Yet Another Markdown Editor! TUI for READMEs and friends.
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use std::time::Duration;
use tui_textarea::CursorMove;
use crate::app::App;
// ---------------------------------------------------------------------------// Column alignment// ---------------------------------------------------------------------------
/// Column alignment parsed from the GFM separator row.#[derive(Debug, Clone, Copy, PartialEq)]pub enum ColAlign { /// No colon: `---` None, /// Leading colon only: `:---` Left, /// Trailing colon only: `---:` Right, /// Both colons: `:---:` Center,}
// ---------------------------------------------------------------------------// Table-bounds detection// ---------------------------------------------------------------------------
/// Return `(start_row, end_row)` of the table that contains `cursor_row`, or/// `None` if the cursor is not on a table line.////// A table line is any non-empty line whose trimmed form starts with `|`./// A valid table requires at least two rows (header + separator).pub fn find_table_bounds(lines: &[String], cursor_row: usize) -> Option<(usize, usize)> { if cursor_row >= lines.len() { return None; } if !is_table_line(&lines[cursor_row]) { return None; }
// Extend upward. let mut start = cursor_row; while start > 0 && is_table_line(&lines[start - 1]) { start -= 1; }
// Extend downward. let mut end = cursor_row; while end + 1 < lines.len() && is_table_line(&lines[end + 1]) { end += 1; }
// Need at least header + separator rows. if end <= start { return None; }
Some((start, end))}
fn is_table_line(line: &str) -> bool { let t = line.trim(); !t.is_empty() && t.starts_with('|')}
// ---------------------------------------------------------------------------// Row parsing// ---------------------------------------------------------------------------
/// Split a table source line into trimmed cell strings.////// Leading and trailing `|` are stripped before splitting, so/// `"| A | B |"` → `["A", "B"]`.pub fn parse_row(line: &str) -> Vec<String> { let t = line.trim(); let inner = t.strip_prefix('|').unwrap_or(t); let inner = inner.strip_suffix('|').unwrap_or(inner); inner.split('|').map(|c| c.trim().to_string()).collect()}
/// Return `true` if every cell in `cells` looks like a separator cell/// (`^:?-+:?$`) and there is at least one cell.fn is_separator_row(cells: &[String]) -> bool { !cells.is_empty() && cells.iter().all(|c| { let t = c.trim(); !t.is_empty() && t.contains('-') && t.chars().all(|ch| matches!(ch, '-' | ':')) })}
/// Parse the alignment marker from a separator cell string.fn parse_alignment(cell: &str) -> ColAlign { let t = cell.trim(); let left = t.starts_with(':'); let right = t.ends_with(':'); match (left, right) { (true, true) => ColAlign::Center, (true, false) => ColAlign::Left, (false, true) => ColAlign::Right, (false, false) => ColAlign::None, }}
// ---------------------------------------------------------------------------// Formatting helpers// ---------------------------------------------------------------------------
/// Build the separator cell string for `align` that is exactly `width`/// characters wide (not counting the surrounding spaces the row emitter adds).////// `width` must be ≥ 3 (the minimum enforced by `format_table`).fn format_sep_cell(align: ColAlign, width: usize) -> String { let w = width.max(3); match align { ColAlign::None => "-".repeat(w), ColAlign::Left => format!(":{}", "-".repeat(w - 1)), ColAlign::Right => format!("{}:", "-".repeat(w - 1)), ColAlign::Center => { // `:` + (w-2) dashes + `:` let dashes = w.saturating_sub(2); format!(":{}:", "-".repeat(dashes)) } }}
/// Left-pad `cell` with trailing spaces so its char-count equals `width`.fn pad_cell(cell: &str, width: usize) -> String { let len = cell.chars().count(); if len >= width { cell.to_string() } else { format!("{}{}", cell, " ".repeat(width - len)) }}
/// Rebuild a single table row as `| cell1 | cell2 | … |`.////// `is_sep` — if `true`, cells are formatted as separator dashes+colons;/// otherwise as padded content.fn format_row(cells: &[String], widths: &[usize], alignments: &[ColAlign], is_sep: bool) -> String { let mut out = String::from("|"); for (ci, &w) in widths.iter().enumerate() { let cell = cells.get(ci).map(String::as_str).unwrap_or(""); let align = alignments.get(ci).copied().unwrap_or(ColAlign::None); out.push(' '); if is_sep { out.push_str(&format_sep_cell(align, w)); } else { out.push_str(&pad_cell(cell, w)); } out.push(' '); out.push('|'); } out}
// ---------------------------------------------------------------------------// Public: format a slice of table lines// ---------------------------------------------------------------------------
/// Reformat `lines` (which must be the rows of a single GFM table) to have/// uniform column widths.////// - Column widths are the max source-char width across all non-separator rows/// (minimum 3 to accommodate the separator markers)./// - The separator row is rebuilt to preserve alignment colons (`:---`, `---:`,/// `:---:`, or `---`) at the computed column width./// - All other rows have cells left-padded with spaces.////// Returns the reformatted lines (same count as input).pub fn format_table(lines: &[String]) -> Vec<String> { let rows: Vec<Vec<String>> = lines.iter().map(|l| parse_row(l)).collect();
let ncols = rows.iter().map(|r| r.len()).max().unwrap_or(0); if ncols == 0 { return lines.to_vec(); }
// The separator row is conventionally the second row (index 1). let sep_row_idx = 1; let has_sep = rows.len() > sep_row_idx && is_separator_row(&rows[sep_row_idx]);
let alignments: Vec<ColAlign> = if has_sep { let mut a: Vec<ColAlign> = rows[sep_row_idx] .iter() .map(|c| parse_alignment(c)) .collect(); // Pad to ncols if the separator has fewer cells than the header. a.resize(ncols, ColAlign::None); a } else { vec![ColAlign::None; ncols] };
// Compute column widths from non-separator rows; minimum 3. let mut widths = vec![3usize; ncols]; for (ri, row) in rows.iter().enumerate() { if ri == sep_row_idx && has_sep { continue; } for (ci, cell) in row.iter().enumerate() { if ci < ncols { widths[ci] = widths[ci].max(cell.chars().count()); } } }
// Rebuild each row. rows.iter() .enumerate() .map(|(ri, row)| { let is_sep = ri == sep_row_idx && has_sep; format_row(row, &widths, &alignments, is_sep) }) .collect()}
// ---------------------------------------------------------------------------// Public: editor command// ---------------------------------------------------------------------------
/// Replace the table under the cursor with a uniformly-padded version.////// Bound to `Alt+T` in normal editing mode. Does nothing (shows a status/// hint) if the cursor is not inside a GFM pipe table.#[mutants::skip] // Requires a live App+TextArea; covered by manual testing only.pub fn handle_format_table(app: &mut App) { let (cursor_row, _) = app.textarea.cursor(); let lines: Vec<String> = app.textarea.lines().iter().map(|s| s.to_string()).collect();
let Some((start, end)) = find_table_bounds(&lines, cursor_row) else { app.status .set_dismissible("Alt+T: cursor is not inside a table.".to_string()); return; };
let table_lines = lines[start..=end].to_vec(); let formatted = format_table(&table_lines);
// Replace each line in place (top-to-bottom; line indices stay stable // because we never add or remove rows, only rewrite their content). for (i, new_line) in formatted.iter().enumerate() { let row = start + i; app.textarea.move_cursor(CursorMove::Jump(row as u16, 0)); app.textarea.delete_line_by_end(); app.textarea.insert_str(new_line); }
// Return cursor to the original row, column 0. app.textarea .move_cursor(CursorMove::Jump(cursor_row as u16, 0));
app.force_redecorate = true; app.mark_keystroke(); app.recompute_dirty();
app.status .set_timed("Table formatted.".to_string(), Duration::from_millis(1500));}
// ---------------------------------------------------------------------------// Tests// ---------------------------------------------------------------------------
#[cfg(test)]mod tests { use super::*;
fn s(v: &[&str]) -> Vec<String> { v.iter().map(|s| s.to_string()).collect() }
// ── find_table_bounds ────────────────────────────────────────────────────
#[test] fn bounds_cursor_on_header_row() { let lines = s(&["| A | B |", "| - | - |", "| 1 | 2 |"]); assert_eq!(find_table_bounds(&lines, 0), Some((0, 2))); }
#[test] fn bounds_cursor_on_body_row() { let lines = s(&["| A | B |", "| - | - |", "| 1 | 2 |"]); assert_eq!(find_table_bounds(&lines, 2), Some((0, 2))); }
#[test] fn bounds_table_surrounded_by_other_content() { let lines = s(&[ "Some text", "| A | B |", "| - | - |", "| 1 | 2 |", "", "More text", ]); assert_eq!(find_table_bounds(&lines, 2), Some((1, 3))); }
#[test] fn bounds_cursor_not_in_table_returns_none() { let lines = s(&["Some text", "| A | B |", "| - | - |"]); assert_eq!(find_table_bounds(&lines, 0), None); }
#[test] fn bounds_single_row_table_returns_none() { // A single line is not a valid table (needs at least header + separator). let lines = s(&["| A | B |"]); assert_eq!(find_table_bounds(&lines, 0), None); }
#[test] fn bounds_empty_line_between_tables_splits_them() { let lines = s(&["| A |", "| - |", "", "| B |", "| - |"]); // Cursor on first table. assert_eq!(find_table_bounds(&lines, 0), Some((0, 1))); // Cursor on second table. assert_eq!(find_table_bounds(&lines, 3), Some((3, 4))); }
// ── parse_row ────────────────────────────────────────────────────────────
#[test] fn parse_row_strips_outer_pipes_and_trims() { let row = parse_row("| Hello | World |"); assert_eq!(row, vec!["Hello", "World"]); }
#[test] fn parse_row_separator_line() { let row = parse_row("|:---|:---:|---:|"); assert_eq!(row, vec![":---", ":---:", "---:"]); }
#[test] fn parse_row_no_trailing_pipe() { let row = parse_row("| A | B"); assert_eq!(row, vec!["A", "B"]); }
// ── is_separator_row ─────────────────────────────────────────────────────
#[test] fn separator_detected_plain_dashes() { assert!(is_separator_row(&s(&["---", "---"]))); }
#[test] fn separator_detected_with_colons() { assert!(is_separator_row(&s(&[":---", ":---:", "---:"]))); }
#[test] fn separator_not_detected_for_content_row() { assert!(!is_separator_row(&s(&["Hello", "World"]))); }
// ── parse_alignment ──────────────────────────────────────────────────────
#[test] fn alignment_none() { assert_eq!(parse_alignment("---"), ColAlign::None); }
#[test] fn alignment_left() { assert_eq!(parse_alignment(":---"), ColAlign::Left); }
#[test] fn alignment_right() { assert_eq!(parse_alignment("---:"), ColAlign::Right); }
#[test] fn alignment_center() { assert_eq!(parse_alignment(":---:"), ColAlign::Center); }
// ── format_sep_cell ──────────────────────────────────────────────────────
#[test] fn sep_cell_none_width_3() { assert_eq!(format_sep_cell(ColAlign::None, 3), "---"); }
#[test] fn sep_cell_left_width_5() { assert_eq!(format_sep_cell(ColAlign::Left, 5), ":----"); }
#[test] fn sep_cell_right_width_5() { assert_eq!(format_sep_cell(ColAlign::Right, 5), "----:"); }
#[test] fn sep_cell_center_width_5() { assert_eq!(format_sep_cell(ColAlign::Center, 5), ":---:"); }
#[test] fn sep_cell_center_width_3() { assert_eq!(format_sep_cell(ColAlign::Center, 3), ":-:"); }
// ── format_table ─────────────────────────────────────────────────────────
#[test] fn format_table_pads_short_cells_to_max_width() { let lines = s(&["| A | Longer header |", "| - | ------------ |", "| x | y |"]); let result = format_table(&lines); // "A" / "x" are 1 char each but minimum column width is 3, so they // pad to 3. "Longer header" / "y" → max 13 chars. assert_eq!(result[0], "| A | Longer header |"); assert_eq!(result[2], "| x | y |"); }
#[test] fn format_table_preserves_alignment_markers() { let lines = s(&[ "| Left | Center | Right |", "|:-----|:------:|------:|", "| a | b | c |", ]); let result = format_table(&lines); // Separator row must use `:` correctly. let sep = &result[1]; assert!(sep.contains(":---"), "left marker: {sep}"); assert!( sep.contains(":---:") || sep.contains("---:"), "other markers: {sep}" ); }
#[test] fn format_table_separator_width_matches_column_width() { let lines = s(&[ "| Short | A very long header |", "| ----- | ------------------ |", "| x | y |", ]); let result = format_table(&lines); let sep = &result[1]; // Separator columns should be exactly as wide as header columns + surrounding spaces. assert_eq!( result[0].len(), result[1].len(), "all rows same total width" ); assert_eq!( result[0].len(), result[2].len(), "all rows same total width" ); // No width regression: separator must not be shorter than its column header. let sep_cells = parse_row(sep); assert!( sep_cells[1].chars().count() >= "A very long header".len(), "sep col width ≥ header width: {:?}", sep_cells ); }
#[test] fn format_table_minimum_column_width_is_3() { // Even single-char headers get a minimum of 3-char-wide separator. let lines = s(&["| A |", "| - |", "| x |"]); let result = format_table(&lines); let sep_cell = parse_row(&result[1]).into_iter().next().unwrap_or_default(); assert!( sep_cell.chars().count() >= 3, "separator cell must be ≥ 3 chars wide: {:?}", sep_cell ); }
#[test] fn format_table_roundtrips_already_formatted_table() { // Calling format_table on an already-formatted table is idempotent. let lines = s(&[ "| Left | Center | Right |", "| ---- | ------ | ----- |", "| a | b | c |", ]); let once = format_table(&lines); let twice = format_table(&once); assert_eq!(once, twice, "format_table must be idempotent"); }
#[test] fn format_table_all_rows_same_total_width() { let lines = s(&[ "| Short | A longer one |", "| ----- | ------------ |", "| x | y |", "| abc | def |", ]); let result = format_table(&lines); let widths: Vec<usize> = result.iter().map(|l| l.chars().count()).collect(); assert!( widths.windows(2).all(|w| w[0] == w[1]), "all rows must have equal total width: {:?}", widths ); }
#[test] fn format_table_inline_markup_counted_as_source_chars() { // **bold** counts 8 source chars, not 4 rendered chars. let lines = s(&[ "| **bold** | plain |", "| -------- | ----- |", "| x | y |", ]); let result = format_table(&lines); let cells = parse_row(&result[0]); assert_eq!( cells[0], "**bold**", "bold cell must not be truncated: {:?}", cells ); }
// ---- T-21: is_separator_row — body rows must not be detected as separators ----
#[test] fn separator_not_detected_for_row_with_letters_and_dash() { // Kills: line 103:46 `replace && with || in is_separator_row` // With `||`, any non-empty cell is a separator because `contains('-')` or // `contains(':')` is often true. "a-b" contains '-' but is not a separator. assert!( !is_separator_row(&s(&["a-b"])), "cell 'a-b' must not be a separator" ); assert!( !is_separator_row(&s(&["a:b"])), "cell 'a:b' must not be a separator" ); assert!( !is_separator_row(&s(&["hello"])), "cell 'hello' must not be a separator" ); // True separators still work. assert!(is_separator_row(&s(&["---"])), "'---' must be a separator"); assert!( is_separator_row(&s(&[":--:"])), "':--:' must be a separator" ); }
// ---- T-22: format_table with single-row input (no separator row) ----
#[test] fn format_table_single_row_does_not_panic() { // Kills: lines 197:30 (`>→>=`) and 197:44 (`&&→||`). // With `>→>=`: `rows.len() >= 1` → tries rows[sep_row_idx=1] on a 1-row input → OOB. // With `&&→||`: same OOB path triggered when len==1. let lines = s(&["| A | B |"]); let result = format_table(&lines); assert_eq!( result.len(), 1, "single-row input must produce single-row output" ); assert!( result[0].contains('|'), "output must still be a pipe-table row: {:?}", result ); }}