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statusline: Avoid unnecessary allocations for `&'static str` spans 

Previously the statusline `write` function only accepted a string
and optional Style, so all rendering functions converted text to
strings. Some elements write spans with `&'static str`s, however, making
this unnecessary since `Span<'a>` is a wrapper around `Cow<'a, str>` and
style, and a `Span<'static>` would outlive all required lifetimes.

Moreover many elements could produce `Span<'a>` according to the
lifetime in `RenderContext` in the future, potentially re-borrowing from
the Editor borrow, so this change could save allocations for many
file-type elements (with more future changes). This is not explored in
this patch since the statusline functions currently add bespoke padding
per-element, but with a future refactor to make spacing consistent this
could be possible.

This change refactors the write function to accept a `Span<'a>` and
rewrites some related code to fit the codebase better (preferring `for`
to iterator's `for_each` for example). The new code is more complicated
lifetime-wise but avoids allocations in these cases:

* spacer for mode name when a pane is not focused
* LSP spinner frames
* '●' (workspace) diagnostic indicators
* " W " workspace diagnostic prefix
* file modification indicators
* read-only indicators
* spacer element

... and opens the door to avoid allocation for file name elements in the
future.
pull/12326/head
Michael Davis 2025-05-14 18:27:46 -04:00
parent b0528bbac4
commit 702b1d0a0f
No known key found for this signature in database
1 changed files with 126 additions and 165 deletions
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275
helix-term/src/ui/statusline.rs
View File

@ -1,3 +1,5 @@
use std::borrow::Cow;
use helix_core::{coords_at_pos, encoding, Position};
use helix_lsp::lsp::DiagnosticSeverity;
use helix_view::document::DEFAULT_LANGUAGE_NAME;
@ -58,25 +60,16 @@ pub fn render(context: &mut RenderContext, viewport: Rect, surface: &mut Surface
surface.set_style(viewport.with_height(1), base_style);
let write_left = |context: &mut RenderContext, text, style| {
append(&mut context.parts.left, text, &base_style, style)
};
let write_center = |context: &mut RenderContext, text, style| {
append(&mut context.parts.center, text, &base_style, style)
};
let write_right = |context: &mut RenderContext, text, style| {
append(&mut context.parts.right, text, &base_style, style)
};
// Left side of the status line.
let config = context.editor.config();
let element_ids = &config.statusline.left;
element_ids
.iter()
.map(|element_id| get_render_function(*element_id))
.for_each(|render| render(context, write_left));
for element_id in &config.statusline.left {
let render = get_render_function(*element_id);
(render)(context, |context, span| {
append(&mut context.parts.left, span, base_style)
});
}
surface.set_spans(
viewport.x,
@ -87,11 +80,12 @@ pub fn render(context: &mut RenderContext, viewport: Rect, surface: &mut Surface
// Right side of the status line.
let element_ids = &config.statusline.right;
element_ids
.iter()
.map(|element_id| get_render_function(*element_id))
.for_each(|render| render(context, write_right));
for element_id in &config.statusline.right {
let render = get_render_function(*element_id);
(render)(context, |context, span| {
append(&mut context.parts.right, span, base_style)
})
}
surface.set_spans(
viewport.x
@ -105,11 +99,12 @@ pub fn render(context: &mut RenderContext, viewport: Rect, surface: &mut Surface
// Center of the status line.
let element_ids = &config.statusline.center;
element_ids
.iter()
.map(|element_id| get_render_function(*element_id))
.for_each(|render| render(context, write_center));
for element_id in &config.statusline.center {
let render = get_render_function(*element_id);
(render)(context, |context, span| {
append(&mut context.parts.center, span, base_style)
})
}
// Width of the empty space between the left and center area and between the center and right area.
let spacing = 1u16;
@ -126,16 +121,14 @@ pub fn render(context: &mut RenderContext, viewport: Rect, surface: &mut Surface
);
}
fn append(buffer: &mut Spans, text: String, base_style: &Style, style: Option<Style>) {
buffer.0.push(Span::styled(
text,
style.map_or(*base_style, |s| (*base_style).patch(s)),
));
fn append<'a>(buffer: &mut Spans<'a>, mut span: Span<'a>, base_style: Style) {
span.style = base_style.patch(span.style);
buffer.0.push(span);
}
fn get_render_function<F>(element_id: StatusLineElementID) -> impl Fn(&mut RenderContext, F)
fn get_render_function<'a, F>(element_id: StatusLineElementID) -> impl Fn(&mut RenderContext<'a>, F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
match element_id {
helix_view::editor::StatusLineElement::Mode => render_mode,
@ -166,44 +159,42 @@ where
}
}
fn render_mode<F>(context: &mut RenderContext, write: F)
fn render_mode<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let visible = context.focused;
let config = context.editor.config();
let modenames = &config.statusline.mode;
write(
context,
format!(
let content = if visible {
Cow::Owned(format!(
" {} ",
if visible {
match context.editor.mode() {
Mode::Insert => &modenames.insert,
Mode::Select => &modenames.select,
Mode::Normal => &modenames.normal,
}
))
} else {
// If not focused, explicitly leave an empty space instead of returning None.
" "
}
),
if visible && config.color_modes {
Cow::Borrowed(" ")
};
let style = if visible && config.color_modes {
match context.editor.mode() {
Mode::Insert => Some(context.editor.theme.get("ui.statusline.insert")),
Mode::Select => Some(context.editor.theme.get("ui.statusline.select")),
Mode::Normal => Some(context.editor.theme.get("ui.statusline.normal")),
Mode::Insert => context.editor.theme.get("ui.statusline.insert"),
Mode::Select => context.editor.theme.get("ui.statusline.select"),
Mode::Normal => context.editor.theme.get("ui.statusline.normal"),
}
} else {
None
},
);
Style::default()
};
write(context, Span::styled(content, style));
}
// TODO think about handling multiple language servers
fn render_lsp_spinner<F>(context: &mut RenderContext, write: F)
fn render_lsp_spinner<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let language_server = context.doc.language_servers().next();
write(
@ -217,14 +208,13 @@ where
})
// Even if there's no spinner; reserve its space to avoid elements frequently shifting.
.unwrap_or(" ")
.to_string(),
None,
.into(),
);
}
fn render_diagnostics<F>(context: &mut RenderContext, write: F)
fn render_diagnostics<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
use helix_core::diagnostic::Severity;
let (hints, info, warnings, errors) =
@ -245,45 +235,35 @@ where
for sev in &context.editor.config().statusline.diagnostics {
match sev {
Severity::Hint if hints > 0 => {
write(
context,
"●".to_string(),
Some(context.editor.theme.get("hint")),
);
write(context, format!(" {} ", hints), None);
write(context, Span::styled("●", context.editor.theme.get("hint")));
write(context, format!(" {} ", hints).into());
}
Severity::Info if info > 0 => {
write(
context,
"●".to_string(),
Some(context.editor.theme.get("info")),
);
write(context, format!(" {} ", info), None);
write(context, Span::styled("●", context.editor.theme.get("info")));
write(context, format!(" {} ", info).into());
}
Severity::Warning if warnings > 0 => {
write(
context,
"●".to_string(),
Some(context.editor.theme.get("warning")),
Span::styled("●", context.editor.theme.get("warning")),
);
write(context, format!(" {} ", warnings), None);
write(context, format!(" {} ", warnings).into());
}
Severity::Error if errors > 0 => {
write(
context,
"●".to_string(),
Some(context.editor.theme.get("error")),
Span::styled("●", context.editor.theme.get("error")),
);
write(context, format!(" {} ", errors), None);
write(context, format!(" {} ", errors).into());
}
_ => {}
}
}
}
fn render_workspace_diagnostics<F>(context: &mut RenderContext, write: F)
fn render_workspace_diagnostics<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
use helix_core::diagnostic::Severity;
let (hints, info, warnings, errors) = context.editor.diagnostics.values().flatten().fold(
@ -317,68 +297,56 @@ where
return;
}
write(context, " W ".into(), None);
write(context, " W ".into());
for sev in sevs_to_show {
match sev {
Severity::Hint if hints > 0 => {
write(
context,
"●".to_string(),
Some(context.editor.theme.get("hint")),
);
write(context, format!(" {} ", hints), None);
write(context, Span::styled("●", context.editor.theme.get("hint")));
write(context, format!(" {} ", hints).into());
}
Severity::Info if info > 0 => {
write(
context,
"●".to_string(),
Some(context.editor.theme.get("info")),
);
write(context, format!(" {} ", info), None);
write(context, Span::styled("●", context.editor.theme.get("info")));
write(context, format!(" {} ", info).into());
}
Severity::Warning if warnings > 0 => {
write(
context,
"●".to_string(),
Some(context.editor.theme.get("warning")),
Span::styled("●", context.editor.theme.get("warning")),
);
write(context, format!(" {} ", warnings), None);
write(context, format!(" {} ", warnings).into());
}
Severity::Error if errors > 0 => {
write(
context,
"●".to_string(),
Some(context.editor.theme.get("error")),
Span::styled("●", context.editor.theme.get("error")),
);
write(context, format!(" {} ", errors), None);
write(context, format!(" {} ", errors).into());
}
_ => {}
}
}
}
fn render_selections<F>(context: &mut RenderContext, write: F)
fn render_selections<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let count = context.doc.selection(context.view.id).len();
write(
context,
format!(" {} sel{} ", count, if count == 1 { "" } else { "s" }),
None,
format!(" {} sel{} ", count, if count == 1 { "" } else { "s" }).into(),
);
}
fn render_primary_selection_length<F>(context: &mut RenderContext, write: F)
fn render_primary_selection_length<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let tot_sel = context.doc.selection(context.view.id).primary().len();
write(
context,
format!(" {} char{} ", tot_sel, if tot_sel == 1 { "" } else { "s" }),
None,
format!(" {} char{} ", tot_sel, if tot_sel == 1 { "" } else { "s" }).into(),
);
}
@ -393,54 +361,52 @@ fn get_position(context: &RenderContext) -> Position {
)
}
fn render_position<F>(context: &mut RenderContext, write: F)
fn render_position<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let position = get_position(context);
write(
context,
format!(" {}:{} ", position.row + 1, position.col + 1),
None,
format!(" {}:{} ", position.row + 1, position.col + 1).into(),
);
}
fn render_total_line_numbers<F>(context: &mut RenderContext, write: F)
fn render_total_line_numbers<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let total_line_numbers = context.doc.text().len_lines();
write(context, format!(" {} ", total_line_numbers), None);
write(context, format!(" {} ", total_line_numbers).into());
}
fn render_position_percentage<F>(context: &mut RenderContext, write: F)
fn render_position_percentage<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let position = get_position(context);
let maxrows = context.doc.text().len_lines();
write(
context,
format!("{}%", (position.row + 1) * 100 / maxrows),
None,
format!("{}%", (position.row + 1) * 100 / maxrows).into(),
);
}
fn render_file_encoding<F>(context: &mut RenderContext, write: F)
fn render_file_encoding<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let enc = context.doc.encoding();
if enc != encoding::UTF_8 {
write(context, format!(" {} ", enc.name()), None);
write(context, format!(" {} ", enc.name()).into());
}
}
fn render_file_line_ending<F>(context: &mut RenderContext, write: F)
fn render_file_line_ending<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
use helix_core::LineEnding::*;
let line_ending = match context.doc.line_ending {
@ -460,21 +426,21 @@ where
PS => "PS", // U+2029 -- ParagraphSeparator
};
write(context, format!(" {} ", line_ending), None);
write(context, format!(" {} ", line_ending).into());
}
fn render_file_type<F>(context: &mut RenderContext, write: F)
fn render_file_type<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let file_type = context.doc.language_name().unwrap_or(DEFAULT_LANGUAGE_NAME);
write(context, format!(" {} ", file_type), None);
write(context, format!(" {} ", file_type).into());
}
fn render_file_name<F>(context: &mut RenderContext, write: F)
fn render_file_name<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let title = {
let rel_path = context.doc.relative_path();
@ -485,12 +451,12 @@ where
format!(" {} ", path)
};
write(context, title, None);
write(context, title.into());
}
fn render_file_absolute_path<F>(context: &mut RenderContext, write: F)
fn render_file_absolute_path<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let title = {
let path = context.doc.path();
@ -501,39 +467,37 @@ where
format!(" {} ", path)
};
write(context, title, None);
write(context, title.into());
}
fn render_file_modification_indicator<F>(context: &mut RenderContext, write: F)
fn render_file_modification_indicator<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let title = (if context.doc.is_modified() {
let title = if context.doc.is_modified() {
"[+]"
} else {
" "
})
.to_string();
};
write(context, title, None);
write(context, title.into());
}
fn render_read_only_indicator<F>(context: &mut RenderContext, write: F)
fn render_read_only_indicator<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let title = if context.doc.readonly {
" [readonly] "
} else {
""
}
.to_string();
write(context, title, None);
};
write(context, title.into());
}
fn render_file_base_name<F>(context: &mut RenderContext, write: F)
fn render_file_base_name<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let title = {
let rel_path = context.doc.relative_path();
@ -544,32 +508,29 @@ where
format!(" {} ", path)
};
write(context, title, None);
write(context, title.into());
}
fn render_separator<F>(context: &mut RenderContext, write: F)
fn render_separator<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let sep = &context.editor.config().statusline.separator;
let style = context.editor.theme.get("ui.statusline.separator");
write(
context,
sep.to_string(),
Some(context.editor.theme.get("ui.statusline.separator")),
);
write(context, Span::styled(sep.to_string(), style));
}
fn render_spacer<F>(context: &mut RenderContext, write: F)
fn render_spacer<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
write(context, String::from(" "), None);
write(context, " ".into());
}
fn render_version_control<F>(context: &mut RenderContext, write: F)
fn render_version_control<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
let head = context
.doc
@ -577,14 +538,14 @@ where
.unwrap_or_default()
.to_string();
write(context, head, None);
write(context, head.into());
}
fn render_register<F>(context: &mut RenderContext, write: F)
fn render_register<'a, F>(context: &mut RenderContext<'a>, write: F)
where
F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
F: Fn(&mut RenderContext<'a>, Span<'a>) + Copy,
{
if let Some(reg) = context.editor.selected_register {
write(context, format!(" reg={} ", reg), None)
write(context, format!(" reg={} ", reg).into())
}
}