Implement text edits for inlay hints

crates/ide/src/inlay_hints.rs

@@ -14,7 +14,7 @@ use smallvec::{smallvec, SmallVec};
 use stdx::never;
 use syntax::{
     ast::{self, AstNode},
-    match_ast, NodeOrToken, SyntaxNode, TextRange,
+    match_ast, NodeOrToken, SyntaxNode, TextRange, TextSize,
 };
 use text_edit::TextEdit;
 
@@ -359,6 +359,23 @@ fn label_of_ty(
     Some(r)
 }
 
+fn ty_to_text_edit(
+    sema: &Semantics<'_, RootDatabase>,
+    node_for_hint: &SyntaxNode,
+    ty: &hir::Type,
+    offset_to_insert: TextSize,
+    prefix: String,
+) -> Option<TextEdit> {
+    let scope = sema.scope(node_for_hint)?;
+    // FIXME: Limit the length and bail out on excess somehow?
+    let rendered = ty.display_source_code(scope.db, scope.module().into(), false).ok()?;
+
+    let mut builder = TextEdit::builder();
+    builder.insert(offset_to_insert, prefix);
+    builder.insert(offset_to_insert, rendered);
+    Some(builder.finish())
+}
+
 // Feature: Inlay Hints
 //
 // rust-analyzer shows additional information inline with the source code.
@@ -566,6 +583,37 @@ mod tests {
         expect.assert_debug_eq(&inlay_hints)
     }
 
+    /// Computes inlay hints for the fixture, applies all the provided text edits and then runs
+    /// expect test.
+    #[track_caller]
+    pub(super) fn check_edit(config: InlayHintsConfig, ra_fixture: &str, expect: Expect) {
+        let (analysis, file_id) = fixture::file(ra_fixture);
+        let inlay_hints = analysis.inlay_hints(&config, file_id, None).unwrap();
+
+        let edits = inlay_hints
+            .into_iter()
+            .filter_map(|hint| hint.text_edit)
+            .reduce(|mut acc, next| {
+                acc.union(next).expect("merging text edits failed");
+                acc
+            })
+            .expect("no edit returned");
+
+        let mut actual = analysis.file_text(file_id).unwrap().to_string();
+        edits.apply(&mut actual);
+        expect.assert_eq(&actual);
+    }
+
+    #[track_caller]
+    pub(super) fn check_no_edit(config: InlayHintsConfig, ra_fixture: &str) {
+        let (analysis, file_id) = fixture::file(ra_fixture);
+        let inlay_hints = analysis.inlay_hints(&config, file_id, None).unwrap();
+
+        let edits: Vec<_> = inlay_hints.into_iter().filter_map(|hint| hint.text_edit).collect();
+
+        assert!(edits.is_empty(), "unexpected edits: {edits:?}");
+    }
+
     #[test]
     fn hints_disabled() {
         check_with_config(