LSP: Support textDocument/prepareRename (#6103)

* LSP: Support textDocument/prepareRename

'textDocument/prepareRename' can be used by the client to ask the
server the range of the symbol under the cursor which would be changed
by a subsequent call to 'textDocument/rename' with that position.

We can use this information to fill the prompt with an accurate prefill
which can improve the UX for renaming symbols when the symbol doesn't
align with the "word" textobject. (We currently use the "word"
textobject as a default value for the prompt.)

Co-authored-by: Michael Davis <mcarsondavis@gmail.com>

* clippy fixes

* rustfmt

* Update helix-term/src/commands/lsp.rs

Co-authored-by: Michael Davis <mcarsondavis@gmail.com>

* Update helix-term/src/commands/lsp.rs

Co-authored-by: Michael Davis <mcarsondavis@gmail.com>

* fix clippy from suggestions

* Update helix-term/src/commands/lsp.rs

Co-authored-by: Michael Davis <mcarsondavis@gmail.com>

---------

Co-authored-by: Michael Davis <mcarsondavis@gmail.com>

1 files changed, 24 insertions, 1 deletions

diff --git a/helix-lsp/src/client.rs b/helix-lsp/src/client.rs
index 95f3ea34..9fa118fb 100644
--- a/helix-lsp/src/client.rs
+++ b/helix-lsp/src/client.rs
@@ -359,7 +359,7 @@ impl Client {
                     }),
                     rename: Some(lsp::RenameClientCapabilities {
                         dynamic_registration: Some(false),
-                        prepare_support: Some(false),
+                        prepare_support: Some(true),
                         prepare_support_default_behavior: None,
                         honors_change_annotations: Some(false),
                     }),
@@ -1034,6 +1034,29 @@ impl Client {
         Some(self.call::<lsp::request::DocumentSymbolRequest>(params))
     }
 
+    pub fn prepare_rename(
+        &self,
+        text_document: lsp::TextDocumentIdentifier,
+        position: lsp::Position,
+    ) -> Option<impl Future<Output = Result<Value>>> {
+        let capabilities = self.capabilities.get().unwrap();
+
+        match capabilities.rename_provider {
+            Some(lsp::OneOf::Right(lsp::RenameOptions {
+                prepare_provider: Some(true),
+                ..
+            })) => (),
+            _ => return None,
+        }
+
+        let params = lsp::TextDocumentPositionParams {
+            text_document,
+            position,
+        };
+
+        Some(self.call::<lsp::request::PrepareRenameRequest>(params))
+    }
+
     // empty string to get all symbols
     pub fn workspace_symbols(&self, query: String) -> Option<impl Future<Output = Result<Value>>> {
         let capabilities = self.capabilities.get().unwrap();