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	escapeEntities(w, s, false)
17}
18
19func escapeAllHTML(w io.Writer, s []byte) {
20	escapeEntities(w, s, true)
21}
22
23func escapeEntities(w io.Writer, s []byte, escapeValidEntities bool) {
24	var start, end int
25	for end < len(s) {
26		escSeq := htmlEscaper[s[end]]
27		if escSeq != nil {
28			isEntity, entityEnd := nodeIsEntity(s, end)
29			if isEntity && !escapeValidEntities {
30				w.Write(s[start : entityEnd+1])
31				start = entityEnd + 1
32			} else {
33				w.Write(s[start:end])
34				w.Write(escSeq)
35				start = end + 1
36			}
37		}
38		end++
39	}
40	if start < len(s) && end <= len(s) {
41		w.Write(s[start:end])
42	}
43}
44
45func nodeIsEntity(s []byte, end int) (isEntity bool, endEntityPos int) {
46	isEntity = false
47	endEntityPos = end + 1
48
49	if s[end] == '&' {
50		for endEntityPos < len(s) {
51			if s[endEntityPos] == ';' {
52				if entities[string(s[end:endEntityPos+1])] {
53					isEntity = true
54					break
55				}
56			}
57			if !isalnum(s[endEntityPos]) && s[endEntityPos] != '&' && s[endEntityPos] != '#' {
58				break
59			}
60			endEntityPos++
61		}
62	}
63
64	return isEntity, endEntityPos
65}
66
67func escLink(w io.Writer, text []byte) {
68	unesc := html.UnescapeString(string(text))
69	escapeHTML(w, []byte(unesc))
70}