Add yank support for Visual mode (#217)

* add setNormal to ModeHandler

This allows safe switching to Normal mode

* add copy to TextEditor class

This allows to copy a selection to the clipboard. The clipboard is
handled by the copy-paste package that was already a dependency.

* add yank operator

This allows to yank selected text in visual mode.

* Remove unused import

* Add missing semicolon

src/mode/modeHandler.ts

@@ -32,6 +32,10 @@ export class ModeHandler implements vscode.Disposable {
     get currentMode() : Mode {
         return this._modes.find(mode => mode.isActive);
     }
+
+    setNormal() {
+        this.setCurrentModeByName(ModeName.Normal);
+    }
 
     setCurrentModeByName(modeName : ModeName) {
         for (let mode of this._modes) {

src/mode/modeVisual.ts

@@ -8,6 +8,7 @@ import { Motion} from './../motion/motion';
 import { Position } from './../motion/position';
 import { Operator } from './../operator/operator';
 import { DeleteOperator } from './../operator/delete';
+import { YankOperator } from './../operator/yank';
 import { ModeHandler } from './modeHandler.ts';
 import { ChangeOperator } from './../operator/change';
 
@@ -35,6 +36,7 @@ export class VisualMode extends Mode {
             'd': new DeleteOperator(modeHandler),
             'x': new DeleteOperator(modeHandler),
             'c': new ChangeOperator(modeHandler),
+            'y': new YankOperator(modeHandler),
         };
     }
 

src/operator/yank.ts

@@ -0,0 +1,27 @@
+"use strict";
+
+import * as vscode from "vscode";
+import { Position } from './../motion/position';
+import { Operator } from './operator';
+import { ModeHandler } from './../mode/modeHandler.ts';
+import { TextEditor } from './../textEditor';
+
+export class YankOperator extends Operator {
+
+    constructor(modeHandler: ModeHandler) {
+        super(modeHandler);
+    }
+
+    public key(): string { return "y"; }
+
+    /**
+     * Run this operator on a range.
+     */
+    public async run(start: Position, end: Position): Promise<void> {
+        // TODO: use start and end
+        return TextEditor.copy(new vscode.Range(start, end)).then(() => {
+            this.modeHandler.currentMode.motion.select(end, end);
+            this.modeHandler.setNormal();
+        });
+    }
+}

src/textEditor.ts

@@ -16,8 +16,17 @@ export class TextEditor {
         });
     }
 
+    static async copy(range: vscode.Range): Promise<void> {
+        return new Promise<void>((resolve, reject) => {
+            const text = vscode.window.activeTextEditor.document.getText(range);
+            copy(text, (err) => {
+                (err) ? reject() : resolve();
+            });
+        });
+    }
+
     static async delete(range: vscode.Range): Promise<boolean> {
-        copy(vscode.window.activeTextEditor.document.getText(range));
+        TextEditor.copy(range);
         return vscode.window.activeTextEditor.edit(editBuilder => {
             editBuilder.delete(range);
         });