1package blackfriday
 2
 3import (
 4	"html"
 5	"io"
 6)
 7
 8var htmlEscaper = [256][]byte{
 9	'&': []byte("&"),
10	'<': []byte("&lt;"),
11	'>': []byte("&gt;"),
12	'"': []byte("&quot;"),
13}
14
15func escapeHTML(w io.Writer, s []byte) {
16	var start, end int
17	for end < len(s) {
18		escSeq := htmlEscaper[s[end]]
19		if escSeq != nil {
20			isEntity, entityEnd := nodeIsEntity(s, end)
21			if isEntity {
22				w.Write(s[start : entityEnd+1])
23				start = entityEnd + 1
24			} else {
25				w.Write(s[start:end])
26				w.Write(escSeq)
27				start = end + 1
28			}
29		}
30		end++
31	}
32	if start < len(s) && end <= len(s) {
33		w.Write(s[start:end])
34	}
35}
36
37func nodeIsEntity(s []byte, end int) (isEntity bool, endEntityPos int) {
38	isEntity = false
39	endEntityPos = end + 1
40
41	if s[end] == '&' {
42		for endEntityPos < len(s) {
43			if s[endEntityPos] == ';' {
44				isEntity = true
45				break
46			}
47			if !isalnum(s[endEntityPos]) && s[endEntityPos] != '&' && s[endEntityPos] != '#' {
48				break
49			}
50			endEntityPos++
51		}
52	}
53
54	return isEntity, endEntityPos
55}
56
57func escLink(w io.Writer, text []byte) {
58	unesc := html.UnescapeString(string(text))
59	escapeHTML(w, []byte(unesc))
60}