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66
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1 package blackfriday
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2
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3 import (
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4 "html"
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5 "io"
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6 )
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7
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8 var htmlEscaper = [256][]byte{
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9 '&': []byte("&"),
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10 '<': []byte("<"),
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11 '>': []byte(">"),
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12 '"': []byte("""),
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13 }
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14
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15 func escapeHTML(w io.Writer, s []byte) {
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16 escapeEntities(w, s, false)
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17 }
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18
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19 func escapeAllHTML(w io.Writer, s []byte) {
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20 escapeEntities(w, s, true)
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21 }
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22
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23 func escapeEntities(w io.Writer, s []byte, escapeValidEntities bool) {
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24 var start, end int
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25 for end < len(s) {
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26 escSeq := htmlEscaper[s[end]]
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27 if escSeq != nil {
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28 isEntity, entityEnd := nodeIsEntity(s, end)
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29 if isEntity && !escapeValidEntities {
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30 w.Write(s[start : entityEnd+1])
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31 start = entityEnd + 1
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32 } else {
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33 w.Write(s[start:end])
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34 w.Write(escSeq)
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35 start = end + 1
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36 }
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37 }
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38 end++
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39 }
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40 if start < len(s) && end <= len(s) {
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41 w.Write(s[start:end])
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42 }
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43 }
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44
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45 func nodeIsEntity(s []byte, end int) (isEntity bool, endEntityPos int) {
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46 isEntity = false
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47 endEntityPos = end + 1
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48
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49 if s[end] == '&' {
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50 for endEntityPos < len(s) {
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51 if s[endEntityPos] == ';' {
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52 if entities[string(s[end:endEntityPos+1])] {
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53 isEntity = true
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54 break
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55 }
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56 }
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57 if !isalnum(s[endEntityPos]) && s[endEntityPos] != '&' && s[endEntityPos] != '#' {
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58 break
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59 }
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60 endEntityPos++
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61 }
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62 }
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63
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64 return isEntity, endEntityPos
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65 }
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66
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67 func escLink(w io.Writer, text []byte) {
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68 unesc := html.UnescapeString(string(text))
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69 escapeHTML(w, []byte(unesc))
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70 }
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