Add other set operations

src/core/operations/PowerSet.mjs

@@ -0,0 +1,91 @@
+/**
+ * @author d98762625 [d98762625@gmail.com]
+ * @copyright Crown Copyright 2018
+ * @license Apache-2.0
+ */
+
+import Utils from "../Utils";
+import Operation from "../Operation";
+
+/**
+ * Power Set operation
+ */
+class PowerSet extends Operation {
+
+    /**
+     * Power set constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Power Set";
+        this.module = "Default";
+        this.description = "Generate the power set of a set";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [
+            {
+                name: "Item delimiter",
+                type: "binaryString",
+                value: ","
+            },
+        ];
+    }
+
+    /**
+     * Generate the power set
+     * @param input
+     * @param args
+     */
+    run(input, args) {
+        [this.itemDelimiter] = args;
+        // Split and filter empty strings
+        const inputArray = input.split(this.itemDelimiter).filter(a => a);
+
+        if (inputArray.length) {
+            return Utils.escapeHtml(this.runPowerSet(inputArray));
+        }
+
+        return "";
+    }
+
+    /**
+     * Return the power set of the inputted set.
+     *
+     * @param {Object[]} a
+     * @returns {Object[]}
+     */
+    runPowerSet(a) {
+        // empty array items getting picked up
+        a = a.filter(i => i.length);
+        if (!a.length) {
+            return [];
+        }
+
+        /**
+         * Decimal to binary function
+         * @param {*} dec
+         */
+        const toBinary = (dec) => (dec >>> 0).toString(2);
+        const result = new Set();
+        // Get the decimal number to make a binary as long as the input
+        const maxBinaryValue = parseInt(Number(a.map(i => "1").reduce((p, c) => p + c)), 2);
+        // Make an array of each binary number from 0 to maximum
+        const binaries = [...Array(maxBinaryValue + 1).keys()]
+            .map(toBinary)
+            .map(i => i.padStart(toBinary(maxBinaryValue).length, "0"));
+
+        // XOR the input with each binary to get each unique permutation
+        binaries.forEach((binary) => {
+            const split = binary.split("");
+            result.add(a.filter((item, index) => split[index] === "1"));
+        });
+
+        // map for formatting & put in length order.
+        return [...result]
+            .map(r => r.join(this.itemDelimiter)).sort((a, b) => a.length - b.length)
+            .map(i => `${i}\n`).join("");
+    }
+}
+
+export default PowerSet;