Prefer RopeSlice to &Rope in helix_core::syntax

Pascal and I discussed this and we think it's generally better to
take a 'RopeSlice' rather than a '&Rope'. The code block rendering
function in the markdown component module is a good example for how
this can be useful: we can remove an allocation of a rope and instead
directly turn a '&str' into a 'RopeSlice' which is very cheap.

A change to prefer 'RopeSlice' to '&Rope' whenever the rope isn't
modified would be nice, but it would be a very large diff (around 500+
500-). Starting off with just the syntax functions seems like a nice
middle-ground, and we can remove a Rope allocation because of it.

Co-authored-by: Pascal Kuthe <pascal.kuthe@semimod.de>

2 files changed, 7 insertions, 7 deletions

diff --git a/helix-term/src/ui/markdown.rs b/helix-term/src/ui/markdown.rs
index def64434..cb2abf68 100644
--- a/helix-term/src/ui/markdown.rs
+++ b/helix-term/src/ui/markdown.rs
@@ -10,7 +10,7 @@ use pulldown_cmark::{CodeBlockKind, Event, HeadingLevel, Options, Parser, Tag};
 
 use helix_core::{
     syntax::{self, HighlightEvent, InjectionLanguageMarker, Syntax},
-    Rope,
+    RopeSlice,
 };
 use helix_view::{
     graphics::{Margin, Rect, Style},
@@ -45,13 +45,13 @@ pub fn highlighted_code_block<'a>(
         None => return styled_multiline_text(text, code_style),
     };
 
-    let rope = Rope::from(text.as_ref());
+    let ropeslice = RopeSlice::from(text);
     let syntax = config_loader
         .language_configuration_for_injection_string(&InjectionLanguageMarker::Name(
             language.into(),
         ))
         .and_then(|config| config.highlight_config(theme.scopes()))
-        .and_then(|config| Syntax::new(&rope, config, Arc::clone(&config_loader)));
+        .and_then(|config| Syntax::new(ropeslice, config, Arc::clone(&config_loader)));
 
     let syntax = match syntax {
         Some(s) => s,
@@ -59,7 +59,7 @@ pub fn highlighted_code_block<'a>(
     };
 
     let highlight_iter = syntax
-        .highlight_iter(rope.slice(..), None, None)
+        .highlight_iter(ropeslice, None, None)
         .map(|e| e.unwrap());
     let highlight_iter: Box<dyn Iterator<Item = HighlightEvent>> =
         if let Some(spans) = additional_highlight_spans {
diff --git a/helix-term/src/ui/picker.rs b/helix-term/src/ui/picker.rs
index 13746cfc..4605e2f1 100644
--- a/helix-term/src/ui/picker.rs
+++ b/helix-term/src/ui/picker.rs
@@ -453,9 +453,9 @@ impl<T: Item + 'static> Picker<T> {
                 let text = doc.text().clone();
                 let loader = cx.editor.syn_loader.clone();
                 let job = tokio::task::spawn_blocking(move || {
-                    let syntax = language_config
-                        .highlight_config(&loader.scopes())
-                        .and_then(|highlight_config| Syntax::new(&text, highlight_config, loader));
+                    let syntax = language_config.highlight_config(&loader.scopes()).and_then(
+                        |highlight_config| Syntax::new(text.slice(..), highlight_config, loader),
+                    );
                     let callback = move |editor: &mut Editor, compositor: &mut Compositor| {
                         let Some(syntax) = syntax else {
                             log::info!("highlighting picker item failed");