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fix: char-safe table cell truncation #677

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Merged
platinummonkey merged 1 commit into from
Jul 27, 2026
Merged

fix: char-safe table cell truncation #677

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52 changes: 35 additions & 17 deletions src/formatter.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -470,17 +470,24 @@ fn extract_rows(value: &serde_json::Value) -> Vec<&serde_json::Value> {
}
}

/// Truncate `s` to at most `max` characters, appending "..." when shortened.
/// Cuts on character boundaries so multi-byte UTF-8 text never panics.
fn truncate_ellipsis(s: &str, max: usize) -> String {
if s.chars().count() > max {
let keep: String = s.chars().take(max.saturating_sub(3)).collect();
format!("{keep}...")
} else {
s.to_string()
}
}

/// Compact label for a single array element, used when previewing arrays in table cells.
/// For objects, tries id/name/title/type in order; falls back to format_cell for primitives.
fn format_array_item(value: &serde_json::Value) -> String {
if let serde_json::Value::Object(map) = value {
for key in &["name", "title", "id", "type"] {
if let Some(serde_json::Value::String(s)) = map.get(*key) {
return if s.len() > 16 {
format!("{}...", &s[..13])
} else {
s.clone()
};
return truncate_ellipsis(s, 16);
}
}
return format!("{{{} fields}}", map.len());
Expand All @@ -491,13 +498,7 @@ fn format_array_item(value: &serde_json::Value) -> String {
fn format_cell(value: Option<&serde_json::Value>) -> String {
match value {
None | Some(serde_json::Value::Null) => String::new(),
Some(serde_json::Value::String(s)) => {
if s.len() > 50 {
format!("{}...", &s[..47])
} else {
s.clone()
}
}
Some(serde_json::Value::String(s)) => truncate_ellipsis(s, 50),
Some(serde_json::Value::Number(n)) => n.to_string(),
Some(serde_json::Value::Bool(b)) => b.to_string(),
Some(serde_json::Value::Array(arr)) => {
Expand All @@ -509,11 +510,7 @@ fn format_cell(value: Option<&serde_json::Value>) -> String {
parts.push(format!("+{} more", arr.len() - 4));
}
let result = format!("[{}]", parts.join(", "));
if result.len() > 50 {
format!("{}...", &result[..47])
} else {
result
}
truncate_ellipsis(&result, 50)
}
Some(serde_json::Value::Object(map)) => format!("{{{} fields}}", map.len()),
}
Expand Down Expand Up @@ -569,6 +566,27 @@ mod tests {
assert!(result.ends_with("..."));
}

#[test]
fn test_format_cell_long_multibyte_string_char_boundary() {
// Regression: truncating by byte index used to panic when the cut point
// landed inside a multi-byte UTF-8 character (issue #676).
let name = "Resx V4 ;-) (vérifier que c'est bien un problème de resx avant de recycler)";
let result = format_cell(Some(&serde_json::json!(name)));
// 47 kept chars + the ellipsis, counted by characters not bytes.
let expected: String = name.chars().take(47).collect();
assert_eq!(result, format!("{expected}..."));
assert_eq!(result.chars().count(), 50, "got: {result}");
}

#[test]
fn test_format_array_item_multibyte_no_panic() {
// The array-preview path (16-char cap) is also char-boundary safe.
let arr = serde_json::json!([{"name": "problème récurrent de résolution"}]);
let result = format_cell(Some(&arr));
assert!(result.contains("..."), "got: {result}");
assert!(result.starts_with("[problème réc"), "got: {result}");
}

#[test]
fn test_format_cell_number() {
assert_eq!(format_cell(Some(&serde_json::json!(42))), "42");
Expand Down