apollo/
text.rs

1//! Small text utilities shared across tools and providers.
2
3pub fn truncate_chars(text: &str, max_chars: usize) -> String {
4    text.chars().take(max_chars).collect()
5}
6
7/// Truncate to `max_chars` characters.
8///
9/// Returns `None` when the text already fits, otherwise the truncated text
10/// and the number of characters dropped. The gate and the truncation use the
11/// same unit so the reported count is always accurate.
12pub fn truncate_chars_counted(text: &str, max_chars: usize) -> Option<(String, usize)> {
13    let total = text.chars().count();
14    if total <= max_chars {
15        return None;
16    }
17    Some((truncate_chars(text, max_chars), total - max_chars))
18}
19
20#[cfg(test)]
21mod tests {
22    use super::*;
23
24    #[test]
25    fn test_truncate_chars() {
26        assert_eq!(truncate_chars("hello world", 5), "hello");
27        assert_eq!(truncate_chars("hello", 5), "hello");
28        assert_eq!(truncate_chars("hi", 5), "hi");
29        assert_eq!(truncate_chars("hello", 0), "");
30        assert_eq!(truncate_chars("", 5), "");
31        assert_eq!(truncate_chars("👋🌎", 1), "👋");
32        assert_eq!(truncate_chars("👋🌎", 2), "👋🌎");
33        assert_eq!(truncate_chars("こんにちは", 2), "こん");
34        assert_eq!(truncate_chars("안녕하세요", 3), "안녕하");
35        assert_eq!(truncate_chars("你好世界", 1), "你");
36    }
37
38    #[test]
39    fn test_truncate_chars_counted() {
40        assert_eq!(truncate_chars_counted("hello", 5), None);
41        assert_eq!(truncate_chars_counted("hello", 6), None);
42        assert_eq!(
43            truncate_chars_counted("hello", 4),
44            Some(("hell".to_string(), 1))
45        );
46        assert_eq!(
47            truncate_chars_counted("hello", 0),
48            Some(("".to_string(), 5))
49        );
50        assert_eq!(truncate_chars_counted("", 0), None);
51        assert_eq!(truncate_chars_counted("", 5), None);
52        assert_eq!(truncate_chars_counted("你好世界", 4), None);
53        assert_eq!(
54            truncate_chars_counted("你好世界", 2),
55            Some(("你好".to_string(), 2))
56        );
57        let cjk = "日".repeat(30_000);
58        let (text, dropped) = truncate_chars_counted(&cjk, 20_000).unwrap();
59        assert_eq!(text.chars().count(), 20_000);
60        assert_eq!(dropped, 10_000);
61    }
62}
apollo/text.rs

apollo/
text.rs
