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use unicode_width::{UnicodeWidthChar, UnicodeWidthStr};
pub(crate) fn display_width(text: &str) -> usize {
UnicodeWidthStr::width(text)
}
pub(crate) fn display_width_u16(text: &str) -> u16 {
display_width(text).min(u16::MAX as usize) as u16
}
pub(crate) fn truncate_end(text: &str, max_width: usize) -> String {
if display_width(text) <= max_width {
return text.to_string();
}
if max_width == 0 {
return String::new();
}
if max_width == 1 {
return "…".to_string();
}
let prefix = take_prefix_width(text, max_width.saturating_sub(1));
format!("{prefix}…")
}
pub(crate) fn middle_elide(text: &str, max_width: usize) -> String {
if display_width(text) <= max_width {
return text.to_string();
}
if max_width <= 1 {
return "…".to_string();
}
let content_width = max_width.saturating_sub(1);
let left_width = content_width / 2;
let right_width = content_width.saturating_sub(left_width);
let prefix = take_prefix_width(text, left_width);
let suffix = take_suffix_width(text, right_width);
format!("{prefix}…{suffix}")
}
fn take_prefix_width(text: &str, max_width: usize) -> String {
let mut output = String::new();
let mut width = 0usize;
for ch in text.chars() {
let ch_width = UnicodeWidthChar::width(ch).unwrap_or(0);
if width + ch_width > max_width {
break;
}
output.push(ch);
width += ch_width;
}
output
}
fn take_suffix_width(text: &str, max_width: usize) -> String {
let mut output = Vec::new();
let mut width = 0usize;
for ch in text.chars().rev() {
let ch_width = UnicodeWidthChar::width(ch).unwrap_or(0);
if width + ch_width > max_width {
break;
}
output.push(ch);
width += ch_width;
}
output.into_iter().rev().collect()
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn truncate_end_uses_display_width() {
let text = truncate_end("提交 herdr 的反馈", 16);
assert_eq!(text, "提交 herdr 的反…");
assert!(display_width(&text) <= 16);
}
#[test]
fn middle_elide_uses_display_width() {
let text = middle_elide("重构用户认证模块并迁移到统一登录服务", 12);
assert!(text.contains('…'));
assert!(display_width(&text) <= 12);
}
}
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