Goimpl implementation

package.json

@@ -129,6 +129,11 @@
         "title": "Go: Generate unit tests for function",
         "description": "Generates unit tests for the selected function in the current file"
       },
+      {
+        "command": "go.impl.cursor",
+        "title": "Go: Generate interface stub",
+        "description": "Generates and inserts stub methods for implementing the provided interface at the cursor."
+      },
       {
         "command": "go.import.add",
         "title": "Go: Add Import",
@@ -730,4 +735,4 @@
       ]
     }
   }
-}
+}

src/goImpl.ts

@@ -0,0 +1,69 @@
+/*---------------------------------------------------------
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ * Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------*/
+
+'use strict';
+
+import vscode = require('vscode');
+import cp = require('child_process');
+import { getBinPath } from './util';
+import { promptForMissingTool } from './goInstallTools';
+
+interface GoImplInput {
+	receiver: string;
+	interface: string;
+}
+
+// Supports only passing interface, see TODO in implCursor to finish
+const inputRegex = /^(\w+\ \*?\w+\ )?([\w.]+)$/;
+
+export function implCursor() {
+	let cursor = vscode.window.activeTextEditor.selection;
+	return vscode.window.showInputBox({
+		placeHolder: 'f *File io.Closer',
+		prompt: 'What interface do you want to implement?'
+	}).then(implInput => {
+		if (typeof implInput === 'undefined') {
+			return;
+		}
+		const matches = implInput.match(inputRegex);
+		if (!matches) {
+			vscode.window.showInformationMessage(`Not parsable input: ${implInput}`);
+			return;
+		}
+
+		// TODO: automatically detect type name at cursor
+		// if matches[1] is undefined then detect receiver type
+		// take first character and use as receiver name
+
+		let input: GoImplInput = {
+			receiver: matches[1],
+			interface: matches[2]
+		};
+
+		runGoImpl(input, cursor.start);
+	});
+}
+
+function runGoImpl(input: GoImplInput, insertPos: vscode.Position) {
+	let goimpl = getBinPath('impl');
+	let editor = vscode.window.activeTextEditor;
+	let p = cp.execFile(goimpl, [input.receiver, input.interface], (err, stdout, stderr) => {
+		if (err && (<any>err).code === 'ENOENT') {
+			promptForMissingTool('impl');
+			return;
+		}
+
+		if (err) {
+			vscode.window.showInformationMessage(`Cannot stub inteface: ${stderr}`);
+			return;
+		}
+
+		let output = stdout;
+		vscode.window.activeTextEditor.edit(editBuilder => {
+			editBuilder.insert(insertPos, stdout);
+		});
+	});
+	p.stdin.end();
+}

src/goInstallTools.ts

@@ -27,7 +27,8 @@ function getTools(goVersion: SemVersion): { [key: string]: string } {
 		'go-symbols': 'github.com/acroca/go-symbols',
 		'guru': 'golang.org/x/tools/cmd/guru',
 		'gorename': 'golang.org/x/tools/cmd/gorename',
-		'gomodifytags': 'github.com/fatih/gomodifytags'
+		'gomodifytags': 'github.com/fatih/gomodifytags',
+		'impl': 'github.com/josharian/impl'
 	};
 	if (goLiveErrorsEnabled()) {
 		tools['gotype-live'] = 'github.com/tylerb/gotype-live';

src/goMain.ts

@@ -34,6 +34,7 @@ import { clearCacheForTools } from './goPath';
 import { addTags, removeTags } from './goModifytags';
 import { parseLiveFile } from './goLiveErrors';
 import { GoCodeLensProvider } from './goCodelens';
+import { implCursor } from './goImpl';
 
 export let errorDiagnosticCollection: vscode.DiagnosticCollection;
 let warningDiagnosticCollection: vscode.DiagnosticCollection;
@@ -117,6 +118,10 @@ export function activate(ctx: vscode.ExtensionContext): void {
 		removeTags(args);
 	}));
 
+	ctx.subscriptions.push(vscode.commands.registerCommand('go.impl.cursor', () => {
+		implCursor();
+	}));
+
 	ctx.subscriptions.push(vscode.commands.registerCommand('go.test.cursor', (args) => {
 		let goConfig = vscode.workspace.getConfiguration('go');
 		testAtCursor(goConfig, args);