Rewrite markdown rendering to blackfriday v2 and rewrite orgmode rendering to go-org (#8560)

* Rewrite markdown rendering to blackfriday v2.0

* Fix style

* Fix go mod with golang 1.13

* Fix blackfriday v2 import

* Inital orgmode renderer migration to go-org

* Vendor go-org dependency

* Ignore errors :/

* Update go-org to latest version

* Update test

* Fix go-org test

* Remove unneeded code

* Fix comments

* Fix markdown test

* Fix blackfriday regression rendering HTML block

vendor/github.com/niklasfasching/go-org/org/block.go

@@ -0,0 +1,84 @@
+package org
+
+import (
+	"regexp"
+	"strings"
+	"unicode"
+)
+
+type Block struct {
+	Name       string
+	Parameters []string
+	Children   []Node
+}
+
+type Example struct {
+	Children []Node
+}
+
+var exampleLineRegexp = regexp.MustCompile(`^(\s*):(\s(.*)|\s*$)`)
+var beginBlockRegexp = regexp.MustCompile(`(?i)^(\s*)#\+BEGIN_(\w+)(.*)`)
+var endBlockRegexp = regexp.MustCompile(`(?i)^(\s*)#\+END_(\w+)`)
+
+func lexBlock(line string) (token, bool) {
+	if m := beginBlockRegexp.FindStringSubmatch(line); m != nil {
+		return token{"beginBlock", len(m[1]), strings.ToUpper(m[2]), m}, true
+	} else if m := endBlockRegexp.FindStringSubmatch(line); m != nil {
+		return token{"endBlock", len(m[1]), strings.ToUpper(m[2]), m}, true
+	}
+	return nilToken, false
+}
+
+func lexExample(line string) (token, bool) {
+	if m := exampleLineRegexp.FindStringSubmatch(line); m != nil {
+		return token{"example", len(m[1]), m[3], m}, true
+	}
+	return nilToken, false
+}
+
+func isRawTextBlock(name string) bool { return name == "SRC" || name == "EXAMPLE" || name == "EXPORT" }
+
+func (d *Document) parseBlock(i int, parentStop stopFn) (int, Node) {
+	t, start := d.tokens[i], i
+	name, parameters := t.content, strings.Fields(t.matches[3])
+	trim := trimIndentUpTo(d.tokens[i].lvl)
+	stop := func(d *Document, i int) bool {
+		return i >= len(d.tokens) || (d.tokens[i].kind == "endBlock" && d.tokens[i].content == name)
+	}
+	block, i := Block{name, parameters, nil}, i+1
+	if isRawTextBlock(name) {
+		rawText := ""
+		for ; !stop(d, i); i++ {
+			rawText += trim(d.tokens[i].matches[0]) + "\n"
+		}
+		block.Children = d.parseRawInline(rawText)
+	} else {
+		consumed, nodes := d.parseMany(i, stop)
+		block.Children = nodes
+		i += consumed
+	}
+	if i < len(d.tokens) && d.tokens[i].kind == "endBlock" && d.tokens[i].content == name {
+		return i + 1 - start, block
+	}
+	return 0, nil
+}
+
+func (d *Document) parseExample(i int, parentStop stopFn) (int, Node) {
+	example, start := Example{}, i
+	for ; !parentStop(d, i) && d.tokens[i].kind == "example"; i++ {
+		example.Children = append(example.Children, Text{d.tokens[i].content, true})
+	}
+	return i - start, example
+}
+
+func trimIndentUpTo(max int) func(string) string {
+	return func(line string) string {
+		i := 0
+		for ; i < len(line) && i < max && unicode.IsSpace(rune(line[i])); i++ {
+		}
+		return line[i:]
+	}
+}
+
+func (n Example) String() string { return orgWriter.nodesAsString(n) }
+func (n Block) String() string   { return orgWriter.nodesAsString(n) }