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Merged
enijburg merged 1 commit into from
May 15, 2026
Merged

Add configurable and auto-detected CSV separators #13

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115 changes: 94 additions & 21 deletions src/main.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -27,10 +27,14 @@ struct Args {
#[arg(long, default_value_t = 4)]
tab_width: usize,

/// Render comma-separated values in aligned columns.
/// Render delimited values in aligned columns.
#[arg(long)]
csv: bool,

/// Field separator for --csv mode (single ASCII character, e.g. ",", ";", "\t", "|").
#[arg(long)]
csv_separator: Option<String>,

/// Enable rudimentary XML syntax highlighting.
#[arg(long)]
xml: bool,
Expand All @@ -52,6 +56,7 @@ struct Viewer {
left_col: usize,
tab_width: usize,
csv_column_widths: Option<Vec<usize>>,
csv_separator: Option<u8>,
xml_syntax_highlighting: bool,
json_syntax_highlighting: bool,
search_query: Option<Vec<u8>>,
Expand Down Expand Up @@ -97,11 +102,52 @@ fn centered_top_line(target_line: usize, viewport_rows: usize, line_count: usize
centered.min(line_count - 1)
}

fn resolve_csv_separator(user_separator: Option<&str>, bytes: &[u8]) -> Result<u8> {
if let Some(separator) = user_separator {
return parse_csv_separator(separator);
}
Ok(detect_csv_separator(bytes))
}

fn parse_csv_separator(raw: &str) -> Result<u8> {
let separator = match raw {
r"\t" => b'\t',
_ => {
let bytes = raw.as_bytes();
if bytes.len() != 1 || !bytes[0].is_ascii() {
anyhow::bail!("--csv-separator must be a single ASCII character or \\t");
}
bytes[0]
}
};
Ok(separator)
}

fn detect_csv_separator(bytes: &[u8]) -> u8 {
const CANDIDATES: [u8; 5] = [b',', b';', b'\t', b'|', b':'];
let sample_lines = bytes
.split(|&b| b == b'\n')
.take(50)
.filter(|line| !line.is_empty());
let mut best = (b',', 0usize);
for candidate in CANDIDATES {
let count = sample_lines
.clone()
.map(|line| line.iter().filter(|&&b| b == candidate).count())
.sum();
if count > best.1 {
best = (candidate, count);
}
}
best.0
}

impl Viewer {
fn open(
path: PathBuf,
tab_width: usize,
csv: bool,
csv_separator: Option<&str>,
xml_syntax_highlighting: bool,
xml_formatting: bool,
json_syntax_highlighting: bool,
Expand All @@ -126,7 +172,13 @@ impl Viewer {
};
let source_bytes = formatted_view.as_deref().unwrap_or(&mmap);
let line_offsets = Self::index_lines(source_bytes);
let csv_column_widths = csv.then(|| Self::index_csv_column_widths(source_bytes, tab_width));
let csv_separator = if csv {
Some(resolve_csv_separator(csv_separator, source_bytes)?)
} else {
None
};
let csv_column_widths = csv_separator
.map(|separator| Self::index_csv_column_widths(source_bytes, tab_width, separator));

let top_line = if csv && line_offsets.len() > 1 { 1 } else { 0 };

Expand All @@ -138,6 +190,7 @@ impl Viewer {
left_col: 0,
tab_width,
csv_column_widths,
csv_separator,
xml_syntax_highlighting,
json_syntax_highlighting,
search_query: None,
Expand Down Expand Up @@ -166,7 +219,7 @@ impl Viewer {
self.line_offsets.len()
}

fn index_csv_column_widths(bytes: &[u8], tab_width: usize) -> Vec<usize> {
fn index_csv_column_widths(bytes: &[u8], tab_width: usize, separator: u8) -> Vec<usize> {
let mut widths: Vec<usize> = Vec::new();
let mut column = 0usize;
let mut current_width = 0usize;
Expand All @@ -182,7 +235,7 @@ impl Viewer {
current_width = 0;
}
b'\r' => {}
b',' => {
b if b == separator => {
if widths.len() <= column {
widths.resize(column + 1, 0);
}
Expand Down Expand Up @@ -326,6 +379,7 @@ impl Viewer {
};

if let Some(column_widths) = &self.csv_column_widths {
let separator = self.csv_separator.unwrap_or(b',');
let mut column_idx = 0usize;
let mut field_width = 0usize;

Expand All @@ -340,12 +394,12 @@ impl Viewer {
.unwrap_or(false);

match b {
b',' => {
b if b == separator => {
let target_width = column_widths.get(column_idx).copied().unwrap_or(0);
for _ in field_width..target_width {
push_char(' ', false, RenderClass::Text);
}
push_char(',', is_highlight, RenderClass::Text);
push_char(separator as char, is_highlight, RenderClass::Text);
push_char(' ', false, RenderClass::Text);
column_idx += 1;
field_width = 0;
Expand Down Expand Up @@ -439,12 +493,7 @@ impl Viewer {
Ok(())
}

fn render_scrollbar(
&self,
out: &mut impl Write,
width: usize,
body_rows: usize,
) -> Result<()> {
fn render_scrollbar(&self, out: &mut impl Write, width: usize, body_rows: usize) -> Result<()> {
if width == 0 || body_rows == 0 {
return Ok(());
}
Expand Down Expand Up @@ -523,7 +572,9 @@ impl Viewer {
return;
}
// screen_row 0 is the status bar; body rows start at screen row 1.
let row = screen_row.saturating_sub(1).min(body_rows.saturating_sub(1));
let row = screen_row
.saturating_sub(1)
.min(body_rows.saturating_sub(1));

let thumb_size = body_rows
.saturating_mul(body_rows)
Expand All @@ -548,7 +599,6 @@ impl Viewer {
self.top_line = top_line.max(min_top);
}


fn scroll_right(&mut self, by: usize) {
self.left_col = self.left_col.saturating_add(by);
}
Expand Down Expand Up @@ -1040,18 +1090,29 @@ fn main() -> Result<()> {
args.file,
args.tab_width,
args.csv,
args.csv_separator.as_deref(),
args.xml,
args.format,
args.json,
)?;

terminal::enable_raw_mode().context("Failed to enable raw mode")?;
let mut stdout = io::stdout();
execute!(stdout, terminal::EnterAlternateScreen, cursor::Hide, event::EnableMouseCapture)?;
execute!(
stdout,
terminal::EnterAlternateScreen,
cursor::Hide,
event::EnableMouseCapture
)?;

let run_result = run_event_loop(&mut viewer, &mut stdout);

execute!(stdout, event::DisableMouseCapture, cursor::Show, terminal::LeaveAlternateScreen)?;
execute!(
stdout,
event::DisableMouseCapture,
cursor::Show,
terminal::LeaveAlternateScreen
)?;
terminal::disable_raw_mode().context("Failed to disable raw mode")?;

run_result
Expand Down Expand Up @@ -1301,8 +1362,9 @@ fn prompt_find(viewer: &Viewer, out: &mut impl Write) -> Result<Option<String>>
#[cfg(test)]
mod tests {
use super::{
centered_top_line, classify_json_line, classify_xml_line, format_json_for_display,
format_xml_for_display, skipped_prefix_len, JsonTokenClass, Viewer, XmlTokenClass,
centered_top_line, classify_json_line, classify_xml_line, detect_csv_separator,
format_json_for_display, format_xml_for_display, parse_csv_separator, skipped_prefix_len,
JsonTokenClass, Viewer, XmlTokenClass,
};
use std::{
fs,
Expand Down Expand Up @@ -1368,13 +1430,13 @@ mod tests {

fn test_viewer_from_bytes(bytes: &[u8]) -> Viewer {
with_temp_file(bytes, |path| {
Viewer::open(path, 4, false, false, false, false).expect("failed to open viewer")
Viewer::open(path, 4, false, None, false, false, false).expect("failed to open viewer")
})
}

#[test]
fn indexes_csv_column_widths() {
let widths = Viewer::index_csv_column_widths(b"a,bbb\ncccc,d", 4);
let widths = Viewer::index_csv_column_widths(b"a,bbb\ncccc,d", 4, b',');
assert_eq!(widths, vec![4, 3]);
}

Expand All @@ -1391,9 +1453,20 @@ mod tests {
assert_eq!(viewer.top_line, 1);
}

#[test]
fn auto_detects_semicolon_separator() {
assert_eq!(detect_csv_separator(b"h1;h2\na;b\nc;d"), b';');
}

#[test]
fn parses_tab_separator_escape() {
assert_eq!(parse_csv_separator(r"\t").expect("should parse"), b'\t');
}

fn test_viewer_with_options(bytes: &[u8], tab_width: usize, csv: bool) -> Viewer {
with_temp_file(bytes, |path| {
Viewer::open(path, tab_width, csv, false, false, false).expect("failed to open viewer")
Viewer::open(path, tab_width, csv, None, false, false, false)
.expect("failed to open viewer")
})
}

Expand Down
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