mirror of https://github.com/docker/cli.git
62 lines
1.4 KiB
Go
62 lines
1.4 KiB
Go
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package formatter
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import (
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"unicode/utf8"
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"golang.org/x/text/width"
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)
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// charWidth returns the number of horizontal positions a character occupies,
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// and is used to account for wide characters when displaying strings.
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//
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// In a broad sense, wide characters include East Asian Wide, East Asian Full-width,
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// (when not in East Asian context) see http://unicode.org/reports/tr11/.
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func charWidth(r rune) int {
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switch width.LookupRune(r).Kind() {
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case width.EastAsianWide, width.EastAsianFullwidth:
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return 2
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default:
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return 1
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}
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}
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// Ellipsis truncates a string to fit within maxDisplayWidth, and appends ellipsis (…).
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// For maxDisplayWidth of 1 and lower, no ellipsis is appended.
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// For maxDisplayWidth of 1, first char of string will return even if its width > 1.
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func Ellipsis(s string, maxDisplayWidth int) string {
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if maxDisplayWidth <= 0 {
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return ""
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}
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rs := []rune(s)
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if maxDisplayWidth == 1 {
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return string(rs[0])
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}
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byteLen := len(s)
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if byteLen == utf8.RuneCountInString(s) {
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if byteLen <= maxDisplayWidth {
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return s
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}
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return string(rs[:maxDisplayWidth-1]) + "…"
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}
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var (
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display []int
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displayWidth int
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)
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for _, r := range rs {
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cw := charWidth(r)
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displayWidth += cw
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display = append(display, displayWidth)
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}
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if displayWidth <= maxDisplayWidth {
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return s
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}
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for i := range display {
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if display[i] <= maxDisplayWidth-1 && display[i+1] > maxDisplayWidth-1 {
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return string(rs[:i+1]) + "…"
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}
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}
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return s
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}
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