Update Blackfriday dependency (closes #522) (#532)

- Fixup Telegram bridge implementation to support updated dependency.

1 files changed, 306 insertions, 246 deletions

diff --git a/vendor/github.com/russross/blackfriday/inline.go b/vendor/github.com/russross/blackfriday/inline.go
index 4483b8f1..3d633106 100644
--- a/vendor/github.com/russross/blackfriday/inline.go
+++ b/vendor/github.com/russross/blackfriday/inline.go
@@ -22,6 +22,9 @@ import (
 var (
 	urlRe    = `((https?|ftp):\/\/|\/)[-A-Za-z0-9+&@#\/%?=~_|!:,.;\(\)]+`
 	anchorRe = regexp.MustCompile(`^(<a\shref="` + urlRe + `"(\stitle="[^"<>]+")?\s?>` + urlRe + `<\/a>)`)
+
+	// TODO: improve this regexp to catch all possible entities:
+	htmlEntityRe = regexp.MustCompile(`&[a-z]{2,5};`)
 )
 
 // Functions to parse text within a block
@@ -29,87 +32,89 @@ var (
 // data is the complete block being rendered
 // offset is the number of valid chars before the current cursor
 
-func (p *parser) inline(out *bytes.Buffer, data []byte) {
-	// this is called recursively: enforce a maximum depth
-	if p.nesting >= p.maxNesting {
+func (p *Markdown) inline(currBlock *Node, data []byte) {
+	// handlers might call us recursively: enforce a maximum depth
+	if p.nesting >= p.maxNesting || len(data) == 0 {
 		return
 	}
 	p.nesting++
-
-	i, end := 0, 0
-	for i < len(data) {
-		// copy inactive chars into the output
-		for end < len(data) && p.inlineCallback[data[end]] == nil {
-			end++
-		}
-
-		p.r.NormalText(out, data[i:end])
-
-		if end >= len(data) {
-			break
-		}
-		i = end
-
-		// call the trigger
+	beg, end := 0, 0
+	for end < len(data) {
 		handler := p.inlineCallback[data[end]]
-		if consumed := handler(p, out, data, i); consumed == 0 {
-			// no action from the callback; buffer the byte for later
-			end = i + 1
+		if handler != nil {
+			if consumed, node := handler(p, data, end); consumed == 0 {
+				// No action from the callback.
+				end++
+			} else {
+				// Copy inactive chars into the output.
+				currBlock.AppendChild(text(data[beg:end]))
+				if node != nil {
+					currBlock.AppendChild(node)
+				}
+				// Skip past whatever the callback used.
+				beg = end + consumed
+				end = beg
+			}
 		} else {
-			// skip past whatever the callback used
-			i += consumed
-			end = i
+			end++
 		}
 	}
-
+	if beg < len(data) {
+		if data[end-1] == '\n' {
+			end--
+		}
+		currBlock.AppendChild(text(data[beg:end]))
+	}
 	p.nesting--
 }
 
 // single and double emphasis parsing
-func emphasis(p *parser, out *bytes.Buffer, data []byte, offset int) int {
+func emphasis(p *Markdown, data []byte, offset int) (int, *Node) {
 	data = data[offset:]
 	c := data[0]
-	ret := 0
 
 	if len(data) > 2 && data[1] != c {
 		// whitespace cannot follow an opening emphasis;
 		// strikethrough only takes two characters '~~'
 		if c == '~' || isspace(data[1]) {
-			return 0
+			return 0, nil
 		}
-		if ret = helperEmphasis(p, out, data[1:], c); ret == 0 {
-			return 0
+		ret, node := helperEmphasis(p, data[1:], c)
+		if ret == 0 {
+			return 0, nil
 		}
 
-		return ret + 1
+		return ret + 1, node
 	}
 
 	if len(data) > 3 && data[1] == c && data[2] != c {
 		if isspace(data[2]) {
-			return 0
+			return 0, nil
 		}
-		if ret = helperDoubleEmphasis(p, out, data[2:], c); ret == 0 {
-			return 0
+		ret, node := helperDoubleEmphasis(p, data[2:], c)
+		if ret == 0 {
+			return 0, nil
 		}
 
-		return ret + 2
+		return ret + 2, node
 	}
 
 	if len(data) > 4 && data[1] == c && data[2] == c && data[3] != c {
 		if c == '~' || isspace(data[3]) {
-			return 0
+			return 0, nil
 		}
-		if ret = helperTripleEmphasis(p, out, data, 3, c); ret == 0 {
-			return 0
+		ret, node := helperTripleEmphasis(p, data, 3, c)
+		if ret == 0 {
+			return 0, nil
 		}
 
-		return ret + 3
+		return ret + 3, node
 	}
 
-	return 0
+	return 0, nil
 }
 
-func codeSpan(p *parser, out *bytes.Buffer, data []byte, offset int) int {
+func codeSpan(p *Markdown, data []byte, offset int) (int, *Node) {
 	data = data[offset:]
 
 	nb := 0
@@ -131,7 +136,7 @@ func codeSpan(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 
 	// no matching delimiter?
 	if i < nb && end >= len(data) {
-		return 0
+		return 0, nil
 	}
 
 	// trim outside whitespace
@@ -147,43 +152,36 @@ func codeSpan(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 
 	// render the code span
 	if fBegin != fEnd {
-		p.r.CodeSpan(out, data[fBegin:fEnd])
+		code := NewNode(Code)
+		code.Literal = data[fBegin:fEnd]
+		return end, code
 	}
 
-	return end
-
+	return end, nil
 }
 
 // newline preceded by two spaces becomes <br>
-// newline without two spaces works when EXTENSION_HARD_LINE_BREAK is enabled
-func lineBreak(p *parser, out *bytes.Buffer, data []byte, offset int) int {
-	// remove trailing spaces from out
-	outBytes := out.Bytes()
-	end := len(outBytes)
-	eol := end
-	for eol > 0 && outBytes[eol-1] == ' ' {
-		eol--
-	}
-	out.Truncate(eol)
-
-	precededByTwoSpaces := offset >= 2 && data[offset-2] == ' ' && data[offset-1] == ' '
-	precededByBackslash := offset >= 1 && data[offset-1] == '\\' // see http://spec.commonmark.org/0.18/#example-527
-	precededByBackslash = precededByBackslash && p.flags&EXTENSION_BACKSLASH_LINE_BREAK != 0
-
-	if p.flags&EXTENSION_JOIN_LINES != 0 {
-		return 1
+func maybeLineBreak(p *Markdown, data []byte, offset int) (int, *Node) {
+	origOffset := offset
+	for offset < len(data) && data[offset] == ' ' {
+		offset++
 	}
 
-	// should there be a hard line break here?
-	if p.flags&EXTENSION_HARD_LINE_BREAK == 0 && !precededByTwoSpaces && !precededByBackslash {
-		return 0
+	if offset < len(data) && data[offset] == '\n' {
+		if offset-origOffset >= 2 {
+			return offset - origOffset + 1, NewNode(Hardbreak)
+		}
+		return offset - origOffset, nil
 	}
+	return 0, nil
+}
 
-	if precededByBackslash && eol > 0 {
-		out.Truncate(eol - 1)
+// newline without two spaces works when HardLineBreak is enabled
+func lineBreak(p *Markdown, data []byte, offset int) (int, *Node) {
+	if p.extensions&HardLineBreak != 0 {
+		return 1, NewNode(Hardbreak)
 	}
-	p.r.LineBreak(out)
-	return 1
+	return 0, nil
 }
 
 type linkType int
@@ -202,27 +200,43 @@ func isReferenceStyleLink(data []byte, pos int, t linkType) bool {
 	return pos < len(data)-1 && data[pos] == '[' && data[pos+1] != '^'
 }
 
+func maybeImage(p *Markdown, data []byte, offset int) (int, *Node) {
+	if offset < len(data)-1 && data[offset+1] == '[' {
+		return link(p, data, offset)
+	}
+	return 0, nil
+}
+
+func maybeInlineFootnote(p *Markdown, data []byte, offset int) (int, *Node) {
+	if offset < len(data)-1 && data[offset+1] == '[' {
+		return link(p, data, offset)
+	}
+	return 0, nil
+}
+
 // '[': parse a link or an image or a footnote
-func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
+func link(p *Markdown, data []byte, offset int) (int, *Node) {
 	// no links allowed inside regular links, footnote, and deferred footnotes
 	if p.insideLink && (offset > 0 && data[offset-1] == '[' || len(data)-1 > offset && data[offset+1] == '^') {
-		return 0
+		return 0, nil
 	}
 
 	var t linkType
 	switch {
 	// special case: ![^text] == deferred footnote (that follows something with
 	// an exclamation point)
-	case p.flags&EXTENSION_FOOTNOTES != 0 && len(data)-1 > offset && data[offset+1] == '^':
+	case p.extensions&Footnotes != 0 && len(data)-1 > offset && data[offset+1] == '^':
 		t = linkDeferredFootnote
 	// ![alt] == image
-	case offset > 0 && data[offset-1] == '!':
+	case offset >= 0 && data[offset] == '!':
 		t = linkImg
+		offset++
 	// ^[text] == inline footnote
 	// [^refId] == deferred footnote
-	case p.flags&EXTENSION_FOOTNOTES != 0:
-		if offset > 0 && data[offset-1] == '^' {
+	case p.extensions&Footnotes != 0:
+		if offset >= 0 && data[offset] == '^' {
 			t = linkInlineFootnote
+			offset++
 		} else if len(data)-1 > offset && data[offset+1] == '^' {
 			t = linkDeferredFootnote
 		}
@@ -235,7 +249,7 @@ func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 
 	var (
 		i                       = 1
-		noteId                  int
+		noteID                  int
 		title, link, altContent []byte
 		textHasNl               = false
 	)
@@ -244,8 +258,6 @@ func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 		i++
 	}
 
-	brace := 0
-
 	// look for the matching closing bracket
 	for level := 1; level > 0 && i < len(data); i++ {
 		switch {
@@ -267,11 +279,12 @@ func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 	}
 
 	if i >= len(data) {
-		return 0
+		return 0, nil
 	}
 
 	txtE := i
 	i++
+	var footnoteNode *Node
 
 	// skip any amount of whitespace or newline
 	// (this is much more lax than original markdown syntax)
@@ -279,8 +292,8 @@ func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 		i++
 	}
 
-	switch {
 	// inline style link
+	switch {
 	case i < len(data) && data[i] == '(':
 		// skip initial whitespace
 		i++
@@ -291,27 +304,14 @@ func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 
 		linkB := i
 
-		// look for link end: ' " ), check for new opening braces and take this
-		// into account, this may lead for overshooting and probably will require
-		// some fine-tuning.
+		// look for link end: ' " )
 	findlinkend:
 		for i < len(data) {
 			switch {
 			case data[i] == '\\':
 				i += 2
 
-			case data[i] == '(':
-				brace++
-				i++
-
-			case data[i] == ')':
-				if brace <= 0 {
-					break findlinkend
-				}
-				brace--
-				i++
-
-			case data[i] == '\'' || data[i] == '"':
+			case data[i] == ')' || data[i] == '\'' || data[i] == '"':
 				break findlinkend
 
 			default:
@@ -320,7 +320,7 @@ func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 		}
 
 		if i >= len(data) {
-			return 0
+			return 0, nil
 		}
 		linkE := i
 
@@ -345,7 +345,7 @@ func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 			}
 
 			if i >= len(data) {
-				return 0
+				return 0, nil
 			}
 
 			// skip whitespace after title
@@ -397,7 +397,7 @@ func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 			i++
 		}
 		if i >= len(data) {
-			return 0
+			return 0, nil
 		}
 		linkE := i
 
@@ -427,7 +427,7 @@ func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 		// find the reference with matching id
 		lr, ok := p.getRef(string(id))
 		if !ok {
-			return 0
+			return 0, nil
 		}
 
 		// keep link and title from reference
@@ -464,9 +464,10 @@ func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 			}
 		}
 
+		footnoteNode = NewNode(Item)
 		if t == linkInlineFootnote {
 			// create a new reference
-			noteId = len(p.notes) + 1
+			noteID = len(p.notes) + 1
 
 			var fragment []byte
 			if len(id) > 0 {
@@ -477,18 +478,18 @@ func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 				}
 				copy(fragment, slugify(id))
 			} else {
-				fragment = append([]byte("footnote-"), []byte(strconv.Itoa(noteId))...)
+				fragment = append([]byte("footnote-"), []byte(strconv.Itoa(noteID))...)
 			}
 
 			ref := &reference{
-				noteId:   noteId,
+				noteID:   noteID,
 				hasBlock: false,
 				link:     fragment,
 				title:    id,
+				footnote: footnoteNode,
 			}
 
 			p.notes = append(p.notes, ref)
-			p.notesRecord[string(ref.link)] = struct{}{}
 
 			link = ref.link
 			title = ref.title
@@ -496,40 +497,26 @@ func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 			// find the reference with matching id
 			lr, ok := p.getRef(string(id))
 			if !ok {
-				return 0
+				return 0, nil
 			}
 
-			if t == linkDeferredFootnote && !p.isFootnote(lr) {
-				lr.noteId = len(p.notes) + 1
+			if t == linkDeferredFootnote {
+				lr.noteID = len(p.notes) + 1
+				lr.footnote = footnoteNode
 				p.notes = append(p.notes, lr)
-				p.notesRecord[string(lr.link)] = struct{}{}
 			}
 
 			// keep link and title from reference
 			link = lr.link
 			// if inline footnote, title == footnote contents
 			title = lr.title
-			noteId = lr.noteId
+			noteID = lr.noteID
 		}
 
 		// rewind the whitespace
 		i = txtE + 1
 	}
 
-	// build content: img alt is escaped, link content is parsed
-	var content bytes.Buffer
-	if txtE > 1 {
-		if t == linkImg {
-			content.Write(data[1:txtE])
-		} else {
-			// links cannot contain other links, so turn off link parsing temporarily
-			insideLink := p.insideLink
-			p.insideLink = true
-			p.inline(&content, data[1:txtE])
-			p.insideLink = insideLink
-		}
-	}
-
 	var uLink []byte
 	if t == linkNormal || t == linkImg {
 		if len(link) > 0 {
@@ -539,49 +526,54 @@ func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 		}
 
 		// links need something to click on and somewhere to go
-		if len(uLink) == 0 || (t == linkNormal && content.Len() == 0) {
-			return 0
+		if len(uLink) == 0 || (t == linkNormal && txtE <= 1) {
+			return 0, nil
 		}
 	}
 
 	// call the relevant rendering function
+	var linkNode *Node
 	switch t {
 	case linkNormal:
+		linkNode = NewNode(Link)
+		linkNode.Destination = normalizeURI(uLink)
+		linkNode.Title = title
 		if len(altContent) > 0 {
-			p.r.Link(out, uLink, title, altContent)
+			linkNode.AppendChild(text(altContent))
 		} else {
-			p.r.Link(out, uLink, title, content.Bytes())
+			// links cannot contain other links, so turn off link parsing
+			// temporarily and recurse
+			insideLink := p.insideLink
+			p.insideLink = true
+			p.inline(linkNode, data[1:txtE])
+			p.insideLink = insideLink
 		}
 
 	case linkImg:
-		outSize := out.Len()
-		outBytes := out.Bytes()
-		if outSize > 0 && outBytes[outSize-1] == '!' {
-			out.Truncate(outSize - 1)
-		}
-
-		p.r.Image(out, uLink, title, content.Bytes())
+		linkNode = NewNode(Image)
+		linkNode.Destination = uLink
+		linkNode.Title = title
+		linkNode.AppendChild(text(data[1:txtE]))
+		i++
 
-	case linkInlineFootnote:
-		outSize := out.Len()
-		outBytes := out.Bytes()
-		if outSize > 0 && outBytes[outSize-1] == '^' {
-			out.Truncate(outSize - 1)
+	case linkInlineFootnote, linkDeferredFootnote:
+		linkNode = NewNode(Link)
+		linkNode.Destination = link
+		linkNode.Title = title
+		linkNode.NoteID = noteID
+		linkNode.Footnote = footnoteNode
+		if t == linkInlineFootnote {
+			i++
 		}
 
-		p.r.FootnoteRef(out, link, noteId)
-
-	case linkDeferredFootnote:
-		p.r.FootnoteRef(out, link, noteId)
-
 	default:
-		return 0
+		return 0, nil
 	}
 
-	return i
+	return i, linkNode
 }
 
-func (p *parser) inlineHTMLComment(out *bytes.Buffer, data []byte) int {
+func (p *Markdown) inlineHTMLComment(data []byte) int {
 	if len(data) < 5 {
 		return 0
 	}
@@ -600,44 +592,75 @@ func (p *parser) inlineHTMLComment(out *bytes.Buffer, data []byte) int {
 	return i + 1
 }
 
+func stripMailto(link []byte) []byte {
+	if bytes.HasPrefix(link, []byte("mailto://")) {
+		return link[9:]
+	} else if bytes.HasPrefix(link, []byte("mailto:")) {
+		return link[7:]
+	} else {
+		return link
+	}
+}
+
+// autolinkType specifies a kind of autolink that gets detected.
+type autolinkType int
+
+// These are the possible flag values for the autolink renderer.
+const (
+	notAutolink autolinkType = iota
+	normalAutolink
+	emailAutolink
+)
+
 // '<' when tags or autolinks are allowed
-func leftAngle(p *parser, out *bytes.Buffer, data []byte, offset int) int {
+func leftAngle(p *Markdown, data []byte, offset int) (int, *Node) {
 	data = data[offset:]
-	altype := LINK_TYPE_NOT_AUTOLINK
-	end := tagLength(data, &altype)
-	if size := p.inlineHTMLComment(out, data); size > 0 {
+	altype, end := tagLength(data)
+	if size := p.inlineHTMLComment(data); size > 0 {
 		end = size
 	}
 	if end > 2 {
-		if altype != LINK_TYPE_NOT_AUTOLINK {
+		if altype != notAutolink {
 			var uLink bytes.Buffer
 			unescapeText(&uLink, data[1:end+1-2])
 			if uLink.Len() > 0 {
-				p.r.AutoLink(out, uLink.Bytes(), altype)
+				link := uLink.Bytes()
+				node := NewNode(Link)
+				node.Destination = link
+				if altype == emailAutolink {
+					node.Destination = append([]byte("mailto:"), link...)
+				}
+				node.AppendChild(text(stripMailto(link)))
+				return end, node
 			}
 		} else {
-			p.r.RawHtmlTag(out, data[:end])
+			htmlTag := NewNode(HTMLSpan)
+			htmlTag.Literal = data[:end]
+			return end, htmlTag
 		}
 	}
 
-	return end
+	return end, nil
 }
 
 // '\\' backslash escape
 var escapeChars = []byte("\\`*_{}[]()#+-.!:|&<>~")
 
-func escape(p *parser, out *bytes.Buffer, data []byte, offset int) int {
+func escape(p *Markdown, data []byte, offset int) (int, *Node) {
 	data = data[offset:]
 
 	if len(data) > 1 {
+		if p.extensions&BackslashLineBreak != 0 && data[1] == '\n' {
+			return 2, NewNode(Hardbreak)
+		}
 		if bytes.IndexByte(escapeChars, data[1]) < 0 {
-			return 0
+			return 0, nil
 		}
 
-		p.r.NormalText(out, data[1:2])
+		return 2, text(data[1:2])
 	}
 
-	return 2
+	return 2, nil
 }
 
 func unescapeText(ob *bytes.Buffer, src []byte) {
@@ -663,7 +686,7 @@ func unescapeText(ob *bytes.Buffer, src []byte) {
 
 // '&' escaped when it doesn't belong to an entity
 // valid entities are assumed to be anything matching &#?[A-Za-z0-9]+;
-func entity(p *parser, out *bytes.Buffer, data []byte, offset int) int {
+func entity(p *Markdown, data []byte, offset int) (int, *Node) {
 	data = data[offset:]
 
 	end := 1
@@ -679,25 +702,70 @@ func entity(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 	if end < len(data) && data[end] == ';' {
 		end++ // real entity
 	} else {
-		return 0 // lone '&'
+		return 0, nil // lone '&'
 	}
 
-	p.r.Entity(out, data[:end])
+	ent := data[:end]
+	// undo &amp; escaping or it will be converted to &amp;amp; by another
+	// escaper in the renderer
+	if bytes.Equal(ent, []byte("&amp;")) {
+		ent = []byte{'&'}
+	}
 
-	return end
+	return end, text(ent)
 }
 
 func linkEndsWithEntity(data []byte, linkEnd int) bool {
-	entityRanges := htmlEntity.FindAllIndex(data[:linkEnd], -1)
+	entityRanges := htmlEntityRe.FindAllIndex(data[:linkEnd], -1)
 	return entityRanges != nil && entityRanges[len(entityRanges)-1][1] == linkEnd
 }
 
-func autoLink(p *parser, out *bytes.Buffer, data []byte, offset int) int {
-	// quick check to rule out most false hits on ':'
-	if p.insideLink || len(data) < offset+3 || data[offset+1] != '/' || data[offset+2] != '/' {
-		return 0
+// hasPrefixCaseInsensitive is a custom implementation of
+//     strings.HasPrefix(strings.ToLower(s), prefix)
+// we rolled our own because ToLower pulls in a huge machinery of lowercasing
+// anything from Unicode and that's very slow. Since this func will only be
+// used on ASCII protocol prefixes, we can take shortcuts.
+func hasPrefixCaseInsensitive(s, prefix []byte) bool {
+	if len(s) < len(prefix) {
+		return false
+	}
+	delta := byte('a' - 'A')
+	for i, b := range prefix {
+		if b != s[i] && b != s[i]+delta {
+			return false
+		}
 	}
+	return true
+}
 
+var protocolPrefixes = [][]byte{
+	[]byte("http://"),
+	[]byte("https://"),
+	[]byte("ftp://"),
+	[]byte("file://"),
+	[]byte("mailto:"),
+}
+
+const shortestPrefix = 6 // len("ftp://"), the shortest of the above
+
+func maybeAutoLink(p *Markdown, data []byte, offset int) (int, *Node) {
+	// quick check to rule out most false hits
+	if p.insideLink || len(data) < offset+shortestPrefix {
+		return 0, nil
+	}
+	for _, prefix := range protocolPrefixes {
+		endOfHead := offset + 8 // 8 is the len() of the longest prefix
+		if endOfHead > len(data) {
+			endOfHead = len(data)
+		}
+		if hasPrefixCaseInsensitive(data[offset:endOfHead], prefix) {
+			return autoLink(p, data, offset)
+		}
+	}
+	return 0, nil
+}
+
+func autoLink(p *Markdown, data []byte, offset int) (int, *Node) {
 	// Now a more expensive check to see if we're not inside an anchor element
 	anchorStart := offset
 	offsetFromAnchor := 0
@@ -708,8 +776,9 @@ func autoLink(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 
 	anchorStr := anchorRe.Find(data[anchorStart:])
 	if anchorStr != nil {
-		out.Write(anchorStr[offsetFromAnchor:])
-		return len(anchorStr) - offsetFromAnchor
+		anchorClose := NewNode(HTMLSpan)
+		anchorClose.Literal = anchorStr[offsetFromAnchor:]
+		return len(anchorStr) - offsetFromAnchor, anchorClose
 	}
 
 	// scan backward for a word boundary
@@ -718,14 +787,14 @@ func autoLink(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 		rewind++
 	}
 	if rewind > 6 { // longest supported protocol is "mailto" which has 6 letters
-		return 0
+		return 0, nil
 	}
 
 	origData := data
 	data = data[offset-rewind:]
 
 	if !isSafeLink(data) {
-		return 0
+		return 0, nil
 	}
 
 	linkEnd := 0
@@ -802,19 +871,17 @@ func autoLink(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 		}
 	}
 
-	// we were triggered on the ':', so we need to rewind the output a bit
-	if out.Len() >= rewind {
-		out.Truncate(len(out.Bytes()) - rewind)
-	}
-
 	var uLink bytes.Buffer
 	unescapeText(&uLink, data[:linkEnd])
 
 	if uLink.Len() > 0 {
-		p.r.AutoLink(out, uLink.Bytes(), LINK_TYPE_NORMAL)
+		node := NewNode(Link)
+		node.Destination = uLink.Bytes()
+		node.AppendChild(text(uLink.Bytes()))
+		return linkEnd, node
 	}
 
-	return linkEnd - rewind
+	return linkEnd, nil
 }
 
 func isEndOfLink(char byte) bool {
@@ -847,17 +914,17 @@ func isSafeLink(link []byte) bool {
 }
 
 // return the length of the given tag, or 0 is it's not valid
-func tagLength(data []byte, autolink *int) int {
+func tagLength(data []byte) (autolink autolinkType, end int) {
 	var i, j int
 
 	// a valid tag can't be shorter than 3 chars
 	if len(data) < 3 {
-		return 0
+		return notAutolink, 0
 	}
 
 	// begins with a '<' optionally followed by '/', followed by letter or number
 	if data[0] != '<' {
-		return 0
+		return notAutolink, 0
 	}
 	if data[1] == '/' {
 		i = 2
@@ -866,11 +933,11 @@ func tagLength(data []byte, autolink *int) int {
 	}
 
 	if !isalnum(data[i]) {
-		return 0
+		return notAutolink, 0
 	}
 
 	// scheme test
-	*autolink = LINK_TYPE_NOT_AUTOLINK
+	autolink = notAutolink
 
 	// try to find the beginning of an URI
 	for i < len(data) && (isalnum(data[i]) || data[i] == '.' || data[i] == '+' || data[i] == '-') {
@@ -879,21 +946,20 @@ func tagLength(data []byte, autolink *int) int {
 
 	if i > 1 && i < len(data) && data[i] == '@' {
 		if j = isMailtoAutoLink(data[i:]); j != 0 {
-			*autolink = LINK_TYPE_EMAIL
-			return i + j
+			return emailAutolink, i + j
 		}
 	}
 
 	if i > 2 && i < len(data) && data[i] == ':' {
-		*autolink = LINK_TYPE_NORMAL
+		autolink = normalAutolink
 		i++
 	}
 
 	// complete autolink test: no whitespace or ' or "
 	switch {
 	case i >= len(data):
-		*autolink = LINK_TYPE_NOT_AUTOLINK
-	case *autolink != 0:
+		autolink = notAutolink
+	case autolink != notAutolink:
 		j = i
 
 		for i < len(data) {
@@ -908,24 +974,20 @@ func tagLength(data []byte, autolink *int) int {
 		}
 
 		if i >= len(data) {
-			return 0
+			return autolink, 0
 		}
 		if i > j && data[i] == '>' {
-			return i + 1
+			return autolink, i + 1
 		}
 
 		// one of the forbidden chars has been found
-		*autolink = LINK_TYPE_NOT_AUTOLINK
+		autolink = notAutolink
 	}
-
-	// look for something looking like a tag end
-	for i < len(data) && data[i] != '>' {
-		i++
-	}
-	if i >= len(data) {
-		return 0
+	i += bytes.IndexByte(data[i:], '>')
+	if i < 0 {
+		return autolink, 0
 	}
-	return i + 1
+	return autolink, i + 1
 }
 
 // look for the address part of a mail autolink and '>'
@@ -944,14 +1006,13 @@ func isMailtoAutoLink(data []byte) int {
 			nb++
 
 		case '-', '.', '_':
-			// Do nothing.
+			break
 
 		case '>':
 			if nb == 1 {
 				return i + 1
-			} else {
-				return 0
 			}
+			return 0
 		default:
 			return 0
 		}
@@ -1014,9 +1075,8 @@ func helperFindEmphChar(data []byte, c byte) int {
 			if data[i] != '[' && data[i] != '(' { // not a link
 				if tmpI > 0 {
 					return tmpI
-				} else {
-					continue
 				}
+				continue
 			}
 			cc := data[i]
 			i++
@@ -1035,7 +1095,7 @@ func helperFindEmphChar(data []byte, c byte) int {
 	return 0
 }
 
-func helperEmphasis(p *parser, out *bytes.Buffer, data []byte, c byte) int {
+func helperEmphasis(p *Markdown, data []byte, c byte) (int, *Node) {
 	i := 0
 
 	// skip one symbol if coming from emph3
@@ -1046,11 +1106,11 @@ func helperEmphasis(p *parser, out *bytes.Buffer, data []byte, c byte) int {
 	for i < len(data) {
 		length := helperFindEmphChar(data[i:], c)
 		if length == 0 {
-			return 0
+			return 0, nil
 		}
 		i += length
 		if i >= len(data) {
-			return 0
+			return 0, nil
 		}
 
 		if i+1 < len(data) && data[i+1] == c {
@@ -1060,52 +1120,46 @@ func helperEmphasis(p *parser, out *bytes.Buffer, data []byte, c byte) int {
 
 		if data[i] == c && !isspace(data[i-1]) {
 
-			if p.flags&EXTENSION_NO_INTRA_EMPHASIS != 0 {
+			if p.extensions&NoIntraEmphasis != 0 {
 				if !(i+1 == len(data) || isspace(data[i+1]) || ispunct(data[i+1])) {
 					continue
 				}
 			}
 
-			var work bytes.Buffer
-			p.inline(&work, data[:i])
-			p.r.Emphasis(out, work.Bytes())
-			return i + 1
+			emph := NewNode(Emph)
+			p.inline(emph, data[:i])
+			return i + 1, emph
 		}
 	}
 
-	return 0
+	return 0, nil
 }
 
-func helperDoubleEmphasis(p *parser, out *bytes.Buffer, data []byte, c byte) int {
+func helperDoubleEmphasis(p *Markdown, data []byte, c byte) (int, *Node) {
 	i := 0
 
 	for i < len(data) {
 		length := helperFindEmphChar(data[i:], c)
 		if length == 0 {
-			return 0
+			return 0, nil
 		}
 		i += length
 
 		if i+1 < len(data) && data[i] == c && data[i+1] == c && i > 0 && !isspace(data[i-1]) {
-			var work bytes.Buffer
-			p.inline(&work, data[:i])
-
-			if work.Len() > 0 {
-				// pick the right renderer
-				if c == '~' {
-					p.r.StrikeThrough(out, work.Bytes())
-				} else {
-					p.r.DoubleEmphasis(out, work.Bytes())
-				}
+			nodeType := Strong
+			if c == '~' {
+				nodeType = Del
 			}
-			return i + 2
+			node := NewNode(nodeType)
+			p.inline(node, data[:i])
+			return i + 2, node
 		}
 		i++
 	}
-	return 0
+	return 0, nil
 }
 
-func helperTripleEmphasis(p *parser, out *bytes.Buffer, data []byte, offset int, c byte) int {
+func helperTripleEmphasis(p *Markdown, data []byte, offset int, c byte) (int, *Node) {
 	i := 0
 	origData := data
 	data = data[offset:]
@@ -1113,7 +1167,7 @@ func helperTripleEmphasis(p *parser, out *bytes.Buffer, data []byte, offset int,
 	for i < len(data) {
 		length := helperFindEmphChar(data[i:], c)
 		if length == 0 {
-			return 0
+			return 0, nil
 		}
 		i += length
 
@@ -1125,30 +1179,36 @@ func helperTripleEmphasis(p *parser, out *bytes.Buffer, data []byte, offset int,
 		switch {
 		case i+2 < len(data) && data[i+1] == c && data[i+2] == c:
 			// triple symbol found
-			var work bytes.Buffer
-
-			p.inline(&work, data[:i])
-			if work.Len() > 0 {
-				p.r.TripleEmphasis(out, work.Bytes())
-			}
-			return i + 3
+			strong := NewNode(Strong)
+			em := NewNode(Emph)
+			strong.AppendChild(em)
+			p.inline(em, data[:i])
+			return i + 3, strong
 		case (i+1 < len(data) && data[i+1] == c):
 			// double symbol found, hand over to emph1
-			length = helperEmphasis(p, out, origData[offset-2:], c)
+			length, node := helperEmphasis(p, origData[offset-2:], c)
 			if length == 0 {
-				return 0
-			} else {
-				return length - 2
+				return 0, nil
 			}
+			return length - 2, node
 		default:
 			// single symbol found, hand over to emph2
-			length = helperDoubleEmphasis(p, out, origData[offset-1:], c)
+			length, node := helperDoubleEmphasis(p, origData[offset-1:], c)
 			if length == 0 {
-				return 0
-			} else {
-				return length - 1
+				return 0, nil
 			}
+			return length - 1, node
 		}
 	}
-	return 0
+	return 0, nil
+}
+
+func text(s []byte) *Node {
+	node := NewNode(Text)
+	node.Literal = s
+	return node
+}
+
+func normalizeURI(s []byte) []byte {
+	return s // TODO: implement
 }