// 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 12.2.3.2) and active formatting // elements (section 12.2.3.3). oe, afe nodeStack // Element pointers (section 12.2.3.4). head, form *Node // Other parsing state flags (section 12.2.3.5). scripting, framesetOK bool // 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 12.2.5.3). 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 12.2.3.2. 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 12.2.3.2). 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 { 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 { p.oe = p.oe[:i+1] return } case tableRowScope: if tagAtom == a.Html || tagAtom == a.Tr { p.oe = p.oe[:i+1] return } case tableBodyScope: if tagAtom == a.Html || tagAtom == a.Tbody || tagAtom == a.Tfoot || tagAtom == a.Thead { p.oe = p.oe[:i+1] return } default: panic("unreachable") } } } // generateImpliedEndTags pops nodes off the stack of open elements as long as // the top node has a tag name of dd, dt, li, option, optgroup, p, rp, or rt. // 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 { switch n.DataAtom { case a.Dd, a.Dt, a.Li, a.Option, a.Optgroup, a.P, a.Rp, a.Rt: 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 12.2.5.3, "foster parenting". func (p *parser) fosterParent(n *Node) { var table, parent, prev *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 } } 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 12.2.3.3. 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 12.2.3.3. func (p *parser) clearActiveFormattingElements() { for { n := p.afe.pop() if len(p.afe) == 0 || n.Type == scopeMarkerNode { return } } } // Section 12.2.3.3. 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 12.2.4. func (p *parser) acknowledgeSelfClosingTag() { p.hasSelfClosingToken = false } // An insertion mode (section 12.2.3.1) 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 12.2.3.1, "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 12.2.3.1, "reset the insertion mode". func (p *parser) resetInsertionMode() { for i := len(p.oe) - 1; i >= 0; i-- { n := p.oe[i] if i == 0 && p.context != nil { n = p.context } switch n.DataAtom { case a.Select: p.im = inSelectIM case a.Td, a.Th: 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.Head: p.im = inBodyIM case a.Body: p.im = inBodyIM case a.Frameset: p.im = inFramesetIM case a.Html: p.im = beforeHeadIM default: continue } return } p.im = inBodyIM } const whitespace = " \t\r\n\f" // Section 12.2.5.4.1. 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 12.2.5.4.2. 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 12.2.5.4.3. 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 12.2.5.4.4. 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.Command, a.Link, a.Meta: p.addElement() p.oe.pop() p.acknowledgeSelfClosingTag() return true case a.Script, a.Title, a.Noscript, a.Noframes, a.Style: p.addElement() p.setOriginalIM() p.im = textIM return true case a.Head: // Ignore the token. return true } case EndTagToken: switch p.tok.DataAtom { case a.Head: n := p.oe.pop() if n.DataAtom != a.Head { panic("html: bad parser state: <head> element not found, in the in-head insertion mode") } p.im = afterHeadIM return true case a.Body, a.Html, a.Br: p.parseImpliedToken(EndTagToken, 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(EndTagToken, a.Head, a.Head.String()) return false } // Section 12.2.5.4.6. 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.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. 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 12.2.5.4.7. 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: copyAttributes(p.oe[0], p.tok) case a.Base, a.Basefont, a.Bgsound, a.Command, a.Link, a.Meta, a.Noframes, a.Script, a.Style, a.Title: return inHeadIM(p) case a.Body: 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.Dir, a.Div, a.Dl, a.Fieldset, a.Figcaption, a.Figure, a.Footer, a.Header, a.Hgroup, 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.popUntil(buttonScope, a.P) p.addElement() 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) 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) 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.Isindex: if p.form != nil { // Ignore the token. return true } action := "" prompt := "This is a searchable index. Enter search keywords: " attr := []Attribute{{Key: "name", Val: "isindex"}} for _, t := range p.tok.Attr { switch t.Key { case "action": action = t.Val case "name": // Ignore the attribute. case "prompt": prompt = t.Val default: attr = append(attr, t) } } p.acknowledgeSelfClosingTag() p.popUntil(buttonScope, a.P) p.parseImpliedToken(StartTagToken, a.Form, a.Form.String()) if action != "" { p.form.Attr = []Attribute{{Key: "action", Val: action}} } p.parseImpliedToken(StartTagToken, a.Hr, a.Hr.String()) p.parseImpliedToken(StartTagToken, a.Label, a.Label.String()) p.addText(prompt) p.addChild(&Node{ Type: ElementNode, DataAtom: a.Input, Data: a.Input.String(), Attr: attr, }) p.oe.pop() p.parseImpliedToken(EndTagToken, a.Label, a.Label.String()) p.parseImpliedToken(StartTagToken, a.Hr, a.Hr.String()) p.parseImpliedToken(EndTagToken, a.Form, a.Form.String()) 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.addElement() p.setOriginalIM() p.im = textIM case a.Iframe: p.framesetOK = false p.addElement() p.setOriginalIM() p.im = textIM case a.Noembed, a.Noscript: p.addElement() p.setOriginalIM() p.im = textIM 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.Rp, a.Rt: if p.elementInScope(defaultScope, a.Ruby) { p.generateImpliedEndTags() } 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.Dir, a.Div, a.Dl, a.Fieldset, a.Figcaption, a.Figure, a.Footer, a.Header, a.Hgroup, a.Listing, a.Menu, a.Nav, a.Ol, a.Pre, a.Section, a.Summary, a.Ul: p.popUntil(defaultScope, p.tok.DataAtom) case a.Form: 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) 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 default: p.inBodyEndTagOther(p.tok.DataAtom) } case CommentToken: p.addChild(&Node{ Type: CommentNode, Data: p.tok.Data, }) } return true } func (p *parser) inBodyEndTagFormatting(tagAtom a.Atom) { // 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 1-4. The outer loop. for i := 0; i < 8; i++ { // Step 5. 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) return } feIndex := p.oe.index(formattingElement) if feIndex == -1 { p.afe.remove(formattingElement) return } if !p.elementInScope(defaultScope, tagAtom) { // Ignore the tag. return } // Steps 9-10. 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 11-12. Find the common ancestor and bookmark node. commonAncestor := p.oe[feIndex-1] bookmark := p.afe.index(formattingElement) // Step 13. The inner loop. Find the lastNode to reparent. lastNode := furthestBlock node := furthestBlock x := p.oe.index(node) // Steps 13.1-13.2 for j := 0; j < 3; j++ { // Step 13.3. x-- node = p.oe[x] // Step 13.4 - 13.5. if p.afe.index(node) == -1 { p.oe.remove(node) continue } // Step 13.6. if node == formattingElement { break } // Step 13.7. clone := node.clone() p.afe[p.afe.index(node)] = clone p.oe[p.oe.index(node)] = clone node = clone // Step 13.8. if lastNode == furthestBlock { bookmark = p.afe.index(node) + 1 } // Step 13.9. if lastNode.Parent != nil { lastNode.Parent.RemoveChild(lastNode) } node.AppendChild(lastNode) // Step 13.10. lastNode = node } // Step 14. 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 15-17. 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 18. 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 19. 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 12.2.5.5 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) { for i := len(p.oe) - 1; i >= 0; i-- { if p.oe[i].DataAtom == tagAtom { p.oe = p.oe[:i] break } if isSpecialElement(p.oe[i]) { break } } } // Section 12.2.5.4.8. 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 12.2.5.4.9. func inTableIM(p *parser) bool { switch p.tok.Type { case ErrorToken: // Stop parsing. return true 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: 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.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 CommentToken: p.addChild(&Node{ Type: CommentNode, Data: p.tok.Data, }) return true case DoctypeToken: // Ignore the token. return true } p.fosterParenting = true defer func() { p.fosterParenting = false }() return inBodyIM(p) } // Section 12.2.5.4.11. 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) { p.clearActiveFormattingElements() p.im = inTableIM return false } else { // 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.Caption: if p.popUntil(tableScope, a.Caption) { p.clearActiveFormattingElements() p.im = inTableIM } return true case a.Table: if p.popUntil(tableScope, a.Caption) { p.clearActiveFormattingElements() p.im = inTableIM return false } else { // Ignore the token. return true } 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 12.2.5.4.12. 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 EndTagToken: switch p.tok.DataAtom { case a.Colgroup: if p.oe.top().DataAtom != a.Html { p.oe.pop() p.im = inTableIM } return true case a.Col: // Ignore the token. return true } } if p.oe.top().DataAtom != a.Html { p.oe.pop() p.im = inTableIM return false } return true } // Section 12.2.5.4.13. 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 12.2.5.4.14. 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 12.2.5.4.15. 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. p.popUntil(tableScope, a.Td, a.Th) p.clearActiveFormattingElements() p.im = inRowIM return false } } return inBodyIM(p) } // Section 12.2.5.4.16. func inSelectIM(p *parser) bool { switch p.tok.Type { case ErrorToken: // Stop parsing. return true 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: p.tok.Type = EndTagToken return false 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: 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) { p.resetInsertionMode() } } case CommentToken: p.addChild(&Node{ Type: CommentNode, Data: p.tok.Data, }) case DoctypeToken: // Ignore the token. return true } return true } // Section 12.2.5.4.17. 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 == StartTagToken || p.elementInScope(tableScope, p.tok.DataAtom) { p.parseImpliedToken(EndTagToken, a.Select, a.Select.String()) return false } else { // Ignore the token. return true } } } return inSelectIM(p) } // Section 12.2.5.4.18. 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 12.2.5.4.19. 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 12.2.5.4.20. 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 12.2.5.4.21. 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 12.2.5.4.22. 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 12.2.5.5. 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: 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 } switch p.top().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 := p.top().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 12.2.5. func (p *parser) inForeignContent() bool { if len(p.oe) == 0 { return false } n := p.oe[len(p.oe)-1] 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. // The input is assumed to be UTF-8 encoded. func Parse(r io.Reader) (*Node, error) { p := &parser{ tokenizer: NewTokenizer(r), doc: &Node{ Type: DocumentNode, }, scripting: true, framesetOK: true, im: initialIM, } err := p.parse() if err != nil { return nil, err } return p.doc, nil } // 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. func ParseFragment(r io.Reader, context *Node) ([]*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{ tokenizer: NewTokenizerFragment(r, contextTag), doc: &Node{ Type: DocumentNode, }, scripting: true, fragment: true, context: context, } root := &Node{ Type: ElementNode, DataAtom: a.Html, Data: a.Html.String(), } p.doc.AppendChild(root) p.oe = nodeStack{root} p.resetInsertionMode() for n := context; n != nil; n = n.Parent { if n.Type == ElementNode && n.DataAtom == a.Form { p.form = n break } } err := p.parse() if 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 }