1 files changed, 107 insertions, 0 deletions
diff --git a/src/modules/utils/truncate.rs b/src/modules/utils/truncate.rs
new file mode 100644
index 000000000..9ec920cb6
--- /dev/null
+++ b/src/modules/utils/truncate.rs
@@ -0,0 +1,107 @@
+use unicode_segmentation::UnicodeSegmentation;
+
+/// Truncate a string to only have a set number of characters
+///
+/// Will truncate a string to only show the last `length` character in the string.
+/// If a length of `0` is provided, the string will not be truncated and the original
+/// will be returned.
+pub fn truncate_text(text: &str, length: usize, truncation_symbol: &str) -> String {
+    if length == 0 {
+        return String::from(text);
+    }
+
+    let truncated_graphemes = get_graphemes(text, length);
+    // The truncation symbol should only be added if we truncated
+    let truncated_and_symbol = if length < graphemes_len(text) {
+        let truncation_symbol = get_graphemes(truncation_symbol, 1);
+        truncated_graphemes + truncation_symbol.as_str()
+    } else {
+        truncated_graphemes
+    };
+
+    truncated_and_symbol
+}
+
+fn get_graphemes(text: &str, length: usize) -> String {
+    UnicodeSegmentation::graphemes(text, true)
+        .take(length)
+        .collect::<Vec<&str>>()
+        .concat()
+}
+
+fn graphemes_len(text: &str) -> usize {
+    UnicodeSegmentation::graphemes(text, true).count()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_multi_char_truncation_symbol() {
+        let actual = truncate_text("1337_hello_world", 15, "apple");
+
+        assert_eq!("1337_hello_worla", actual);
+    }
+
+    #[test]
+    fn test_changed_truncation_symbol() {
+        test_truncate_length("1337_hello_world", 15, "1337_hello_worl", "%")
+    }
+
+    #[test]
+    fn test_no_truncation_symbol() {
+        test_truncate_length("1337_hello_world", 15, "1337_hello_worl", "")
+    }
+
+    #[test]
+    fn test_ascii_boundary_below() {
+        test_truncate_length("1337_hello_world", 15, "1337_hello_worl", "…")
+    }
+
+    #[test]
+    fn test_ascii_boundary_on() {
+        test_truncate_length("1337_hello_world", 16, "1337_hello_world", "")
+    }
+
+    #[test]
+    fn test_ascii_boundary_above() {
+        test_truncate_length("1337_hello_world", 17, "1337_hello_world", "")
+    }
+
+    #[test]
+    fn test_one() {
+        test_truncate_length("1337_hello_world", 1, "1", "…")
+    }
+
+    #[test]
+    fn test_negative() {
+        test_truncate_length("1337_hello_world", -1, "1337_hello_world", "")
+    }
+
+    #[test]
+    fn test_hindi_truncation() {
+        test_truncate_length("नमस्ते", 3, "नमस्", "…")
+    }
+
+    #[test]
+    fn test_hindi_truncation2() {
+        test_truncate_length("नमस्त", 3, "नमस्", "…")
+    }
+
+    #[test]
+    fn test_japanese_truncation() {
+        test_truncate_length("がんばってね", 4, "がんばっ", "…")
+    }
+
+    fn test_truncate_length(
+        text: &str,
+        truncate_length: i64,
+        expected: &str,
+        truncation_symbol: &str,
+    ) {
+        let actual = truncate_text(text, truncate_length as usize, truncation_symbol);
+
+        assert_eq!(format!("{}{}", expected, truncation_symbol), actual);
+    }
+}