Create InputHandler which performs C0 actions

Part of #459

src/InputHandler.ts

@@ -0,0 +1,50 @@
+import { IInputHandler, ITerminal } from './Interfaces';
+
+export class InputHandler implements IInputHandler {
+  // TODO: We want to type _terminal when it's pulled into TS
+  constructor(private _terminal: any) { }
+
+  public bell(): void {
+    if (!this._terminal.visualBell) {
+      return;
+    }
+    this._terminal.element.style.borderColor = 'white';
+    setTimeout(() => this._terminal.element.style.borderColor = '', 10);
+    if (this._terminal.popOnBell) {
+      this._terminal.focus();
+    }
+  }
+
+  public lineFeed(): void {
+    if (this._terminal.convertEol) {
+      this._terminal.x = 0;
+    }
+    this._terminal.y++;
+    if (this._terminal.y > this._terminal.scrollBottom) {
+      this._terminal.y--;
+      this._terminal.scroll();
+    }
+  }
+
+  public carriageReturn(): void {
+    this._terminal.x = 0;
+  }
+
+  public backspace(): void {
+    if (this._terminal.x > 0) {
+      this._terminal.x--;
+    }
+  }
+
+  public tab(): void {
+    this._terminal.x = this._terminal.nextStop();
+  }
+
+  public shiftOut(): void {
+    this._terminal.setgLevel(1);
+  }
+
+  public shiftIn(): void {
+    this._terminal.setgLevel(0);
+  }
+}

src/Interfaces.ts

@@ -32,3 +32,16 @@ export interface ITerminal {
   scrollDisp(disp: number, suppressScrollEvent: boolean);
   cancel(ev: Event, force?: boolean);
 }
+
+/**
+ * Handles actions generated by the parser.
+ */
+export interface IInputHandler {
+  bell(): void;
+  lineFeed(): void;
+  carriageReturn(): void;
+  backspace(): void;
+  tab(): void;
+  shiftOut(): void;
+  shiftIn(): void;
+}

src/xterm.js

@@ -16,6 +16,7 @@ import { Viewport } from './Viewport.js';
 import { rightClickHandler, pasteHandler, copyHandler } from './handlers/Clipboard.js';
 import { CircularList } from './utils/CircularList.js';
 import { C0 } from './EscapeSequences';
+import { InputHandler } from './InputHandler';
 import * as Browser from './utils/Browser';
 import * as Keyboard from './utils/Keyboard';
 
@@ -203,6 +204,8 @@ function Terminal(options) {
   this.prefix = '';
   this.postfix = '';
 
+  this.inputHandler = new InputHandler(this);
+
   // leftover surrogate high from previous write invocation
   this.surrogate_high = '';
 
@@ -1378,47 +1381,38 @@ Terminal.prototype.write = function(data) {
       case normal:
         switch (ch) {
           case C0.BEL:
-            this.bell();
+            this.inputHandler.bell();
             break;
 
           case C0.LF:
           case C0.VT:
           case C0.FF:
-            if (this.convertEol) {
-              this.x = 0;
-            }
-            this.y++;
-            if (this.y > this.scrollBottom) {
-              this.y--;
-              this.scroll();
-            }
+            this.inputHandler.lineFeed();
             break;
 
           // '\r'
           case C0.CR:
-            this.x = 0;
+            this.inputHandler.carriageReturn();
             break;
 
           // '\b'
           case C0.BS:
-            if (this.x > 0) {
-              this.x--;
-            }
+            this.inputHandler.backspace();
             break;
 
           // '\t'
           case C0.HT:
-            this.x = this.nextStop();
+            this.inputHandler.tab();
             break;
 
           // shift out
           case C0.SO:
-            this.setgLevel(1);
+            this.inputHandler.shiftOut();
             break;
 
           // shift in
           case C0.SI:
-            this.setgLevel(0);
+            this.inputHandler.shiftIn();
             break;
 
           // '\e'