Files
docker-cli/cli/command/formatter/displayutils.go
Sebastiaan van Stijn e0f4bc699c cli/command/formatter: add TrunateID utility
We were depending on pkg/stringid to truncate IDs for presentation. While
traditionally, we used a fixed length for "truncated" IDs, this is not
a strict requirement (any ID-prefix should work, but conflicts may
happen on shorter IDs).

This patch adds a local `TruncateID()` utility in the formatter package;
it's currently using the same implementation and length as the
`stringid.TruncateID` function, but may diverge in future.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2025-07-14 20:10:56 +02:00

112 lines
2.8 KiB
Go

// FIXME(thaJeztah): remove once we are a module; the go:build directive prevents go from downgrading language version to go1.16:
//go:build go1.23
package formatter
import (
"fmt"
"strings"
"unicode/utf8"
"golang.org/x/text/width"
)
// charWidth returns the number of horizontal positions a character occupies,
// and is used to account for wide characters when displaying strings.
//
// In a broad sense, wide characters include East Asian Wide, East Asian Full-width,
// (when not in East Asian context) see http://unicode.org/reports/tr11/.
func charWidth(r rune) int {
switch width.LookupRune(r).Kind() {
case width.EastAsianWide, width.EastAsianFullwidth:
return 2
case width.Neutral, width.EastAsianAmbiguous, width.EastAsianNarrow, width.EastAsianHalfwidth:
return 1
default:
return 1
}
}
const shortLen = 12
// TruncateID returns a shorthand version of a string identifier for presentation,
// after trimming digest algorithm prefix (if any).
//
// This function is a copy of [stringid.TruncateID] for presentation / formatting
// purposes.
//
// [stringid.TruncateID]: https://github.com/moby/moby/blob/v28.3.2/pkg/stringid/stringid.go#L19
func TruncateID(id string) string {
if i := strings.IndexRune(id, ':'); i >= 0 {
id = id[i+1:]
}
if len(id) > shortLen {
id = id[:shortLen]
}
return id
}
// Ellipsis truncates a string to fit within maxDisplayWidth, and appends ellipsis (…).
// For maxDisplayWidth of 1 and lower, no ellipsis is appended.
// For maxDisplayWidth of 1, first char of string will return even if its width > 1.
func Ellipsis(s string, maxDisplayWidth int) string {
if maxDisplayWidth <= 0 {
return ""
}
rs := []rune(s)
if maxDisplayWidth == 1 {
return string(rs[0])
}
byteLen := len(s)
if byteLen == utf8.RuneCountInString(s) {
if byteLen <= maxDisplayWidth {
return s
}
return string(rs[:maxDisplayWidth-1]) + "…"
}
var (
display = make([]int, 0, len(rs))
displayWidth int
)
for _, r := range rs {
cw := charWidth(r)
displayWidth += cw
display = append(display, displayWidth)
}
if displayWidth <= maxDisplayWidth {
return s
}
for i := range display {
if display[i] <= maxDisplayWidth-1 && display[i+1] > maxDisplayWidth-1 {
return string(rs[:i+1]) + "…"
}
}
return s
}
// capitalizeFirst capitalizes the first character of string
func capitalizeFirst(s string) string {
switch l := len(s); l {
case 0:
return s
case 1:
return strings.ToLower(s)
default:
return strings.ToUpper(string(s[0])) + strings.ToLower(s[1:])
}
}
// PrettyPrint outputs arbitrary data for human formatted output by uppercasing the first letter.
func PrettyPrint(i any) string {
switch t := i.(type) {
case nil:
return "None"
case string:
return capitalizeFirst(t)
default:
return capitalizeFirst(fmt.Sprintf("%s", t))
}
}