From 558686e3fea738ae832923d4f38dd0684c6b1cb2 Mon Sep 17 00:00:00 2001
From: xconverge <sevendaystillsean@gmail.com>
Date: Mon, 24 Apr 2017 20:17:16 -0700
Subject: [PATCH] fixes #1357

---
 src/register/register.ts       | 12 ++++++++++++
 test/register/register.test.ts |  7 +++++++
 2 files changed, 19 insertions(+)

diff --git a/src/register/register.ts b/src/register/register.ts
index 43757a0cda9..4a9344e2348 100644
--- a/src/register/register.ts
+++ b/src/register/register.ts
@@ -38,6 +38,7 @@ export class Register {
     '.': { text: "", registerMode: RegisterMode.CharacterWise, isClipboardRegister: false },
     '*': { text: "", registerMode: RegisterMode.CharacterWise, isClipboardRegister: true },
     '+': { text: "", registerMode: RegisterMode.CharacterWise, isClipboardRegister: true },
+    '_': { text: "", registerMode: RegisterMode.CharacterWise, isClipboardRegister: false },
     '0': { text: "", registerMode: RegisterMode.CharacterWise, isClipboardRegister: false },
     '1': { text: "", registerMode: RegisterMode.CharacterWise, isClipboardRegister: false },
     '2': { text: "", registerMode: RegisterMode.CharacterWise, isClipboardRegister: false },
@@ -50,6 +51,9 @@ export class Register {
     '9': { text: "", registerMode: RegisterMode.CharacterWise, isClipboardRegister: false }
   };
 
+  public static isBlackHoleRegister(registerName: string): boolean {
+    return (registerName === "_");
+  }
 
   public static isClipboardRegister(registerName: string): boolean {
     const register = Register.registers[registerName];
@@ -90,6 +94,10 @@ export class Register {
       throw new Error(`Invalid register ${register}`);
     }
 
+    if (Register.isBlackHoleRegister(register)) {
+      return;
+    }
+
     if (vimState.isMultiCursor) {
       if (Register.isValidUppercaseRegister(register)) {
         Register.appendMulticursorRegister(content, register, vimState, multicursorIndex as number);
@@ -243,6 +251,10 @@ export class Register {
       util.clipboardCopy(content.toString());
     }
 
+    if (Register.isBlackHoleRegister(register)) {
+      return;
+    }
+
     Register.registers[register] = {
       text               : content,
       registerMode       : registerMode || RegisterMode.FigureItOutFromCurrentMode,
diff --git a/test/register/register.test.ts b/test/register/register.test.ts
index 706ee59bce9..81a47aa2906 100644
--- a/test/register/register.test.ts
+++ b/test/register/register.test.ts
@@ -51,6 +51,13 @@ suite("register", () => {
     end: ["one", "two", "one", "|two"],
   });
 
+  newTest({
+    title: "Can use black hole register",
+    start: ['|asdf', "qwer"],
+    keysPressed: 'yyj"_ddkp',
+    end: ["asdf", "|asdf"],
+  });
+
   test("System clipboard works with chinese characters", async () => {
     const testString = '你好';
     util.clipboardCopy(testString);