElement()
+		case a.Frame:
+			p.addElement()
+			p.oe.pop()
+			p.acknowledgeSelfClosingTag()
+		case a.Noframes:
+			return inHeadIM(p)
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Frameset:
+			if p.oe.top().DataAtom != a.Html {
+				p.oe.pop()
+				if p.oe.top().DataAtom != a.Frameset {
+					p.im = afterFramesetIM
+					return true
+				}
+			}
+		}
+	default:
+		// Ignore the token.
+	}
+	return true
+}
+
+// Section 12.2.6.4.21.
+func afterFramesetIM(p *parser) bool {
+	switch p.tok.Type {
+	case CommentToken:
+		p.addChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+	case TextToken:
+		// Ignore all text but whitespace.
+		s := strings.Map(func(c rune) rune {
+			switch c {
+			case ' ', '\t', '\n', '\f', '\r':
+				return c
+			}
+			return -1
+		}, p.tok.Data)
+		if s != "" {
+			p.addText(s)
+		}
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Html:
+			return inBodyIM(p)
+		case a.Noframes:
+			return inHeadIM(p)
+		}
+	case EndTagToken:
+		switch p.tok.DataAtom {
+		case a.Html:
+			p.im = afterAfterFramesetIM
+			return true
+		}
+	default:
+		// Ignore the token.
+	}
+	return true
+}
+
+// Section 12.2.6.4.22.
+func afterAfterBodyIM(p *parser) bool {
+	switch p.tok.Type {
+	case ErrorToken:
+		// Stop parsing.
+		return true
+	case TextToken:
+		s := strings.TrimLeft(p.tok.Data, whitespace)
+		if len(s) == 0 {
+			// It was all whitespace.
+			return inBodyIM(p)
+		}
+	case StartTagToken:
+		if p.tok.DataAtom == a.Html {
+			return inBodyIM(p)
+		}
+	case CommentToken:
+		p.doc.AppendChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+		return true
+	case DoctypeToken:
+		return inBodyIM(p)
+	}
+	p.im = inBodyIM
+	return false
+}
+
+// Section 12.2.6.4.23.
+func afterAfterFramesetIM(p *parser) bool {
+	switch p.tok.Type {
+	case CommentToken:
+		p.doc.AppendChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+	case TextToken:
+		// Ignore all text but whitespace.
+		s := strings.Map(func(c rune) rune {
+			switch c {
+			case ' ', '\t', '\n', '\f', '\r':
+				return c
+			}
+			return -1
+		}, p.tok.Data)
+		if s != "" {
+			p.tok.Data = s
+			return inBodyIM(p)
+		}
+	case StartTagToken:
+		switch p.tok.DataAtom {
+		case a.Html:
+			return inBodyIM(p)
+		case a.Noframes:
+			return inHeadIM(p)
+		}
+	case DoctypeToken:
+		return inBodyIM(p)
+	default:
+		// Ignore the token.
+	}
+	return true
+}
+
+const whitespaceOrNUL = whitespace + "\x00"
+
+// Section 12.2.6.5
+func parseForeignContent(p *parser) bool {
+	switch p.tok.Type {
+	case TextToken:
+		if p.framesetOK {
+			p.framesetOK = strings.TrimLeft(p.tok.Data, whitespaceOrNUL) == ""
+		}
+		p.tok.Data = strings.Replace(p.tok.Data, "\x00", "\ufffd", -1)
+		p.addText(p.tok.Data)
+	case CommentToken:
+		p.addChild(&Node{
+			Type: CommentNode,
+			Data: p.tok.Data,
+		})
+	case StartTagToken:
+		if !p.fragment {
+			b := breakout[p.tok.Data]
+			if p.tok.DataAtom == a.Font {
+			loop:
+				for _, attr := range p.tok.Attr {
+					switch attr.Key {
+					case "color", "face", "size":
+						b = true
+						break loop
+					}
+				}
+			}
+			if b {
+				for i := len(p.oe) - 1; i >= 0; i-- {
+					n := p.oe[i]
+					if n.Namespace == "" || htmlIntegrationPoint(n) || mathMLTextIntegrationPoint(n) {
+						p.oe = p.oe[:i+1]
+						break
+					}
+				}
+				return false
+			}
+		}
+		current := p.adjustedCurrentNode()
+		switch current.Namespace {
+		case "math":
+			adjustAttributeNames(p.tok.Attr, mathMLAttributeAdjustments)
+		case "svg":
+			// Adjust SVG tag names. The tokenizer lower-cases tag names, but
+			// SVG wants e.g. "foreignObject" with a capital second "O".
+			if x := svgTagNameAdjustments[p.tok.Data]; x != "" {
+				p.tok.DataAtom = a.Lookup([]byte(x))
+				p.tok.Data = x
+			}
+			adjustAttributeNames(p.tok.Attr, svgAttributeAdjustments)
+		default:
+			panic("html: bad parser state: unexpected namespace")
+		}
+		adjustForeignAttributes(p.tok.Attr)
+		namespace := current.Namespace
+		p.addElement()
+		p.top().Namespace = namespace
+		if namespace != "" {
+			// Don't let the tokenizer go into raw text mode in foreign content
+			// (e.g. in an SVG <title> tag).
+			p.tokenizer.NextIsNotRawText()
+		}
+		if p.hasSelfClosingToken {
+			p.oe.pop()
+			p.acknowledgeSelfClosingTag()
+		}
+	case EndTagToken:
+		for i := len(p.oe) - 1; i >= 0; i-- {
+			if p.oe[i].Namespace == "" {
+				return p.im(p)
+			}
+			if strings.EqualFold(p.oe[i].Data, p.tok.Data) {
+				p.oe = p.oe[:i]
+				break
+			}
+		}
+		return true
+	default:
+		// Ignore the token.
+	}
+	return true
+}
+
+// Section 12.2.4.2.
+func (p *parser) adjustedCurrentNode() *Node {
+	if len(p.oe) == 1 && p.fragment && p.context != nil {
+		return p.context
+	}
+	return p.oe.top()
+}
+
+// Section 12.2.6.
+func (p *parser) inForeignContent() bool {
+	if len(p.oe) == 0 {
+		return false
+	}
+	n := p.adjustedCurrentNode()
+	if n.Namespace == "" {
+		return false
+	}
+	if mathMLTextIntegrationPoint(n) {
+		if p.tok.Type == StartTagToken && p.tok.DataAtom != a.Mglyph && p.tok.DataAtom != a.Malignmark {
+			return false
+		}
+		if p.tok.Type == TextToken {
+			return false
+		}
+	}
+	if n.Namespace == "math" && n.DataAtom == a.AnnotationXml && p.tok.Type == StartTagToken && p.tok.DataAtom == a.Svg {
+		return false
+	}
+	if htmlIntegrationPoint(n) && (p.tok.Type == StartTagToken || p.tok.Type == TextToken) {
+		return false
+	}
+	if p.tok.Type == ErrorToken {
+		return false
+	}
+	return true
+}
+
+// parseImpliedToken parses a token as though it had appeared in the parser's
+// input.
+func (p *parser) parseImpliedToken(t TokenType, dataAtom a.Atom, data string) {
+	realToken, selfClosing := p.tok, p.hasSelfClosingToken
+	p.tok = Token{
+		Type:     t,
+		DataAtom: dataAtom,
+		Data:     data,
+	}
+	p.hasSelfClosingToken = false
+	p.parseCurrentToken()
+	p.tok, p.hasSelfClosingToken = realToken, selfClosing
+}
+
+// parseCurrentToken runs the current token through the parsing routines
+// until it is consumed.
+func (p *parser) parseCurrentToken() {
+	if p.tok.Type == SelfClosingTagToken {
+		p.hasSelfClosingToken = true
+		p.tok.Type = StartTagToken
+	}
+
+	consumed := false
+	for !consumed {
+		if p.inForeignContent() {
+			consumed = parseForeignContent(p)
+		} else {
+			consumed = p.im(p)
+		}
+	}
+
+	if p.hasSelfClosingToken {
+		// This is a parse error, but ignore it.
+		p.hasSelfClosingToken = false
+	}
+}
+
+func (p *parser) parse() error {
+	// Iterate until EOF. Any other error will cause an early return.
+	var err error
+	for err != io.EOF {
+		// CDATA sections are allowed only in foreign content.
+		n := p.oe.top()
+		p.tokenizer.AllowCDATA(n != nil && n.Namespace != "")
+		// Read and parse the next token.
+		p.tokenizer.Next()
+		p.tok = p.tokenizer.Token()
+		if p.tok.Type == ErrorToken {
+			err = p.tokenizer.Err()
+			if err != nil && err != io.EOF {
+				return err
+			}
+		}
+		p.parseCurrentToken()
+	}
+	return nil
+}
+
+// Parse returns the parse tree for the HTML from the given Reader.
+//
+// It implements the HTML5 parsing algorithm
+// (https://html.spec.whatwg.org/multipage/syntax.html#tree-construction),
+// which is very complicated. The resultant tree can contain implicitly created
+// nodes that have no explicit <tag> listed in r's data, and nodes' parents can
+// differ from the nesting implied by a naive processing of start and end
+// <tag>s. Conversely, explicit <tag>s in r's data can be silently dropped,
+// with no corresponding node in the resulting tree.
+//
+// The input is assumed to be UTF-8 encoded.
+func Parse(r io.Reader) (*Node, error) {
+	return ParseWithOptions(r)
+}
+
+// ParseFragment parses a fragment of HTML and returns the nodes that were
+// found. If the fragment is the InnerHTML for an existing element, pass that
+// element in context.
+//
+// It has the same intricacies as Parse.
+func ParseFragment(r io.Reader, context *Node) ([]*Node, error) {
+	return ParseFragmentWithOptions(r, context)
+}
+
+// ParseOption configures a parser.
+type ParseOption func(p *parser)
+
+// ParseOptionEnableScripting configures the scripting flag.
+// https://html.spec.whatwg.org/multipage/webappapis.html#enabling-and-disabling-scripting
+//
+// By default, scripting is enabled.
+func ParseOptionEnableScripting(enable bool) ParseOption {
+	return func(p *parser) {
+		p.scripting = enable
+	}
+}
+
+// ParseWithOptions is like Parse, with options.
+func ParseWithOptions(r io.Reader, opts ...ParseOption) (*Node, error) {
+	p := &parser{
+		tokenizer: NewTokenizer(r),
+		doc: &Node{
+			Type: DocumentNode,
+		},
+		scripting:  true,
+		framesetOK: true,
+		im:         initialIM,
+	}
+
+	for _, f := range opts {
+		f(p)
+	}
+
+	if err := p.parse(); err != nil {
+		return nil, err
+	}
+	return p.doc, nil
+}
+
+// ParseFragmentWithOptions is like ParseFragment, with options.
+func ParseFragmentWithOptions(r io.Reader, context *Node, opts ...ParseOption) ([]*Node, error) {
+	contextTag := ""
+	if context != nil {
+		if context.Type != ElementNode {
+			return nil, errors.New("html: ParseFragment of non-element Node")
+		}
+		// The next check isn't just context.DataAtom.String() == context.Data because
+		// it is valid to pass an element whose tag isn't a known atom. For example,
+		// DataAtom == 0 and Data = "tagfromthefuture" is perfectly consistent.
+		if context.DataAtom != a.Lookup([]byte(context.Data)) {
+			return nil, fmt.Errorf("html: inconsistent Node: DataAtom=%q, Data=%q", context.DataAtom, context.Data)
+		}
+		contextTag = context.DataAtom.String()
+	}
+	p := &parser{
+		doc: &Node{
+			Type: DocumentNode,
+		},
+		scripting: true,
+		fragment:  true,
+		context:   context,
+	}
+	if context != nil && context.Namespace != "" {
+		p.tokenizer = NewTokenizer(r)
+	} else {
+		p.tokenizer = NewTokenizerFragment(r, contextTag)
+	}
+
+	for _, f := range opts {
+		f(p)
+	}
+
+	root := &Node{
+		Type:     ElementNode,
+		DataAtom: a.Html,
+		Data:     a.Html.String(),
+	}
+	p.doc.AppendChild(root)
+	p.oe = nodeStack{root}
+	if context != nil && context.DataAtom == a.Template {
+		p.templateStack = append(p.templateStack, inTemplateIM)
+	}
+	p.resetInsertionMode()
+
+	for n := context; n != nil; n = n.Parent {
+		if n.Type == ElementNode && n.DataAtom == a.Form {
+			p.form = n
+			break
+		}
+	}
+
+	if err := p.parse(); err != nil {
+		return nil, err
+	}
+
+	parent := p.doc
+	if context != nil {
+		parent = root
+	}
+
+	var result []*Node
+	for c := parent.FirstChild; c != nil; {
+		next := c.NextSibling
+		parent.RemoveChild(c)
+		result = append(result, c)
+		c = next
+	}
+	return result, nil
+}