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Merged
rezigned merged 1 commit into from
Aug 23, 2026
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perf(tui): batch and reuse syntax highlights #35

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207 changes: 125 additions & 82 deletions src/apps/tui/markdown.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ use ratatui::style::{Color, Modifier, Style, Stylize};
use ratatui::text::{Line, Span, Text};
use std::cell::RefCell;
use std::collections::HashMap;
use std::ops::Range;
use std::rc::Rc;
use unicode_width::UnicodeWidthChar;

Expand Down Expand Up @@ -85,6 +86,10 @@ impl LazyText {
text.spans = spans;
text
}

pub(crate) fn same_content(&self, other: &Self) -> bool {
self.text == other.text && self.language == other.language && self.spans == other.spans
}
}

impl Default for LazyText {
Expand All @@ -98,56 +103,6 @@ impl Default for LazyText {
}
}

#[derive(Debug)]
pub struct MarkdownHtml {
source: String,
lines: Vec<String>,
cached: RefCell<Option<Text<'static>>>,
}

impl MarkdownHtml {
fn new(source: String) -> Self {
let lines = source.lines().map(str::to_owned).collect();
Self {
source,
lines,
cached: RefCell::new(None),
}
}

pub(crate) fn source(&self) -> &str {
&self.source
}

fn len(&self) -> usize {
self.lines.len()
}

fn raw_line(&self, row_idx: usize) -> &str {
self.lines.get(row_idx).map_or("", String::as_str)
}

fn line(&self, row_idx: usize, theme: &Theme) -> Line<'static> {
let mut cached = self.cached.borrow_mut();
if cached.is_none() {
let mut rendered = theme.highlight(&self.source, "html");
for line in &mut rendered.lines {
*line = expand_tabs_in_line(std::mem::take(line));
}
*cached = Some(rendered);
}
cached
.as_ref()
.and_then(|text| text.lines.get(row_idx))
.cloned()
.unwrap_or_else(|| expand_tabs_in_line(Line::raw(self.raw_line(row_idx).to_owned())))
}

fn clear_cache(&self) {
*self.cached.borrow_mut() = None;
}
}

/// Lazily highlighted frontmatter.
#[derive(Debug)]
pub struct FrontmatterBlock {
Expand Down Expand Up @@ -263,6 +218,8 @@ impl MarkdownTable {
#[derive(Debug, Clone, Default)]
pub enum LogicalLineSource {
Text(LazyText),
/// Raw Markdown source prepared in viewport-sized syntax-highlighted batches.
Markup(LazyText),
ListItem(LazyText),
Heading {
level: u8,
Expand All @@ -275,11 +232,8 @@ pub enum LogicalLineSource {
},
CodeBody(LazyText),
Output(Text<'static>),
/// One row of a raw HTML block highlighted and cached as a complete block.
Html {
block: Rc<MarkdownHtml>,
row_idx: usize,
},
/// One row of a raw HTML block.
Html(LazyText),
Frontmatter {
block: Rc<FrontmatterBlock>,
row_idx: usize,
Expand All @@ -306,6 +260,8 @@ impl LogicalLineSource {
fn lazy_text_mut(&mut self) -> Option<&mut LazyText> {
match self {
LogicalLineSource::Text(text)
| LogicalLineSource::Markup(text)
| LogicalLineSource::Html(text)
| LogicalLineSource::ListItem(text)
| LogicalLineSource::CodeBody(text)
| LogicalLineSource::Heading { text, .. } => Some(text),
Expand All @@ -316,6 +272,8 @@ impl LogicalLineSource {
fn lazy_text(&self) -> Option<&LazyText> {
match self {
LogicalLineSource::Text(text)
| LogicalLineSource::Markup(text)
| LogicalLineSource::Html(text)
| LogicalLineSource::ListItem(text)
| LogicalLineSource::CodeBody(text)
| LogicalLineSource::Heading { text, .. } => Some(text),
Expand Down Expand Up @@ -440,7 +398,7 @@ impl LogicalLine {
let text = text.into();
Self {
wrap_prefix_width: source_quote_width(&text),
source: LogicalLineSource::Text(LazyText::markdown(text)),
source: LogicalLineSource::Markup(LazyText::markdown(text)),
is_block_start,
..Self::default()
}
Expand Down Expand Up @@ -484,9 +442,9 @@ impl LogicalLine {
}

/// Creates one row of a raw HTML block.
pub fn html(block: Rc<MarkdownHtml>, row_idx: usize, is_block_start: bool) -> Self {
pub fn html(text: impl Into<String>, is_block_start: bool) -> Self {
Self {
source: LogicalLineSource::Html { block, row_idx },
source: LogicalLineSource::Html(LazyText::new(text, "html")),
is_block_start,
..Self::default()
}
Expand Down Expand Up @@ -537,26 +495,10 @@ impl LogicalLine {
self.source.lazy_text()
}

pub fn html_block(&self) -> Option<&Rc<MarkdownHtml>> {
match &self.source {
LogicalLineSource::Html { block, .. } => Some(block),
_ => None,
}
}

pub fn reuse_html_block(&mut self, cached: &Rc<MarkdownHtml>) {
if let LogicalLineSource::Html { block, .. } = &mut self.source {
if block.source() == cached.source() {
*block = Rc::clone(cached);
}
}
}

/// Clears cached content so the next render uses the current theme.
pub fn clear_cache(&self) {
match &self.source {
LogicalLineSource::TableRow { table, .. } => table.clear_cache(),
LogicalLineSource::Html { block, .. } => block.clear_cache(),
LogicalLineSource::Frontmatter { block, .. } => block.clear_cache(),
_ => {
if let Some(text) = self.lazy_text() {
Expand Down Expand Up @@ -655,6 +597,8 @@ impl LogicalLine {
pub fn text_content(&self) -> String {
match &self.source {
LogicalLineSource::Text(text)
| LogicalLineSource::Markup(text)
| LogicalLineSource::Html(text)
| LogicalLineSource::ListItem(text)
| LogicalLineSource::CodeBody(text)
| LogicalLineSource::Heading { text, .. } => text.text.clone(),
Expand All @@ -663,7 +607,6 @@ impl LogicalLine {
format!("{left} {}", right.trim_end())
}
LogicalLineSource::Output(text) => text.to_string(),
LogicalLineSource::Html { block, row_idx } => block.raw_line(*row_idx).to_owned(),
LogicalLineSource::Frontmatter { block, row_idx } => {
block.raw_line(*row_idx).to_owned()
}
Expand Down Expand Up @@ -787,9 +730,6 @@ impl LogicalLine {
/// Renders text-identical content without syntax highlighting.
fn render_plain_content(&self, ctx: &LineRenderContext<'_>) -> Line<'static> {
match &self.source {
LogicalLineSource::Html { block, row_idx } => {
expand_tabs_in_line(Line::raw(block.raw_line(*row_idx).to_owned()))
}
LogicalLineSource::Frontmatter { block, row_idx } => {
expand_tabs_in_line(Line::raw(block.raw_line(*row_idx).to_owned()))
}
Expand All @@ -805,6 +745,8 @@ impl LogicalLine {
fn render_content(&self, ctx: &LineRenderContext<'_>) -> Line<'static> {
match &self.source {
LogicalLineSource::Text(text)
| LogicalLineSource::Markup(text)
| LogicalLineSource::Html(text)
| LogicalLineSource::ListItem(text)
| LogicalLineSource::CodeBody(text)
| LogicalLineSource::Heading { text, .. } => {
Expand Down Expand Up @@ -844,7 +786,6 @@ impl LogicalLine {
*cache = Some(rendered);
line
}
LogicalLineSource::Html { block, row_idx } => block.line(*row_idx, ctx.theme),
LogicalLineSource::Frontmatter { block, row_idx } => block.line(*row_idx, ctx.theme),
LogicalLineSource::CodeInfo { left, right, style } => {
let prefix_width = self.prefix_width();
Expand Down Expand Up @@ -897,6 +838,95 @@ impl LogicalLine {
}
}

/// Returns line text eligible for batched syntax highlighting.
fn batch_text(line: &LogicalLine) -> Option<&LazyText> {
match &line.source {
LogicalLineSource::Markup(text) | LogicalLineSource::Html(text) => Some(text),
_ => None,
}
}

/// Prepares cached line content for a logical range.
pub(super) fn prepare_lines(
lines: &[LogicalLine],
range: Range<usize>,
ctx: &LineRenderContext<'_>,
) -> usize {
let same_batch =
|left: &LogicalLine, right: &LogicalLine| match (batch_text(left), batch_text(right)) {
(Some(left), Some(right)) => left.language == right.language,
(None, None) => true,
_ => false,
};

let end = range.end.min(lines.len());
let mut start = range.start.min(end);
while start > 0
&& start < end
&& batch_text(&lines[start]).is_some()
&& !lines[start].is_block_start
&& same_batch(&lines[start - 1], &lines[start])
{
start -= 1;
}

let mut populated = 0;
for batch in lines[start..end].chunk_by(same_batch) {
if batch_text(&batch[0]).is_some() {
populated += prepare_syntax_batch(batch, ctx);
} else {
populated += batch
.iter()
.filter(|line| line.ensure_rendered(ctx))
.count();
}
}
populated
}

/// Highlights a same-language line batch once and fills its missing caches.
fn prepare_syntax_batch(batch: &[LogicalLine], ctx: &LineRenderContext<'_>) -> usize {
if batch
.iter()
.all(|line| batch_text(line).is_some_and(|text| text.cached.borrow().is_some()))
{
return 0;
}

let source_len = batch
.iter()
.filter_map(batch_text)
.map(|text| text.text.len() + 1)
.sum();
let mut source = String::with_capacity(source_len);
for line in batch {
source.push_str(&batch_text(line).expect("syntax batch line").text);
source.push('\n');
}

let mut populated = 0;
let mut rendered = ctx
.theme
.highlight(
&source,
&batch_text(&batch[0]).expect("syntax batch line").language,
)
.lines
.into_iter();
for line in batch {
let text = batch_text(line).expect("syntax batch line");
let rendered_line = rendered
.next()
.unwrap_or_else(|| Line::raw(text.text.clone()));
let mut cache = text.cached.borrow_mut();
if cache.is_none() {
*cache = Some(Text::from(expand_tabs_in_line(rendered_line)));
populated += 1;
}
}
populated
}

/// Prepends gutter "▎". Priority: running > active > status > inactive.
pub fn apply_gutter(
line: &mut Line<'static>,
Expand Down Expand Up @@ -972,8 +1002,7 @@ fn render_table(
}

let n = table.headers.len();
let min_col_width = 3usize; // enough for "…"
// Table frame overhead: left border + right border + n separators between columns.
let min_col_width = 3usize;
let frame_overhead = 3 * n + 1;

let natural_widths: Vec<usize> = (0..n)
Expand Down Expand Up @@ -1703,12 +1732,13 @@ mod tests {
fn source_label(line: &LogicalLine) -> String {
match &line.source {
LogicalLineSource::Text(_) => "Text".to_string(),
LogicalLineSource::Markup(_) => "Markup".to_string(),
LogicalLineSource::ListItem(_) => "ListItem".to_string(),
LogicalLineSource::Heading { level, .. } => format!("Heading({level})"),
LogicalLineSource::CodeInfo { .. } => "CodeInfo".to_string(),
LogicalLineSource::CodeBody(_) => "CodeBody".to_string(),
LogicalLineSource::Output(_) => "Output".to_string(),
LogicalLineSource::Html { .. } => "Html".to_string(),
LogicalLineSource::Html(_) => "Html".to_string(),
LogicalLineSource::Frontmatter { .. } => "Frontmatter".to_string(),
LogicalLineSource::TableRow { .. } => "Table".to_string(),
LogicalLineSource::Image { .. } => "Image".to_string(),
Expand Down Expand Up @@ -1740,6 +1770,19 @@ mod tests {
.join("\n")
}

#[test]
fn test_prepare_lines_batches_adjacent_markup_blocks() {
let lines = vec![
LogicalLine::markup_text("# Heading", true),
LogicalLine::markup_text("paragraph", true),
LogicalLine::markup_text("> quote", true),
];
let theme = test_theme();
let populated = prepare_lines(&lines, 0..lines.len(), &test_ctx(&theme, 80));

assert_eq!(populated, 3);
}

#[test]
fn test_apply_gutter_prefers_active_color_without_prefer_status_gutter() {
let theme = test_theme();
Expand Down
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