4 files changed, 148 insertions, 5 deletions

diff --git a/crates/ra_ide_api/src/lib.rs b/crates/ra_ide_api/src/lib.rs
index 6546d0644..3e7cfbb54 100644
--- a/crates/ra_ide_api/src/lib.rs
+++ b/crates/ra_ide_api/src/lib.rs
@@ -38,7 +38,7 @@ mod marks;
 
 use std::sync::Arc;
 
-use ra_syntax::{SourceFile, TreeArc, TextRange, TextUnit, AstNode};
+use ra_syntax::{SourceFile, TreeArc, TextRange, TextUnit, AstNode, algo};
 use ra_text_edit::TextEdit;
 use ra_db::{
     SourceDatabase, CheckCanceled,
@@ -245,8 +245,14 @@ impl Analysis {
 
     /// Returns a syntax tree represented as `String`, for debug purposes.
     // FIXME: use a better name here.
-    pub fn syntax_tree(&self, file_id: FileId) -> String {
-        self.db.parse(file_id).syntax().debug_dump()
+    pub fn syntax_tree(&self, file_id: FileId, text_range: Option<TextRange>) -> String {
+        if let Some(text_range) = text_range {
+            let file = self.db.parse(file_id);
+            let node = algo::find_covering_node(file.syntax(), text_range);
+            node.debug_dump()
+        } else {
+            self.db.parse(file_id).syntax().debug_dump()
+        }
     }
 
     /// Returns an edit to remove all newlines in the range, cleaning up minor
diff --git a/crates/ra_ide_api/tests/test/main.rs b/crates/ra_ide_api/tests/test/main.rs
index ff1a0e46b..b0c80e255 100644
--- a/crates/ra_ide_api/tests/test/main.rs
+++ b/crates/ra_ide_api/tests/test/main.rs
@@ -1,6 +1,6 @@
 use insta::assert_debug_snapshot_matches;
 use ra_ide_api::{
-    mock_analysis::{single_file, single_file_with_position, MockAnalysis},
+    mock_analysis::{single_file, single_file_with_position, single_file_with_range, MockAnalysis},
     AnalysisChange, CrateGraph, Edition::Edition2018, Query, NavigationTarget,
     ReferenceSearchResult,
 };
@@ -138,3 +138,137 @@ mod foo {
     assert_eq!(s.name(), "FooInner");
     assert_eq!(s.container_name(), Some(&SmolStr::new("foo")));
 }
+
+#[test]
+fn test_syntax_tree_without_range() {
+    // Basic syntax
+    let (analysis, file_id) = single_file(r#"fn foo() {}"#);
+    let syn = analysis.syntax_tree(file_id, None);
+
+    assert_eq!(
+        syn.trim(),
+        r#"
+SOURCE_FILE@[0; 11)
+  FN_DEF@[0; 11)
+    FN_KW@[0; 2)
+    WHITESPACE@[2; 3)
+    NAME@[3; 6)
+      IDENT@[3; 6) "foo"
+    PARAM_LIST@[6; 8)
+      L_PAREN@[6; 7)
+      R_PAREN@[7; 8)
+    WHITESPACE@[8; 9)
+    BLOCK@[9; 11)
+      L_CURLY@[9; 10)
+      R_CURLY@[10; 11)
+    "#
+        .trim()
+    );
+
+    let (analysis, file_id) = single_file(
+        r#"
+fn test() {
+    assert!("
+    fn foo() {
+    }
+    ", "");
+}"#
+        .trim(),
+    );
+    let syn = analysis.syntax_tree(file_id, None);
+
+    assert_eq!(
+        syn.trim(),
+        r#"
+SOURCE_FILE@[0; 60)
+  FN_DEF@[0; 60)
+    FN_KW@[0; 2)
+    WHITESPACE@[2; 3)
+    NAME@[3; 7)
+      IDENT@[3; 7) "test"
+    PARAM_LIST@[7; 9)
+      L_PAREN@[7; 8)
+      R_PAREN@[8; 9)
+    WHITESPACE@[9; 10)
+    BLOCK@[10; 60)
+      L_CURLY@[10; 11)
+      WHITESPACE@[11; 16)
+      EXPR_STMT@[16; 58)
+        MACRO_CALL@[16; 57)
+          PATH@[16; 22)
+            PATH_SEGMENT@[16; 22)
+              NAME_REF@[16; 22)
+                IDENT@[16; 22) "assert"
+          EXCL@[22; 23)
+          TOKEN_TREE@[23; 57)
+            L_PAREN@[23; 24)
+            STRING@[24; 52)
+            COMMA@[52; 53)
+            WHITESPACE@[53; 54)
+            STRING@[54; 56)
+            R_PAREN@[56; 57)
+        SEMI@[57; 58)
+      WHITESPACE@[58; 59)
+      R_CURLY@[59; 60)
+    "#
+        .trim()
+    );
+}
+
+#[test]
+fn test_syntax_tree_with_range() {
+    let (analysis, range) = single_file_with_range(r#"<|>fn foo() {}<|>"#.trim());
+    let syn = analysis.syntax_tree(range.file_id, Some(range.range));
+
+    assert_eq!(
+        syn.trim(),
+        r#"
+FN_DEF@[0; 11)
+  FN_KW@[0; 2)
+  WHITESPACE@[2; 3)
+  NAME@[3; 6)
+    IDENT@[3; 6) "foo"
+  PARAM_LIST@[6; 8)
+    L_PAREN@[6; 7)
+    R_PAREN@[7; 8)
+  WHITESPACE@[8; 9)
+  BLOCK@[9; 11)
+    L_CURLY@[9; 10)
+    R_CURLY@[10; 11)
+    "#
+        .trim()
+    );
+
+    let (analysis, range) = single_file_with_range(
+        r#"fn test() {
+    <|>assert!("
+    fn foo() {
+    }
+    ", "");<|>
+}"#
+        .trim(),
+    );
+    let syn = analysis.syntax_tree(range.file_id, Some(range.range));
+
+    assert_eq!(
+        syn.trim(),
+        r#"
+EXPR_STMT@[16; 58)
+  MACRO_CALL@[16; 57)
+    PATH@[16; 22)
+      PATH_SEGMENT@[16; 22)
+        NAME_REF@[16; 22)
+          IDENT@[16; 22) "assert"
+    EXCL@[22; 23)
+    TOKEN_TREE@[23; 57)
+      L_PAREN@[23; 24)
+      STRING@[24; 52)
+      COMMA@[52; 53)
+      WHITESPACE@[53; 54)
+      STRING@[54; 56)
+      R_PAREN@[56; 57)
+  SEMI@[57; 58)
+    "#
+        .trim()
+    );
+}
diff --git a/crates/ra_lsp_server/src/main_loop/handlers.rs b/crates/ra_lsp_server/src/main_loop/handlers.rs
index dce6fcc67..89e96a33a 100644
--- a/crates/ra_lsp_server/src/main_loop/handlers.rs
+++ b/crates/ra_lsp_server/src/main_loop/handlers.rs
@@ -32,7 +32,9 @@ pub fn handle_analyzer_status(world: ServerWorld, _: ()) -> Result<String> {
 
 pub fn handle_syntax_tree(world: ServerWorld, params: req::SyntaxTreeParams) -> Result<String> {
     let id = params.text_document.try_conv_with(&world)?;
-    let res = world.analysis().syntax_tree(id);
+    let line_index = world.analysis().file_line_index(id);
+    let text_range = params.range.map(|p| p.conv_with(&line_index));
+    let res = world.analysis().syntax_tree(id, text_range);
     Ok(res)
 }
 
diff --git a/crates/ra_lsp_server/src/req.rs b/crates/ra_lsp_server/src/req.rs
index e224ede80..5c589f969 100644
--- a/crates/ra_lsp_server/src/req.rs
+++ b/crates/ra_lsp_server/src/req.rs
@@ -39,6 +39,7 @@ impl Request for SyntaxTree {
 #[serde(rename_all = "camelCase")]
 pub struct SyntaxTreeParams {
     pub text_document: TextDocumentIdentifier,
+    pub range: Option<Range>,
 }
 
 pub enum ExtendSelection {}