add Set Difference operation

src/core/operations/SetDifference.mjs

@@ -0,0 +1,86 @@
+/**
+ * @author d98762625 [d98762625@gmail.com]
+ * @copyright Crown Copyright 2018
+ * @license Apache-2.0
+ */
+
+import Utils from "../Utils";
+import Operation from "../Operation";
+
+/**
+ * Set Difference operation
+ */
+class SetDifference extends Operation {
+
+    /**
+     * Set Difference constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Set Difference";
+        this.module = "Default";
+        this.description = "Get the Difference of two sets";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [
+            {
+                name: "Sample delimiter",
+                type: "binaryString",
+                value: Utils.escapeHtml("\\n\\n")
+            },
+            {
+                name: "Item delimiter",
+                type: "binaryString",
+                value: ","
+            },
+        ];
+    }
+
+    /**
+     * Validate input length
+     * @param {Object[]} sets
+     * @throws {Error} if not two sets
+     */
+    validateSampleNumbers(sets) {
+        if (!sets || (sets.length !== 2)) {
+            throw "Incorrect number of sets, perhaps you need to modify the sample delimiter or add more samples?";
+        }
+    }
+
+    /**
+     * Run the difference operation
+     * @param input
+     * @param args
+     */
+    run(input, args) {
+        [this.sampleDelim, this.itemDelimiter] = args;
+        const sets = input.split(this.sampleDelim);
+
+        try {
+            this.validateSampleNumbers(sets);
+        } catch (e) {
+            return e;
+        }
+
+        return Utils.escapeHtml(this.runSetDifferencez(...sets.map(s => s.split(this.itemDelimiter))));
+    }
+
+    /**
+     * Get elements in set a that are not in set b
+     *
+     * @param {Object[]} a
+     * @param {Object[]} b
+     * @returns {Object[]}
+     */
+    runSetDifference(a, b) {
+        return a
+            .filter((item) => {
+                return b.indexOf(item) === -1;
+            })
+            .join(this.itemDelimiter);
+    }
+
+}
+
+export default SetDifference;

src/core/operations/SetUnion.mjs

@@ -1,3 +1,9 @@
+/**
+ * @author d98762625 [d98762625@gmail.com]
+ * @copyright Crown Copyright 2018
+ * @license Apache-2.0
+ */
+
 import Utils from "../Utils";
 import Operation from "../Operation";
 

src/core/operations/index.mjs

@@ -12,6 +12,7 @@ import Gunzip from "./Gunzip";
 import Gzip from "./Gzip";
 import RawDeflate from "./RawDeflate";
 import RawInflate from "./RawInflate";
+import SetDifference from "./SetDifference";
 import SetIntersection from "./SetIntersection";
 import SetOps from "./SetOps";
 import SetUnion from "./SetUnion";
@@ -32,6 +33,7 @@ export {
     Gzip,
     RawDeflate,
     RawInflate,
+    SetDifference,
     SetIntersection,
     SetOps,
     SetUnion,