From b120515613ba24aff224d093b28d85049c774cad Mon Sep 17 00:00:00 2001
From: Blaž Hrastnik
Date: Sat, 19 Sep 2020 11:55:42 +0900
Subject: Range based highlight_iter. Only works on limiting the start right
 now

---
 helix-core/src/syntax.rs | 12 ++++++++++--
 helix-term/src/editor.rs | 13 ++++++++++++-
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/helix-core/src/syntax.rs b/helix-core/src/syntax.rs
index 1eb15633..8b55fc3e 100644
--- a/helix-core/src/syntax.rs
+++ b/helix-core/src/syntax.rs
@@ -77,6 +77,7 @@ impl Syntax {
     pub fn highlight_iter<'a>(
         &'a mut self,
         source: &'a [u8],
+        range: Option<std::ops::Range<usize>>,
         cancellation_flag: Option<&'a AtomicUsize>,
         mut injection_callback: impl FnMut(&str) -> Option<&'a HighlightConfiguration> + 'a,
     ) -> Result<impl Iterator<Item = Result<HighlightEvent, Error>> + 'a, Error> {
@@ -90,6 +91,12 @@ impl Syntax {
         let query_ref = unsafe { mem::transmute::<_, &'static mut Query>(&mut self.config.query) };
         let config_ref =
             unsafe { mem::transmute::<_, &'static HighlightConfiguration>(&self.config) };
+
+        // TODO: if reusing cursors this might need resetting
+        if let Some(range) = &range {
+            cursor_ref.set_byte_range(range.start, range.end);
+        }
+
         let captures = cursor_ref
             .captures(query_ref, tree_ref.root_node(), move |n: Node| {
                 &source[n.byte_range()]
@@ -119,7 +126,7 @@ impl Syntax {
 
         let mut result = HighlightIter {
             source,
-            byte_offset: 0,
+            byte_offset: range.map(|r| r.start).unwrap_or(0), // TODO: simplify
             injection_callback,
             cancellation_flag,
             highlighter: self,
@@ -1098,7 +1105,8 @@ where
                 layer.highlight_end_stack.pop();
                 return self.emit_event(end_byte, Some(HighlightEvent::HighlightEnd));
             } else {
-                return self.emit_event(self.source.len(), None);
+                // return self.emit_event(self.source.len(), None);
+                return None;
             };
 
             let (mut match_, capture_index) = layer.captures.next().unwrap();
diff --git a/helix-term/src/editor.rs b/helix-term/src/editor.rs
index ed2d3a13..e1288e07 100644
--- a/helix-term/src/editor.rs
+++ b/helix-term/src/editor.rs
@@ -104,13 +104,24 @@ impl Editor {
                     state.doc().len_lines() - 1,
                 );
 
+                let range = {
+                    // calculate viewport byte ranges
+                    let start = state.doc().line_to_byte(self.first_line.into());
+                    let end = state.doc().line_to_byte(last_line)
+                        + state.doc().line(last_line).len_bytes();
+
+                    start..end
+                };
+
+                // TODO: range doesn't actually restrict source, just highlight range
+
                 // TODO: cache highlight results
                 // TODO: only recalculate when state.doc is actually modified
                 let highlights: Vec<_> = state
                     .syntax
                     .as_mut()
                     .unwrap()
-                    .highlight_iter(source_code.as_bytes(), None, |_| None)
+                    .highlight_iter(source_code.as_bytes(), Some(range), None, |_| None)
                     .unwrap()
                     .collect(); // TODO: we collect here to avoid double borrow, fix later
 
-- 
cgit v1.2.3-70-g09d2