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// Copyright 2021 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package util
import "unicode/utf8"
// in UTF8 "…" is 3 bytes so doesn't really gain us anything...
const (
utf8Ellipsis = "…"
asciiEllipsis = "..."
)
// SplitStringAtByteN splits a string at byte n accounting for rune boundaries. (Combining characters are not accounted for.)
func SplitStringAtByteN(input string, n int) (left, right string) {
if len(input) <= n {
return input, ""
}
if !utf8.ValidString(input) {
if n-3 < 0 {
return input, ""
}
return input[:n-3] + asciiEllipsis, asciiEllipsis + input[n-3:]
}
end := 0
for end <= n-3 {
_, size := utf8.DecodeRuneInString(input[end:])
if end+size > n-3 {
break
}
end += size
}
return input[:end] + utf8Ellipsis, utf8Ellipsis + input[end:]
}
// SplitStringAtRuneN splits a string at rune n accounting for rune boundaries. (Combining characters are not accounted for.)
func SplitStringAtRuneN(input string, n int) (left, right string) {
if !utf8.ValidString(input) {
if len(input) <= n || n-3 < 0 {
return input, ""
}
return input[:n-3] + asciiEllipsis, asciiEllipsis + input[n-3:]
}
if utf8.RuneCountInString(input) <= n {
return input, ""
}
count := 0
end := 0
for count < n-1 {
_, size := utf8.DecodeRuneInString(input[end:])
end += size
count++
}
return input[:end] + utf8Ellipsis, utf8Ellipsis + input[end:]
}
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