Add UhkBuffer.backtrack() and implement the KeyAction class.

model/KeyAction.ts

@@ -0,0 +1,30 @@
+/// <reference path="KeystrokeAction.ts" />
+
+class KeyAction {
+
+    static fromJsObject(jsObject: any): KeyAction {
+        switch (jsObject.actionType) {
+            case 'keyStroke':
+                let keystrokeAction = new KeystrokeAction();
+                keystrokeAction.fromJsObject(jsObject);
+                return keystrokeAction;
+            default:
+                throw 'Unknown KeyAction actionType "${jsObject.actionType}"';
+        }
+    }
+
+    static fromBinary(buffer: UhkBuffer) {
+        let keyActionFirstByte = buffer.readUInt8();
+        buffer.backtrack();
+
+        if (KeystrokeAction.firstValidScancode <= keyActionFirstByte &&
+            keyActionFirstByte <= KeystrokeAction.lastValidScancode)
+        {
+            let keystrokeAction = new KeystrokeAction();
+            keystrokeAction.fromBinary(buffer);
+            return keystrokeAction;
+        } else {
+            throw 'Unknown KeyAction first byte "${keyActionFirstByte}"';
+        }
+    }
+}

model/KeystrokeAction.ts

@@ -1,9 +1,10 @@
+/// <reference path="KeyAction.ts" />
 /// <reference path="Serializable.ts" />
 
-class KeystrokeAction implements Serializable {
+class KeystrokeAction extends KeyAction implements Serializable {
 
-    private static firstValidScancode = 1;
-    private static lastValidScancode = 231;
+    static firstValidScancode = 1;
+    static lastValidScancode = 231;
 
     _scancode: number;
     modifierMask: number;

model/Serializable.ts

@@ -2,7 +2,7 @@
 
 interface Serializable {
     fromJsObject(jsObject: any);
-    toJsObject(): any;
     fromBinary(buffer: UhkBuffer);
+    toJsObject(): any;
     toBinary(buffer: UhkBuffer);
 }

model/UhkBuffer.ts

@@ -7,16 +7,19 @@ class UhkBuffer {
 
     buffer: Buffer;
     offset: number;
+    bytesToBacktrack: number;
 
     constructor() {
         this.offset = 0;
+        this.bytesToBacktrack = 0;
         this.buffer = new Buffer(UhkBuffer.eepromSize);
         this.buffer.fill(0);
     }
 
     readInt8(): number {
         let value = this.buffer.readInt8(this.offset);
-        this.offset += 1;
+        this.bytesToBacktrack = 1;
+        this.offset += this.bytesToBacktrack;
         return value;
     }
 
@@ -27,7 +30,8 @@ class UhkBuffer {
 
     readUInt8(): number {
         let value = this.buffer.readUInt8(this.offset);
-        this.offset += 1;
+        this.bytesToBacktrack = 1;
+        this.offset += this.bytesToBacktrack;
         return value;
     }
 
@@ -38,7 +42,8 @@ class UhkBuffer {
 
     readInt16(): number {
         let value = this.buffer.readInt16LE(this.offset);
-        this.offset += 2;
+        this.bytesToBacktrack = 2;
+        this.offset += this.bytesToBacktrack;
         return value;
     }
 
@@ -49,7 +54,8 @@ class UhkBuffer {
 
     readUInt16(): number {
         let value = this.buffer.readUInt16LE(this.offset);
-        this.offset += 2;
+        this.bytesToBacktrack = 2;
+        this.offset += this.bytesToBacktrack;
         return value;
     }
 
@@ -60,7 +66,8 @@ class UhkBuffer {
 
     readInt32(): number {
         let value = this.buffer.readInt32LE(this.offset);
-        this.offset += 4;
+        this.bytesToBacktrack = 4;
+        this.offset += this.bytesToBacktrack;
         return value;
     }
 
@@ -71,7 +78,8 @@ class UhkBuffer {
 
     readUInt32(): number {
         let value = this.buffer.readUInt32LE(this.offset);
-        this.offset += 4;
+        this.bytesToBacktrack = 4;
+        this.offset += this.bytesToBacktrack;
         return value;
     }
 
@@ -88,6 +96,7 @@ class UhkBuffer {
         }
 
         let str = this.buffer.toString(UhkBuffer.stringEncoding, this.offset, stringByteLength);
+        this.bytesToBacktrack = stringByteLength;
         this.offset += stringByteLength;
         return str;
     }
@@ -110,4 +119,9 @@ class UhkBuffer {
         this.buffer.write(str, this.offset, stringByteLength, UhkBuffer.stringEncoding);
         this.offset += stringByteLength;
     }
+
+    backtrack(): void {
+        this.offset -= this.bytesToBacktrack;
+        this.bytesToBacktrack = 0;
+    }
 }