mirror of
https://github.com/go-gitea/gitea.git
synced 2024-12-12 07:09:36 +08:00
301 lines
6.2 KiB
Go
301 lines
6.2 KiB
Go
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package html2text
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import (
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"bytes"
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"io"
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"regexp"
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"strings"
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"unicode"
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"golang.org/x/net/html"
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"golang.org/x/net/html/atom"
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)
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var (
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spacingRe = regexp.MustCompile(`[ \r\n\t]+`)
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newlineRe = regexp.MustCompile(`\n\n+`)
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)
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type textifyTraverseCtx struct {
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Buf bytes.Buffer
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prefix string
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blockquoteLevel int
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lineLength int
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endsWithSpace bool
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endsWithNewline bool
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justClosedDiv bool
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}
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func (ctx *textifyTraverseCtx) traverse(node *html.Node) error {
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switch node.Type {
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default:
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return ctx.traverseChildren(node)
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case html.TextNode:
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data := strings.Trim(spacingRe.ReplaceAllString(node.Data, " "), " ")
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return ctx.emit(data)
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case html.ElementNode:
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ctx.justClosedDiv = false
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switch node.DataAtom {
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case atom.Br:
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return ctx.emit("\n")
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case atom.H1, atom.H2, atom.H3:
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subCtx := textifyTraverseCtx{}
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if err := subCtx.traverseChildren(node); err != nil {
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return err
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}
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str := subCtx.Buf.String()
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dividerLen := 0
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for _, line := range strings.Split(str, "\n") {
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if lineLen := len([]rune(line)); lineLen-1 > dividerLen {
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dividerLen = lineLen - 1
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}
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}
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divider := ""
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if node.DataAtom == atom.H1 {
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divider = strings.Repeat("*", dividerLen)
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} else {
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divider = strings.Repeat("-", dividerLen)
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}
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if node.DataAtom == atom.H3 {
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return ctx.emit("\n\n" + str + "\n" + divider + "\n\n")
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}
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return ctx.emit("\n\n" + divider + "\n" + str + "\n" + divider + "\n\n")
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case atom.Blockquote:
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ctx.blockquoteLevel++
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ctx.prefix = strings.Repeat(">", ctx.blockquoteLevel) + " "
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if err := ctx.emit("\n"); err != nil {
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return err
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}
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if ctx.blockquoteLevel == 1 {
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if err := ctx.emit("\n"); err != nil {
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return err
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}
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}
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if err := ctx.traverseChildren(node); err != nil {
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return err
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}
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ctx.blockquoteLevel--
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ctx.prefix = strings.Repeat(">", ctx.blockquoteLevel)
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if ctx.blockquoteLevel > 0 {
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ctx.prefix += " "
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}
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return ctx.emit("\n\n")
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case atom.Div:
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if ctx.lineLength > 0 {
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if err := ctx.emit("\n"); err != nil {
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return err
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}
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}
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if err := ctx.traverseChildren(node); err != nil {
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return err
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}
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var err error
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if ctx.justClosedDiv == false {
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err = ctx.emit("\n")
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}
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ctx.justClosedDiv = true
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return err
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case atom.Li:
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if err := ctx.emit("* "); err != nil {
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return err
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}
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if err := ctx.traverseChildren(node); err != nil {
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return err
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}
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return ctx.emit("\n")
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case atom.B, atom.Strong:
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subCtx := textifyTraverseCtx{}
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subCtx.endsWithSpace = true
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if err := subCtx.traverseChildren(node); err != nil {
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return err
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}
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str := subCtx.Buf.String()
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return ctx.emit("*" + str + "*")
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case atom.A:
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// If image is the only child, take its alt text as the link text
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if img := node.FirstChild; img != nil && node.LastChild == img && img.DataAtom == atom.Img {
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if altText := getAttrVal(img, "alt"); altText != "" {
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ctx.emit(altText)
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}
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} else if err := ctx.traverseChildren(node); err != nil {
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return err
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}
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hrefLink := ""
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if attrVal := getAttrVal(node, "href"); attrVal != "" {
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attrVal = ctx.normalizeHrefLink(attrVal)
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if attrVal != "" {
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hrefLink = "( " + attrVal + " )"
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}
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}
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return ctx.emit(hrefLink)
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case atom.P, atom.Ul, atom.Table:
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if err := ctx.emit("\n\n"); err != nil {
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return err
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}
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if err := ctx.traverseChildren(node); err != nil {
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return err
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}
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return ctx.emit("\n\n")
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case atom.Tr:
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if err := ctx.traverseChildren(node); err != nil {
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return err
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}
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return ctx.emit("\n")
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case atom.Style, atom.Script, atom.Head:
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// Ignore the subtree
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return nil
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default:
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return ctx.traverseChildren(node)
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}
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}
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}
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func (ctx *textifyTraverseCtx) traverseChildren(node *html.Node) error {
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for c := node.FirstChild; c != nil; c = c.NextSibling {
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if err := ctx.traverse(c); err != nil {
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return err
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}
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}
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return nil
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}
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func (ctx *textifyTraverseCtx) emit(data string) error {
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if len(data) == 0 {
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return nil
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}
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lines := ctx.breakLongLines(data)
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var err error
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for _, line := range lines {
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runes := []rune(line)
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startsWithSpace := unicode.IsSpace(runes[0])
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if !startsWithSpace && !ctx.endsWithSpace {
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ctx.Buf.WriteByte(' ')
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ctx.lineLength++
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}
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ctx.endsWithSpace = unicode.IsSpace(runes[len(runes)-1])
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for _, c := range line {
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_, err = ctx.Buf.WriteString(string(c))
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if err != nil {
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return err
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}
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ctx.lineLength++
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if c == '\n' {
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ctx.lineLength = 0
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if ctx.prefix != "" {
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_, err = ctx.Buf.WriteString(ctx.prefix)
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if err != nil {
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return err
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}
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}
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}
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}
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}
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return nil
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}
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func (ctx *textifyTraverseCtx) breakLongLines(data string) []string {
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// only break lines when we are in blockquotes
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if ctx.blockquoteLevel == 0 {
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return []string{data}
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}
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var ret []string
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runes := []rune(data)
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l := len(runes)
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existing := ctx.lineLength
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if existing >= 74 {
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ret = append(ret, "\n")
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existing = 0
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}
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for l+existing > 74 {
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i := 74 - existing
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for i >= 0 && !unicode.IsSpace(runes[i]) {
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i--
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}
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if i == -1 {
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// no spaces, so go the other way
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i = 74 - existing
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for i < l && !unicode.IsSpace(runes[i]) {
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i++
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}
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}
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ret = append(ret, string(runes[:i])+"\n")
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for i < l && unicode.IsSpace(runes[i]) {
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i++
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}
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runes = runes[i:]
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l = len(runes)
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existing = 0
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}
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if len(runes) > 0 {
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ret = append(ret, string(runes))
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}
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return ret
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}
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func (ctx *textifyTraverseCtx) normalizeHrefLink(link string) string {
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link = strings.TrimSpace(link)
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link = strings.TrimPrefix(link, "mailto:")
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return link
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}
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func getAttrVal(node *html.Node, attrName string) string {
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for _, attr := range node.Attr {
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if attr.Key == attrName {
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return attr.Val
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}
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}
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return ""
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}
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func FromReader(reader io.Reader) (string, error) {
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doc, err := html.Parse(reader)
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if err != nil {
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return "", err
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}
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ctx := textifyTraverseCtx{
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Buf: bytes.Buffer{},
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}
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if err = ctx.traverse(doc); err != nil {
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return "", err
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}
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text := strings.TrimSpace(newlineRe.ReplaceAllString(
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strings.Replace(ctx.Buf.String(), "\n ", "\n", -1), "\n\n"))
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return text, nil
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}
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func FromString(input string) (string, error) {
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text, err := FromReader(strings.NewReader(input))
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if err != nil {
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return "", err
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}
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return text, nil
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}
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