initial functionality commit

src/core/operations/SetOperations.js

@@ -0,0 +1,181 @@
+import Utils from "../Utils.js";
+
+/**
+ * 
+ */
+class SetOps {
+    /**
+     * 
+     */
+    constructor() {
+        this._sampleDelimiter = "\\n\\n";
+        this._operation = ["Union", "Intersection", "Set Difference", "Symmetric Difference", "Cartesian Product", "Power Set"];
+        this._itemDelimiter = ",";
+    }
+
+    /**
+     * 
+     */
+    get OPERATION() {
+        return this._operation;
+    }
+
+    /**
+     * 
+     */
+    get SAMPLE_DELIMITER() {
+        return this._sampleDelimiter;
+    }
+
+    /**
+     * 
+     */
+    get ITEM_DELIMITER() {
+        return this._itemDelimiter;
+    }
+
+
+    /**
+     * 
+     * @param {*} input 
+     * @param {*} args 
+     */
+    runSetOperation(input, args) {
+        const [sampleDelim, itemDelimiter, operation] = args;
+        const sets = input.split(sampleDelim);
+
+        if (!sets || (sets.length !== 2 && operation !== "Power Set") || (sets.length !== 1 && operation === "Power Set")) {
+            return "Incorrect number of sets, perhaps you need to modify the sample delimiter or add more samples?";
+        }
+        
+        if (this._operation.indexOf(operation) === -1) {
+            return "Invalid 'Operation' option.";
+        }
+
+        let result = {
+            Union: this.runUnion,
+            Intersection: this.runIntersect,
+            "Set Difference": this.runSetDifference,
+            "Symmetric Difference": this.runSymmetricDifference,
+            "Cartesian Product": this.runCartesianProduct,
+            "Power Set": this.runPowerSet(itemDelimiter),
+        }[operation]
+            .apply(null, sets.map(s => s.split(itemDelimiter)));
+
+        // Formatting issues due to the nested characteristics of power set.
+        if (operation === "Power Set") {
+            result = result.map(i => `${i}\n`).join("");
+        } else {
+            result = result.join(itemDelimiter);
+        }
+
+        return Utils.escapeHtml(result);
+    }
+
+    /**
+     * 
+     * @param {*} a 
+     * @param {*} a 
+     */
+    runUnion(a, b) {
+
+        const result = {};
+
+        /**
+         * 
+         * @param {*} r 
+         */
+        const addUnique = (hash) => (item) => {
+            if (!hash[item]) {
+                hash[item] = true;
+            }
+        };
+
+        a.map(addUnique(result));
+        b.map(addUnique(result));
+
+        return Object.keys(result);
+    }
+
+    /**
+     * 
+     * @param {*} a 
+     * @param {*} b 
+     */
+    runIntersect(a, b) {
+        return a.filter((item) => {
+            return b.indexOf(item) > -1;
+        });
+    }
+
+    /**
+     * 
+     * @param {*} a 
+     * @param {*} b 
+     */
+    runSetDifference(a, b) {
+        return a.filter((item) => {
+            return b.indexOf(item) === -1;
+        });
+    }
+
+    /**
+     * 
+     * @param {*} a 
+     * @param {*} b 
+     */
+    runSymmetricDifference(a, b) {
+        /**
+         * 
+         * @param {*} refArray 
+         */
+        const getDifference = (refArray) => (item) => {
+            return refArray.indexOf(item) === -1;
+        };
+
+        return a
+            .filter(getDifference(b))
+            .concat(b.filter(getDifference(a)));
+    }
+
+    /**
+     * 
+     * @param {*} a 
+     * @param {*} b 
+     */
+    runCartesianProduct(a, b) {
+        return Array(Math.max(a.length, b.length))
+            .fill(null)
+            .map((item, index) => `(${a[index] || undefined},${b[index] || undefined})`);
+    }
+
+    /**
+     * 
+     * @param {*} a 
+     */
+    runPowerSet(delimiter) {
+        return function(a) {
+            /**
+             * 
+             * @param {*} dec 
+             */
+            const toBinary = (dec) => (dec >>> 0).toString(2);
+
+            const result = new Set();
+            const maxBinaryValue = parseInt(Number(a.map(i => "1").reduce((p, c) => p + c)), 2);
+            const binaries = [...Array(maxBinaryValue + 1).keys()]
+                .map(toBinary)
+                .map(i => i.padStart(toBinary(maxBinaryValue).length, "0"));
+
+            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(delimiter)).sort((a, b) => a.length - b.length);
+        };
+    }
+}
+
+export default new SetOps();