Infer expressions if there is no selection range when extracting method (#1680)

* Infer expressions if there is no selection range when extracting method

Signed-off-by: Shi Chen <chenshi@microsoft.com>

* Add the capability of inferExpresstion

Signed-off-by: Shi Chen <chenshi@microsoft.com>

* tune wording according to PR in eclipse.jdt.ls

Signed-off-by: Shi Chen <chenshi@microsoft.com>

* Tune wording to keep the name consistent with the server

Signed-off-by: Shi Chen <chenshi@microsoft.com>

Author: CsCherrYY

src/extension.ts

@@ -174,6 +174,7 @@ export function activate(context: ExtensionContext): Promise<ExtensionAPI> {
 						generateConstructorsPromptSupport: true,
 						generateDelegateMethodsPromptSupport: true,
 						advancedExtractRefactoringSupport: true,
+						inferSelectionSupport: ["extractMethod"],
 						moveRefactoringSupport: true,
 						clientHoverProvider: true,
 						clientDocumentSymbolProvider: true,

src/protocol.ts

@@ -329,6 +329,21 @@ export namespace GetRefactorEditRequest {
     export const type = new RequestType<GetRefactorEditParams, RefactorWorkspaceEdit, void, void>('java/getRefactorEdit');
 }
 
+export interface SelectionInfo {
+    name: string;
+    length: number;
+    offset: number;
+}
+
+export interface InferSelectionParams {
+    command: string;
+    context: CodeActionParams;
+}
+
+export namespace InferSelectionRequest {
+    export const type = new RequestType<InferSelectionParams, SelectionInfo[], void, void>('java/inferSelection');
+}
+
 export interface PackageNode {
     displayName: string;
     uri: string;

src/refactorAction.ts

@@ -2,10 +2,10 @@
 
 import { existsSync } from 'fs';
 import * as path from 'path';
-import { commands, ExtensionContext, Position, TextDocument, Uri, window, workspace } from 'vscode';
+import { commands, ExtensionContext, Position, QuickPickItem, TextDocument, Uri, window, workspace } from 'vscode';
 import { FormattingOptions, LanguageClient, WorkspaceEdit, CreateFile, RenameFile, DeleteFile, TextDocumentEdit, CodeActionParams, SymbolInformation } from 'vscode-languageclient';
 import { Commands as javaCommands } from './commands';
-import { GetRefactorEditRequest, MoveRequest, RefactorWorkspaceEdit, RenamePosition, GetMoveDestinationsRequest, SearchSymbols } from './protocol';
+import { GetRefactorEditRequest, MoveRequest, RefactorWorkspaceEdit, RenamePosition, GetMoveDestinationsRequest, SearchSymbols, SelectionInfo, InferSelectionRequest } from './protocol';
 
 export function registerCommands(languageClient: LanguageClient, context: ExtensionContext) {
     registerApplyRefactorCommand(languageClient, context);
@@ -70,6 +70,42 @@ function registerApplyRefactorCommand(languageClient: LanguageClient, context: E
 
                     commandArguments.push(initializeIn);
                 }
+            } else if (command === 'extractMethod') {
+                if (!params || !params.range) {
+                    return;
+                }
+                if (params.range.start.character === params.range.end.character && params.range.start.line === params.range.end.line) {
+                    const expressions: SelectionInfo[] = await languageClient.sendRequest(InferSelectionRequest.type, {
+                        command: command,
+                        context: params,
+                    });
+                    const options: IExpressionItem[] = [];
+                    for (const expression of expressions) {
+                        const extractMethodItem: IExpressionItem = {
+                            label: expression.name,
+                            length: expression.length,
+                            offset: expression.offset,
+                        };
+                        options.push(extractMethodItem);
+                    }
+                    let resultItem: IExpressionItem;
+                    if (options.length === 1) {
+                        resultItem = options[0];
+                    } else if (options.length > 1) {
+                        resultItem = await window.showQuickPick<IExpressionItem>(options, {
+                            placeHolder: "Choose the expression to extract",
+                        });
+                    }
+                    if (!resultItem) {
+                        return;
+                    }
+                    const resultExpression: SelectionInfo = {
+                        name: resultItem.label,
+                        length: resultItem.length,
+                        offset: resultItem.offset,
+                    };
+                    commandArguments.push(resultExpression);
+                }
             }
 
             const result: RefactorWorkspaceEdit = await languageClient.sendRequest(GetRefactorEditRequest.type, {
@@ -96,6 +132,12 @@ function registerApplyRefactorCommand(languageClient: LanguageClient, context: E
     }));
 }
 
+interface IExpressionItem extends QuickPickItem {
+	label: string;
+	length: number;
+	offset: number;
+}
+
 async function applyRefactorEdit(languageClient: LanguageClient, refactorEdit: RefactorWorkspaceEdit) {
     if (!refactorEdit) {
         return;