Update blackfriday dependency per #2994 (#3857)

Signed-off-by: PJ Eby <pje@telecommunity.com>

vendor/github.com/russross/blackfriday/block.go

@@ -15,8 +15,8 @@ package blackfriday
 
 import (
 	"bytes"
-
-	"github.com/shurcooL/sanitized_anchor_name"
+	"strings"
+	"unicode"
 )
 
 // Parse block-level data.
@@ -93,7 +93,7 @@ func (p *parser) block(out *bytes.Buffer, data []byte) {
 
 		// fenced code block:
 		//
-		// ``` go
+		// ``` go info string here
 		// func fact(n int) int {
 		//     if n <= 1 {
 		//         return n
@@ -243,7 +243,7 @@ func (p *parser) prefixHeader(out *bytes.Buffer, data []byte) int {
 	}
 	if end > i {
 		if id == "" && p.flags&EXTENSION_AUTO_HEADER_IDS != 0 {
-			id = sanitized_anchor_name.Create(string(data[i:end]))
+			id = SanitizedAnchorName(string(data[i:end]))
 		}
 		work := func() bool {
 			p.inline(out, data[i:end])
@@ -563,7 +563,7 @@ func (*parser) isHRule(data []byte) bool {
 // and returns the end index if so, or 0 otherwise. It also returns the marker found.
 // If syntax is not nil, it gets set to the syntax specified in the fence line.
 // A final newline is mandatory to recognize the fence line, unless newlineOptional is true.
-func isFenceLine(data []byte, syntax *string, oldmarker string, newlineOptional bool) (end int, marker string) {
+func isFenceLine(data []byte, info *string, oldmarker string, newlineOptional bool) (end int, marker string) {
 	i, size := 0, 0
 
 	// skip up to three spaces
@@ -599,9 +599,9 @@ func isFenceLine(data []byte, syntax *string, oldmarker string, newlineOptional
 	}
 
 	// TODO(shurcooL): It's probably a good idea to simplify the 2 code paths here
-	// into one, always get the syntax, and discard it if the caller doesn't care.
-	if syntax != nil {
-		syn := 0
+	// into one, always get the info string, and discard it if the caller doesn't care.
+	if info != nil {
+		infoLength := 0
 		i = skipChar(data, i, ' ')
 
 		if i >= len(data) {
@@ -611,14 +611,14 @@ func isFenceLine(data []byte, syntax *string, oldmarker string, newlineOptional
 			return 0, ""
 		}
 
-		syntaxStart := i
+		infoStart := i
 
 		if data[i] == '{' {
 			i++
-			syntaxStart++
+			infoStart++
 
 			for i < len(data) && data[i] != '}' && data[i] != '\n' {
-				syn++
+				infoLength++
 				i++
 			}
 
@@ -628,24 +628,24 @@ func isFenceLine(data []byte, syntax *string, oldmarker string, newlineOptional
 
 			// strip all whitespace at the beginning and the end
 			// of the {} block
-			for syn > 0 && isspace(data[syntaxStart]) {
-				syntaxStart++
-				syn--
+			for infoLength > 0 && isspace(data[infoStart]) {
+				infoStart++
+				infoLength--
 			}
 
-			for syn > 0 && isspace(data[syntaxStart+syn-1]) {
-				syn--
+			for infoLength > 0 && isspace(data[infoStart+infoLength-1]) {
+				infoLength--
 			}
 
 			i++
 		} else {
-			for i < len(data) && !isspace(data[i]) {
-				syn++
+			for i < len(data) && !isverticalspace(data[i]) {
+				infoLength++
 				i++
 			}
 		}
 
-		*syntax = string(data[syntaxStart : syntaxStart+syn])
+		*info = strings.TrimSpace(string(data[infoStart : infoStart+infoLength]))
 	}
 
 	i = skipChar(data, i, ' ')
@@ -663,8 +663,8 @@ func isFenceLine(data []byte, syntax *string, oldmarker string, newlineOptional
 // or 0 otherwise. It writes to out if doRender is true, otherwise it has no side effects.
 // If doRender is true, a final newline is mandatory to recognize the fenced code block.
 func (p *parser) fencedCodeBlock(out *bytes.Buffer, data []byte, doRender bool) int {
-	var syntax string
-	beg, marker := isFenceLine(data, &syntax, "", false)
+	var infoString string
+	beg, marker := isFenceLine(data, &infoString, "", false)
 	if beg == 0 || beg >= len(data) {
 		return 0
 	}
@@ -698,7 +698,7 @@ func (p *parser) fencedCodeBlock(out *bytes.Buffer, data []byte, doRender bool)
 	}
 
 	if doRender {
-		p.r.BlockCode(out, work.Bytes(), syntax)
+		p.r.BlockCode(out, work.Bytes(), infoString)
 	}
 
 	return beg
@@ -1364,7 +1364,7 @@ func (p *parser) paragraph(out *bytes.Buffer, data []byte) int {
 
 				id := ""
 				if p.flags&EXTENSION_AUTO_HEADER_IDS != 0 {
-					id = sanitized_anchor_name.Create(string(data[prev:eol]))
+					id = SanitizedAnchorName(string(data[prev:eol]))
 				}
 
 				p.r.Header(out, work, level, id)
@@ -1428,3 +1428,24 @@ func (p *parser) paragraph(out *bytes.Buffer, data []byte) int {
 	p.renderParagraph(out, data[:i])
 	return i
 }
+
+// SanitizedAnchorName returns a sanitized anchor name for the given text.
+//
+// It implements the algorithm specified in the package comment.
+func SanitizedAnchorName(text string) string {
+	var anchorName []rune
+	futureDash := false
+	for _, r := range text {
+		switch {
+		case unicode.IsLetter(r) || unicode.IsNumber(r):
+			if futureDash && len(anchorName) > 0 {
+				anchorName = append(anchorName, '-')
+			}
+			futureDash = false
+			anchorName = append(anchorName, unicode.ToLower(r))
+		default:
+			futureDash = true
+		}
+	}
+	return string(anchorName)
+}