75 lines
1.2 KiB
Go
75 lines
1.2 KiB
Go
package text
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import (
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runewidth "github.com/mattn/go-runewidth"
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"github.com/rivo/uniseg"
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)
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const (
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ellipsisWidth = 3
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minWidthForEllipsis = 5
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)
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// DisplayWidth calculates what the rendered width of a string may be
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func DisplayWidth(s string) int {
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g := uniseg.NewGraphemes(s)
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w := 0
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for g.Next() {
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w += graphemeWidth(g)
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}
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return w
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}
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// Truncate shortens a string to fit the maximum display width
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func Truncate(maxWidth int, s string) string {
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w := DisplayWidth(s)
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if w <= maxWidth {
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return s
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}
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useEllipsis := false
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if maxWidth >= minWidthForEllipsis {
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useEllipsis = true
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maxWidth -= ellipsisWidth
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}
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g := uniseg.NewGraphemes(s)
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r := ""
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rWidth := 0
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for {
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g.Next()
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gWidth := graphemeWidth(g)
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if rWidth+gWidth <= maxWidth {
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r += g.Str()
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rWidth += gWidth
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continue
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} else {
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break
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}
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}
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if useEllipsis {
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r += "..."
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}
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if rWidth < maxWidth {
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r += " "
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}
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return r
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}
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// graphemeWidth calculates what the rendered width of a grapheme may be
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func graphemeWidth(g *uniseg.Graphemes) int {
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// If grapheme spans one rune use that rune width
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// If grapheme spans multiple runes use the first non-zero rune width
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w := 0
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for _, r := range g.Runes() {
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w = runewidth.RuneWidth(r)
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if w > 0 {
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break
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}
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}
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return w
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}
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