Added 'Protobuf Decode', 'VarInt Decode' and 'VarInt Encode' operations

src/core/operations/VarIntDecode.mjs

@@ -0,0 +1,46 @@
+/**
+ * @author GCHQ Contributor [3]
+ * @copyright Crown Copyright 2019
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+import OperationError from "../errors/OperationError";
+import Protobuf from "../lib/Protobuf";
+
+/**
+ * VarInt Decode operation
+ */
+class VarIntDecode extends Operation {
+
+    /**
+     * VarIntDecode constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "VarInt Decode";
+        this.module = "Default";
+        this.description = "Decodes a VarInt encoded integer. VarInt is an efficient way of encoding variable length integers and is commonly used with Protobuf.";
+        this.infoURL = "https://developers.google.com/protocol-buffers/docs/encoding#varints";
+        this.inputType = "byteArray";
+        this.outputType = "number";
+        this.args = [];
+    }
+
+    /**
+     * @param {byteArray} input
+     * @param {Object[]} args
+     * @returns {number}
+     */
+    run(input, args) {
+        try {
+            return Protobuf.varIntDecode(input);
+        } catch (err) {
+            throw new OperationError(err);
+        }
+    }
+
+}
+
+export default VarIntDecode;