6 files changed, 92 insertions, 16 deletions

diff --git a/crates/ra_ide/src/lib.rs b/crates/ra_ide/src/lib.rs
index 82e10bc7e..c02bb08a0 100644
--- a/crates/ra_ide/src/lib.rs
+++ b/crates/ra_ide/src/lib.rs
@@ -430,6 +430,13 @@ impl Analysis {
         self.with_db(|db| syntax_highlighting::highlight(db, file_id))
     }
 
+    /// Computes syntax highlighting for the given file range.
+    pub fn highlight_range(&self, frange: FileRange) -> Cancelable<Vec<HighlightedRange>> {
+        self.with_db(|db| {
+            syntax_highlighting::highlight_range(db, frange.file_id, Some(frange.range))
+        })
+    }
+
     /// Computes syntax highlighting for the given file.
     pub fn highlight_as_html(&self, file_id: FileId, rainbow: bool) -> Cancelable<String> {
         self.with_db(|db| syntax_highlighting::highlight_as_html(db, file_id, rainbow))
diff --git a/crates/ra_ide/src/syntax_highlighting.rs b/crates/ra_ide/src/syntax_highlighting.rs
index 812229b4e..22c84561f 100644
--- a/crates/ra_ide/src/syntax_highlighting.rs
+++ b/crates/ra_ide/src/syntax_highlighting.rs
@@ -5,8 +5,8 @@ use ra_db::SourceDatabase;
 use ra_ide_db::{defs::NameDefinition, RootDatabase};
 use ra_prof::profile;
 use ra_syntax::{
-    ast, AstNode, Direction, SyntaxElement, SyntaxKind, SyntaxKind::*, SyntaxToken, TextRange,
-    WalkEvent, T,
+    ast, AstNode, Direction, NodeOrToken, SyntaxElement, SyntaxKind, SyntaxKind::*, SyntaxToken,
+    TextRange, WalkEvent, T,
 };
 use rustc_hash::FxHashMap;
 
@@ -69,6 +69,16 @@ fn is_control_keyword(kind: SyntaxKind) -> bool {
 
 pub(crate) fn highlight(db: &RootDatabase, file_id: FileId) -> Vec<HighlightedRange> {
     let _p = profile("highlight");
+    highlight_range(db, file_id, None)
+}
+
+pub(crate) fn highlight_range(
+    db: &RootDatabase,
+    file_id: FileId,
+    range: Option<TextRange>,
+) -> Vec<HighlightedRange> {
+    let _p = profile("highlight_range");
+
     let parse = db.parse(file_id);
     let root = parse.tree().syntax().clone();
 
@@ -79,6 +89,15 @@ pub(crate) fn highlight(db: &RootDatabase, file_id: FileId) -> Vec<HighlightedRa
 
     let mut in_macro_call = None;
 
+    // Determine the root based on the range
+    let root = match range {
+        Some(range) => match root.covering_element(range) {
+            NodeOrToken::Node(node) => node,
+            NodeOrToken::Token(token) => token.parent(),
+        },
+        None => root,
+    };
+
     for event in root.preorder_with_tokens() {
         match event {
             WalkEvent::Enter(node) => match node.kind() {
@@ -374,7 +393,10 @@ mod tests {
 
     use test_utils::{assert_eq_text, project_dir, read_text};
 
-    use crate::mock_analysis::{single_file, MockAnalysis};
+    use crate::{
+        mock_analysis::{single_file, MockAnalysis},
+        FileRange, TextRange,
+    };
 
     #[test]
     fn test_highlighting() {
@@ -475,4 +497,25 @@ fn bar() {
         let _ = host.analysis().highlight(file_id).unwrap();
         // eprintln!("elapsed: {:?}", t.elapsed());
     }
+
+    #[test]
+    fn test_ranges() {
+        let (analysis, file_id) = single_file(
+            r#"
+            #[derive(Clone, Debug)]
+            struct Foo {
+                pub x: i32,
+                pub y: i32,
+            }"#,
+        );
+
+        let highlights = &analysis
+            .highlight_range(FileRange {
+                file_id,
+                range: TextRange::offset_len(82.into(), 1.into()), // "x"
+            })
+            .unwrap();
+
+        assert_eq!(highlights[0].tag, "field");
+    }
 }
diff --git a/crates/rust-analyzer/src/caps.rs b/crates/rust-analyzer/src/caps.rs
index 638987ee8..db82eeb1c 100644
--- a/crates/rust-analyzer/src/caps.rs
+++ b/crates/rust-analyzer/src/caps.rs
@@ -7,9 +7,9 @@ use lsp_types::{
     CompletionOptions, DocumentOnTypeFormattingOptions, FoldingRangeProviderCapability,
     ImplementationProviderCapability, RenameOptions, RenameProviderCapability, SaveOptions,
     SelectionRangeProviderCapability, SemanticTokensDocumentProvider, SemanticTokensLegend,
-    SemanticTokensOptions, SemanticTokensServerCapabilities, ServerCapabilities,
-    SignatureHelpOptions, TextDocumentSyncCapability, TextDocumentSyncKind,
-    TextDocumentSyncOptions, TypeDefinitionProviderCapability, WorkDoneProgressOptions,
+    SemanticTokensOptions, ServerCapabilities, SignatureHelpOptions, TextDocumentSyncCapability,
+    TextDocumentSyncKind, TextDocumentSyncOptions, TypeDefinitionProviderCapability,
+    WorkDoneProgressOptions,
 };
 
 pub fn server_capabilities() -> ServerCapabilities {
@@ -60,7 +60,7 @@ pub fn server_capabilities() -> ServerCapabilities {
         execute_command_provider: None,
         workspace: None,
         call_hierarchy_provider: Some(CallHierarchyServerCapability::Simple(true)),
-        semantic_tokens_provider: Some(SemanticTokensServerCapabilities::SemanticTokensOptions(
+        semantic_tokens_provider: Some(
             SemanticTokensOptions {
                 legend: SemanticTokensLegend {
                     token_types: semantic_tokens::supported_token_types().iter().cloned().collect(),
@@ -71,9 +71,11 @@ pub fn server_capabilities() -> ServerCapabilities {
                 },
 
                 document_provider: Some(SemanticTokensDocumentProvider::Bool(true)),
-                ..SemanticTokensOptions::default()
-            },
-        )),
+                range_provider: Some(true),
+                work_done_progress_options: Default::default(),
+            }
+            .into(),
+        ),
         experimental: Default::default(),
     }
 }
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index 6e9e604a6..2b25f5443 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -527,8 +527,9 @@ fn on_request(
         .on::<req::CallHierarchyPrepare>(handlers::handle_call_hierarchy_prepare)?
         .on::<req::CallHierarchyIncomingCalls>(handlers::handle_call_hierarchy_incoming)?
         .on::<req::CallHierarchyOutgoingCalls>(handlers::handle_call_hierarchy_outgoing)?
-        .on::<req::Ssr>(handlers::handle_ssr)?
         .on::<req::SemanticTokensRequest>(handlers::handle_semantic_tokens)?
+        .on::<req::SemanticTokensRangeRequest>(handlers::handle_semantic_tokens_range)?
+        .on::<req::Ssr>(handlers::handle_ssr)?
         .finish();
     Ok(())
 }
diff --git a/crates/rust-analyzer/src/main_loop/handlers.rs b/crates/rust-analyzer/src/main_loop/handlers.rs
index e13e7c95a..267edd578 100644
--- a/crates/rust-analyzer/src/main_loop/handlers.rs
+++ b/crates/rust-analyzer/src/main_loop/handlers.rs
@@ -17,8 +17,8 @@ use lsp_types::{
     Diagnostic, DocumentFormattingParams, DocumentHighlight, DocumentSymbol, FoldingRange,
     FoldingRangeParams, Hover, HoverContents, Location, MarkupContent, MarkupKind, Position,
     PrepareRenameResponse, Range, RenameParams, SemanticTokenModifier, SemanticTokenType,
-    SemanticTokens, SemanticTokensParams, SemanticTokensResult, SymbolInformation,
-    TextDocumentIdentifier, TextEdit, WorkspaceEdit,
+    SemanticTokens, SemanticTokensParams, SemanticTokensRangeParams, SemanticTokensRangeResult,
+    SemanticTokensResult, SymbolInformation, TextDocumentIdentifier, TextEdit, WorkspaceEdit,
 };
 use ra_ide::{
     AssistId, FileId, FilePosition, FileRange, Query, RangeInfo, Runnable, RunnableKind,
@@ -1092,3 +1092,25 @@ pub fn handle_semantic_tokens(
 
     Ok(Some(tokens.into()))
 }
+
+pub fn handle_semantic_tokens_range(
+    world: WorldSnapshot,
+    params: SemanticTokensRangeParams,
+) -> Result<Option<SemanticTokensRangeResult>> {
+    let _p = profile("handle_semantic_tokens_range");
+
+    let frange = (&params.text_document, params.range).try_conv_with(&world)?;
+    let line_index = world.analysis().file_line_index(frange.file_id)?;
+
+    let mut builder = SemanticTokensBuilder::default();
+
+    for h in world.analysis().highlight_range(frange)?.into_iter() {
+        let type_and_modifiers: (SemanticTokenType, Vec<SemanticTokenModifier>) = h.tag.conv();
+        let (token_type, token_modifiers) = type_and_modifiers.conv();
+        builder.push(h.range.conv_with(&line_index), token_type, token_modifiers);
+    }
+
+    let tokens = SemanticTokens { data: builder.build(), ..Default::default() };
+
+    Ok(Some(tokens.into()))
+}
diff --git a/crates/rust-analyzer/src/req.rs b/crates/rust-analyzer/src/req.rs
index 3734899bc..642ac41ac 100644
--- a/crates/rust-analyzer/src/req.rs
+++ b/crates/rust-analyzer/src/req.rs
@@ -12,9 +12,10 @@ pub use lsp_types::{
     DocumentSymbolResponse, FileSystemWatcher, Hover, InitializeResult, MessageType,
     PartialResultParams, ProgressParams, ProgressParamsValue, ProgressToken,
     PublishDiagnosticsParams, ReferenceParams, Registration, RegistrationParams, SelectionRange,
-    SelectionRangeParams, SemanticTokensParams, SemanticTokensResult, ServerCapabilities,
-    ShowMessageParams, SignatureHelp, SymbolKind, TextDocumentEdit, TextDocumentPositionParams,
-    TextEdit, WorkDoneProgressParams, WorkspaceEdit, WorkspaceSymbolParams,
+    SelectionRangeParams, SemanticTokensParams, SemanticTokensRangeParams,
+    SemanticTokensRangeResult, SemanticTokensResult, ServerCapabilities, ShowMessageParams,
+    SignatureHelp, SymbolKind, TextDocumentEdit, TextDocumentPositionParams, TextEdit,
+    WorkDoneProgressParams, WorkspaceEdit, WorkspaceSymbolParams,
 };
 
 pub enum AnalyzerStatus {}