2 files changed, 52 insertions, 3 deletions

diff --git a/crates/ra_ide_db/src/line_index.rs b/crates/ra_ide_db/src/line_index.rs
index af7b759e5..b9db5c276 100644
--- a/crates/ra_ide_db/src/line_index.rs
+++ b/crates/ra_ide_db/src/line_index.rs
@@ -1,7 +1,8 @@
 //! `LineIndex` maps flat `TextUnit` offsets into `(Line, Column)`
 //! representation.
+use std::iter;
 
-use ra_syntax::TextUnit;
+use ra_syntax::{TextRange, TextUnit};
 use rustc_hash::FxHashMap;
 use superslice::Ext;
 
@@ -87,6 +88,19 @@ impl LineIndex {
         self.newlines[line_col.line as usize] + col
     }
 
+    pub fn lines(&self, range: TextRange) -> impl Iterator<Item = TextRange> + '_ {
+        let lo = self.newlines.lower_bound(&range.start());
+        let hi = self.newlines.upper_bound(&range.end());
+        let all = iter::once(range.start())
+            .chain(self.newlines[lo..hi].iter().copied())
+            .chain(iter::once(range.end()));
+
+        all.clone()
+            .zip(all.skip(1))
+            .map(|(lo, hi)| TextRange::from_to(lo, hi))
+            .filter(|it| !it.is_empty())
+    }
+
     fn utf8_to_utf16_col(&self, line: u32, mut col: TextUnit) -> usize {
         if let Some(utf16_chars) = self.utf16_lines.get(&line) {
             let mut correction = TextUnit::from_usize(0);
@@ -221,4 +235,32 @@ const C: char = \"メ メ\";
 
         assert_eq!(col_index.utf16_to_utf8_col(2, 15), TextUnit::from_usize(15));
     }
+
+    #[test]
+    fn test_splitlines() {
+        fn r(lo: u32, hi: u32) -> TextRange {
+            TextRange::from_to(lo.into(), hi.into())
+        }
+
+        let text = "a\nbb\nccc\n";
+        let line_index = LineIndex::new(text);
+
+        let actual = line_index.lines(r(0, 9)).collect::<Vec<_>>();
+        let expected = vec![r(0, 2), r(2, 5), r(5, 9)];
+        assert_eq!(actual, expected);
+
+        let text = "";
+        let line_index = LineIndex::new(text);
+
+        let actual = line_index.lines(r(0, 0)).collect::<Vec<_>>();
+        let expected = vec![];
+        assert_eq!(actual, expected);
+
+        let text = "\n";
+        let line_index = LineIndex::new(text);
+
+        let actual = line_index.lines(r(0, 1)).collect::<Vec<_>>();
+        let expected = vec![r(0, 1)];
+        assert_eq!(actual, expected)
+    }
 }
diff --git a/crates/rust-analyzer/src/main_loop/handlers.rs b/crates/rust-analyzer/src/main_loop/handlers.rs
index 9ed53169c..6f517760f 100644
--- a/crates/rust-analyzer/src/main_loop/handlers.rs
+++ b/crates/rust-analyzer/src/main_loop/handlers.rs
@@ -1078,13 +1078,20 @@ pub fn handle_semantic_tokens(
     let _p = profile("handle_semantic_tokens");
 
     let file_id = params.text_document.try_conv_with(&world)?;
+    let text = world.analysis().file_text(file_id)?;
     let line_index = world.analysis().file_line_index(file_id)?;
 
     let mut builder = SemanticTokensBuilder::default();
 
     for highlight_range in world.analysis().highlight(file_id)?.into_iter() {
-        let (token_type, token_modifiers) = highlight_range.highlight.conv();
-        builder.push(highlight_range.range.conv_with(&line_index), token_type, token_modifiers);
+        let (token_index, modifier_bitset) = highlight_range.highlight.conv();
+        for mut range in line_index.lines(highlight_range.range) {
+            if text[range].ends_with('\n') {
+                range = TextRange::from_to(range.start(), range.end() - TextUnit::of_char('\n'));
+            }
+            let range = range.conv_with(&line_index);
+            builder.push(range, token_index, modifier_bitset);
+        }
     }
 
     let tokens = SemanticTokens { data: builder.build(), ..Default::default() };