source: code/trunk/vendor/github.com/russross/blackfriday/v2/esc.go@ 67

package blackfriday

import (
        "html"
        "io"
)

var htmlEscaper = [256][]byte{
        '&': []byte("&"),
        '<': []byte("&lt;"),
        '>': []byte("&gt;"),
        '"': []byte("&quot;"),
}

func escapeHTML(w io.Writer, s []byte) {
        escapeEntities(w, s, false)
}

func escapeAllHTML(w io.Writer, s []byte) {
        escapeEntities(w, s, true)
}

func escapeEntities(w io.Writer, s []byte, escapeValidEntities bool) {
        var start, end int
        for end < len(s) {
                escSeq := htmlEscaper[s[end]]
                if escSeq != nil {
                        isEntity, entityEnd := nodeIsEntity(s, end)
                        if isEntity && !escapeValidEntities {
                                w.Write(s[start : entityEnd+1])
                                start = entityEnd + 1
                        } else {
                                w.Write(s[start:end])
                                w.Write(escSeq)
                                start = end + 1
                        }
                }
                end++
        }
        if start < len(s) && end <= len(s) {
                w.Write(s[start:end])
        }
}

func nodeIsEntity(s []byte, end int) (isEntity bool, endEntityPos int) {
        isEntity = false
        endEntityPos = end + 1

        if s[end] == '&' {
                for endEntityPos < len(s) {
                        if s[endEntityPos] == ';' {
                                if entities[string(s[end:endEntityPos+1])] {
                                        isEntity = true
                                        break
                                }
                        }
                        if !isalnum(s[endEntityPos]) && s[endEntityPos] != '&' && s[endEntityPos] != '#' {
                                break
                        }
                        endEntityPos++
                }
        }

        return isEntity, endEntityPos
}

func escLink(w io.Writer, text []byte) {
        unesc := html.UnescapeString(string(text))
        escapeHTML(w, []byte(unesc))
}