138 lines
4.5 KiB
Rust
138 lines
4.5 KiB
Rust
//! Utility functions for `ZeroClaw`.
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//!
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//! This module contains reusable helper functions used across the codebase.
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/// Truncate a string to at most `max_chars` characters, appending "..." if truncated.
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///
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/// This function safely handles multi-byte UTF-8 characters (emoji, CJK, accented characters)
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/// by using character boundaries instead of byte indices.
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///
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/// # Arguments
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/// * `s` - The string to truncate
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/// * `max_chars` - Maximum number of characters to keep (excluding "...")
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///
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/// # Returns
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/// * Original string if length <= `max_chars`
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/// * Truncated string with "..." appended if length > `max_chars`
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///
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/// # Examples
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/// ```
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/// use zeroclaw::util::truncate_with_ellipsis;
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///
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/// // ASCII string - no truncation needed
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/// assert_eq!(truncate_with_ellipsis("hello", 10), "hello");
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///
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/// // ASCII string - truncation needed
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/// assert_eq!(truncate_with_ellipsis("hello world", 5), "hello...");
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///
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/// // Multi-byte UTF-8 (emoji) - safe truncation
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/// assert_eq!(truncate_with_ellipsis("Hello 🦀 World", 8), "Hello 🦀...");
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/// assert_eq!(truncate_with_ellipsis("😀😀😀😀", 2), "😀😀...");
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///
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/// // Empty string
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/// assert_eq!(truncate_with_ellipsis("", 10), "");
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/// ```
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pub fn truncate_with_ellipsis(s: &str, max_chars: usize) -> String {
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match s.char_indices().nth(max_chars) {
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Some((idx, _)) => {
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let truncated = &s[..idx];
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// Trim trailing whitespace for cleaner output
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format!("{}...", truncated.trim_end())
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}
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None => s.to_string(),
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_truncate_ascii_no_truncation() {
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// ASCII string shorter than limit - no change
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assert_eq!(truncate_with_ellipsis("hello", 10), "hello");
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assert_eq!(truncate_with_ellipsis("hello world", 50), "hello world");
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}
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#[test]
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fn test_truncate_ascii_with_truncation() {
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// ASCII string longer than limit - truncates
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assert_eq!(truncate_with_ellipsis("hello world", 5), "hello...");
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assert_eq!(
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truncate_with_ellipsis("This is a long message", 10),
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"This is a..."
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);
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}
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#[test]
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fn test_truncate_empty_string() {
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assert_eq!(truncate_with_ellipsis("", 10), "");
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}
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#[test]
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fn test_truncate_at_exact_boundary() {
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// String exactly at boundary - no truncation
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assert_eq!(truncate_with_ellipsis("hello", 5), "hello");
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}
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#[test]
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fn test_truncate_emoji_single() {
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// Single emoji (4 bytes) - should not panic
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let s = "🦀";
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assert_eq!(truncate_with_ellipsis(s, 10), s);
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assert_eq!(truncate_with_ellipsis(s, 1), s);
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}
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#[test]
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fn test_truncate_emoji_multiple() {
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// Multiple emoji - safe truncation at character boundary
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let s = "😀😀😀😀"; // 4 emoji, each 4 bytes = 16 bytes total
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assert_eq!(truncate_with_ellipsis(s, 2), "😀😀...");
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assert_eq!(truncate_with_ellipsis(s, 3), "😀😀😀...");
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}
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#[test]
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fn test_truncate_mixed_ascii_emoji() {
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// Mixed ASCII and emoji
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assert_eq!(truncate_with_ellipsis("Hello 🦀 World", 8), "Hello 🦀...");
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assert_eq!(truncate_with_ellipsis("Hi 😊", 10), "Hi 😊");
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}
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#[test]
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fn test_truncate_cjk_characters() {
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// CJK characters (Chinese - each is 3 bytes)
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let s = "这是一个测试消息用来触发崩溃的中文"; // 21 characters
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let result = truncate_with_ellipsis(s, 16);
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assert!(result.ends_with("..."));
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assert!(result.is_char_boundary(result.len() - 1));
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}
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#[test]
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fn test_truncate_accented_characters() {
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// Accented characters (2 bytes each in UTF-8)
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let s = "café résumé naïve";
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assert_eq!(truncate_with_ellipsis(s, 10), "café résum...");
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}
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#[test]
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fn test_truncate_unicode_edge_case() {
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// Mix of 1-byte, 2-byte, 3-byte, and 4-byte characters
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let s = "aé你好🦀"; // 1 + 1 + 2 + 2 + 4 bytes = 10 bytes, 5 chars
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assert_eq!(truncate_with_ellipsis(s, 3), "aé你...");
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}
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#[test]
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fn test_truncate_long_string() {
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// Long ASCII string
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let s = "a".repeat(200);
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let result = truncate_with_ellipsis(&s, 50);
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assert_eq!(result.len(), 53); // 50 + "..."
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assert!(result.ends_with("..."));
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}
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#[test]
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fn test_truncate_zero_max_chars() {
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// Edge case: max_chars = 0
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assert_eq!(truncate_with_ellipsis("hello", 0), "...");
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}
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}
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