116 lines
2.3 KiB
Go
116 lines
2.3 KiB
Go
package richtext
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import "strings"
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func push(out []Span, text string, st Style, target string) []Span {
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if text == "" {
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return out
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}
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if n := len(out); n > 0 && out[n-1].Style == st && out[n-1].Target == target {
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out[n-1].Text += text
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return out
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}
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return append(out, Span{Text: text, Style: st, Target: target})
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}
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func wordChar(c byte) bool {
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return c == '_' || c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c >= '0' && c <= '9'
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}
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func edge(s string, i int, closing bool) bool {
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if closing {
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return i > 0 && s[i-1] != ' '
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}
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if i+1 >= len(s) || s[i+1] == ' ' {
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return false
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}
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return s[i] == '*' || i == 0 || !wordChar(s[i-1])
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}
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func Inline(s string) []Span {
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return inline(s, "")
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}
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func inline(s, target string) []Span {
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var out []Span
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var cur strings.Builder
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strong, em := false, false
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style := func() Style {
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switch {
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case strong:
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return Strong
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case em:
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return Emphasis
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}
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return Plain
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}
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emit := func() {
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out = push(out, cur.String(), style(), target)
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cur.Reset()
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}
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for i := 0; i < len(s); i++ {
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c := s[i]
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switch {
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case c == '\\' && i+1 < len(s) && strings.IndexByte("\\`*_[]()#|<>-!", s[i+1]) >= 0:
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cur.WriteByte(s[i+1])
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i++
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case c == '`':
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j := strings.IndexByte(s[i+1:], '`')
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if j < 0 {
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cur.WriteByte(c)
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continue
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}
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emit()
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out = push(out, s[i+1:i+1+j], Code, target)
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i += j + 1
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case c == '!' && i+1 < len(s) && s[i+1] == '[':
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j := strings.Index(s[i:], "](")
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k := -1
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if j >= 0 {
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k = strings.IndexByte(s[i+j+2:], ')')
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}
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if k < 0 {
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cur.WriteByte(c)
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continue
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}
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i += j + 2 + k
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case c == '[':
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j := strings.Index(s[i:], "](")
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if j < 0 {
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cur.WriteByte(c)
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continue
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}
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k := strings.IndexByte(s[i+j+2:], ')')
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if k < 0 {
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cur.WriteByte(c)
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continue
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}
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emit()
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label, dest := s[i+1:i+j], s[i+j+2:i+j+2+k]
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for _, sp := range inline(label, dest) {
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out = push(out, sp.Text, sp.Style, sp.Target)
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}
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i += j + 2 + k
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case c == '*' && i+1 < len(s) && s[i+1] == '*':
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emit()
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strong = !strong
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i++
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case (c == '*' || c == '_') && edge(s, i, em):
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emit()
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em = !em
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default:
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cur.WriteByte(c)
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}
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}
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emit()
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return out
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}
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func PlainText(spans []Span) string {
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var b strings.Builder
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for _, sp := range spans {
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b.WriteString(sp.Text)
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}
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return b.String()
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}
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