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// Package stripmd strips Markdown from text
package stripmd
import (
"regexp"
)
var (
listLeadersReg = regexp.MustCompile(`(?m)^([\s\t]*)([\*\-\+]|\d\.)\s+`)
headerReg = regexp.MustCompile(`\n={2,}`)
strikeReg = regexp.MustCompile(`~~`)
codeReg = regexp.MustCompile("`{3}" + `.*\n`)
htmlReg = regexp.MustCompile("<(.*?)>")
emphReg = regexp.MustCompile(`\*\*([^*]+)\*\*`)
emphReg2 = regexp.MustCompile(`\*([^*]+)\*`)
emphReg3 = regexp.MustCompile(`__([^_]+)__`)
emphReg4 = regexp.MustCompile(`_([^_]+)_`)
setextHeaderReg = regexp.MustCompile(`^[=\-]{2,}\s*$`)
footnotesReg = regexp.MustCompile(`\[\^.+?\](\: .*?$)?`)
footnotes2Reg = regexp.MustCompile(`\s{0,2}\[.*?\]: .*?$`)
imagesReg = regexp.MustCompile(`\!\[(.*?)\]\s?[\[\(].*?[\]\)]`)
linksReg = regexp.MustCompile(`\[(.*?)\][\[\(].*?[\]\)]`)
blockquoteReg = regexp.MustCompile(`>\s*`)
refLinkReg = regexp.MustCompile(`^\s{1,2}\[(.*?)\]: (\S+)( ".*?")?\s*$`)
atxHeaderReg = regexp.MustCompile(`(?m)^\#{1,6}\s*([^#]+)\s*(\#{1,6})?$`)
atxHeaderReg2 = regexp.MustCompile(`([\*_]{1,3})(\S.*?\S)?P1`)
atxHeaderReg3 = regexp.MustCompile("(?m)(`{3,})" + `(.*?)?P1`)
atxHeaderReg4 = regexp.MustCompile(`^-{3,}\s*$`)
atxHeaderReg5 = regexp.MustCompile("`(.+?)`")
atxHeaderReg6 = regexp.MustCompile(`\n{2,}`)
)
// Strip returns the given string sans any Markdown.
// Where necessary, elements are replaced with their best textual forms, so
// for example, hyperlinks are stripped of their URL and become only the link
// text, and images lose their URL and become only the alt text.
func Strip(s string) string {
res := s
res = listLeadersReg.ReplaceAllString(res, "$1")
res = headerReg.ReplaceAllString(res, "\n")
res = strikeReg.ReplaceAllString(res, "")
res = codeReg.ReplaceAllString(res, "")
res = emphReg.ReplaceAllString(res, "$1")
res = emphReg2.ReplaceAllString(res, "$1")
res = emphReg3.ReplaceAllString(res, "$1")
res = emphReg4.ReplaceAllString(res, "$1")
res = htmlReg.ReplaceAllString(res, "$1")
res = setextHeaderReg.ReplaceAllString(res, "")
res = footnotesReg.ReplaceAllString(res, "")
res = footnotes2Reg.ReplaceAllString(res, "")
res = imagesReg.ReplaceAllString(res, "$1")
res = linksReg.ReplaceAllString(res, "$1")
res = blockquoteReg.ReplaceAllString(res, " ")
res = refLinkReg.ReplaceAllString(res, "")
res = atxHeaderReg.ReplaceAllString(res, "$1")
res = atxHeaderReg2.ReplaceAllString(res, "$2")
res = atxHeaderReg3.ReplaceAllString(res, "$2")
res = atxHeaderReg4.ReplaceAllString(res, "")
res = atxHeaderReg5.ReplaceAllString(res, "$1")
res = atxHeaderReg6.ReplaceAllString(res, "\n\n")
return res
}
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