2 files changed, 31 insertions, 23 deletions

diff --git a/crates/rust-analyzer/src/lsp_utils.rs b/crates/rust-analyzer/src/lsp_utils.rs
index 0bc3ff115..d4cc9dd04 100644
--- a/crates/rust-analyzer/src/lsp_utils.rs
+++ b/crates/rust-analyzer/src/lsp_utils.rs
@@ -1,5 +1,5 @@
 //! Utilities for LSP-related boilerplate code.
-use std::{error::Error, ops::Range};
+use std::{borrow::Cow, error::Error, ops::Range};
 
 use lsp_server::Notification;
 use ra_db::Canceled;
@@ -84,8 +84,8 @@ impl GlobalState {
 pub(crate) fn apply_document_changes(
     old_text: &mut String,
     content_changes: Vec<lsp_types::TextDocumentContentChangeEvent>,
+    mut line_index: Cow<'_, LineIndex>,
 ) {
-    let mut line_index = LineIndex::new(old_text);
     // The changes we got must be applied sequentially, but can cross lines so we
     // have to keep our line index updated.
     // Some clients (e.g. Code) sort the ranges in reverse. As an optimization, we
@@ -110,7 +110,7 @@ pub(crate) fn apply_document_changes(
         match change.range {
             Some(range) => {
                 if !index_valid.covers(range.end.line) {
-                    line_index = LineIndex::new(&old_text);
+                    line_index = Cow::Owned(LineIndex::new(old_text));
                 }
                 index_valid = IndexValid::UpToLineExclusive(range.start.line);
                 let range = from_proto::text_range(&line_index, range);
@@ -145,10 +145,15 @@ mod tests {
             };
         }
 
+        fn run(text: &mut String, changes: Vec<TextDocumentContentChangeEvent>) {
+            let line_index = Cow::Owned(LineIndex::new(&text));
+            super::apply_document_changes(text, changes, line_index);
+        }
+
         let mut text = String::new();
-        apply_document_changes(&mut text, vec![]);
+        run(&mut text, vec![]);
         assert_eq!(text, "");
-        apply_document_changes(
+        run(
             &mut text,
             vec![TextDocumentContentChangeEvent {
                 range: None,
@@ -157,39 +162,36 @@ mod tests {
             }],
         );
         assert_eq!(text, "the");
-        apply_document_changes(&mut text, c![0, 3; 0, 3 => " quick"]);
+        run(&mut text, c![0, 3; 0, 3 => " quick"]);
         assert_eq!(text, "the quick");
-        apply_document_changes(&mut text, c![0, 0; 0, 4 => "", 0, 5; 0, 5 => " foxes"]);
+        run(&mut text, c![0, 0; 0, 4 => "", 0, 5; 0, 5 => " foxes"]);
         assert_eq!(text, "quick foxes");
-        apply_document_changes(&mut text, c![0, 11; 0, 11 => "\ndream"]);
+        run(&mut text, c![0, 11; 0, 11 => "\ndream"]);
         assert_eq!(text, "quick foxes\ndream");
-        apply_document_changes(&mut text, c![1, 0; 1, 0 => "have "]);
+        run(&mut text, c![1, 0; 1, 0 => "have "]);
         assert_eq!(text, "quick foxes\nhave dream");
-        apply_document_changes(
-            &mut text,
-            c![0, 0; 0, 0 => "the ", 1, 4; 1, 4 => " quiet", 1, 16; 1, 16 => "s\n"],
-        );
+        run(&mut text, c![0, 0; 0, 0 => "the ", 1, 4; 1, 4 => " quiet", 1, 16; 1, 16 => "s\n"]);
         assert_eq!(text, "the quick foxes\nhave quiet dreams\n");
-        apply_document_changes(&mut text, c![0, 15; 0, 15 => "\n", 2, 17; 2, 17 => "\n"]);
+        run(&mut text, c![0, 15; 0, 15 => "\n", 2, 17; 2, 17 => "\n"]);
         assert_eq!(text, "the quick foxes\n\nhave quiet dreams\n\n");
-        apply_document_changes(
+        run(
             &mut text,
             c![1, 0; 1, 0 => "DREAM", 2, 0; 2, 0 => "they ", 3, 0; 3, 0 => "DON'T THEY?"],
         );
         assert_eq!(text, "the quick foxes\nDREAM\nthey have quiet dreams\nDON'T THEY?\n");
-        apply_document_changes(&mut text, c![0, 10; 1, 5 => "", 2, 0; 2, 12 => ""]);
+        run(&mut text, c![0, 10; 1, 5 => "", 2, 0; 2, 12 => ""]);
         assert_eq!(text, "the quick \nthey have quiet dreams\n");
 
         text = String::from("❤️");
-        apply_document_changes(&mut text, c![0, 0; 0, 0 => "a"]);
+        run(&mut text, c![0, 0; 0, 0 => "a"]);
         assert_eq!(text, "a❤️");
 
         text = String::from("a\nb");
-        apply_document_changes(&mut text, c![0, 1; 1, 0 => "\nțc", 0, 1; 1, 1 => "d"]);
+        run(&mut text, c![0, 1; 1, 0 => "\nțc", 0, 1; 1, 1 => "d"]);
         assert_eq!(text, "adcb");
 
         text = String::from("a\nb");
-        apply_document_changes(&mut text, c![0, 1; 1, 0 => "ț\nc", 0, 2; 0, 2 => "c"]);
+        run(&mut text, c![0, 1; 1, 0 => "ț\nc", 0, 2; 0, 2 => "c"]);
         assert_eq!(text, "ațc\ncb");
     }
 }
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index 51626fcd5..0ace4cb45 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -1,13 +1,14 @@
 //! The main loop of `rust-analyzer` responsible for dispatching LSP
 //! requests/replies and notifications back to the client.
 use std::{
+    borrow::Cow,
     env, fmt, panic,
     time::{Duration, Instant},
 };
 
 use crossbeam_channel::{select, Receiver};
 use lsp_server::{Connection, Notification, Request, Response};
-use lsp_types::notification::Notification as _;
+use lsp_types::{notification::Notification as _, DidChangeTextDocumentParams};
 use ra_db::VfsPath;
 use ra_ide::{Canceled, FileId};
 use ra_prof::profile;
@@ -421,15 +422,20 @@ impl GlobalState {
             })?
             .on::<lsp_types::notification::DidChangeTextDocument>(|this, params| {
                 if let Ok(path) = from_proto::vfs_path(&params.text_document.uri) {
-                    let doc = this.mem_docs.get_mut(&path).unwrap();
+                    let DidChangeTextDocumentParams { text_document, content_changes } = params;
                     let vfs = &mut this.vfs.write().0;
+                    let world = this.snapshot();
                     let file_id = vfs.file_id(&path).unwrap();
+
+                    // let file_id = vfs.file_id(&path).unwrap();
                     let mut text = String::from_utf8(vfs.file_contents(file_id).to_vec()).unwrap();
-                    apply_document_changes(&mut text, params.content_changes);
+                    let line_index = world.analysis.file_line_index(file_id)?;
+                    apply_document_changes(&mut text, content_changes, Cow::Borrowed(&line_index));
 
                     // The version passed in DidChangeTextDocument is the version after all edits are applied
                     // so we should apply it before the vfs is notified.
-                    doc.version = params.text_document.version;
+                    let doc = this.mem_docs.get_mut(&path).unwrap();
+                    doc.version = text_document.version;
 
                     vfs.set_file_contents(path.clone(), Some(text.into_bytes()));
                 }